U.S. patent application number 14/096763 was filed with the patent office on 2015-06-04 for co-current adiabatic reaction system for conversion of triacylglycerides rich feedstocks.
This patent application is currently assigned to LUMMUS TECHNOLOGY INC.. The applicant listed for this patent is Lummus Technology Inc.. Invention is credited to Marvin I. Greene.
Application Number | 20150152336 14/096763 |
Document ID | / |
Family ID | 53264852 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150152336 |
Kind Code |
A1 |
Greene; Marvin I. |
June 4, 2015 |
CO-CURRENT ADIABATIC REACTION SYSTEM FOR CONVERSION OF
TRIACYLGLYCERIDES RICH FEEDSTOCKS
Abstract
A process for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels is
disclosed. The process may include: reacting a
triacylglycerides-containing oil-water-hydrogen mixture in a single
reactor at a temperature in the range from about 250.degree. C. to
about 650.degree. C. and a pressure greater than about 75 bar to
convert at least a portion of the triacylglycerides via
homogeneously catalyzed hydrothermolysis and heterogeneously
catalyzed hydrotreatment.
Inventors: |
Greene; Marvin I.; (Clifton,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lummus Technology Inc. |
Bloomfield |
NJ |
US |
|
|
Assignee: |
LUMMUS TECHNOLOGY INC.
Bloomfield
NJ
|
Family ID: |
53264852 |
Appl. No.: |
14/096763 |
Filed: |
December 4, 2013 |
Current U.S.
Class: |
585/256 ;
422/162 |
Current CPC
Class: |
Y02E 50/13 20130101;
C10G 3/42 20130101; C10G 3/50 20130101; Y02P 30/20 20151101; C10G
65/04 20130101; Y02E 50/10 20130101 |
International
Class: |
C10G 3/00 20060101
C10G003/00 |
Claims
1. A process for converting triacylglycerides-containing oils or
fatty acids derived from plants, algae, organic wastes or animal
sources into crude oil precursors and/or distillate hydrocarbon
fuels, the process comprising: feeding hydrogen, water, and a
triacylglyceride-containing oil into a co-current reactor having a
homogeneously catalyzed hydrothermolysis reaction zone and a
heterogeneously catalyzed hydrotreatment zone; hydrothermolyzing at
least a portion of the triacylglyceride-containing oil in the
hydrothermolysis reaction zone to form a hydrothermolysis reaction
product; and hydrotreating the hydrothermolysis reaction product
directly without any componential separations in the catalytic
hydrotreatment zone; and recovering an effluent from the catalytic
hydrotreatment zone.
2. The process of claim 1, wherein the hydrothermolysis reaction
zone and the catalytic hydrotreatment zone are adiabatic reaction
zones.
3. The process of claim 1, wherein the hydrothermolysis reaction
zone and the catalytic hydrotreatment zone are contained within the
same reactor vessel.
4. The process of claim 3, wherein the hydrothermolysis reaction
zone contains one or more beds of inert solids to promote
mixing.
5. The process of claim 3, wherein the catalytic hydrotreatment
zone comprises one or more beds containing one or more
hydrotreating catalysts.
6. The process of claim 1, further comprising feeding at least one
of hydrogen and water intermediate the hydrothermolysis reaction
zone and the catalytic hydrotreatment zone.
7. The process of claim 1, further comprising indirectly heating
the triacylglyceride-containing oil feed to the co-current reactor
with the effluent recovered from the catalytic hydrotreatment
zone.
8. The process of claim 1, wherein the reactor is operated at a
temperature in the range of 250.degree. C. to 650.degree. C. and a
pressure of at least 75 bar.
9. The process of claim 1, wherein the co-current reactor is a
downflow reactor.
10. The process of claim 1, wherein the hydrothermolysis reaction
product is heated by direct heat exchange with a superheated
hydrogen/water mixture prior to hydrotreating the hydrothermolysis
reaction product.
11. A reactor system for converting triacylglycerides-containing
oils into crude oil precursors and/or distillate hydrocarbon fuels,
the reactor system comprising: a homogeneously catalyzed
hydrothermolysis reaction zone for hydrothermolyzing at least a
portion of a triacylglyceride-containing oil to form a
hydrothermolysis reaction product; and a heterogeneously catalyzed
hydrotreatment zone for hydrotreating the hydrothermolysis reaction
product.
12. The reactor system of claim 11, wherein the hydrothermolysis
reaction zone and the catalytic hydrotreatment zone are fluidly
coupled within the same reactor.
13. The reactor system of claim 11, wherein the hydrothermolysis
reaction zone is in a first reactor and the catalytic
hydrotreatment zone is in a second reactor, the first and second
reactor being fluidly coupled.
14. The reactor system of claim 11, wherein the hydrothermolysis
reaction zone and the catalytic hydrotreatment zone are adiabatic
reaction zones.
15. The reactor system of claim 11, wherein the hydrothermolysis
reaction zone contains one or more beds of inert solids to promote
mixing, and wherein the catalytic hydrotreatment zone comprises one
or more beds containing one or more hydrotreating catalysts.
16. The reactor system of claim 15, wherein the catalytic
hydrotreatment comprises a first catalyst bed containing a catalyst
having hydrogenation activity and a second catalyst bed containing
a catalyst having hydrocracking activity.
17. A process for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels, the
process comprising: mixing hydrogen with water to form a
superheated mixed water stream; injecting the mixed water stream
into a co-current reaction system comprising a hydrothermolysis
adiabatic reaction zone and a catalytic adiabatic hydrotreatment
zone; injecting a triacylglyceride-containing oil into the
co-current reaction system; reacting the first portion of the mixed
water stream and the triacylglyceride-containing oil in a first
hydrothermolysis adiabatic reaction zone under reaction conditions
sufficient to convert at least a portion of the triacylglycerides
via hydrothermolysis to produce a hydrothermolysis reaction product
comprising one or more of isoolefins, isoparaffins, cycloolefins,
cycloparaffins, and aromatics; feeding hydrogen and the
hydrothermolysis reaction product to a first catalytic adiabatic
hydrotreatment zone to hydrotreat at least a portion of the
reaction product; and recovering a hydrotreated effluent.
18. The process of claim 17, wherein the adiabatic hydrothermolysis
reaction zone is operated at a temperature in the range from about
250.degree. C. to about 650.degree. C.
19. The process of claim 17, wherein the reaction system is
operated at a pressure of at least 75 bar.
20. The process of claim 17, wherein the hydrothermolysis reaction
conditions comprise a pressure and a temperature greater than the
critical pressure and temperature of water.
21. The process of claim 17, wherein the mass ratio of water to
triacylglyceride-containing oil ranges from about 0.001:1 to about
1:1.
22. The process of claim 17, wherein the mixed water feed has a
hydrogen to water mass ratio in the range from about 0.005:1 to
about 500:1.
23. The process of claim 17, further comprising mixing a
non-renewable hydrocarbon feedstock with the
triacylglyceride-containing oil.
24. The process of claim 17, wherein the
triacylglycerides-containing oil comprises a renewable oil from at
least one of camelina, carinata, cotton, jatropha, karanja,
moringa, lesquerella, physaria, palm, castor, corn, linseed,
peanut, soybean, sunflower, tung, babassu, or at least one
triacylglycerides-containing oil from at least one of canola, shea
butter, tall oil, tallow, algal oil, and pongamia, or at least one
of animal-derived fats/oils from at least one of tallow, lard,
chicken fats, butter fat, fish oil, or at least one of organic
wastes from at least one of municipal solid wastes, sewage sludge
solids, Kraft plant waste liquor, restaurant greases and used
vegetable oils.
25. The process of claim 17, further comprising fractionating the
hydrotreated effluent to recover one or more hydrocarbon fractions
boiling in the range of naphtha, diesel, or jet.
26. The process of claim 25, further comprising quenching the
hydrotreated effluent with a hydrogen stream prior to fractionating
the hydrotreated effluent.
27. The process of claim 25, further comprising recovering a heavy
hydrocarbon fraction having a boiling point greater than end point
of the diesel fraction and recycling the heavy hydrocarbon fraction
to the co-current reaction system.
28. A system for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels, the
system comprising: a mixing device for mixing hydrogen with water
to form a hydrogen-water mixture; at least one co-current adiabatic
reaction system comprising; at least one hydrothermolysis reaction
zone for reacting the hydrogen-water mixture and
triacylglycerides-containing oils at a temperature in the range of
250.degree. C. to about 650.degree. C. and a pressure greater than
about 75 bar to produce a hydrothermolysis effluent; and at least
one hydrotreatment zone for hydrotreating the hydrothermolysis
effluent to produce a hydrotreated effluent.
29. The system of claim 28, further comprising one or more fluid
conduits for recycling a compressed hydrogen stream to the mixing
device for mixing hydrogen.
30. The system of claim 28, further comprising a fractionator for
fractionating hydrocarbons in the co-current adiabatic reaction
system effluent to form one or more hydrocarbon fractions boiling
in the naphtha, jet or diesel range.
31. The system of claim 28, further comprising a heat exchange
apparatus for exchanging heat between the co-current adiabatic
reaction system effluent and the triacylglycerides-containing
oils.
32. The system of claim 28, wherein the at least one hydrotreatment
zone comprises at least two catalyst beds, and wherein: a first
catalyst bed comprising at least one catalyst bed comprising a
catalyst having hydrogenation activity; a second catalyst bed
downstream the first catalyst bed, the second catalyst bed
comprising at least one catalyst bed comprising a catalyst having
hydrocracking activity.
33. The system of claim 32, wherein the first catalyst bed of the
hydrotreatment zone comprises a catalyst useful for at least one
of: decarboxylation of carboxylic groups; hydrodeoxygenation of
unsaturated or saturated free fatty acids to produce C6-C24
paraffins; saturation of mono-, di- and tri-olefins contained in
the alkyl backbone of the free fatty acids; hydrodenitrogenation of
trace organic nitrogen compounds; and catalyst tolerance for water
coming in with the hydrocarbonaceous feed.
34. The system of claim 28, further comprising one or more fluid
conduits for co-processing a non-renewable hydrocarbon feedstock
with the triacylglycerides-containing oils in at least one of the
hydrothermolysis reaction zone and the hydrotreatment zone.
35. The system of claim 28, wherein the at least one
hydrothermolysis reaction zone comprises at least two beds
comprised of one or more of aluminas, ceramics, foams, wires,
meshes, microchannels, rods, and tubes having little or no chemical
conversion activity for pyrolysis, thermolysis, hydrothermolysis or
hydrotreatment reactions.
36. The system of claim 25, further comprising one or more fluid
conduits for feeding at least one of hydrogen and water
intermediate the beds of the hydrothermolysis reaction zone.
37. The system of claim 28, wherein a cumulative weight hourly
space velocity defined as kilograms triacylglycerides-containing
oils fed per hour per kilogram total active hydrotreatment catalyst
inventory is at least 0.5:1.
38. A process for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels, the
process comprising: injecting a superheated mixed water stream
comprising water and hydrogen into a co-current adiabatic reaction
system; co-currently, injecting a triacylglyceride-containing oil
into the co-current adiabatic reaction system; and reacting the
mixed water stream and the triacylglyceride-containing oil in a
plurality of adiabatic reaction zones under reaction conditions
sufficient to convert the triacylglycerides via hydrothermolysis
and hydrotreatment to produce a hydrotreated effluent comprising
one or more of isoolefins, isoparaffins, cycloolefins,
cycloparaffins, and aromatics.
39. The process of claim 38, wherein the plurality of adiabatic
reaction zones includes a plurality of hydrothermolysis reaction
zones and a plurality of hydrotreatment reaction zones.
40. The process of claim 38, further comprising injecting at least
one of hydrogen and water stream between the plurality of adiabatic
reaction zones.
41. The process of claim 38, further comprising pre-heating the
triacylglyceride-containing oil via indirect heat exchange with the
hydrotreated effluent.
42. A process for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels, the
process comprising: mixing hydrogen with water to form a
superheated mixed water stream; injecting a first portion of the
mixed water stream into a co-current reactor system including a
hydrothermolysis reaction zone, comprising at least a first
hydrothermolysis reaction zone and a second hydrothermolysis
reaction zone, and a hydrotreatment reaction zone, comprising at
least a first hydrotreatement reaction zone and a second
hydrotreatment reaction zone; injecting a
triacylglyceride-containing oil into the co-current reaction
system; reacting the first portion of the mixed water stream and
the triacylglyceride-containing oil in the first hydrothermolysis
reaction zone under reaction conditions sufficient to convert at
least a portion of the triacylglycerides via hydrothermolysis to
produce a first intermediate product comprising one or more of
isoolefins, isoparaffins, cycloolefins, cycloparaffins, aromatics,
and unreacted triacylglyceride-containing oil; mixing a second
portion of the mixed water stream and the first intermediate
product intermediate the first hydrothermolysis reaction zone and
the second hydrothermolysis reaction zone; reacting the second
portion of the mixed water stream and the first intermediate
product in the second hydrothermolysis reaction zone under reaction
conditions sufficient to convert at least a portion of the first
intermediate product via hydrothermolysis to produce a
hydrothermolysis product comprising one or more of isoolefins,
isoparaffins, cycloolefins, cycloparaffins, and aromatics; mixing
the hydrothermolysis product from the second hydrothermolysis
reaction zone, with a first portion of an unheated hydrogen stream
intermediate the second hydrothermolysis reaction zone and the
first hydrotreatment reaction zone; hydrotreating a portion of the
hydrothermolysis product in the first hydrotreatment reaction zone
to form a partially hydrotreated product; mixing the partially
hydrotreated product with a second portion of the unheated hydrogen
stream intermediate the first and second hydrotreatment reaction
zones; hydrotreating the partially hydrotreated product in the
second hydrotreatment reaction zone to form a hydrotreated product;
recovering a hydrotreated effluent from the co-current reactor
system.
43. The system of claim 28, further comprising a heat exchange
apparatus for exchanging heat between the hydrotreated effluent and
the triacylglycerides-containing oils.
44. The system of claim 28, further comprising a heat exchange
apparatus for exchanging heat between the hydrothermolysis effluent
and the hydrotreated effluent.
45. The system of claim 28, further comprising a heat exchange
apparatus for exchanging heat between the hydrothermolysis effluent
and the triacylglycerides-containing oils.
Description
FIELD OF THE DISCLOSURE
[0001] Embodiments disclosed herein relate generally to production
of useful hydrocarbons, such as distillate fuels, from
triacylglycerides-containing plant or animal fats-containing
oils.
BACKGROUND
[0002] Hydrothermolysis of triacylglycerides-containing oils such
as those derived from crops, animal fats or waste vegetable and
animal-derived oils involves many types of chemical reactions. As
one example, some prior art processes catalytically hydrotreat the
triacylglyceride containing oils, converting the unsaturated
aliphatic chains in the triacylglyceride containing oils to
straight chain paraffins while simultaneously
deoxygenating/decarboxylating the acid and glyceryl groups to form
water, carbon dioxide and propane. Two downstream processes are
then required to (a) skeletally isomerize the n-paraffins to
isoparaffins to produce specification grade diesel fuels, and (b)
hydrocracking the diesel range n-paraffins and isoparaffins to
hydrocarbons to produce specification grade jet fuels.
[0003] U.S. Pat. No. 7,691,159, for example, discloses a
hydrothermolysis process to convert triacylglycerides to smaller
organic acids in the presence of hot compressed water at
supercritical water conditions. During the process, the backbone of
the triacylglycerides undergoes rearrangement reactions. These
reactions may occur in hydrothermolysis zones contained in a fired
furnace which provides endothermic heats of reaction. Coke
formation in the fired furnace results from the contact of
hydrothermolyzed intermediate products with high temperature metal
surfaces.
SUMMARY OF THE DISCLOSURE
[0004] In one aspect, embodiments disclosed herein relate to a
process for converting triacylglycerides-containing oils or fatty
acids derived from plants, algae, organic wastes or animal sources
into crude oil precursors and/or distillate hydrocarbon fuels. The
process may include feeding hydrogen, water, and a
triacylglyceride-containing oil into a co-current reactor having a
homogeneously catalyzed hydrothermolysis reaction zone and a
heterogeneously catalyzed hydrotreatment zone, hydrothermolyzing at
least a portion of the triacylglyceride-containing oil in the
hydrothermolysis reaction zone to form a hydrothermolysis reaction
product, and hydrotreating the hydrothermolysis reaction product
directly without any componential separations in the catalytic
hydrotreatment zone, and recovering an effluent from the catalytic
hydrotreatment zone.
[0005] In another aspect, embodiments disclosed herein relate to a
reactor system for converting triacylglycerides-containing oils
into crude oil precursors and/or distillate hydrocarbon fuels. The
reactor system may include a homogeneously catalyzed
hydrothermolysis reaction zone for hydrothermolyzing at least a
portion of a triacylglyceride-containing oil to form a
hydrothermolysis reaction product, and a heterogeneously catalyzed
hydrotreatment zone for hydrotreating the hydrothermolysis reaction
product.
[0006] In another aspect, embodiments disclosed herein relate to a
process for converting triacylglycerides-containing oils into crude
oil precursors and/or distillate hydrocarbon fuels. The process may
include mixing hydrogen with water to form a superheated mixed
water stream, injecting the mixed water stream into a co-current
reaction system comprising a hydrothermolysis adiabatic reaction
zone and a catalytic adiabatic hydrotreatment zone, injecting a
triacylglyceride-containing oil into the co-current reaction
system, reacting the first portion of the mixed water stream and
the triacylglyceride-containing oil in a first hydrothermolysis
adiabatic reaction zone under reaction conditions sufficient to
convert at least a portion of the triacylglycerides via
hydrothermolysis to produce a hydrothermolysis reaction product
comprising one or more of isoolefins, isoparaffins, cycloolefins,
cycloparaffins, and aromatics, feeding hydrogen and the
hydrothermolysis reaction product to a first catalytic adiabatic
hydrotreatment zone to hydrotreat at least a portion of the
reaction product, and recovering a hydrotreated effluent.
[0007] In another aspect, embodiments disclosed herein relate to a
system for converting triacylglycerides-containing oils into crude
oil precursors and/or distillate hydrocarbon fuels. The system may
include a mixing device for mixing hydrogen with water to form a
hydrogen-water mixture, at least one co-current adiabatic reaction
system comprising, at least one hydrothermolysis reaction zone for
reacting the hydrogen-water mixture and
triacylglycerides-containing oils at a temperature in the range of
250.degree. C. to about 650.degree. C. and a pressure greater than
about 75 bar to produce a hydrothermolysis effluent, and at least
one hydrotreatment zone for hydrotreating the hydrothermolysis
effluent.
[0008] In another aspect, embodiments disclosed herein relate to a
process for converting triacylglycerides-containing oils into crude
oil precursors and/or distillate hydrocarbon fuels. The process may
include injecting a superheated mixed water stream comprising water
and hydrogen into a co-current adiabatic reaction system,
co-currently, injecting a triacylglyceride-containing oil into the
co-current adiabatic reaction system, and reacting the mixed water
stream and the triacylglyceride-containing oil in a plurality of
adiabatic reaction zones under reaction conditions sufficient to
convert the triacylglycerides via hydrothermolysis and
hydrotreatment to produce a hydrotreated effluent comprising one or
more of isoolefins, isoparaffins, cycloolefins, cycloparaffins, and
aromatics.
[0009] In another aspect, embodiments disclosed herein relate to a
process for converting triacylglycerides-containing oils into crude
oil precursors and/or distillate hydrocarbon fuels. The process may
include mixing hydrogen with water to form a superheated mixed
water stream, injecting a first portion of the mixed water stream
into a co-current reactor system including a hydrothermolysis
reaction zone, comprising at least a first hydrothermolysis
reaction zone and a second hydrothermolysis reaction zone, and a
hydrotreatment reaction zone, comprising at least a first
hydrotreatement reaction zone and a second hydrotreatment reaction
zone, injecting a triacylglyceride-containing oil into the
co-current reaction system, reacting the first portion of the mixed
water stream and the triacylglyceride-containing oil in the first
hydrothermolysis reaction zone under reaction conditions sufficient
to convert at least a portion of the triacylglycerides via
hydrothermolysis to produce a first intermediate product comprising
one or more of isoolefins, isoparaffins, cycloolefins,
cycloparaffins, aromatics, and unreacted
triacylglyceride-containing oil, mixing a second portion of the
mixed water stream and the first intermediate product intermediate
the first hydrothermolysis reaction zone and the second
hydrothermolysis reaction zone, reacting the second portion of the
mixed water stream and the first intermediate product in the second
hydrothermolysis reaction zone under reaction conditions sufficient
to convert at least a portion of the first intermediate product via
hydrothermolysis to produce a hydrothermolysis product comprising
one or more of isoolefins, isoparaffins, cycloolefins,
cycloparaffins, and aromatics, mixing the hydrothermolysis product
from the second hydrothermolysis reaction zone, with a first
portion of an unheated hydrogen stream intermediate the second
hydrothermolysis reaction zone and the first hydrotreatment
reaction zone, hydrotreating a portion of the hydrothermolysis
product in the first hydrotreatment reaction zone to form a
partially hydrotreated product, mixing the partially hydrotreated
product with a second portion of the unheated hydrogen stream
intermediate the first and second hydrotreatment reaction zones,
hydrotreating the partially hydrotreated product in the second
hydrotreatment reaction zone to form a hydrotreated product, and
recovering a hydrotreated effluent from the co-current reactor
system.
[0010] Other aspects and advantages will be apparent from the
following description and the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a simplified process flow diagram of a process
according to embodiments herein.
[0012] FIG. 2 is a simplified process flow diagram of an alternate
process according to embodiments herein.
[0013] FIG. 3 is a simplified process flow diagram of an alternate
process according to embodiments herein.
DETAILED DESCRIPTION
[0014] In one aspect, embodiments disclosed herein relate generally
to production of useful hydrocarbons, such as paraffins, from
triacylglycerides-containing oils, such as from renewable
feedstocks. In another aspect, embodiments disclosed herein relate
to processes and systems for converting
triacylglycerides-containing oils into crude oil precursors and/or
distillate hydrocarbon fuels. The process typically includes
catalytic hydrothermolysis, hydrotreating and fractionation.
[0015] Renewable feedstocks having triacylglycerides-containing
oils useful in embodiments disclosed herein may include fatty
acids, saturated triacylglycerides, and triacylglycerides having
one or more olefinic bonds such as those from any plant, animal or
algae. For example, triacylglycerides-containing oils may include
oils from at least one of camelina, carinata, jatropha, karanja,
moringa, lesquerella, physaria, palm, castor, cotton, corn,
linseed, peanut, soybean, sunflower, tung, babassu, and canola, or
at least one triacylglycerides-containing oil from at least one of
shea butter, tall oil, tallow, waste vegetable oil, algal oil, and
pongamia.
[0016] Hydrothermolysis under supercritical water conditions
includes a number of different chemical reactions such as for
example, but not limited to, hydrolysis, cyclization,
cross-linking, conjugation, thermal cracking, decarboxylation, and
Diels-Alder reaction. During homogeneously catalyzed
hydrothermolysis, up to a maximum of about 9 wt % water, depending
upon the carbon number of the free fatty acid associated with the
triacylglycerides, is consumed and much of the glycerin byproduct
(approximately 10-13 wt % of the feed), if not all, is further
dehydrated and converted to gases or partially deoxygenated
compounds. Low molecular weight organic acids are hydrogenated to
their corresponding paraffins in the downstream heterogeneously
catalyzed hydrotreatment step.
[0017] A triacylglycerides-containing oil may be reacted with water
and hydrogen, fed as H.sub.2, diatomic hydrogen, at a temperature
in the range from about 250.degree. C. to about 650.degree. C. and
a pressure greater than about 75 Bar to about 250 Bar to convert at
least a portion of the triacylglycerides via homogeneously
catalyzed hydrothermolysis to a hydrocarbon or mixture of
hydrocarbons comprising one or more of isoolefins, isoparaffins,
cycloolefins, cycloparaffins, and aromatics. In some embodiments,
the reaction conditions are such that the temperature and pressure
are above the supercritical temperature and pressure of water. The
resulting reaction effluent may then be further treated and
separated to recover the hydrocarbon products.
[0018] To form the triacylglycerides-water-hydrogen mixture, a
triacylglycerides-containing oil may be mixed with water and
diatomic hydrogen in any order or with a mixture of water and
diatomic hydrogen.
[0019] At supercritical water hydrothermolysis reaction conditions
for homogeneously catalyzed hydrothermolysis, protonic hydrogen may
be generated in situ. For example, U.S. Pat. No. 7,691,159
hypothesizes that, for each mole of soybean oil, 1.5 moles of
H.sub.2 are extracted from the water and added to the resulting
hydrocarbon. While presenting this in terms of diatomic hydrogen
equivalents, the in situ derived protonic hydrogen atoms would
rapidly react and incorporate into the carboxylate molecules
derived from the triacylglycerides. The diatomic hydrogen feed used
in embodiments herein is in addition to any hydrogen that may be
generated in situ from water or other components in the
homogeneously catalyzed hydrothermolysis reactor, and, although
being an additional operating expense, may provide the benefits of
enhanced reactivity within the homogeneously catalyzed
hydrothermolysis reactor as well as an increased H/C ratio in the
resulting product. Externally supplied diatomic hydrogen also
provides an independent means of controlling the process
performance, which cannot be obtained via in situ monoatomic
hydrogen production alone, as it is dependent upon the
homogeneously catalyzed hydrothermolysis reaction conditions and
the composition of the triacylglycerides-containing feedstock.
Overall, adding an external supply of diatomic hydrogen to the
homogeneously catalyzed hydrothermolysis reactor, along with the
super critical water and the renewable oil feed provides a
different process, different reaction mechanism, and added
performance over in situ monoatomic hydrogen generation alone.
[0020] Another advantage of co-feeding externally supplied diatomic
hydrogen to the homogeneously catalyzed hydrothermolysis reactor is
the hydrogen capping effect of stabilizing any free radicals formed
during the homogeneously catalyzed hydrothermolysis reactions,
thereby avoiding formation of oligomeric and/or polymeric
materials, often referred to as coke or coke precursors or coke
deposits, that would otherwise form as a result of condensation of
these free radicals. Thus, co-feeding externally supplied diatomic
hydrogen provides improved on-stream operability relative to
processes that do not co-feed diatomic hydrogen gas.
[0021] In some embodiments, to form the
triacylglycerides-water-diatomic hydrogen mixture,
triacylglycerides-containing oil is first mixed with water to form
a triacylglyceride-water mixture. The resulting
triacylglycerides-water mixture is then mixed with diatomic
hydrogen to form the triacylglycerides-water-diatomic hydrogen
mixture.
[0022] The triacylglycerides-water-diatomic hydrogen mixture may
have a water to triacylglycerides mass ratio in the range from
about 0.001:1 to about 1:1 in some embodiments; from about 0.01:1
to about 1:1 in other embodiments; and from about 0.1:1 to about
1:1 in yet other embodiments.
[0023] The triacylglycerides-water-diatomic hydrogen mixture may
have a diatomic hydrogen to triacylglycerides mass ratio in the
range from about 0.001:1 to about 1:1 in some embodiments; from
about 0.005:1 to about 0.5:1 or 1:1 in other embodiments; from
about 0.01:1 to about 0.5:1 in other embodiments; and from about
0.1:1 to about 0.5:1 in yet other embodiments. In some embodiments,
the diatomic hydrogen to triacylglycerides mass ratio may be in the
range from about 0.1:1 to about 0.2:1. The total diatomic hydrogen
feed rate in some embodiments may be sufficient to supply a portion
or all of the hydrogen necessary for the homogeneously catalyzed
hydrothermolysis as well as any close-coupled downstream processing
steps, such as heterogeneously catalyzed hydrotreatment.
[0024] The triacylglycerides-water-hydrogen mixture may have a
water to triacylglycerides mass ratio in the range from about
0.001:1 to about 1:1 in some embodiments; from about 0.01:1 to
about 1:1 in other embodiments; and from about 0.1:1 to about 1:1
in yet other embodiments.
[0025] The water-hydrogen mixture may have a hydrogen to water mass
ratio in the range from about 0.005:1 to about 500:1 in some
embodiments; from about 0.1:1 to about 250:1 in other embodiments;
and from about 5:1 to about 50:1 in yet other embodiments.
[0026] The homogeneously catalyzed hydrothermolysis reaction
effluent may then be directly catalytically hydrotreated using
heterogeneous catalysts, such as in the same reactor, without
intermediate separations of water, unreacted diatomic hydrogen, or
other light gas byproducts, to form additional distillate range
hydrocarbons and/or to convert precursors in the reaction effluent
to distillate range hydrocarbons. Homogeneously catalyzed
hydrothermolysis produces a crude oil that requires heterogeneously
catalyzed catalytic hydrotreatment to be converted to useful
infrastructure-compatible distillate fuels. Heterogeneously
catalyzed hydrotreatment processes may operate at elevated
pressures, such as 500-2000+ psig, using supported catalysts having
activity towards both heteroatom removal and double bond saturation
reactions. Also required is an excess flow of diatomic hydrogen gas
over and above the stoichiometric requirement, which for the case
of homogeneously catalyzed hydrothermolysis-derived crude oil
feedstocks may be in the range of 1000 to 2000 scf per barrel, the
latter depending upon renewable feedstock type and homogeneously
catalyzed hydrothermolysis reaction conditions. The need for excess
diatomic hydrogen gas is to: a) drive the desired hydrotreatment
reactions to a high degree of conversion; and b) to provide a heat
sink to control unmanageable exotherms that would otherwise result
from the high heats of hydrotreatment reactions. The adiabatic
temperature rise, i.e., the temperature increase from reactant
inlet stream to product effluent stream across the hydrotreating
catalyst bed, can amount to about 180-200.degree. F. per each
thousand standard cubic feet hydrogen consumed. An advantage of
co-feeding externally supplied diatomic hydrogen to the
homogeneously catalyzed hydrothermolysis reactor is that the
diatomic hydrogen contained in the effluent gas stream from the
homogeneously catalyzed hydrothermolysis reactor can provide a part
or all of the diatomic hydrogen gas feed requirement for the
downstream heterogeneously catalyzed catalytic hydrotreating
reactor, as well as enhancing the reaction within the homogeneously
catalyzed hydrothermolysis reactor itself, as discussed above.
[0027] In some embodiments, the above-mentioned
triacylglycerides-containing oils, following homogeneously
catalyzed hydrothermolysis, may be co-processed in either the
homogeneously catalyzed hydrothermolysis or heterogeneously
catalyzed hydrotreatment zone with other hydrocarbon feedstocks,
such as atmospheric gas oil (AGO), vacuum gas oil (VGO), or other
feeds derived from petroleum, shale oil, tar sands, coal-derived
oils, organic waste oils, and the like. Organic waste oil examples
may be selected from at least one of municipal solid wastes, sewage
sludge solids, Kraft plant waste liquor, restaurant greases and
used vegetable oils. Both the hydrothermolysis and hydrotreatment
reactions occur within a co-current adiabatic reactor.
[0028] Following hydrotreatment, the hydrotreatment effluent may
then be processed to separate water, unreacted diatomic hydrogen,
and light gases from the hydrotreatment effluent and to fractionate
the hydrocarbons into one or more hydrocarbon fractions, such as
those boiling in the range of naphtha, diesel, or jet. The water
and diatomic hydrogen may then be recycled for admixture with the
triacylglycerides-containing oil as described above.
[0029] The reaction of the triacylglycerides to produce
hydrocarbons may be primarily one or more hydrothermolysis
reactions homogeneously catalyzed by water and performed at a
reaction temperature in the range from about 250.degree. C. to
about 650.degree. C.; from about 350.degree. C. to about
550.degree. C. in some embodiments; and from about 425.degree. C.
to about 525.degree. C. in other embodiments. Reaction conditions
may also include a pressure of greater than 75 bar; greater than
140 bar in other embodiments; greater than 218 bar in other
embodiments; between about 75 bar and about 300 bar in some
embodiments; and between about 165 bar and about 250 bar in other
embodiments. Conditions of temperature and/or pressure may be
selected to be above the critical temperature and/or pressure of
water. In all embodiments, the homogeneously catalyzed
hydrothermolysis reactions may be performed in the absence of added
catalysts, such as an inorganic heterogeneous catalyst or a soluble
metallic catalyst.
[0030] Referring now to FIG. 1, a simplified process flow diagram
of a process for converting triacylglycerides-containing oils into
crude oil precursors and/or distillate hydrocarbon fuels according
to embodiments herein is illustrated. Makeup or fresh hydrogen 14a
and recycle hydrogen 14b (if present) may be fed to a fired furnace
20. The term "hydrogen" is used here to represent diatomic hydrogen
or molecular hydrogen. While very high purity H.sub.2 can be used,
in practice, the H.sub.2 will contain diluents, such as methane,
ethane, possibly CO.sub.x. Makeup H.sub.2 should be a H.sub.2-rich
stream of purity in the high 90 percentages. Recycle hydrogen could
have lower purity with the limit being the size and cost of
recompressing the recycle stream. Typically 85-95 vol %
concentrations are considered in petroleum hydroprocessing. Boiler
feed water 10 may also be fed to the fired furnace 20 in a separate
coil. The combined (make-up plus recycle) hydrogen stream 14 may be
compressed to a pressure greater than 221 bar, for example, prior
to entering the fired furnace 20. The water 10 may also be pumped
to a pressure greater than 221 bar, for example, prior to entering
the fired furnace 20. Heated hydrogen 16 may exit the fired furnace
20 at temperatures in excess of 500.degree. C., for example. Heated
water 12 may also exit the fired furnace 20 at temperatures in
excess of 500.degree. C., for example. In some embodiments, water
10 and hydrogen 14 may be mixed prior to entering the fired furnace
in a common coil. The enthalpies of the heated water 12 and heated
hydrogen 16 supply the bulk of the endothermic heats of the
homogeneously catalyzed hydrothermolysis reactions, particularly
the hydrolysis reactions that produce free fatty acids and
glycerol. The temperatures and flow rates of the heated hydrogen 16
and heated water 12 will be set to meet enthalpy requirements. The
hydrogen/water ratio may impact the required temperature of each
stream in meeting the enthalpy requirements. The hydrogen/water
ratio may be varied to manage the enthalpy requirements while
satisfying the kinetics and reaction stoichiometry requirements.
The heated hydrogen 16 and heated water 12 are mixed to form a
heated water-hydrogen mixture 22, a portion of which may be fed to
the top of a co-current adiabatic reactor 24. Mixing of the
hydrogen with water may be performed in a mixing device, such as a
mixing tee, an agitated vessel, an in-line mixer or other mixing
devices as known to those of skill in the art.
[0031] A triacylglycerides-containing oil 2 is also provided to
reactor 24. The heated water-hydrogen mixture 22 and the
triacylglycerides-containing oil 2 are injected to the top of the
reactor 24 where they mix and equilibrate at the desired adiabatic
bed inlet temperature. The reactor 24, as illustrated, is a
co-current downflow adiabatic reactor; other co-current reactor
types may also be used. The reactor 24 may include at least a first
inert solids bed 26a in the upper portion of the reactor 24 wherein
the homogeneously catalyzed hydrothermolysis reactions may occur.
In some embodiments, a plurality of inert solids beds 26 may be
used, such as a second inert solids bed 26b, as illustrated. The
inert solids beds 26 promote heat transfer, mass transfer and
mixing. The reactor 24 may also include at least a first
heterogeneous hydrotreatment catalyst bed 28a in the lower portion
of the reactor 24. In some embodiments, a plurality of
heterogeneous hydrotreatment catalyst beds 28 may be used, such as
a second hydrotreatment bed 28b, as illustrated. The number of
inert solids beds 26 and hydrotreatment beds 28 will depend on the
kinetics of the targeted chemical reactions for a particular
triacylglycerides-containing oil and the residence time
requirements for completing the targeted chemical reactions for a
particular triacylglycerides-containing oil. Although FIG. 1 shows
only a single reactor vessel with a single diameter, other
embodiments are envisioned with the reactor having various sections
each having different diameters to allow adjustments to superficial
velocities, the latter of which would impact both the degree of
turbulence and the residence times in each zone.
[0032] In an alternate embodiment, as shown in FIG. 2, the reactor
24 may include more than one co-current downflow adiabatic reactor
such as a first reactor 56 and a second reactor 58. Like reference
numbers are used to indicate like parts between FIGS. 1 and 2. The
first reactor 56 may include the first inert solids bed 26a in the
upper portion of the first reactor 26 wherein homogeneously
catalyzed hydrothermolysis reactions may occur. In some
embodiments, a plurality of inert solids beds 26 may be used, such
as the second inert solids bed 26b, as illustrated. The inert
solids beds 26 promote heat transfer and mixing. The second reactor
58 may also include the at least first hydrotreatment bed 28a in
the upper portion of the second reactor 58. In some embodiments, a
plurality of hydrotreatment beds 28 may be used, such as the second
hydrotreatment bed 28b, as illustrated. Although FIG. 2 only shows
reactors 56 and 58 having a single diameter, other embodiments are
envisioned with the reactors 56 and 58 having various sections each
having different diameters to allow adjustments to superficial
velocities, the latter of which would impact both the degree of
turbulence and the residence times in each zone.
[0033] The triacylglycerides-containing oil 2 may undergo
homogeneously catalyzed hydrothermolysis reactions in the first
inert solids bed 26a. The hydrothermolysis reactions in the first
bed 26a may be endothermic and the temperature of the reactants and
products may decrease through the first inert solids bed 26a. At
the bottom of the first inert solids bed 26, a portion 30 of the
heated water-hydrogen mixture 22 may be injected to elevate the
temperature of the partially converted triacylglycerides-containing
oil prior to entering the second inert solids bed 26b wherein the
hydrothermolysis reactions will occur. The hydrothermolysis
reactions in the second bed 26b may be more exothermic than those
occurring in the first bed 26a and may elevate the temperature
proximate the bottom of the second inert solids bed 26b in the
range from about 490.degree. C. to about 510.degree. C.
[0034] The inert solids beds 26 may be maintained at reaction
conditions, and flow rates may be adjusted to provide for a time
sufficient to convert at least a portion of the triacylglycerides
to distillate hydrocarbons or precursors thereof. Reaction
conditions may include a temperature in the range from about
250.degree. C. to about 650.degree. C. and a pressure of at least
75 bar. The residence time required in the inert solids beds 26 to
convert the triacylglycerides may vary depending upon the reaction
conditions as well as the specific triacylglycerides-containing oil
used. In some embodiments, residence times in the inert solids beds
26 may be in the range from about 1 second to about 10 minutes,
such as from about 3 minutes to about 6 minutes. The
hydrothermolysis reaction can also include some exothermic
reactions, which may supply additional heat to maintain the
required reaction temperature conditions and to reduce external
heat input requirements. In some embodiments, one or more water
feed lines (not shown) may be provided to control the exotherm and
the temperature or temperature profile in the inert solids beds
26.
[0035] Following reaction of the triacylglycerides in the inert
solids beds 26, the hydrothermolysis effluent may then be passed to
the hydrotreatment beds 28 to further treat the effluent.
Hydrotreatment beds 28 may contain a hydroconversion catalyst to
convert at least a portion of the hydrothermolysis effluent to
distillate hydrocarbons.
[0036] The effluent from the second inert solids bed 26b may be
cooled to desirable catalytic hydrotreatment bed temperatures, such
as from about 300.degree. C. to about 400.degree. C., utilizing
unheated hydrogen 32 prior to entering the first hydrotreatment bed
28a. Optionally, the effluent from the second inert solids bed 26b
may also be heated to desirable catalytic hydrotreatment bed
temperatures, such as from about 300.degree. C. to about
400.degree. C., utilizing direct heat exchange with a
hydrogen/water mixture stream 52 prior to entering the first
hydrotreatment bed 28a. A first portion 32a of unheated hydrogen
may be injected below the second inert solids bed 26b to cool the
hydrothermolysis effluent. The reactions in the first
hydrotreatment bed 28a are exothermic, e.g., saturation of olefinic
bonds on the acyl backbone of the triacylglycerides-rich
feedstocks. A resulting rise in temperature should be limited to a
maximum temperature of about 425.degree. C. which may be achieved
by injecting a second portion 32b of unheated hydrogen intermediate
the first hydrotreatment bed 28a and the second hydrotreatment bed
28b to reduce the reacting stream temperature back within a range
from about 300 to about 400.degree. C. While two catalytic
hydrotreatment adiabatic beds are shown on the figure, more or less
beds may be required. The exact number of adiabatic beds and quench
requirements may, for example, be determined from a simulation of
the catalytic hydrotreatment reactions using kinetics obtained in
bench-scale test units, for a given feedstock.
[0037] The homogeneously catalyzed hydrothermolysis and the
heterogeneously catalyzed hydrotreatment systems may be
"close-coupled," where the effluent from the inert solids beds 26
is passed to the hydrotreatment beds 28 without phase separation
(no separation of water, oil, and diatomic hydrogen). In some
embodiments, the effluent from the hydrothermolysis reaction step
may be passed to the hydrotreatment system under autogenous
pressure, i.e., without any pressure letdown between
hydrothermolysis and hydrotreatment other than that which may occur
by normal flow-induced pressure drops in piping and feed-effluent
heat exchangers. Additionally, due to the diatomic hydrogen feed to
the hydrothermolysis reactor, little or no additional diatomic
hydrogen, and thus minimal or no hydrogen compression or
re-compression is necessary for hydrotreatment. Due to compatible
reaction conditions, including pressures, diatomic hydrogen to
triacylglycerides ratios, and space velocities, the diatomic
hydrogen may be carried through the entire reaction system,
providing enhanced system performance including suppressed coking
rates and at higher thermal efficiencies and lower cost.
[0038] The effluent 34 from the hydrotreatment beds 28 may then be
fed to an effluent treatment system 36 for separation and recovery
of reaction products. For example, the resulting hydrocarbons may
be fractionated into two or more fractions, which, as illustrated,
may include distillate hydrocarbons boiling in the range of naphtha
38, diesel 41, or jet 40, and vacuum gas oil (VGO) 42. Some offgas
44 may also be produced. The effluent treatment system 36 may also
separate water and hydrogen from the hydrocarbons. Excess hydrogen
may also be recovered and recycled back as recycle hydrogen 14b. A
purge may be necessary to remove unwanted components, such as CO,
CO2, CH4, etc., that would otherwise buildup and lower the hydrogen
purity to an undesirably low level.
[0039] As noted above, the effluent from the inert solids beds 26
may be close-coupled, being passed to the hydrotreatment beds 28
under autogeneous pressure, i.e., without any pressure letdown
between hydrothermolysis and hydrotreatment other than that which
may occur by normal flow-induced pressure drops in piping and
feed-effluent heat exchangers. In such embodiments, a pressure
letdown valve or valves (not shown) may be provided intermediate
hydrotreatment beds 28 and effluent treatment system 36 to decrease
the pressure from an autogeneous pressure, for example, at or above
the supercritical pressure of water, to a pressure less than the
supercritical pressure of water, such as atmospheric pressure, in
one or more letdown steps. The pressure letdown system may also
provide for an initial phase separation of light gases (including
diatomic hydrogen), water, and hydrocarbons.
[0040] In some embodiments, effluent 34 may be sent to a heat
exchanger 50 to be cooled while simultaneously preheating the
triacylglycerides-containing oil 2 prior to being sent to the
effluent treatment system 36. Optionally, the effluent 34 may also
be quenched prior to entering the heat exchanger by a stream of
hydrogen 54.
[0041] To produce additional distillate range fuels, such as where
C20+ hydrocarbons are produced in hydrothermolysis reactor 18, some
of the VGO fraction 42, or other hydrocarbon fractions heavier than
diesel, may be recycled back to the reactor 24 for additional
processing, such as within the inert solids beds 26.
[0042] As described with respect to the embodiments of FIG. 1,
there is no intermediate processing, phase separation or separation
of the hydrothermolysis effluent before hydrotreatment; rather, the
hydrothermolysis effluent may be further processed in the same
reactor. The hydrothermolysis step and feed of the entire
hydrothermolysis effluent stream to the hydrotreatment reaction
zone is performed in a close-coupled system, where no intermediate
separations are performed. One skilled in the art may anticipate
that such a close-coupled system would not be technically feasible,
expecting the active metals in the supported catalysts to be
solubilized or decrepitated. However, it has been found that
catalyst activity may be maintained, over several hundred hours of
pilot plant operations, even in the presence of high water
concentrations and high organic acid concentrations (i.e., a much
higher level of oxygenates than are normally encountered with
typical petroleum feedstocks). Injection of water, hydrocarbons,
free fatty acids, alcohols, and unconverted triacylglycerides
directly to a hydrotreatment zone may thus provide for a
significant reduction in unit operations and processing steps
required to produce the desired distillate fuels.
[0043] Additional hydrocarbon feedstocks may be co-processed with
triacylglycerides-containing oil 2. The additional hydrocarbon
feedstocks may be fed to the reactor 24 along with the
triacylglycerides-containing oil 2. Non-renewable hydrocarbon
feedstocks, for example, may include one or more of petroleum
distillates; shale oil distillates; tar sands-derived distillates;
coal gasification byproduct oils; and coal pyrolysis oils, among
others. If necessary, some sulfur-containing compound such as, for
example, dimethyl disulfide dissolved in a suitable hydrocarbon
solvent, may be fed, either intermittently or continuously, to
hydrotreatment beds 28 in order to maintain the catalysts in their
most active states.
[0044] In an alternate embodiment, as shown in FIG. 3, the effluent
stream 68 from bed 26b of reactor 24 may be cooled sequentially in
a first heat exchanger 50 and a second heat exchanger 53 before
being introduced into an olefins saturation reactor 84 where it is
contacted with a H2-rich gas stream 69. Reactor 84 may include more
than one co-current downflow adiabatic catalyst bed containing
suitable hydrogenation catalysts with activity and selectivity
towards the saturation of olefinic bonds on the alkyl backbone of
the free fatty acids. The olefins saturation reactions can proceed
over the range of from about 150.degree. C. to about 232.degree. C.
The olefins saturation reactions are exothermic and results in a
temperature rise. The quantity of hydrogen stream 69 can be
controlled to maintain the outlet of the catalyst beds of reactor
84 to less than about 260.degree. C. and preferably less than about
232.degree. C. For the case of multiple catalyst beds (not shown on
diagram), hydrogen split off from stream 69 may be introduced
between catalyst beds to control bed temperature profiles. The
reactor 84 may operate at the autogeneous pressure of the upstream
hydrothermolysis reactor system diminished by the hydraulic losses
in the heat exchangers 50 and 53. An alternate embodiment may
comprise reducing the system pressure via throttling pressure
control valve 71. Control valve 71 may also be one or more
fixed-orifices or turbines or other pressure letdown devices.
[0045] The effluent stream 61 may be heated in heat exchanger 53
and introduced into a hydrodeoxygenation reactor 55 where it is
contacted with a hydrogen-rich gas stream 70. Reactor 55 may
include more than one co-current downflow adiabatic catalyst beds
containing suitable hydrogenation catalysts with activity and
selectivity towards the production of paraffins via
hydrodeoxygenation of the hydroxyl and carbonyl groups on the free
fatty acids as well by hydrodeoxygenation of any alcohols, ketones
or aldehydes contained in reactor inlet stream 62. The
hydrodeoxygenation reactions can proceed over the range of about
315.degree. C. to about 400.degree. C. The hydrodeoxygenation
reactions are exothermic and this results in a temperature rise.
The quantity of hydrogen stream 70 can be controlled to maintain
the outlet of the catalyst beds of reactor 55 to less than
385.degree. C. and preferably less than 357.degree. C. For the case
of multiple catalyst beds (not shown on diagram), hydrogen split
off from stream 70 can be introduced between catalyst beds to
control bed temperature profiles. The effluent stream 63 is cooled
sequentially in a first heat exchanger 51 and a second heat
exchanger 86 and then fed to a cold high pressure separator 57
wherein the following three streams are recovered; high pressure
hydrogen-rich gas stream 75, hydrotreated liquid product stream 67
and aqueous product stream 66.
[0046] The inert solids beds 26 may include, but are not limited
to, one or more of aluminas, alundum, ceramics, foams, sand, fused
glass, wires, meshes, rods, tubes having little or no chemical
conversion activity for pyrolysis, hydrothermolysis or
hydrotreatment reactions and which have geometric properties which
promote mixing of reactants and products without resulting in
adversely high pressure drops. In other embodiments, the inert
solids beds 26 may be void of any internals.
[0047] Catalysts useful in hydrotreatment beds 28 may include
catalysts that may be used for the hydrotreating or hydrocracking
of a hydrocarbon feedstock. In some embodiments, the hydrotreating
catalyst may effectively hydrodeoxygenate and/or decarboxylate the
oxygen bonds contained in the hydrotreatment feed and reduce or
eliminate the organic acid concentration in effluent 34. In some
embodiments, greater than 99%, 99.9%, or 99.99% of the organic
acids may be converted over the hydrotreatment catalyst.
[0048] Hydrotreating catalysts that may be useful include catalysts
selected from those elements known to provide catalytic
hydrogenation activity. At least one metal component selected from
Group 8-10 elements and/or from Group 6 elements is generally
chosen. Group 6 elements may include chromium, molybdenum and
tungsten. Group 8-10 elements may include iron, cobalt, nickel,
ruthenium, rhodium, palladium, osmium, iridium and platinum. The
amount(s) of hydrogenation component(s) in the catalyst suitably
range from about 0.5% to about 10% by weight of Group 8-10 metal
component(s) and from about 5% to about 25% by weight of Group 6
metal component(s), calculated as metal oxide(s) per 100 parts by
weight of total catalyst, where the percentages by weight are based
on the weight of the catalyst before sulfiding. The hydrogenation
components in the catalyst may be in the oxidic and/or the sulfidic
form. If a combination of at least a Group 6 and a Group 8 metal
component is present as (mixed) oxides, it will be subjected to a
sulfiding treatment prior to proper use in hydrocracking. In some
embodiments, the catalyst comprises one or more components of
nickel and/or cobalt and one or more components of molybdenum
and/or tungsten or one or more components of platinum and/or
palladium. Catalysts containing nickel and molybdenum, nickel and
tungsten, platinum and/or palladium are useful.
[0049] In some embodiments, hydrotreatment beds 28 may include two
or more beds or layers of catalyst, such as a first layer including
a hydrotreating catalyst and a second layer including a
hydrocracking catalyst.
[0050] In some embodiments, the layered catalyst system may include
a lower catalyst layer that includes a bed of a hydrocracking
catalyst suitable for hydrocracking any vacuum gas oil (VGO) range
hydrothermolysis products or added feeds to diesel range or lighter
hydrocarbons. The hydrocracking catalysts used may also be selected
to minimize or reduce dearomatization of the alkylaromatics formed
in the hydrothermolysis reactor. VGO hydrocracking catalysts that
may be used according to embodiments herein include one or more
noble metals supported on low acidity zeolites wherein the zeolite
acidity is widely distributed throughout each catalyst particle.
For example, one or more catalysts as described in U.S. Pat. No.
4,990,243, U.S. Pat. No. 5,069,890, U.S. Pat. No. 5,071,805, U.S.
Pat. No. 5,073,530, U.S. Pat. No. 5,141,909, U.S. Pat. No.
5,277,793, U.S. Pat. No. 5,366,615, U.S. Pat. No. 5,439,860, U.S.
Pat. No. 5,593,570, U.S. Pat. No. 6,860,986, U.S. Pat. No.
6,902,664, and U.S. Pat. No. 6,872,685 may be used in embodiments
herein, each of which are incorporated herein by reference with
respect to the hydrocracking catalysts described therein. In some
embodiments, the inclusion of the VGO hydrocracking may result in
extinctive hydrocracking of the heavy hydrocarbons, such that the
only net hydrocarbon products include diesel range and lighter
hydrocarbons.
[0051] One skilled in the art will recognize that the various
catalyst layers may not be made up of only a single catalyst, but
may be composed of an intermixture of different catalysts to
achieve the optimal level of metals or carbon residue removal and
deoxygenation for that layer. Although some olefinic bond
hydrogenation will occur in the lower portion of the zone, the
removal of oxygen, nitrogen, and sulfur may take place primarily in
the upper layer or layers. Obviously additional metals removal also
will take place. The specific catalyst or catalyst mixture selected
for each layer, the number of layers in the zone, the proportional
volume in the bed of each layer, and the specific hydrotreating
conditions selected will depend on the feedstock being processed by
the unit, the desired product to be recovered, as well as
commercial considerations such as cost of the catalyst. All of
these parameters are within the skill of a person engaged in the
petroleum processing industry and should not need further
elaboration here.
[0052] As described above, processes according to embodiments
herein provide for converting triacylglycerides-containing oils
into crude oil precursors and/or distillate hydrocarbon fuels. In
some embodiments, the process may include feeding hydrogen, water,
and a triacylglyceride-containing oil into a co-current reactor
having a homogeneously catalyzed hydrothermolysis reaction zone and
a heterogeneously catalyzed hydrotreatment zone. The reactor may be
operated at conditions suitable for hydrothermolyzing at least a
portion of the triacylglyceride-containing oil in the homogeneously
catalyzed hydrothermolysis reaction zone to form a hydrothermolysis
reaction product, and for hydrotreating the hydrothermolysis
reaction product in the heterogeneously catalyzed hydrotreatment
zone. A reaction effluent may then be recovered from the catalytic
hydrotreatment zone.
[0053] The homogeneously catalyzed hydrothermolysis reaction zone
and the heterogeneously catalyzed hydrotreatment zone are adiabatic
reaction zones. Such zones may also be contained within the same
reactor, such as a co-current reactor, including downflow
co-current reactors.
[0054] The homogeneously catalyzed hydrothermolysis reaction zone
may contain one or more beds of inert solids to promote mixing. The
homogeneously catalyzed hydrotreatment zone may include one or more
catalyst beds containing a hydrotreating catalyst. To control
temperature, as well as reactant concentrations, at least one of
hydrogen and water may be fed to the co-current reactor
intermediate the one or more homogeneously catalyzed
hydrothermolysis reaction zones, intermediate the one or more
heterogeneously catalyzed hydrotreatment zones, as well as
intermediate the hydrothermolysis reaction zones and the
hydrotreatment zones.
[0055] Embodiments herein also relate to a reactor system for
converting triacylglycerides-containing oils into crude oil
precursors and/or distillate hydrocarbon fuels. The reactor system
may include: a homogeneously catalyzed hydrothermolysis reaction
zone for hydrothermolyzing at least a portion of a
triacylglyceride-containing oil to form a hydrothermolysis reaction
product; and a heterogeneously catalyzed hydrotreatment zone for
hydrotreating the hydrothermolysis reaction product. The
homogeneously catalyzed hydrothermolysis reaction zone and the
heterogeneously catalyzed hydrotreatment zone are fluidly coupled
within the same reactor, and may have one or more adiabatic
reaction zones. The hydrothermolysis reaction zone contains one or
more beds of inert solids to promote mixing, and the catalytic
hydrotreatment zone may include one or more beds containing a
hydrotreating catalyst. The catalytic hydrotreatment zone may
include, for example, a first catalyst bed containing a catalyst
having hydrogenation activity and a second catalyst bed containing
a catalyst having hydrocracking activity.
[0056] While the above-described systems are described with respect
to a single reactor having multiple inert solids beds 26 and
multiple hydrotreatment beds 28, the reaction zones may include two
or more reactors arranged in series or in parallel. Likewise,
back-up compressors, filters, pumps, and the like may also be used.
Further, compressors may be single stage or multi-stage
compressors, which in some embodiments may be used to compress a
single gas stream in sequential stages or may be used to compress
separate gas streams, depending on plant layout.
[0057] As described above with respect to FIG. 1, a fractionator
may be used to recover various hydrocarbon fractions. Where
hydrotreatment beds 28 includes a bed or layer of hydrocracking
catalyst, production of heavy hydrocarbons may be reduced or
eliminated. In such embodiments, the fractionator may be used to
recover a diesel fraction as the bottoms from the column, and
recycle of heavy hydrocarbons, such as VGO, may be unnecessary.
When produced, the VGO may be recycled, as described above, or may
be recovered as a low sulfur fuel oil product.
[0058] As described above, processes disclosed herein may be
performed in a system or apparatus for converting
triacylglycerides-containing oils into crude oil precursors and/or
distillate hydrocarbon fuels. The system may include one or more
mixing devices for mixing a triacylglycerides-containing oil feed
with water and hydrogen. For example, the system may include a
first mixing device for mixing a triacylglycerides-containing oil
feed with water to form an oil-water mixture, and a second mixing
device for mixing the oil-water mixture with hydrogen to form a
feed mixture.
[0059] The furnace 20 may be, for example, an electrically heated
furnace, or a furnace fired with a fuel gas, such as a natural gas,
synthesis gas, or light hydrocarbon gases, including those produced
in and recovered from the adiabatic reactor. Reaction conditions
may be achieved by use of one or more pumps, compressors, and heat
exchangers. A separator may then be used for separating water and
hydrogen from hydrocarbons in the reaction effluent.
[0060] The system may also include a compressor for compressing
hydrogen recovered from the separator, as well as one or more fluid
conduits for recycling the compressed hydrogen and/or the recovered
water to the mixing device for mixing hydrogen or the mixing device
for mixing water.
[0061] The system may also include a fractionator for fractionating
hydrocarbons in the hydrotreatment effluent to form one or more
hydrocarbon fractions boiling in the naphtha, jet or diesel
range.
[0062] To control reaction temperatures and exotherms in the
adiabatic reactor, the system may include one or more fluid
conduits for injecting water into the homogeneously catalyzed
hydrothermolysis reactor beds.
[0063] As described above, embodiments disclosed herein provide
processes for the conversion of renewable feedstocks to
infrastructure-compatible distillate fuels. For example, in some
embodiments, the jet fraction recovered may have a total acid
number of less than 0.1 in some embodiments, expressed as mg KOH
per gram; less than 0.015 expressed as mg KOH per gram in other
embodiments; and less than 0.010 in other embodiments. The jet
fraction may have an olefins content of less than about 5 vol % and
an aromatics content of less than about 25 vol % in some
embodiments. These properties, among others, may allow the jet
and/or the diesel fractions produced in embodiments herein to be
used directly as engine fuels without blending. In some
embodiments, the whole hydrocarbon liquid product recovered from
the hydrotreatment reaction zone may be used to produce distillate
fuels meeting military, ASTM, EN, ISO, or equivalent fuel
specifications.
[0064] The process may be carried out in an economically feasible
method at a commercial scale. Embodiments herein may maximize the
thermal efficiency of the triacylglycerides-containing oil
conversion in an economically attractive manner without being
hampered by operability problems associated with catalyst fouling.
During the homogeneously catalyzed hydrothermolysis process, water,
such as about 5% of the feed water, may be consumed in the upper
inert-solids containing beds. In the hydrotreatment bed, any
glycerin intermediate product that did not undergo extinctive
hydrothermolysis reactions in the upstream homogeneously catalyzed
hydrothermolysis reaction system may be further catalytically
hydrogenated and converted to propane in the close-coupled
heterogeneously catalyzed hydrotreatment reaction system. Hydrogen
is consumed during the hydrotreatment step, and accordingly the
average specific gravity of the product may be reduced, such as
from approximately 0.91 to about 0.81. Decarboxylation reactions
form COx and that carbon loss may result in a reduced mass yield of
liquid products, and an equivalent lower volumetric yield. The
actual crude yield may be in the range from about 75% to about 90%,
such as in the range from about 80% to 84%, depending on how the
hydrothermolysis/hydrotreatment processes are executed.
[0065] Naphtha, jet, and diesel fuels may be produced by processes
disclosed herein. A higher boiling gas oil material may also be
produced, and may contain high-quality, high hydrogen content
paraffins in the C17 to C24 boiling range. These heavier
hydrocarbons may be recycled to the hydrothermolysis beds of the
concurrent adiabatic reactor for further treatment and production
of naphtha, jet, and diesel range products. Fuel gases (off gases)
may also be produced, which may be used in some embodiments for
process heat, hydrogen production, or recovered as individual
products (LPG, ethylene, propylene, n-butane, iso-butane, etc.). In
another embodiment, these heavier hydrocarbons may be recycled to
the catalytic hydrotreatment beds containing selective
hydrocracking catalysts for further treatment and production of
naphtha, jet and diesel range products.
[0066] Fuels produced by embodiments herein may: contain
cycloparaffins and aromatics; exhibit high density; exhibit high
energy density; exhibit good low-temperature properties (freezing
point, cloud point, pour point, and viscosity); exhibit natural
lubricity; exhibit a wide range of hydrocarbon types and molecular
weights similar to petroleum distillates; and/or have good thermal
stability. These fuels may thus be true "drop in" analogs of their
petroleum counterparts and do not require blending to meet current
petroleum specifications.
[0067] Close coupling of the homogeneously catalyzed
hydrothermolysis reaction and the heterogeneously catalyzed
hydrotreatment reaction system without separation of the
intermediate products is unique and may result in many process and
economic benefits. For example, benefits may include: elimination
of reactions occurring in a fired furnace zone wherein high metal
wall temperatures can promote coking, elimination of a
hydrothermolysis product cool down step and separation step of gas,
oil, and water components; elimination of acid water production and
treatment; elimination of additional liquid pumping, gas
compression, and heat exchange operations for the hydrotreatment
feed; reduced heat loss; and/or reduced power consumption.
[0068] While the disclosure includes a limited number of
embodiments, those skilled in the art, having benefit of this
disclosure, will appreciate that other embodiments may be devised
which do not depart from the scope of the present disclosure.
Accordingly, the scope should be limited only by the attached
claims.
* * * * *