U.S. patent application number 15/452912 was filed with the patent office on 2017-07-13 for process for producing hydrocarbons.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Alan Anthony DEL PAGGIO, Larry Gordon FELIX, Martin Brendan LINCK, Terry Louise MARKER, Michael John ROBERTS.
Application Number | 20170198222 15/452912 |
Document ID | / |
Family ID | 48430067 |
Filed Date | 2017-07-13 |
United States Patent
Application |
20170198222 |
Kind Code |
A1 |
DEL PAGGIO; Alan Anthony ;
et al. |
July 13, 2017 |
PROCESS FOR PRODUCING HYDROCARBONS
Abstract
A process for converting biomass to products is described.
Biomasss is contacted with hydrogen in the presence of a fluidized
bed of hydropyrolysis catalyst in a reactor vessel under
hydropyrolysis conditions; and products and char are removed from
the reactor vessel. The products leave the fluidized bed at an exit
bed velocity, the char has a settling velocity that is less than
the exit bed velocity and hydropyrolysis catalyst has a settling
velocity that is greater than the exit bed velocity.
Inventors: |
DEL PAGGIO; Alan Anthony;
(Spring, TX) ; ROBERTS; Michael John; (Itasca,
IL) ; MARKER; Terry Louise; (Palos Heights, IL)
; FELIX; Larry Gordon; (Pelhan, AL) ; LINCK;
Martin Brendan; (Grayslake, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
48430067 |
Appl. No.: |
15/452912 |
Filed: |
March 8, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14356781 |
May 7, 2014 |
9657232 |
|
|
PCT/US2012/064619 |
Nov 12, 2012 |
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15452912 |
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61559248 |
Nov 14, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 2400/02 20130101;
Y02E 50/13 20130101; C10B 53/02 20130101; Y02P 30/20 20151101; B01J
23/882 20130101; B01J 35/026 20130101; Y02E 50/14 20130101; B01J
35/0026 20130101; C10G 1/02 20130101; B01J 37/20 20130101; C10G
1/002 20130101; C10G 2400/08 20130101; C10L 2290/02 20130101; Y02E
50/32 20130101; C10B 49/10 20130101; C10G 3/50 20130101; Y02P
20/145 20151101; C10L 2270/04 20130101; C10G 1/06 20130101; Y02E
50/30 20130101; C10B 57/06 20130101; C10L 1/023 20130101; C10L
2270/026 20130101; B01J 23/883 20130101; B01J 37/0201 20130101;
B01J 23/755 20130101; C10B 57/12 20130101; C10L 2270/023 20130101;
C10B 47/00 20130101; C10G 1/08 20130101; C10L 1/026 20130101; C10G
2400/04 20130101; Y02E 50/10 20130101; B01D 45/12 20130101; C10K
1/024 20130101; C10L 2200/0469 20130101; C10G 1/008 20130101 |
International
Class: |
C10B 57/06 20060101
C10B057/06; C10G 1/02 20060101 C10G001/02; B01D 45/12 20060101
B01D045/12; C10B 53/02 20060101 C10B053/02; C10B 57/12 20060101
C10B057/12; C10B 47/00 20060101 C10B047/00; C10G 1/00 20060101
C10G001/00; C10G 1/08 20060101 C10G001/08 |
Claims
1. A process for converting biomass to products comprising: a.
contacting the biomass with hydrogen in the presence of a fluidized
bed of hydropyrolysis catalyst in a reactor vessel under
hydropyrolysis conditions; and b. removing products and char from
the reactor vessel wherein the products leave the fluidized bed at
an exit bed velocity, the char has a settling velocity that is less
than the exit bed velocity and hydropyrolysis catalyst has a
settling velocity that is greater than the exit bed velocity.
2. The process of claim 1 wherein the settling velocity of the char
is less than 90% of the exit bed velocity.
3. The process of claim 1 wherein the settling velocity of the char
is less than 75% of the exit bed velocity.
4. The process of claim 1 wherein the settling velocity of the
hydropyrolysis catalyst is greater than 110% of the exit bed
velocity.
5. The process of claim 1 wherein the settling velocity of the
hydropyrolysis catalyst is greater than 150% of the exit bed
velocity.
6. The process of claim 1 wherein the hydropyrolysis conditions
comprise a temperature in the range of from 270.degree. C. to
450.degree. C. and a pressure in the range of from 1 MPa to 7.5
MPa.
7. The process of claim 1 wherein the biomass is selected from the
group consisting of lignin, wood, algae, paper, and cardboard.
8. The process of claim 1 further comprising passing the products
through a cyclone to remove the char and then passing the products
through a porous filter to remove hydropyrolysis catalyst.
9. The process of claim 1 further comprising separating the
products to remove the carbon monoxide and light hydrocarbons from
the remainder of the products.
10. The process of claim 8 further comprising passing the remainder
of the products to a hydroconversion reactor wherein the remainder
of the products are contacted with a hydroconversion catalyst under
suitable hydroconversion conditions to produce a condensable liquid
hydrocarbon product that has less than 1% oxygen.
11. A hydropyrolysis process wherein the bulk density of the
catalyst in the fluidized bed is significantly higher than the bulk
density of the char.
12. The process of claim 10 wherein the bulk density of the char is
in the range of from 0.3-0.6 g/cc.
13. The process of claim 10 wherein the bulk density of the
catalyst is in the range of from 0.8-1.5 g/cc.
Description
FIELD OF INVENTION
[0001] The invention relates to a process for producing
hydrocarbons from biomass by contacting the biomass with a
hydropyrolysis catalyst. The invention further relates to an
improved separation between the catalyst and solids produced in the
process.
BACKGROUND
[0002] There is considerable interest in finding ways to convert
biomass into valuable products, especially products that can be
used as transportation fuels or in other chemical processes.
[0003] US Patent Application Publication No. 2010/0251600, which is
herein incorporated by reference, describes a multi-stage process
for producing liquid products from biomass in which the biomass is
hydropyrolyzed in a reactor vessel containing molecular hydrogen
and a deoxygenating catalyst, producing a partially deoxygenated
pyrolysis liquid, char, and first stage process heat. The partially
deoxygenated pyrolysis liquid is hydrogenated using a
hydroconversion catalyst, producing a substantially fully
deoxygenated pyrolysis liquid, a gaseous mixture comprising carbon
monoxide and light hydrocarbon gases (C.sub.1-C.sub.4), and second
stage process heat. The gaseous mixture is then reformed in a steam
reformer, producing reformed molecular hydrogen. The reformed
molecular hydrogen is then introduced into the reactor vessel for
the hydropyrolysis of additional biomass.
[0004] Continued improvements in this type of process are needed so
that it will be economically and technically feasible and able to
be carried out on a commercial scale.
SUMMARY OF THE INVENTION
[0005] This invention provides a process for converting biomass to
products comprising: contacting the biomass with hydrogen in the
presence of a fluidized bed of hydropyrolysis catalyst in a reactor
vessel under hydropyrolysis conditions; and removing products and
char from the reactor vessel wherein the products leave the
fluidized bed at an exit bed velocity, the char has a settling
velocity that is less than the exit bed velocity and hydropyrolysis
catalyst has a settling velocity that is greater than the exit bed
velocity.
[0006] This invention provides a process for converting biomass to
products comprising: contacting the biomass with hydrogen in the
presence of a fluidized bed of fresh hydropyrolysis catalyst in a
reactor vessel under hydropyrolysis conditions; removing products
and char from the reactor vessel; carrying out the contacting and
removing steps for a period of time such that the fresh
hydropyrolysis catalyst attrits in the fluidized bed to form small
catalyst particles; and removing at least a portion of the small
catalyst particles with the products and char wherein the products
leave the fluidized bed at an exit bed velocity, the char has a
settling velocity that is less than the exit bed velocity, the
fresh hydropyrolysis catalyst has a settling velocity that is
greater than the exit bed velocity, and the small catalyst
particles have a settling velocity that is less than the exit bed
velocity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 depicts the process flow of the hydropyrolysis
process.
[0008] FIG. 2 depicts the inside of the reactor vessel during
operation.
DETAILED DESCRIPTION
[0009] This process is used to convert biomass into liquid products
that may meet the specifications for gasoline, diesel fuel, jet
fuel and/or other valuable liquid hydrocarbon products. Biomass
feeds for the hydropyrolysis reactor may include a wide variety of
biologically-derived materials, including everything from fat from
rendering plants to dried chicken litter. Mixtures of materials
from municipal solid waste dumps, for example, plastics, paper,
cardboard, yard waste, food residue, etc., may be fed to the
hydropyrolysis reactor. It is presumed that any material which
breaks down, upon heating, into oxygenated hydrocarbons and/or
non-oxygenated hydrocarbons with boiling points in the gasoline,
diesel, or kerosene range could potentially be used as feedstock.
Preferred biomass feedstocks include lignin, wood and algae. Algae
may include whole algae and algal residues, for example, residues
derived after any extractive procedures to remove lipids, proteins
and/or carbohydrates. The biomass feed is typically prepared for
use in the reaction by sizing and drying. The selection of biomass
and the feed treatment process play a large role in the
characteristics of the char formed in the reaction.
[0010] The other feed to the process is hydrogen. The hydrogen may
be imported for use in the process or produced in a steam reformer.
The steam reformer may be fed light hydrocarbons (C.sub.1-C.sub.4)
and carbon monoxide produced in the hydropyrolysis process.
[0011] The hydropyrolysis reaction is carried out under suitable
hydropyrolysis conditions that provide for the production of a
partially deoxygenated pyrolysis liquid, char, light hydrocarbons
(C.sub.1-C.sub.4) and carbon monoxide. The temperature of the
reaction may be in the range of from about 300.degree. C. to about
600.degree. C., preferably in the range of from about 350.degree.
C. to about 540.degree. C. and more preferably in the range of from
about 399.degree. C. to about 450.degree. C. The pressure of the
reaction may be in the range of from about 1.38 MPa to about 6.00
MPa, preferably in the range of from about 1.72 MPa to about 5.50
MPa, more preferably in the range of from about 2.06 MPa to about
5.00 MPa and most preferably in the range of from about 2.76 MPa to
about 4.14 MPa.
[0012] The hydropyrolysis catalyst in the reactor is in the form of
a fluidized bed. The velocity of the feed and products upward
through the bed is sufficient to maintain the catalyst in a
fluidized state. Most of the products are in a gaseous form under
the hydropyrolysis reaction conditions and therefore pass in an
upward direction through the bed. They pass through the upper
portion of the bed and exit the catalyst bed. The velocity at which
the gaseous products exit the catalyst bed is referred to herein as
the exit bed velocity. The exit bed velocity will be a result of
the feed rate, reaction rate, reactor pressure and temperature and
reactor dimensions.
[0013] In order to maintain the upper portion of the catalyst bed
in the reactor, the exit bed velocity must not be so high that the
vapor entrains catalyst particles and carries them overhead with
the products. The tendency of the catalyst or other solids formed
in the reactor to be entrained with the vapor is determined by the
settling velocity of the individual particles.
[0014] The settling velocity of a particle is the terminal velocity
a particle reaches when traveling in a fluid and is achieved when
the drag force of the fluid on the particle is equal and opposite
to the force of gravity on the particle. The settling velocity of a
particle is a function of the density of the particle, the diameter
of the particle, the fluid (gas) density and gravitational
acceleration. See Kunii, Daizo and Octave Levenspiel, Fluidization
Engineering. 2.sup.nd ed. (Butterworth-Heinemann 1991), p. 80,
which is herein incorporated by reference. The shape and other
factors are incorporated into an experimentally determined
dimensionless drag coefficient.
[0015] In a fluidized bed, the settling velocity of the individual
particles and the gas velocity in the bed can be combined to arrive
at a net particle velocity, i.e., the gas velocity in the bed minus
the settling velocity of the particle will be the net velocity of
the particle. For example, a char particle with a net upward
velocity will be carried out of the bed and entrained with the
gaseous products because the gas velocity is greater than the
settling velocity of the char particles. On the other hand, a
catalyst particle will have a net negative (downward) velocity when
the settling velocity of the catalyst particle is greater than the
gas velocity in the bed, and the catalyst particle will tend to
remain in the catalyst bed.
[0016] In this process, it is preferred for the majority of the
catalyst to remain in the fluidized catalyst bed and for the
majority of the char to be entrained with the gaseous products and
carried out of the reaction. It is important to keep as much
catalyst as possible in the fluidized bed to maintain the reaction
activity and prevent contamination of the char by the metals on the
catalyst.
[0017] The exit bed velocity is a function of the process
conditions and the reactor configuration. Specifically, the exit
bed velocity can be calculated as the volumetric flow rate of
gaseous products exiting the bed divided by the cross sectional
area of the reactor at the top of the fluidized catalyst bed. It is
preferred for the settling velocity of the catalyst to be at least
1.5 times the settling velocity of the char to achieve an effective
separation between the char and catalyst, but the main factor in
carrying out this separation is the exit bed velocity.
[0018] The hydropyrolysis catalyst can be any catalyst known to one
of ordinary skill in the art to be useful in this reaction. A
suitable catalyst for use in this process has certain physical
characteristics that affect its performance in the fluidized bed
hydropyrolysis reactor. In this process, the settling velocity of
the catalyst determines whether the catalyst will remain in the
fluidized bed or be eluted from the reactor and carried out with
the gaseous products. If the settling velocity of the catalyst is
greater than the exit bed velocity then the catalyst will remain in
the fluidized bed and not be entrained with the gaseous
products.
[0019] The settling velocity of the catalyst may be any velocity
greater than the exit bed velocity, preferably greater than 110% of
the exit bed velocity, more preferably greater than 125% of the
exit bed velocity and most preferably greater than 150% of the exit
bed velocity.
[0020] Suitable hydropyrolysis catalysts include supported and bulk
catalysts. A suitable catalyst for this is a sulfided CoMo or NiMo
catalyst impregnated on a spherical alumina support. These
catalysts are placed on spherical supports to minimize attrition
for use in a fluid bed reactor. Another suitable catalyst is a
nickel aluminate or nickel catalyst impregnated on a spherical
alumina support. In all cases the catalyst must have enough
activity to add hydrogen to the structure and minimize coking
reactions.
[0021] It is possible that in addition to these catalysts, other
catalysts might work as well. Glass-ceramic catalysts can be
extremely strong and attrition resistant and can be prepared as
thermally impregnated or as bulk catalysts. When employed as a
sulfided NiMo, Ni/NiO, or Co based glass-ceramic catalyst, the
resulting catalyst is an attrition resistant version of a readily
available, but soft, conventional NiMo, Ni/NiO, or Co based
catalyst. Glass-ceramic sulfided NiMo, Ni/NiO, or Co based
catalysts are particularly suitable for use in a hot fluidized bed
because these materials can provide the catalytic effect of a
conventional supported catalyst, but in a much more robust,
attrition resistant form. In addition, due to the attrition
resistance of the catalyst, the biomass and char are simultaneously
ground into smaller particles as the hydropyrolysis reactions
proceed within the hydropyrolysis reactor.
[0022] During the process, char is produced. Char is the solid
biomass residue remaining after the hydropyrolysis reaction. The
char is preferably entrained with the gaseous products and carried
out of the reactor. The physical characteristics of the char
determine whether it will be entrained with the gaseous products.
Specifically, if the settling velocity of the char is less than the
exit bed velocity then the char will be entrained with the gaseous
products and carried out of the reactor. The char will not
necessarily be uniform as its characteristics are determined by the
type of biomass, the biomass pretreatment steps, and the
hydropyrolysis reaction conditions. Further, the char may be
reduced in size by the vigorous mixing in the fluidized bed.
[0023] The settling velocity of the char may be any velocity less
than the exit bed velocity, preferably less than 90% of the exit
bed velocity, more preferably less than 75% of the exit bed
velocity and most preferably less than 60% of the exit bed
velocity. It is understood that the individual char particles
formed in the reactor may have an initial settling velocity greater
than the exit bed velocity, but that over time, the settling
velocity of the char particles may be reduced by contact with the
catalyst and other char particles until the settling velocity of
the char particles is less than the exit bed velocity.
[0024] The settling velocity of the catalyst after it has been in
the fluidized bed reactor will decrease over time as the catalyst
attrits due to the vigorous mixing in the fluidized bed. As the
average settling velocity of the catalyst particles decreases, it
will reach a point where the settling velocity of the attritted
catalyst or the small catalyst particles that are broken off of the
catalyst will be less than the exit bed velocity and the attritted
catalyst or small catalyst particles will be entrained and carried
over with the gaseous products. A suitable catalyst is preferably
attrition resistant so this process of attrition of the catalyst
will happen very slowly.
[0025] The gaseous products will contain solid particles, such as
char and catalyst particles which are entrained with the gaseous
products. These solid particles must be removed from the gaseous
products before the gaseous products are further processed, and it
is preferred for the char to be separated from the catalyst
particles. This separation can be carried out by any suitable
method including filters, cyclones, or other centrifugal or
centripetal separators.
[0026] In one embodiment, the gaseous products are passed through a
cyclone to remove the char and then through a filter to remove the
catalyst fines. Char may be removed by cyclone from the gaseous
products stream or by way of coarse filtering. If the char is
separated by hot gas filtration, then the dust cake caught on the
filters will have to be periodically removed. It will be easier to
remove because the hydrogen produced in the hydropyrolysis reaction
will have stabilized the free radicals and saturated the olefins
produced in the reaction. In conventional fast pyrolysis, the
removal of this dust cake is much more difficult because the char
tends to coat the filter and react with oxygenated pyrolysis vapors
to form viscous coatings.
[0027] In an embodiment, a cyclone is first used to collect char
fines from the process vapors leaving the fluidized bed, and a
porous filter is then used to collect catalyst particles (which
have a greater particle density, but a much smaller diameter than
the char). Further, two porous filters may be used in parallel, so
that one may be cleaned via backpulsing while the other is
online.
[0028] Electrostatic precipitation or a virtual impactor separator
may also be used to remove char and ash particles from the hot
gaseous products stream before cooling and condensation of the
pyrolysis liquid.
[0029] In another embodiment, the char may be removed by bubbling
the gaseous products stream through a recirculating liquid that is
preferably the high boiling point portion of the finished oil from
the process. Char and catalyst fines may be captured in this
liquid, which can then be filtered to remove the char and catalyst
particles and/or recirculated to the hydropyrolysis reactor.
[0030] In another embodiment, large size NiMo or CoMo catalysts,
deployed in an ebullated bed, are used for char removal and to
provide further deoxygenation simultaneous with the removal of fine
particulates. These catalyst particles are large, preferably from
1/8 to 1/16 inch in size so they are easily separable from the fine
char carried over from the hydropyrolysis reaction.
[0031] After removal of the char, the partially deoxygenated
pyrolysis liquid, together with hydrogen, carbon monoxide, carbon
dioxide, water and light hydrocarbon gases (C.sub.1-C.sub.4) from
the hydropyrolysis reaction may be fed to a hydroconversion reactor
or another type of reaction zone that is used to further process
the pyrolysis liquid.
[0032] In a preferred embodiment, the hydroconversion reactor is
operated at a lower temperature than the hydropyrolysis reaction,
in the range of from about 315.degree. C. to about 425.degree. C.
and at about the same pressure. The liquid hourly space velocity of
this step is in the range of from about 0.3 to about 2.0. The
catalyst used in this reactor should be protected from catalyst
poisons, such as sodium, potassium, calcium, phosphorous and other
metals that may be present in the biomass. The catalyst will be
protected from olefins and free radicals by the catalytic upgrading
carried out in the hydropyrolysis reactor. Catalysts typically
selected for this step are high activity hydroconversion catalysts,
for example, sulfided NiMo and sulfided CoMo catalysts. In this
reaction stage, the catalyst is used to catalyze a water-gas shift
reaction of CO+H.sub.2O to make CO.sub.2+H.sub.2, thereby enabling
in-situ production of hydrogen in the hydroconversion reactor.
[0033] Following the hydroconversion step, the liquid products will
be almost completely deoxygenated. These products can be used as a
transportation fuel after separation by means of high pressure
separators and a low pressure separator by distillation into
gasoline and diesel portions. The gases exiting the hydroconversion
step are mainly carbon monoxide, carbon dioxide, methane, ethane,
propane, and butanes that can be sent to an optional steam reformer
together with water to form hydrogen to be used in the process. A
portion of these gases may also be burned to produce heat needed
for the steam reformer step.
[0034] An embodiment of the hydropyrolysis reaction system 100 will
be described with respect to FIG. 1. A hydropyrolysis reaction
system 100 comprises a hydropyrolysis reactor 110 that contains a
bed of fluidized catalyst. Biomass is fed into the reactor through
biomass feed line 120 and hydrogen is fed into the reactor by
hydrogen feed line 122. The hydrogen and biomass react in the
presence of the catalyst and the products, including pyrolysis
liquids, light gases, carbon monoxide and char are carried out of
the reactor via product line 124. The products are passed through a
cyclone 130 where the char is separated out via line 126 and the
products are removed via line 128. Other embodiments include the
use of a filter and/or other means for separating the solids from
the product. Small catalyst particles may also be carried out of
the reactor via line 124 and these would be separated from the
products, either with the char or separately.
[0035] An embodiment of the hydropyrolysis reaction will be
described with respect to FIG. 2. A hydropyrolysis reactor 210
contains a fluidized bed of hydropyrolysis catalyst 230. The
biomass is fed through line 220 and the hydrogen is fed through
line 222. The arrows 240 depict the exit bed velocity of the gases
leaving the top of the catalyst bed. The particles 232 are either
solid char particles or small catalyst particles that are entrained
with the gaseous product stream that is removed via line 224.
Examples
[0036] A hydropyrolysis reactor was operated under conditions
consistent with those described above, in order to demonstrate
removal of biomass char and attrited catalyst particles from a
catalyst bed via entrainment. The hydropyrolysis reactor consisted
of a tubular vessel, with an interior diameter of 1.28 inches. A
catalyst bed was disposed within the reactor. Hydrogen, at a
temperature of approximately 371.degree. C., was fed into the
bottom of the bed of catalyst in order to fluidize it. Prior to
loading, the catalyst particles were sieved, so that each particle
was small enough to pass through a sieve with a screen opening of
500 microns, but large enough to be retained on a sieve with a
screen opening of 300 microns. The reactor was operated at 2.41 MPa
and thermocouples, disposed within the fluidized bed, indicated
that the average temperature of the bed was approximately
404.degree. C. This bed temperature was maintained and controlled
by electric heaters. The flow rate of hydrogen into the bottom of
the bed was such that the exit velocity of vapors leaving the bed
(exit bed velocity) was 0.13 meter/second. A heated filter assembly
was disposed downstream of the fluidized-bed hydropyrolysis
reactor, and was used to trap any particles, consisting of either
char or attrited catalyst, that left the fluidized bed during the
experiment. The filter was maintained at a temperature high enough
to prevent any of the vapors from condensing to form liquids in the
filter assembly.
[0037] Initially, 200 grams of fresh, sulfided catalyst were
disposed within the hydropyrolysis reactor. It was established that
the exit bed velocity of 0.13 meter/second was too low to remove
any measurable quantity of intact catalyst particles from the bed.
The settling velocity of all the intact catalyst particles in the
bed was thus found to be larger than the exit velocity of vapors
from the bed. It should be noted that the catalyst particles were
not spherical when they were loaded, and that the settling velocity
of individual particles was not determined directly. It was
established that the particles were small enough to be vigorously
fluidized and effectively mixed by the stream of fluidizing gas,
but also large enough to be retained, without being carried out by
the stream of process vapors leaving the bed. No further
characterization of the aerodynamic properties of the catalyst was
conducted.
[0038] The reactor was then fed a feedstock consisting of powdered
hardwood. The feedstock had a maximum particle size small enough to
pass through a screen with an opening of 250 microns. The feedstock
was effectively cooled and transported in such a manner that
individual feedstock particles could not interact with each other,
and could not heat up significantly, during transport into the
fluidized bed. Once the feedstock particles arrived in the bed,
they were heated very rapidly to the temperature of the bed, via
interaction with hot hydrogen, process vapors and catalyst
particles present in the bed. Each feedstock particle was rapidly
devolatilized, and the resulting vapors then had the opportunity to
react with hydrogen present in the reactor. These reactions were
facilitated by the presence of the catalyst particles. Once the
feedstock particles were devolatilized, only a char particle,
consisting largely of carbon from the original feedstock, remained
behind. These char particles were significantly smaller in size
than the catalyst particles in the bed, and also had a lower
particle density. As a result, these char particles were carried
rapidly to the top of the fluidized bed, and were then conveyed out
of the hydropyrolysis reactor, and into the heated filter assembly
downstream of the reactor.
[0039] The system was operated over a period of three days. 2100
grams of feedstock were loaded into the system the first day; 2100
grams of feedstock were again loaded into the system on the second
day, and 1800 grams of feedstock were loaded into the system on the
third day. After the system was shut down, 15 grams of unprocessed
feedstock were recovered. Thus, 5985 grams of feedstock were
processed in the hydropyrolysis reactor.
[0040] As described above, 200 grams of fresh catalyst were
initially loaded into the reactor. On the second day of the
experiment, 17 grams of fresh catalyst were sent into the reactor,
in order to replace any catalyst that had been removed via
attrition after the first day of processing. On the third day, 17
grams of fresh catalyst were again loaded into the reactor. When
the system was shut down and unloaded, the weight of the bed was
228 grams. The bed consisted mostly of catalyst, but also contained
some carbonaceous char material.
[0041] Since solids were recovered from the reactor and the filter
assembly, an analysis of the solids was used to confirm that the
preponderance of the catalyst had been left in the fluidized bed in
the hydropyrolysis reactor, and had not been carried out into the
filter assembly. Further, the analysis confirmed that the
preponderance of the biomass char particles had been removed from
the fluidized bed in the reactor, and carried over into the filter
assembly. The catalyst contained no detectible quantities of carbon
when initially loaded into the reactor. When recovered, the bed
contained 22.5% carbon, meaning that 51 grams of carbon remained in
the bed. This carbon originated in the feedstock.
[0042] The filter fines weighed 573 grams, and were 78.7% carbon.
This means 451 grams of carbon were recovered from the char fines
in the filter. Sizing of the particles in the filter and the bed
confirmed that the particles of the fines from the filter assembly
were in a much lower range than particles left behind in the
hydropyrolysis reactor.
[0043] Effectively, 90% of the char produced during operation of
the reactor was rapidly carried out of the fluidized bed, and
accumulated in the filter assembly. The proportion of char left
behind in the reactor was related to the largest of the biomass
particles present in the feedstock. These particles would
eventually have been carried over to the filter assembly, if the
fluidization in the bed had been maintained for an extended period
after cessation of feedstock addition to the bed. However, the
experiment was terminated immediately after the feedstock was used
up, and there was no opportunity to reduce the remaining char in
size to a point where it would have been carried over to the filter
assembly.
[0044] The process vapors from the hydropyrolysis reactor were sent
on to a second-stage reactor after they passed through the filter
assembly. In the second-stage reactor, the process vapors were
contacted with a fixed bed of catalyst, and further hydrotreating
occurred. After the experiment was over, the products were
analyzed. On a moisture and ash-free basis, 26.7% of the mass of
feedstock sent into the reactor was accounted for as gasoline-range
and diesel-range hydrocarbons. The oxygen content of the liquid
hydrocarbon products was less than 1% by mass.
[0045] The bulk density of the char, collected in the filter
assembly, was also assessed, and was determined to be 0.3 g/cc. The
bulk density of the catalyst in the fluidized bed was found to be
0.9 g/cc. This difference in the bulk densities of the char and the
catalyst particles was partly responsible for the effective
separation of the char from the bed, since particles of the
lower-density char could be readily carried out of the bed, while
particles of higher-density catalyst were retained.
* * * * *