U.S. patent application number 12/973151 was filed with the patent office on 2012-06-21 for catalytic cracking process of a lipid-containing feedstock.
Invention is credited to Colin John SCHAVERIEN, Nicolaas Wilhelmus Joseph WAY.
Application Number | 20120151832 12/973151 |
Document ID | / |
Family ID | 46232538 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120151832 |
Kind Code |
A1 |
SCHAVERIEN; Colin John ; et
al. |
June 21, 2012 |
CATALYTIC CRACKING PROCESS OF A LIPID-CONTAINING FEEDSTOCK
Abstract
A process for catalytic cracking of a lipid-containing feedstock
is provided. The lipid-containing feedstock contains lipids derived
from a diatomic microalgae species. The lipid-containing feedstock
is contacted with at least one cracking catalyst at a temperature
of at least 450.degree. C., to obtain a product stream; and
separating at least one hydrocarbon fraction from the product
stream.
Inventors: |
SCHAVERIEN; Colin John;
(Amsterdam, NL) ; WAY; Nicolaas Wilhelmus Joseph;
(Amsterdam, NL) |
Family ID: |
46232538 |
Appl. No.: |
12/973151 |
Filed: |
December 20, 2010 |
Current U.S.
Class: |
44/385 |
Current CPC
Class: |
C10G 2400/02 20130101;
C10G 3/49 20130101; C10G 1/086 20130101; Y02P 30/20 20151101; C10G
3/42 20130101; C10L 1/18 20130101; C10G 2300/1014 20130101; C10G
11/05 20130101 |
Class at
Publication: |
44/385 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Claims
1. A process for catalytic cracking of a lipid-containing
feedstock, the process comprising contacting the lipid-containing
feedstock with at least one cracking catalyst at a temperature of
at least 450.degree. C., to obtain a product stream; and separating
at least one hydrocarbon fraction from the product stream; wherein
the lipid-containing feedstock comprises lipids derived from a
diatomic microalgae species.
2. The process of claim 1 wherein the temperature ranges from equal
to or more than 450.degree. C. to equal to or less than 650.degree.
C.
3. The process of claim 1 wherein the lipid-containing feedstock
further comprises a hydrocarbon feedstock.
4. The process of claim 3 wherein the hydrocarbon feedstock
comprises a vacuum gas oil, atmospheric residue or vacuum
residue.
5. The process of claim 3 wherein the hydrocarbon feedstock
comprises hydrocarbons with an initial boiling point of at least
220.degree. C. as measured according to ASTM D-2887.
6. The process of claim 1 wherein the hydrocarbon feedstock has an
initial boiling point of at least 180.degree. C. as measured
according to ASTM D-2887.
7. The process of claim 1 wherein the lipid-containing feedstock
comprises from 2 wt % to 30 wt % lipids.
8. The process of claim 7 wherein the lipid-containing feedstock
comprises from 5 wt % to 20 wt % lipids.
9. The process of claim 2 wherein the temperature ranges from equal
to or more than 480.degree. C. to equal to or less than 560.degree.
C.
10. The process of claim 1 wherein the cracking catalyst comprises
a zeolite.
11. A gasoline product prepared from a hydrocarbon fraction of the
at least one hydrocarbon fraction of claim 1.
12. A gasoline product prepared from a hydrocarbon fraction of the
at least one hydrocarbon fraction of claim 3.
13. A gasoline product prepared from a hydrocarbon fraction of the
at least one hydrocarbon fraction of claim 4.
14. A gasoline product prepared from a hydrocarbon fraction of the
at least one hydrocarbon fraction of claim 5.
15. A gasoline product prepared from a hydrocarbon fraction of the
at least one hydrocarbon fraction of claim 6.
16. A gasoline composition having less than 1000 ppmw sulfur
comprising a gasoline product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction of claim 1 and one or more
additives.
17. A gasoline composition having less than 1000 ppmw sulfur
comprising a gasoline product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction of claim 3 and one or more
additives.
18. A gasoline composition having less than 1000 ppmw sulfur
comprising a gasoline product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction of claim 4 and one or more
additives.
19. A gasoline composition having less than 1000 ppmw sulfur
comprising a gasoline product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction of claim 5 and one or more
additives.
20. A gasoline composition having less than 1000 ppmw sulfur
comprising a gasoline product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction of claim 6 and one or more
additives.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a process for catalytic
cracking of a lipid-containing feedstock.
BACKGROUND OF THE INVENTION
[0002] Various processes for catalytic cracking of heavy
hydrocarbons are known in the art. In these processes, heavy
hydrocarbons, such as heavy oils and vacuum residues, are brought
in contact with a cracking catalyst and are converted into lighter
products having lower boiling points. Exemplary descriptions of
such processes have been provided for instance in U.S. Pat. No.
4,917,790 and in U.S. Pat. No. 6,905,591.
[0003] However, with the diminishing supply of crude oil, use of
renewable energy sources is becoming increasingly important for the
production of chemicals and fuels. Plant and animal biomass, are
being used to produce liquid and gaseous fuels through the
catalytic cracking process. One of the advantages of using biomass
is that the CO.sub.2 balance is more favourable as compared with
the conventional hydrocarbon feedstock.
[0004] US2009/0047721 describes a process for producing
hydrocarbons for use in diesel and jet fuels by subjecting lipids
derived from algae to a catalytic cracking process. However, the
products obtained through this cracking process predominantly
include a mixture of C2 to C5 olefins and need additional chemical
treatment to produce usable fuel products.
[0005] EP1970425 describes a process for producing gaseous and
liquid fuels by cracking lipids derived from high viscosity
carbon-based energy carrier materials and WO-A-2009/000838,
describes a process for producing bio oils by cracking of lipids
derived from aquatic biomass. However, these references disclose
using a cracking temperature of below 450.degree. C., and only
yield products in low yields and with limited selectivity.
[0006] Kitazato et al. describe in their article titled "Catalytic
cracking of hydrocarbons from microalgae", International Chemical
Engineering, Volume 31, no 3, July 1991, a process for the
production of gasoline by catalytic cracking of hydrocarbons
obtained from the microalgae Botryococcus braunii Berkeley (a green
algae). For the catalytic cracking process a commercial FCC zeolite
was used. Exemplified reaction conditions included temperatures in
the range from 450 to 500.degree. C. Also Kitazato et al. teach,
however, that low temperatures of cracking (below 450.degree. C.)
are necessary to ensure a high yield of gasoline. In addition, the
use of a catalyst comprising 100 wt % zeolite is too expensive for
commercial operation.
[0007] It would be an advancement in the art if a process would be
provided for catalytic cracking of biomass with improved
efficacy.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention provides a process for
catalytic cracking of a lipid-containing feedstock, the process
comprising contacting the lipid-containing feedstock with at least
one cracking catalyst at a temperature of at least 450.degree. C.,
to obtain a product stream; and separating at least one hydrocarbon
fraction from the product stream; wherein the lipid-containing
feedstock comprises lipids derived from a diatomic microalgae
species.
[0009] According to a further embodiment, the present invention
provides a gasoline product prepared from a hydrocarbon fraction of
the at least one hydrocarbon fraction.
[0010] According to yet another embodiment, the present invention
provides a liquefied gaseous fuel composition comprising a
liquefied gaseous fuel product prepared from a hydrocarbon fraction
of the at least one hydrocarbon fraction, less than 1000 ppmw
sulfur, and one or more additives.
DETAILED DESCRIPTION OF THE INVENTION
[0011] It was found that, when using lipids derived from a diatomic
microalgae species as a feedstock, contrary to the teachings in the
prior art, a higher cracking temperature gives a higher conversion
and hence more valuable lighter products (that is, more products
having a boiling point below 221.degree. C. such as, for example,
LPG and gasoline).
[0012] The process according to the invention is further
advantageous because diatomic microalgae have high growth rates,
utilise a large fraction of solar energy and can grow in conditions
that are not favourable for terrestrial biomass. Additionally,
diatomic microalgae consume CO.sub.2 at a high rate, and may reduce
the carbon footprint of the overall process. Further diatomic
microalgae contain high concentrations of lipids.
[0013] It has now been found that cracking of a lipid-containing
feedstock, that comprises lipids derived from a diatomic microalgae
species, over a cracking catalyst at a temperature of at least
450.degree. C. results in a desirable product stream.
[0014] Diatomic microalgae as referred to in the present invention
are a large and diverse group of microorganisms living in an
aquatic environment that have a cell wall comprising silica. They
can be unicellular or multicellular, but are preferably
unicellular. The diatomic microalgae preferably have a diameter
smaller than 1 mm, more preferably a diameter smaller than 0.6 mm
and still more preferably a diameter smaller than 0.4 mm. The
diameter is measured at its largest point. Most preferably the
diatomic microalgae comprise a diameter in the range from 0.5 to
200 micrometer, even more preferably in the range from 1 to 100
micrometer. The diatomic microalgae can be cultivated under
difficult agro-climatic conditions, including cultivation in
freshwater, saline water, moist earth, dry sand and other
open-culture conditions known in the art. The diatomic microalgae
can also be cultivated and genetically engineered in controlled
closed-culture systems, for example, in closed bioreactors.
Preferably, the diatomic microalgae used in the present invention
are marine diatomic microalgae cultivated in fresh water, saline
water or other moist conditions, more preferably marine diatomic
microalgae cultivated in saline water. Yet more preferably, the
marine diatomic microalgae are cultivated in open-culture
conditions, for example, in open ponds.
[0015] Lipids as referred to in the present invention are a group
of naturally occurring compounds that are usually hydrophobic in
nature and contain long-chain aliphatic hydrocarbons and their
derivatives such as fatty acids, alcohols, amines, amino alcohols
and aldehydes. The lipid-containing feedstock as disclosed in the
invention includes lipids derived from marine diatomic microalgae.
These lipids include monoglycerides, diglycerides and
triglycerides, which are esters of glycerol and fatty acids, and
phospholipids, which are esters of glycerol and phosphate
group-substituted fatty acids.
[0016] The fatty acid moiety in the lipids used in the invention
ranges from 4 carbon atoms to 30 carbon atoms, and includes
saturated fatty acids containing one, two or three double bonds.
Preferably, the fatty acid moiety includes 8 carbon atoms to 26
carbon atoms, more preferably the fatty acid moiety includes 10
carbon atoms to 25 carbon atoms, again more preferably the fatty
acid moiety includes 12 carbon atoms to 23 carbon atoms, and yet
more preferably 14 carbon atoms to 20 carbon atoms. The lipids may
contain variable amounts of free fatty acids and/or esters, both of
which may also be converted into hydrocarbons during the process of
this invention. In one embodiment the lipids may be composed of
natural glycerides only. Alternatively, the lipids may also include
carotenoids, hydrocarbons, phosphatides, simple fatty acids and
their esters, terpenes, sterols, fatty alcohols, tocopherols,
polyisoprene, carbohydrates and proteins. It is to be understood
that for the purpose of this invention, a mixture of lipids
extracted from different diatomic microalgae sources can also be
used in the lipid-containing feedstock.
[0017] The diatomic microalgae may be processed to extract lipids
using processes known in the art. The said processes may include
the steps of harvesting the diatomic microalgae, dewatering the
diatomic microalgae, disrupting the diatomic microalgae's cell
walls to liberate lipids, and then extracting the lipids using
solvents, supercritical fluids or other extraction processes. In a
preferred embodiment, the diatomic microalgae are cultivated,
harvested, dried, milled and then lipids are extracted using a
water immiscible solvent at 25.degree. C. Suitable solvents for the
extraction are organic solvents such as aromatic or aliphatic
hydrocarbons, higher alcohols, ethers and esters. Examples for such
solvents are toluene, hexane, heptane, dimethyl ether, acetic acid
ester and mixtures thereof. Other solvents include supercritical
liquids, such as supercritical carbon dioxide.
[0018] The extracted lipids may conveniently be isolated by
evaporating the solvent, or by other methods, such as membrane
separation.
[0019] Preferably, the lipid-containing feedstock includes lipids
in the range of 1 wt % to 50 wt %, more preferably in the range of
2 wt % to 40 wt %, more preferably in the range of 3 wt % to 30 wt
%, and yet more preferably in the range of 5 wt % to 20 wt %, based
on the total weight of lipid-containing feedstock.
[0020] The lipid-containing feedstock further preferably comprises
a hydrocarbon feedstock. That is, the lipids (also referred to as
lipid feedstock) may preferably be co-fed together with a
hydrocarbon feedstock. The co-feeding may be attained by blending
the two feedstock streams prior to entry into the cracking unit, or
alternatively, by adding them at different stages.
[0021] The hydrocarbon feedstock preferably comprises hydrocarbons
with a boiling point of at least 220.degree. C., as measured by Gas
Chromatograph Distillation (GCD) according to ASTM D-6352-98.
Preferably, the boiling points range from 220.degree. C. to
650.degree. C., more preferably from 300.degree. C. to 600.degree.
C. Furthermore, the hydrocarbon feedstock preferably has an initial
boiling point above 180.degree. C., as measured by Gas
Chromatograph Distillation (GCD) according to the methods described
in ASTM D-6352-98.
[0022] In one embodiment the hydrocarbon feedstock includes
hydrocarbons having a mineral origin. Preferably such hydrocarbon
feedstock comprises a mineral oil or a derivative of a mineral oil.
The hydrocarbon feedstock may be a conventional fluid catalytic
cracking feedstock. Examples of the hydrocarbon feedstock include
high boiling, non-residual oils such as straight run (atmospheric)
gas oils, vacuum gas oils, flashed distillate, coker gas oils, or
atmospheric residue ('long residue') and vacuum residue (`short
residue`).
[0023] In another embodiment the hydrocarbon feedstock may include
a paraffinic feedstock, for example, an optionally hydroisomerised
fraction of the synthesis product of a Fischer-Tropsch reaction, or
the fraction boiling above the middle distillate boiling range of
the effluent of fuel hydrocracker, also referred to as hydrowax. An
advantage of using said paraffinic feedstock in admixture with the
lipids is that the aromatic content of gasoline fraction, can be
reduced by co-processing the paraffinic feedstock. It has been
found that on cracking a paraffinic feedstock a gasoline having a
very low aromatic content can be obtained.
[0024] Further, lipids derived from other biomass sources such as
plant and vegetable oils may also be added to the lipid-containing
feedstock as an additional cracking feedstock.
[0025] Preferably, the total feed going into the catalytic cracking
unit may comprise the hydrocarbon feedstock in the range of 50 wt %
to 99 wt %, preferably in the range from 60 wt % to 98 wt %, more
preferably 70 wt % to 98 wt %, more preferably 70 wt % to 97 wt %,
most preferably in the range of 80 wt % to 95 wt % based on the
total weight of lipid-containing feedstock, the remainder being the
lipid feedstock.
[0026] The process of catalytic cracking of the lipid-containing
feedstock according to the invention preferably comprises a
catalytic cracking step, which may be followed with a regeneration
step.
[0027] More preferably the catalytic cracking process includes a
catalytic cracking step, in which the cracking reaction takes place
in the presence of a catalyst; a regeneration step, in which the
catalyst is regenerated, for example by burning off the coke
deposited on the catalyst as a result of the reaction, to restore
the catalytic activity; and a recycle step, wherein the regenerated
catalyst is recycled to the catalytic cracking step. The heat
generated in the exothermic regeneration step is preferably
employed to provide energy for the endothermic cracking step.
[0028] The catalytic cracking step comprises contacting the
lipid-containing feedstock with a cracking catalyst, preferably in
the reaction zone of a fluidized catalytic cracking (FCC)
apparatus. The reaction temperature preferably ranges from equal to
or more than 450.degree. C. to equal to or less than 650.degree.
C., more preferably from equal to or more than 480.degree. C. to
equal to or less than 600.degree. C., and most preferably from
equal to or more than 480.degree. C. to equal to or less than
560.degree. C. The pressure in the reaction zone preferably ranges
from equal to or more than 0.5 bar to equal to or less than 10 bar
(0.05 MPa-1 MPa), more preferably from equal to or more than 1.0
bar to equal to or less than 6 bar (0.15 MPa to 0.6 MPa). The
residence time of the cracking catalyst in the reaction zone
preferably ranges from equal to or more than 0.1 seconds to equal
to or less than 15 seconds, more preferably from equal to or more
than 0.5 seconds to equal to or less than 10 seconds. The product
stream obtained from the cracking step may be separated into one or
more hydrocarbon fractions using, for example, a fractionator.
[0029] Preferably, a catalyst to lipid-containing feedstock mass
ratio ranging from equal to or more than 3 to equal to or less than
8 is used. Preferably, the catalyst to feedstock mass ratio used is
at least 3.5. The use of a higher catalyst to feedstock mass ratio
results in an increase in conversion.
[0030] The process according to the invention further preferably
comprises a catalyst regeneration step. A regeneration step
preferably may comprise burning off the coke to restore the
catalyst activity by combusting the cracking catalyst in the
presence of an oxygen-containing gas in a regenerator. The
regeneration temperature preferably ranges from equal to or more
than 575.degree. C. to equal to or less than 950.degree. C., more
preferably from equal to or more than 600.degree. C. to equal to or
less than 850.degree. C. The pressure in the regenerator preferably
ranges from equal to or more than 0.5 bar to equal to or less than
10 bar (0.05 Mpa to 1 MPa), more preferably from equal to or more
than 1.0 bar to equal to or less than 6 bar (0.1 MPa to 0.6
MPa.
[0031] Cracking catalysts suitable for use in the process according
to the invention are well known in the art. Preferably, the
cracking catalyst comprises a zeolitic component, and more
preferably, an amorphous binder. Examples of such binder materials
include silica, alumina, titania, zirconia and magnesium oxide, or
combinations of two or more of them.
[0032] The zeolite is preferably a large pore zeolite. The large
pore zeolite includes a zeolite comprising a porous, crystalline
aluminosilicate structure having a porous internal cell structure
on which the major axis of the pores is in the range of 0.62
nanometer to 0.8 nanometer. The axes of zeolites are depicted in
the `Atlas of Zeolite Structure Types`, of W. M. Meier, D. H.
Olson, and Ch. Baerlocher, Fourth Revised Edition 1996, Elsevier,
ISBN 0-444-10015-6. Examples of such large pore zeolites include
FAU or faujasite, preferably synthetic faujasite, for example,
zeolite Y or X, ultra-stable zeolite Y (USY), Rare Earth zeolite Y
(=REY) and Rare Earth USY (REUSY). According to the present
invention USY is preferably used as the large pore zeolite.
[0033] The cracking catalyst can also comprise a medium pore
zeolite. The medium pore zeolite that can be used according to the
present invention is a zeolite comprising a porous, crystalline
aluminosilicate structure having a porous internal cell structure
on which the major axis of the pores is in the range of 0.45
nanometer to 0.62 nanometer. Examples of such medium pore zeolites
are of the MFI structural type, for example, ZSM-5; the MTW type,
for example, ZSM-12; the TON structural type, for example, theta
one; and the FER structural type, for example, ferrierite.
According to the present invention, ZSM-5 is preferably used as the
medium pore zeolite.
[0034] According to another embodiment, a blend of large pore and
medium pore zeolites may be used. The ratio of the large pore
zeolite to the medium pore size zeolite in the cracking catalyst is
preferably in the range of 99:1 to 70:30, more preferably in the
range of 98:2 to 85:15.
[0035] The total amount of the large pore size zeolite and/or
medium pore zeolite that is present in the cracking catalyst is
preferably in the range of 5 wt % to 40 wt %, more preferably in
the range of 10 wt % to 30 wt %, and even more preferably in the
range of 10 wt % to 25 wt % relative to the total mass of the
cracking catalyst, the remainder being amorphous binder.
[0036] According to the invention, the reaction zone is usually an
elongated tube-like reactor, preferably a vertical reactor in which
the lipid-containing feedstock and the cracking catalyst flow in an
upward direction. The lipid-containing feedstock and the cracking
catalyst may also flow in a downward direction. Combinations of
downward and upward flow are also within the scope of the present
invention. The lipid-containing feedstock and the cracking catalyst
may be contacted in counterflow or crossflow configurations.
[0037] According to an embodiment of the invention, the CO.sub.2
produced in the cracking step and the catalyst regeneration step
may be reused for cultivation and propagation of the diatomic
microalgae being used in the process. This process integration
preferably mitigates the emissions from the overall process and
facilitates cultivation of diatomic microalgae.
[0038] The product stream can comprise products that may include
gaseous hydrocarbons with four or less carbon atoms, gasoline,
diesel, cycle oils and other hydrocarbons.
[0039] The product stream, comprising cracked hydrocarbons,
obtained from the FCC apparatus is preferably sent to a
fractionation zone, where it is separated into one or more
hydrocarbon fractions. Preferably, these hydrocarbon fractions
include dry gas, propylene, Liquefied Petroleum Gas (LPG),
gasoline, light cycle oils and coke. According to an embodiment,
the product stream composition includes a gasoline fraction ranging
from 30 wt % to 60 wt %, preferably from 40 wt % to 50 wt %, based
on the total product stream composition, as measured by Gas
Chromatograph Distillation (GCD) according to the methods described
in ASTM D-2887. Further, the total product stream composition
includes a LPG fraction ranging from 5 wt % to 20 wt %, preferably
from 10 wt % to 15 wt % of the total product stream composition
(ASTM D-2887).
[0040] These hydrocarbon fractions may undergo further processing
before they are provided for commercial use. Examples of the said
processing may include desulfurization, cracking of heavier
fractions and addition of additives.
[0041] The commercial products obtained from these hydrocarbon
fractions are also within the scope of the invention. For example,
the gasoline fraction may be desulfurized to reduce the sulfur
content to less than 1000 ppmw, preferably to less than 500 ppmw,
more preferably to less than 200 ppmw to prepare a gasoline
product. One or more additives may be added to the desulfurized
gasoline product to prepare a gasoline composition for commercial
use. The additives may include performance enhancers such as
anti-oxidants, corrosion inhibitors, ashless detergents, dehazers,
dyes, lubricity improvers, synthetic or mineral oil carrier fluids.
Examples of such suitable additives may also be identified in U.S.
Pat. No. 5,855,629, which is incorporated herein by reference. For
the purpose of the invention, it should be understood that the one
or more additives can be added separately to the gasoline product
or can be blended with one or more diluents, forming an additive
concentrate, and together added to the gasoline product. The
gasoline composition according to the invention preferably
comprises a major amount (more than 50 wt %) of the gasoline
product and a minor amount of the one or more additives described
above, preferably ranging from 0.005 wt % to 10 wt %, more
preferably from 0.01 wt % to 5 wt %, and most preferably from 0.02
wt % to 1 wt %, based on the gasoline composition.
[0042] It may be understood that processing of the aforementioned
hydrocarbon fractions is well known in the art and is in no way
limiting to the scope of the invention. While some of the methods
have been described herein, several other processes may be used to
convert the hydrocarbon fractions into commercially usable
products. These processes may include isomerisation, cracking into
more valuable lighter products, blending with other fuels for
commercial use, and other similar uses that have been disclosed in
the art.
[0043] The invention is further illustrated by the following
experiments.
Experiment 1
[0044] A batch of marine microalgae of species Chlorella was
partially dried and milled. Lipids were then extracted from the
marine microalgae using toluene as a solvent in a solvent
extraction process. The extracted lipids were analysed online using
gas chromatography (GC) and inductively coupled plasma mass
spectrometry (ICP-MS) and were found to have the following
distribution:
TABLE-US-00001 TABLE 1 Extracted lipids from Chlorella microalgae
Component Weight % Phospholipids 4.5% Mono-glyceride 4%
Di-glyceride 24% Tri-glyceride 58% Free Fatty Acid 9% Total 95%
[0045] A blend of 20 wt % of these extracted lipids and 80 wt % of
a mineral oil derived vacuum gas oil was mixed. The Blend had the
following metal content (see table 2 in mg/kg as determined by
ICP-AES).
TABLE-US-00002 TABLE 2 metal content in a blend of 20 wt % of
extracted lipids with 80 wt % a mineral oil derived vacuum gas oil
(in mg/kg) Al 50 Ca 73 Fe 50 Mg 635 Mn 10 Na 92 P 370 Si 52
Experiment 2
[0046] The lipids obtained from experiment 1 were blended with
mineral Vacuum Gas Oil (VGO) to form a first batch of the
lipid-containing feedstock comprising 20% extracted lipids from
microalgae and 80% VGO (by weight). The first batch was subjected
to catalytic cracking in a small-scale fluidised catalytic cracking
reactor. A commercial equilibrium catalyst comprising ultra stable
zeolite Y (USY) in an amorphous alumina matrix was used as the
cracking catalyst. The reaction temperature was kept at 500.degree.
C., and the pressure was maintained at 1.1 bar (0.11 MPa). For the
feedstock containing 20 wt % extracted lipids from microalgae and
80 wt % VGO a catalyst to oil ratio of about 8 was used. The
product stream obtained was separated in a small-scale fractionator
and analysed online using gas chromatography (GC) and inductively
coupled plasma mass spectrometry (ICP-MS). The results of the
experiment with regard to product distribution at 67 wt %
conversion are provided in Table 3.
TABLE-US-00003 TABLE 3 Product distribution Product Yield (wt %)
Dry gas 1.9 Propylene 2.8 LPG 12.0 Gasoline 43.5 LCO 25.2 HCO 3.2
Slurry Oil 1.75 Coke 9.0
[0047] Dry gas includes ethylene and LPG includes propane and
butane gas. Gasoline is defined as the fraction starting with C5
isomers, and boiling up to 221.degree. C. (EP); Light Cycle Oil
(LCO) as the fraction boiling from 221-370.degree. C. (IBP-EP);
Heavy Cycle Oil (HCO) as the fraction boiling from 370-425.degree.
C. (IBP-EP); and Slurry Oil as the fraction boiling above
>425.degree. C., determined according to ASTM 2887, using the
total boiling point method.
Experiment 3
[0048] To establish the efficacy of the cracking process of the
invention, the product stream was compared with the products
obtained from the cracking of other conventionally used feedstock.
VGO was used as the second batch and a blend of 20% rapeseed oil
and 80% VGO was used as the third batch. The experiments were
conducted in the same fluidised catalytic cracking reactor and
under the same conditions as were used in experiment 2, except that
a different catalyst to oil ratio may be used to achieve the
constant conversion rate of 67 wt %. A comparison of the product
stream obtained from experiments 2 and 3 is provided in Table
4.
TABLE-US-00004 TABLE 4 Product yields at constant 67% conversion
(wt %) First batch: Second Batch Third 20% lipids Conventional
batch: 20% marine algae/ cracking feedstock rapeseed 80% VGO batch:
VGO only oil/80% VGO Dry gas 1.9 1.9 2.0 Propylene 2.8 3.3 3.5 LPG
12.0 13.0 13.0 Gasoline 43.5 46.4 45.0 LCO 25.2 26.9 24.6 HCO 3.2
3.9 3.5 Slurry Oil 1.75 2.2 2.1 Coke 9.0 5.8 6.9
[0049] The product yield of each batch of cracking feedstock was
calculated at 67 wt % conversion of the cracking feedstock. It is
evident from the results above that the product stream obtained
from the first batch of cracking feedstock comprising lipids
derived from marine microalgae is substantially similar to the
product stream obtained from the two conventional cracking
feedstock. This is highly surprising in view of the high content in
heteroatoms such as phosphorus and metals. Moreover, the amount of
light cycle oil obtained was above that generated from rapeseed
oil.
[0050] The additional coke formed in the process according to the
invention can be advantageous when co-processing a further
paraffinic feedstock such as for example an optionally
hydroisomerised fraction of the synthesis product of a
Fisher-Tropsch reaction.
* * * * *