Description:FIELD OF INVENTION:
The present disclosure relates to a method for preparation of a catalyst for conversion of vacuum residue or heavy hydrocar bons to middle distillates. In particular, it relates to an improved method for catalyst preparation involving compounding of at least one metal with alumina along with additives. In other word, the present invention involves co-mulling of Group VI metal and additives with pseudo-boehmite which provides minimization of process steps.
BACKGROUND OF THE INVENTION:
The importance of processing of heavy crudes or vacuum residue as feedstock for the production of fuels and chemicals is increasing around the world. The heavy hydrocarbons or vacuum residue feedstock contain high metal content, sulphur, micro carbon residue and asphaltenes which are the key obstacles for conversion of these feedstocks into middle distillates and low boiling products. The hydrocracking route where these feedstocks are treated with hydrogen in presence of a catalyst results in low boiling hydrocarbons and middle distillates. Among various vacuum residues and heavy hydrocarbons hydrocracking processes, ebullated-bed, fixed bed and slurry phase processes utilize supported metal catalysts. In general, the supported metal catalysts comprise of γ-Al2O3 as support and Group VIB and Group VIIIB metals as active metals.
EP 1684899 B1 discloses a stabilized aqueous composition as impregnation solution to impregnate on pseudo-boehmite and co-mulling with active metal Group VIB and Group VIIIB components along with phosphorous acid to form final catalyst. The final catalyst is applied for hydro conversion of high boiling hydrocarbons to light products. The formation of stable active species is due to the sequential addition of metal precursors in the impregnation solution.
US 20220062871A1 discloses preparation of heavy hydrocarbon processing catalyst by co-mulling of pseudo-boehmite with molybdenum oxide, nickel nitrate and hydro processing catalyst fines. The final catalyst has a surface area of >250 m2/g and exhibited a higher heavy hydrocarbon conversion than a comparative catalyst with a surface area <250 m2/g.
US 10518251 B2 discloses preparation of hydrotreating catalyst for residue hydrocarbon feedstock. It discloses preparation of impregnation solution containing molybdenum, nickel and phosphorus and two step co-impregnation of the same over alumina support.
EP2906344A1 discloses preparation of supported hydrotreating catalyst comprising of Group VI, Group VIII metals, phosphorous compound and a polymer additive.
There are continuing efforts to develop residue hydrocracking catalysts with improved product yields and catalytic performance. The improved catalysts are being prepared by using addition of additives to formed catalyst support bodies or precursor of the support material. In residue upgradation processes such as ebullated bed residue hydrocracking the catalysts are unique in terms of properties and quantities. The development of residue hydrocracking catalysts with simplified processes is essential.
OBJECTIVE OF THE INVENTION:
It is an object of the present invention to provide a method for preparation of a residue hydrocracking catalyst for the conversion of residue and or heavy hydrocarbons into middle distillates under ebullated bed hydrocracking conditions.
An object of the invention is to provide a process for preparation of residue hydrocracking catalyst with minimized process steps.
Another object of the invention is to provide a method for preparation of support extrudates with at least one active metal.
Another object of the present invention is to provide a process for preparation of metal loaded catalyst formed bodies for residue hydrocracking.
Another object of the present invention is to convert residue and or heavy hydrocarbons into middle distillates with at least 80% conversion of asphaltenes and CCR.
SUMMARY OF THE INVENTION:
Accordingly, the present invention provides a method for preparation of a catalyst for hydrocracking of vacuum residue or heavy hydrocarbons to middle distillates, the method comprising the steps of:
(a) preparing an extrudable dough containing a first metal precursor, a carbohydrate, an organic acid, water and pseudo-boehmite;
wherein the extrudable dough is obtained by adding a solution containing the first metal precursor, the carbohydrate, the organic acid, and water, to pseudo-boehmite powder;
(b) extruding the extrudable dough into a cylindrical extrudate followed by aging, drying and calcination to get extrudates loaded with first metal; and
(c) impregnating an aqueous solution of second metal precursor containing an organic acid on the calcined extrudates of first metal followed by aging, drying and calcination to obtain the catalyst;
wherein the first metal is selected from Group VI and the second metal is selected from Group VIIIB, wherein the catalyst for hydrocracking has a surface area of 250-350 m2/g, pore volume of 0.5-0.8 cc/g and average pore diameter of 8-12 nm.
In one of the features of the present invention, the preparation of extrudable dough contains molybdenum precursor as the first metal precursor, disaccharides as the carbohydrate and carboxylic acid with 1 to 3 carbon number as the organic acid.
In another feature of the present invention, the molybdenum precursor is selected from one or combinations of molybdenum oxide, ammonium heptamolybdate; where the disaccharide is selected from one or combination of sucrose, maltose, lactose; where the organic acid is selected from one or combination of formic acid, acetic acid, propionic acid.
In yet another feature of the present invention, the extrudable dough contains the weight ratios of molybdenum: organic acid: disaccharide: pseudo-boehmite are in the range of 0.5-3: 0.24-1.22:0.8-3:6-22.
In yet another feature of the present invention, the solution added to pseudo-boehmite is heated under reflux conditions at a temperature of 40-70 °C for a period of 0.5- 3 hours.
In yet another feature of the present invention, the solution added to pseudo-boehmite for the preparation of extrudable dough has a pH of 2.5-5.
In yet another feature of the present invention, the extrudates of step (b) are aged at a temperature of 25-35 °C for a period of 6-12 hours; where the extrudates are dried at a temperature of 50-90 °C for a period of 6-10 hours; where the extrudates are calcined at a temperature of 500-600 °C for a period of 1-5 hours.
In yet another feature of the present invention, the second metal precursor is nickel precursor and carboxylic acid with 1 to 3 carbon number as organic acid; where nickel precursor is selected from one or combination of nickel chloride, nickel acetate, nickel sulphate; organic acid is selected from one or combination of formic acid, acetic acid.
In yet another feature of the present invention, the nickel to molybdenum mole ratio is maintained at in the range of 0.2-1.
In yet another feature of the present invention, the second metal precursor loaded extrudates are aged at a temperature of 25-35 °C for a period of 1-12 hours; where the extrudates are dried at a temperature of 80-140 °C for a period of 6-10 hours, where the extrudates are calcined at a temperature of 400-550 °C for a period of 1-6 hours.
In yet another feature of the present invention, the catalyst for hydrocracking has metal oxide reduction temperature in the range of 380-450 °C.
In yet another feature of the present invention, the vacuum residue or heavy hydrocarbons contain at least 3-5 wt.% sulphur, 15-20 wt.% CCR, 8-15 wt.% asphaltenes and at least 80 wt.% hydrocarbons having boiling point of >540 °C.
In yet another feature of the present invention, the catalyst for hydrocracking exhibits at least 75-90% conversion of >540 °C hydrocarbons.
In yet another feature of the present invention, the catalyst exhibits at least 80% asphaltene conversion and at least 85% of CCR removal.
The present invention also provides a catalyst for hydrocracking of vacuum residue or heavy hydrocarbons to middle distillates comprises pseudo boehmite as a support precursor and combination of Group VI and Group VIIB metals as active species, carbohydrate and organic acids.
In an embodiment, the present invention provides a residue hydrocracking catalyst for conversion of vacuum residue and or heavy hydrocarbons into middle distillates with minimized process steps for ebullated bed reaction conditions.
In another embodiment, the present invention provides a supported residue hydrocracking catalyst comprising of first metal containing extrudates preparation followed by second metal deposition wherein the first metal is selected from Group VI and the second metal is selected from Group VIIIB.
In another embodiment, the present invention provides a method for preparation of supported residue hydrocracking catalyst consists of preparation of first metal containing support extrudates using first metal precursor solution, additives and pseudo-boehmite and subsequent thermal treatments followed by second metal deposition using second metal precursor solution and additive.
In one of the features of the present invention, in the preparation of first metal containing support extrudate the additive used comprises poly hydroxy carbohydrate molecules and an organic acid and the additive used in the second metal deposition comprises organic carboxylic acids having carbon number not more than three.
In another embodiment, the present invention provides a method for preparation of supported residue hydrocracking catalyst consisting of the weight ratios of molybdenum: organic acid: disaccharide: pseudo-boehmite are in the range of 0.5-3:0.24-1.22:0.8-3:6-22; the second metal precursor is nickel precursor and carboxylic acid with 1 to 3 carbon number as organic acid and the nickel to molybdenum mole ratio is maintained at in the range of 0.2-1.
In another embodiment, the present invention provides a supported residue hydrocracking catalyst that has a surface area of 250-350 m2/g, pore volume of 0.5-0.8 cc/g and average pore diameter of 8-12 nm.
In another feature of the present invention, carboxylic acid with 1 to 2 carbon number as the organic acid.
DETAILED DESCRIPTION OF THE INVENTION:
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments in the specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated process, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The composition, methods, and examples provided herein are illustrative only and not intended to be limiting.

The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.
Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

The base values are the properties and activity values of the comparative catalyst.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.

The terminology and structure employed herein is for describing, teaching, and illuminating some embodiments and their specific features and elements and does not limit, restrict, or reduce the spirit and scope of the invention.
The present invention provides a method for preparation of a catalyst for hydrocracking of vacuum residue or heavy hydrocarbons to middle distillates, the method comprising the steps of:
(a) Preparation of extrudable dough containing first metal precursor, carbohydrate, organic acid, water and pseudo-boehmite
(b) Extrusion of extrudable dough into cylindrical extrudates of 1 mm diameter followed by aging, drying and calcination to get extrudates loaded with first metal.
(c) Deposition of second metal precursor using aqueous solution containing organic acid followed by drying and calcination.
Wherein the catalyst for vacuum residue or heavy hydrocarbons hydrocracking the first metal is selected from Group VI and the second metal is selected from Group VIIIB. Where in the catalyst for hydrocracking of vacuum residue has a surface area of 250-350 m2/g, pore volume of 0.5-0.8 cc/g and average pore diameter of 8-12 nm.
In one of the features of the present invention, the pseudo-boehmite used for the preparation of the catalyst has a surface area of at least 250 m2/g, pore volume of at least 0.5 cc/g; dispersibility index of at least 35% and 27% of maximum loss of ignition at 550 °C. The extrudable dough contains 8-22 parts of pseudo-boehmite weight.
In another feature of the present invention, the first metal is molybdenum and its precursor is selected from one or combinations of molybdenum oxide, ammonium heptamolybdate with 1-3 parts of molybdenum weight in the total weight of the extrudable dough.
In another feature of the present invention, carboxylic acid is an organic acid having 1 to 3 carbon number with 0.25-1.5 parts of carboxylic acid weight in the total weight of the extrudable dough.
In another feature of the present invention, the disaccharide is selected from one or combination of sucrose, maltose, lactose with 0.5-3 parts of disaccharide weight in the total weight of the extrudable dough.
In yet another feature of the present invention, the extrudates have a diameter of 1 mm in size and subjected to thermal treatments at a temperature range of 90-600 °C.
In yet another feature of the present invention, the aging step after extrudates preparation and impregnation is done at 25-35 °C for period of 1-12 hours. The drying step is performed at 50-140° C. for a period of 6-10 hours. The calcination step after extrudates preparation and impregnation is done at temperature of 400-600° C. for a period of 1-6 hours.
In yet another feature of the present invention, the second metal is nickel and its precursor is selected from one or combination of nickel chloride, nickel acetate, nickel sulphate with nickel to molybdenum mole ratio of 0.2-1.
In yet another feature of the present invention, the vacuum residue or heavy hydrocarbons comprises at least 40-80 wt.% hydrocarbon having boiling point above 540° C.
In yet another feature of the present invention, it provides a process for conversion of residue or heavy hydrocarbons to middle distillates by contacting the same with the catalyst prepared using above method under ebullated bed conditions.
In one of the features of the present invention, the ebullated-bed reactor hydrocracking stage is operated at a partial pressure of between about 80 bars and about 210 bars; an operating temperature of between about 380° C and about 490° C; a liquid hourly space velocity of between about 0.15 h-1 and about 4.0 h-1.
In yet another feature of the present invention, the residue hydrocracking catalyst is capable of conducting hydrogenation, hydrodesulfurization, hydrodemetallization, hydrodenitrification, hydrodearomatization reactions.
In yet another feature of the present invention, the residue hydrocracking catalyst exhibited a residue or heavy hydrocarbon conversion of at least 55%.
EXAMPLES
The present disclosure with reference to the accompanying examples describes the present invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention. It is understood that the examples are provided for the purpose of illustrating the invention only and are not intended to limit the scope of the invention in any way.
Example 1:
The comparative catalyst synthesis procedure contains the following steps:
a. The synthesis of catalyst involves dissolving 7.72 g of ammonium heptamolybdate in deionized water. The solution is heated at 60oC for 2 h. The resultant solution is impregnated with pseudo-boehmite powder with a dispersibility index of 35-40%. The impregnated powder is mixed and kneaded to get an extrudable dough using acetic acid as peptizing agent. The extrudable dough maintained at a weight ratio of molybdenum: pseudo-boehmite of 1:7. The extrudable dough is extruded into cylindrical extrudates with diameter of ~ 1 mm. The extrudates are aged at room temperature followed by drying at 90oC. The dried extrudates are calcined at 550oC.
b. The calcined extrudates are impregnated with an aqueous solution containing nickel acetate at a Ni to Mo mole ratio of 0.65. The impregnated extrudates are aged at room temperature followed by drying at 90oC and calcined at 500oC.
Example 2:
The inventive catalyst synthesis procedure contains the following steps:
a. The synthesis of catalyst involves dissolving 7.72 g of ammonium heptamolybdate in a solution mixture containing deionized water, formic acid and sucrose. The solution is heated at 60oC for 2 h and final pH is 3. The resultant solution is impregnated with pseudo-boehmite powder with a dispersibility index of 35-40%. The impregnated powder is mixed and kneaded to get an extrudable dough using acetic acid as peptizing agent. The extrudable dough maintained at a weight ratio of molybdenum: formic acid: sucrose: pseudo-boehmite of 1:0.32:0.83:7. The extrudable dough is extruded into cylindrical extrudates with diameter of ~ 1 mm. The extrudates are aged at room temperature for 6 h followed by drying at 90oC for 6 h. The dried extrudates are calcined at 550oC for 4 h.
b. The calcined extrudates are impregnated with an aqueous solution containing nickel acetate and acetic acid at a Ni to Mo mole ratio of 0.65. The impregnated extrudates are aged at room temperature for 6 h followed by drying at 90oC for 6 h and calcination at 500oC for 3 h.

Properties Example 1
Catalyst Example 2
Catalyst
Surface area (m2/g) Base +60
Pore Volume (cc/g) Base +0.1
Average Pore Diameter (nm) Base +2.0
Acidity (NH3 µmol/g) Base +550
Reduction Temperature (°C) Base -100

Example 3:
The catalytic performance of the prepared catalysts was evaluated in an ebullated bed reactor at hydrocracking stage conditions. The residue or heavy hydrocarbon feed is obtained after demetallization stage with a characteristic of 50wt.% boiling above 540 °C, sulfur content of 4.3 wt.%, asphaltene content of 11%, and CCR of 18%. Ebullated bed hydrocracking reaction performed at 435 ºC and 175 bar of hydrogen pressure with residence time of 2 h. During the reaction, catalyst is maintained in ebullated state by mixing. The liquid product is characterized through simulated distillation to get the different fractions. The activity results are presented in Table 2.

Products Example 1
Catalyst
(Yield%) Example 2
Catalyst
(Yield%)
C1, C2 Base +1.0
H2S Base +0.2
LPG (C3 & C4) Base +0.3
Naphtha (IBP -180 ºC) Base +1.1
Middle distillates (180 -370 ºC) Base +9.0
VGO (370 -540 ºC) Base -4.0%
Residue (>540 ºC) Base -8.9%
Conversion (%) Base +8.9

The catalyst of example 2 exhibits 75-90% conversion of >540 °C hydrocarbons after hydrocracking. Also, the catalyst of example 2, exhibits at least 80% of asphaltene conversion and at least 85% of CCR removal after hydrocracking.
, Claims:1. A method for preparation of a catalyst for hydrocracking of vacuum residue or heavy hydrocarbons to middle distillates, the method comprising the steps of:
(a) preparing an extrudable dough containing a first metal precursor, a carbohydrate, an organic acid, water and pseudo-boehmite;
wherein the extrudable dough is obtained by adding a solution containing the first metal precursor, the carbohydrate, the organic acid, and water, to pseudo-boehmite powder;
(b) extruding the extrudable dough into a cylindrical extrudate followed by aging, drying and calcination to get extrudates loaded with first metal; and
(c) impregnating an aqueous solution of second metal precursor containing an organic acid on the calcined extrudates of first metal followed by aging, drying and calcination to obtain the catalyst;
wherein the first metal is selected from Group VI and the second metal is selected from Group VIIIB, wherein the catalyst for hydrocracking has a surface area of 250-350 m2/g, pore volume of 0.5-0.8 cc/g and average pore diameter of 8-12 nm.
2. The method of claim 1, wherein the preparation of extrudable dough contains molybdenum precursor as the first metal precursor, disaccharides as the carbohydrate and carboxylic acid with 1 to 3 carbon number as the organic acid.
3. The method of claims 1 and 2, wherein the molybdenum precursor is selected from one or combinations of molybdenum oxide, ammonium heptamolybdate; where the disaccharide is selected from one or combination of sucrose, maltose, lactose; where the organic acid is selected from one or combination of formic acid, acetic acid, propionic acid.
4. The method of claim 1, wherein the extrudable dough contains the weight ratios of molybdenum: organic acid: disaccharide: pseudo-boehmite are in the range of 0.5-3: 0.24-1.22:0.8-3:6-22.
5. The method of claim 1, wherein the solution added to pseudo-boehmite is heated under reflux conditions at a temperature of 40-70 °C for a period of 0.5- 3 hours.
6. The method of claim 1, wherein the solution added to pseudo-boehmite for the preparation of extrudable dough has a pH of 2.5-5.
7. The method of claim 1, wherein the extrudates of step (b) are aged at a temperature of 25-35 °C for a period of 6-12 hours; where the extrudates are dried at a temperature of 50-90 °C for a period of 6-10 hours; where the extrudates are calcined at a temperature of 500-600 °C for a period of 1-5 hours.
8. The method of claim 1, wherein the second metal precursor is nickel precursor and carboxylic acid with 1 to 3 carbon number as organic acid; where nickel precursor is selected from one or combination of nickel chloride, nickel acetate, nickel sulphate; organic acid is selected from one or combination of formic acid, acetic acid.
9. The method of claim 1, wherein the nickel to molybdenum mole ratio is maintained at in the range of 0.2-1.
10. The method of claim 1, wherein the second metal precursor loaded extrudates are aged at a temperature of 25-35 °C for a period of 1-12 hours; where the extrudates are dried at a temperature of 80-140 °C for a period of 6-10 hours, where the extrudates are calcined at a temperature of 400-550 °C for a period of 1-6 hours.
11. The method of claim 1, wherein the catalyst for hydrocracking has metal oxide reduction temperature in the range of 380-450 °C.
12. The method of claim 1, wherein the vacuum residue or heavy hydrocarbons contain at least 3-5 wt.% sulphur, 15-20 wt.% CCR, 8-15 wt.% asphaltenes and at least 80 wt.% hydrocarbons have boiling point of >540 °C.
13. The method of claims 1 and 12, wherein the catalyst for hydrocracking exhibits at least 75-90% conversion of >540 °C hydrocarbons.
14. The method of claims 1 and 12, wherein the catalyst exhibits at least 80% asphaltene conversion and at least 85% of CCR removal.
15. A catalyst for hydrocracking of vacuum residue or heavy hydrocarbons to middle distillates where the catalyst comprises pseudo boehmite as a support precursor and combination of Group VI and Group VIIB metals as active species, carbohydrate and organic acids.