Catalyst, a process for its preparation, and its use

Abstract

Process for the preparation of a catalyst comprising the steps of (a) preparing a slurry comprising clay, zeolite, and quasi-crystalline boehmite, provided that the slurry does not comprise peptized quasi-crystalline boehmite, (b) adding a monovalent acid to the slurry, (c) adding a silicon source to the slurry, and (d) shaping the slurry to form particles. This process leads to a catalyst with high accessibility and high attrition resistance.

Claims

1. A process for the preparation of a catalyst comprising the steps of: a) preparing a slurry comprising clay, zeolite, and quasi-crystalline boehmite, provided that the slurry does not comprise peptised quasi-crystalline boehmite, b) adding a monovalent acid to the slurry, c) preparing a silicon source by preparing a slurry of diluted water glass and H.sub.2SO.sub.4 at a weight ratio of DWG/H.sub.2SO.sub.4 of at least 2.0 in an amount sufficient to provide silica in an amount of 1-35 wt %, based on dry solids content and calculated as SiO.sub.2, d) adding the silicon source to the slurry of step b) less than 30 minutes before step e) and e) shaping the mixture of step d) to form particles.

2. The process according to claim 1 wherein the slurry obtained in step a) does not comprise a silicon source selected from the group consisting of sodium silicate, potassium silicate, lithium silicate, calcium silicate, magnesium silicate, barium silicate, strontium silicate, zinc silicate, phosphorus silicate, borium silicate, polyorganosiloxanes, methyl chlorosilane, dimethyl chlorosiline, trimethyl chlorosilane, and mixtures thereof.

3. The process according to claim 1 further comprising an additional silicon source added in step d), wherein said silicon source is selected from the group consisting of sodium silicate, potassium silicate, lithium silicate, calcium silicate, magnesium silicate, barium silicate, strontium silicate, zinc silicate, phosphorus silicate, borium silicate, polyorganosiloxanes, methyl chlorosilane, dimethyl chlorosiline, trimethyl chlorosilane, and mixtures thereof.

4. The process according to claim 1, further comprising adding a base to the mixture of step (d) prior to the shaping step of step (e).

5. The process according to claim 4, wherein the pH of the mixture is raised by the base to be between about 3 and about 7.

6. The process according to claim 1, wherein the solids content of the slurry is between 10-30 wt %.

7. The process according to claim 1, wherein the solids content of the mixture after step d) is between 20-30 wt %.

8. A catalyst composition comprising clay, zeolite, and quasi-crystalline boehmite, wherein the composition is prepared by a) preparing a slurry comprising clay, zeolite, and quasi-crystalline boehmite, provided that the slurry does not comprise peptised quasi-crystalline boehmite; b) adding a monovalent acid to the slurry; c) preparing a silica source by preparing a slurry of diluted water glass and H2SO4 at a weight ratio of DWG/H.sub.2SO.sub.4 of at least 2.00 in an amount sufficient to provide silica in an amount of 1-35 wt %, based on dry solids content and calculated as SiO.sub.2; d) adding the silica source to the slurry of step b) less than 30 minutes before step e), and e) shaping the mixture of step d) to form particles.

Description

EXAMPLES

(1) Accessibility Measurement

(2) The accessibility of the catalysts prepared according to the Examples below was measured by adding 1 g of the catalyst to a stirred vessel containing 50 g of a 15 g/l Kuwait vacuum gas oil (KVGO) in toluene solution. The solution was circulated between the vessel and a spectrophotometer, in which process the KVGO-concentration was continuously measured.

(3) The accessibility of the catalysts to KVGO was quantified by the Akzo Accessibility Index (AAI). The relative concentration of KVGO in the solution was plotted against the square root of time. The AAI is defined as the initial slope of this graph:
AAI=d(C.sub.t/C.sub.0)/d(t.sup.1/2)*100%

(4) In this equation, t is the time (in minutes) and C.sub.0 and C.sub.t denote the concentrations of high-molecular weight compound in the solvent at the start of the experiment and at time t, respectively.

(5) Attrition Resistance

(6) The attrition resistance of the catalysts was measured by the standard Attrition Test. In this test the catalyst bed resides on an attrition plate with three nozzles. The attrition plate is situated within an attrition tube, which is at ambient temperature. Air is forced to the nozzles and the resulting jets bring about upward transport of catalyst particles and generated fines. On top of the attrition tube is a separation chamber where the flow dissipates, and most particles larger than about 16 microns fall back into the attrition tube. Smaller particles are collected in a collection bag.

(7) This test is conducted after calcination of the catalyst samples at 600 C., and it is first run for 5 hours and the weight percentage of fines collected in the collection bag, based on an imaginary intake of 50 grams, is determined. This is the initial attrition. The test is then conducted for another 15 hours and the weight percentage of fines in this time period (5-20 hours) is determined. This is the inherent attrition. The Attrition Index (AI) is the extrapolated wt % fines after 25 hours. So, the more attrition resistant the catalyst is, the lower the AI value.

Example 1

(8) A slurry was prepared by mixing 60.6 kg of a zeolite Y slurry (29.7 wt % solids) with 23.3 kg of a microcrystalline boehmite slurry (23.2 wt % Al.sub.2O.sub.3), 16.2 kg of a kaolin slurry (85.3 wt % solids), 14.2 kg of slurry containing non-peptised pseudoboehmite (71.9 wt % Al.sub.2O.sub.3), and 48.9 kg water. HNO.sub.3 was added to the resulting slurry until the pH was 3.3.

(9) A silica sol was made in a pipeline mixer (5,900 rpm) by mixing diluted water glass (DWG) with H.sub.2SO.sub.4. The weight ratio DWG/H.sub.2SO.sub.4 was 2.9.

(10) Both this silica sol and the slurry prepared above were pumped to a mixing vessel (1450 rpm), resulting in a slurry of 21 wt % solids. The silica sol was pumped to this vessel with a flow of 0.88 kg/min; the slurry was pumped with a flow of 2.12 kg/min. The resulting slurry, which had a pH of about 2.5, was then fed to a spray-dryer with a flow of 3.0 kg/min, an inlet temperature of 300 C., an outlet temperature of 125 C., and a nozzle pressure of 40 bar.

(11) The spray-dried particles had a d50 of about 75 microns.

(12) The particles contained 30 wt % zeolite, 17 wt % QCB, 9 wt % MCB, 21 wt % silica, and balance kaolin.

(13) Using this recipe, four samples according to the invention were made:

(14) Sample A1 was made exactly as above;

(15) Sample B1 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 3.8;

(16) Sample C1 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 4.2;

(17) Sample D1 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 4.6.

(18) Two comparative samples (CC1 and CD1) were made by the same procedure by increasing the pH to 4.2 (CC1) and 4.6 (CD1) just before spray-drying, except that peptised pseudoboehmite (peptised with nitric acid) was used.

(19) The samples were subsequently washed in order to reduce their sodium content to below 0.5 wt % (as Na.sub.2O) by re-slurrying 12 kg of the particles in a 40-litre ammonia solution at pH 5.0. Next, the particles were filtered and washed with a 30-litre ammonia solution containing 420 g ammonium sulphate and a pH of 8.3, re-slurried again in a 30-litre ammonia solution at pH 7.8, and filtered and washed again with a 30-litre ammonia solution containing 420 g ammonium sulphate at pH 8.3. Finally, the particles were washed with water and subsequently flash-calcined (outlet gas temperature 150 C.).

(20) All washing steps were conducted at 45 C.

(21) The Attrition Index (AI) and Akzo Accessibility Index (AAI) were measured for all the above samples: see Table 1. This Table also indicates the ratio AAI/AI. It is clear that the catalysts prepared according to the process of the present invention have a lower attrition (i.e. a higher attrition resistance) and a higher AAI/AI ratio. Comparing the results for Samples A1 through D1 further shows that the accessibility increases with the pH just before spray-drying.

(22) TABLE-US-00001 TABLE 1 Sample AI AAI AAI/AI A1 1.2 0.9 0.8 B1 2.5 3.3 1.3 C1 2.7 4.4 1.6 D1 4.5 6.6 1.5 CC1 6 4.5 0.75 CD1 10.1 6.1 0.6

Example 2

(23) A slurry was prepared by mixing 66.445 kg of a zeolite Y slurry (27.1 wt % solids) with 25.851 kg of a microcrystalline boehmite slurry (23.2 wt % Al.sub.2O.sub.3), 24.619 kg of a kaolin slurry (85.3 wt % solids), 8.054 kg of slurry containing non-peptised pseudoboehmite (74.5 wt % Al.sub.2O.sub.3), and 48.9 kg water. To the resulting slurry, 5.6 kg HNO3 were added until the pH was 3.3.

(24) A silica sol was made in a pipeline mixer (5,900 rpm) by mixing diluted water glass (DWG) with H.sub.2SO.sub.4. The weight ratio DWG/H.sub.2SO.sub.4 was 2.92.

(25) Both this silica sol and the slurry prepared above were pumped to a mixing vessel (1,450 rpm), resulting in a slurry of 25 wt % solids. The silica sol was pumped to this vessel with a flow of 0.75 kg/min; the slurry was pumped with a flow of 2.25 kg/min. The resulting slurry, which had a pH of about 2.5, was then fed to a spray-dryer with a flow of 3.0 kg/min, an inlet temperature of 300 C., an outlet temperature of 125 C., and a nozzle pressure of 40 bar.

(26) The spray-dried particles had a d50 of about 75 microns.

(27) The particles contained 30 wt % zeolite, 10 wt % QCB, 10 wt % MCB, 15 wt % silica, and balance kaolin.

(28) Using this recipe, four samples according to the invention were made:

(29) Sample A2 was made exactly as above;

(30) Sample B2 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 3.8;

(31) Sample C2 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 4.2;

(32) Sample D2 was obtained by adding caustic to the slurry just before spray-drying, thereby arriving at a pH of 4.6.

(33) Two comparative samples (CB2 and CE2) were made by the same procedure by increasing the pH to 3.8 (CB2) or 5 (CE2) just before spray-drying, except that peptised pseudoboehmite was used.

(34) The samples were subsequently washed in order to reduce their sodium content to below 0.5 wt % (as Na.sub.2O) by re-slurrying 12 kg of the particles in a 40-litre ammonia solution at pH 5.0. Next, the particles were filtered and washed with a 30-litre ammonia solution containing 420 g ammonium sulphate and a pH of 8.3, reslurried again in a 30-litre ammonia solution at pH 7.8, and filtered and washed again with a 30-litre ammonia solution containing 420 g ammonium sulphate at pH 8.3. Finally, the particles were washed with water and subsequently flash-calcined (outlet gas temperature 150 C.).

(35) All washing steps were conducted at 45 C.

(36) The Attrition Index (AI) and Akzo Accessibility Index (AAI) were measured for all the above samples: see Table 2. This Table also indicates the ratio AAI/AI. This ratio is substantially higher for the catalysts according to the invention than for the comparative catalysts. Again, this Table shows that the accessibility increases with the pH before spray-drying.

(37) TABLE-US-00002 TABLE 2 Sample AI AAI AAI/AI A2 0.7 0.9 1.3 B2 0.8 4.4 5.5 C2 1.5 5.3 3.5 D2 2.8 7.7 2.75 CB2 2.1 2.7 1.3 CE2 5.7 5 0.9

Example 3

(38) A slurry was prepared by mixing 10.4 kg of a zeolite Y slurry (23.1 wt % solids) with kg of a kaolin slurry (86 wt % solids), 16.8 kg of slurry containing non-peptised pseudoboehmite (17.3 wt % Al.sub.2O.sub.3), and 0.92 kg water. To the resulting slurry, HNO3 was added until the pH was 3.3.

(39) A silica sol was made in a pipeline mixer (5,900 rpm) by mixing diluted water glass (DWG) with H.sub.2SO.sub.4. The weight ratio DWG/H.sub.2SO.sub.4 was 2.3.

(40) Both this silica sol and the slurry prepared above were pumped to a mixing vessel (1450 rpm), resulting in a slurry of 25 wt % solids. The silica sol was pumped to this vessel with a flow of 0.75 kg/min; the slurry was pumped with a flow of 0.93 kg/min. The resulting slurry, which had a pH of about 2.5, was then fed to a spray-dryer with a flow of 3.0 kg/min, an inlet temperature of 500 C., an outlet temperature of 120 C., and a nozzle pressure of 40 bar.

(41) The spray-dried particles had a d50 of about 65 microns.

(42) The particles contained 24 wt % zeolite, 29 wt % QCB, 4 wt % silica, and balance kaolin.

(43) Using this recipe, five samples according to the invention were made:

(44) Sample A3 was made exactly as above;

(45) Sample B3 was obtained by adding ammonia to the slurry just before spray-drying, thereby arriving at a pH of 3.6;

(46) Sample C3 was obtained by adding ammonia to the slurry just before spray-drying, thereby arriving at a pH of 3.9;

(47) Sample D3 was obtained by adding ammonia to the slurry just before spray-drying, thereby arriving at a pH of 4.2.

(48) Sample E3 was obtained by adding ammonia to the slurry just before spray-drying, thereby arriving at a pH of 5.0.

(49) Two comparative samples (CD3 and CE3) were made by the same procedure by increasing the pH to 4.2 (CD3) and 5.0 (CE3) just before spray-drying, except that peptised pseudoboehmite was used.

(50) The samples were subsequently washed in order to reduce their sodium content to below 0.5 wt % (as Na.sub.2O) by re-slurrying 2 kg of the particles in hot water and ammonia solution at pH 5.0. Next, 200 g of ammonium sulphate were added to this slurry. The particles were then filtered and washed. The filter cake was re-slurried in hot water with 200 g ammonium sulphate, filtered, washed, and re-slurried in ammonium sulphate again. Finally, the particles were filtered and washed with hot water and ammonia at a pH between 8.0 and 8.5. After a last filtration, the particles were tray-dried in an oven.

(51) Table 3 lists the AI, AAI, and the ratio AAI/AI for these catalysts. Comparison of the results for D3 and E3 with those of CD3 and CE3 illustrates the positive effect of the process of the invention on the accessibility of the catalysts, without giving in on attrition resistance.

(52) Further, the accessibility increases with the pH before spray-drying.

(53) TABLE-US-00003 TABLE 3 Sample AI AAI AAI/AI A3 1.17 2.8 2.4 B3 1.58 7 4.4 C3 8.20 10.8 1.3 D3 5.00 13.5 2.7 E3 7.20 20.3 2.8 CD3 5.00 10 2 CE3 12.6 10 0.8

Example 4

(54) A slurry was prepared by mixing 8 kg of a zeolite Y slurry (25 wt % solids) with 4.17 kg of a kaolin slurry (86 wt % solids), 5 kg micro-crystalline boehmite (25 wt % Al.sub.2O.sub.3), 13.3 kg of slurry containing non-peptised pseudoboehmite (17.3 wt % Al.sub.2O.sub.3), and 0.92 kg water. To the resulting slurry, HNO3 was added until the pH was 3.3.

(55) A silica sol was made in a pipeline mixer (5,900 rpm) by mixing diluted water glass (DWG) with H.sub.2SO.sub.4. The weight ratio DWG/H.sub.2SO.sub.4 was 2.36.

(56) Both this silica sol and the slurry prepared above were pumped to a mixing vessel (1450 rpm), resulting in a slurry of 25 wt % solids. The silica sol was pumped to this vessel with a flow of 0.112 kg/min; the slurry was pumped with a flow of 0.888 kg/min. Ammonia was added to the slurry. The slurry was then fed to a spray-dryer with a flow of 3.0 kg/min, an inlet temperature of 500 C., an outlet temperature of 120 C., and a nozzle pressure of 40 bar.

(57) The spray-dried particles had a d50 of about 65 microns.

(58) The particles contained 20 wt % zeolite, 24 wt % QCB, 14 wt % MCB, 6 wt % silica, and balance kaolin.

(59) Using this recipe, two samples according to the invention were made:

(60) Sample A4 was obtained by adding ammonia to the slurry just before spray-drying in such an amount as to reach a pH of 4.2;

(61) Sample B4 was obtained by adding ammonia to the slurry just before spray-drying in such an amount as to reach a pH of 5.0;

(62) One comparative sample (CB4) was made by the same procedure by increasing the pH to 5 just before spray-drying, except that peptised pseudoboehmite was used.

(63) The samples were subsequently washed in order to reduce their sodium content to below 0.5 wt % (as Na.sub.2O) by re-slurrying 2 kg of the particles in hot water and ammonia solution at pH 5.0. Next, 200 g of ammonium sulphate were added to this slurry. The particles were then filtered and washed. The filter cake was re-slurried in hot water with 200 g ammonium sulphate, filtered, washed, and re-slurried in ammonium sulphate again. Finally, the particles were filtered and washed with hot water and ammonia at a pH between 8.0 and 8.5. After a last filtration, the particles were tray-dried in an oven.

(64) Table 4 lists the AI, AAI, and the ratio AAI/AI for these catalysts. It clearly shows the positive effect of the process of the invention on the accessibility of these catalysts.

(65) TABLE-US-00004 TABLE 4 Sample AI AAI AAI/AI A4 5.8 17 2.9 B4 8.6 26 3.0 CB4 5.8 12 2.1