FI62960C - FOER REFRIGERATION FOR EXTRUDING CATALYTIC COMPOSITION - Google Patents

Description

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Patent and registration authorities An * »kan utlsgd odi utLskrtfun public · rad ιι.ΐέ.οέ (32) (33) (31) Pyr4« t * y stuelkeui — fefftrd priori '* (71) UOP Inc., Ten U0P Plaza - Algonquin & Mt. Prospect Roads, Des Plaines,

Illinois, USA (72) Stanley Arthur Gembicki, Western Springs, Illinois, USA (US),

Stefan H. Aeschbach, Zurich, Switzerland-Schweiz (CH) (7 ^ +) Berggren Oy Ab (5 ^) Process for the preparation of an extruded catalyst mixture -Förfarande för framställning av extruderad katalytkompositiön

It has become well known that sulfur oxides plus smaller amounts of other sulfur-containing compounds are major atmospheric pollutants. It is estimated that in this country alone, more than 23 million tonnes of sulfur dioxide have been released into the atmosphere each year. The increasingly damaging effects of sulfur-containing pollutants on cardiovascular and respiratory diseases, eye irritation, etc. have prompted quite strong legislative action to curb the amount of sulfur dioxide released into the atmosphere, especially in densely populated areas where the problem is more serious. It has been established that the combustion of petroleum products is to blame for a substantial part of these sulfur oxides and legislation has been implemented or proposed, in particular to limit sulfur compounds in residual fuel oils burned in densely populated areas. The supply of residual fuel oils with a suitable low sulfur content is completely inadequate for current needs and it is becoming increasingly important to develop improved desulphurisation technology to handle fuel oils with relatively high sulfur content, which are more readily available and rich.

Desulfurization techniques today involve hydrotreating or hydrodesulfurization processes and the development of hydrodesulfurization catalysts, which are more selective and / or operate under less stringent conditions, preventing hydrocracking of the residual fuel oils being treated. Said reaction conditions typically include a temperature of about 95-425 ° C, although temperatures in the higher range, e.g., between about 315-425 ° C, are generally preferred. Conditions for the hydrodeulfurization reaction further include an operating pressure of about 0.7-13.8 MPa and hydrogen is normally fed into the process mixed with recycled hydrogen to provide about 180-9000 standard cubic meters per cubic meter of hydrocarbon feedstock. It is suitable to treat the sulfur-containing feedstock above the catalyst together with the hydrogen feed at a liquid volume flow rate of about 0.5 to 20 times.

It is an object of the present invention to provide an extruded mixture having particular use in connection with a Group VIA and Group VIII metal component to provide a catalyst with improved activity for hydrodesulfurization of residual fuel oils under the hydrodesulfurization reaction conditions set forth.

The preparation of the extruded catalyst according to the invention comprises mixing the powdered refractory inorganic oxide with a Group VIA metal compound and a Group VIII metal compound in such proportions as to provide a dry mixture containing 4-30% by weight of Group VIA metal and 1-10% by weight. Group VIII metal, liquid peptizing acid, and water are added to the mixture to provide a moist paste, which paste is extruded and cut into particles, dried and calcined, and is characterized in that catalyst particles are prepared that are increasingly active to form a moist paste containing such amounts of water. the paste, which has a loss on ignition at 900 ° C when calcined at 50-70% by weight, is stirred under shear mixing conditions at such an intensity that the energy input is 33-260 Wh / kg of dry oxide contained in the mixture, for 0.5-5 minutes.

A more specific embodiment of this invention is an extruded mixture prepared by mixing a finely divided alpha alumina monohydrate, a peptizing agent, and a sufficient amount of water to form a mixture characterized by an annealing loss of about 50-70% at 900 ° C; maintaining said mixture under shear mixing conditions, the intensity of said shear mixing being characterized by an energy supply corresponding to about 33-130 watt hours per kg of dry alumina contained in said mixture for about 1-3 minutes; extruding the obtained paste; and calcining the compact at a temperature of about 315-650 ° C.

62960 An even more specific embodiment of the present invention relates to an extruded mixture prepared by mixing a peptizing agent with finely divided alpha alumina monohydrate and sufficient water to form a mixture characterized by an annealing loss of about 55-65% C. said alumina being a mixture of alpha alumina monohydrate having an average bulk density of about 0.7 to 0.9 g / cm 3 and alpha alumina monohydrate having an average bulk density of about 0, 2-0.3 g / cm, with an average bulk density of about 0.4-0.5 g / cm; maintaining said mixture under shear-mixing conditions, the intensity of said shear mixture being characterized by an energy supply corresponding to about 33-130 watt-hours per kg of dry alumina contained in said mixture, for about 1-3 minutes; extruding the obtained paste; and calcining the compact at a temperature of about 315-650 ° C.

Other objects and embodiments of the present invention will become apparent from the following detailed specification.

According to the present invention, the peptizing agent is initially mixed with a finely divided refractory inorganic oxide and a sufficient amount of water to form a mixture characterized by n.

50-70% annealing loss at 900 ° C. The term "finely divided" is intended to describe particles having an average diameter of less than about 150 microns, for example, particles that can be recovered through a 105 micron microscreen. The refractory inorganic oxide may be such as alumina, silica, zirconia, thorium oxide, boron trioxide, chromium oxide, magnesia, titanium dioxide, etc., or combinations thereof, for example, alumina-silica, alumina-zirconia, alumina-alumina, etc. , especially alpha alumina monohydrate having a boehmite structure. Fine alpha alumina monohydrate is commercially available in various densities. However, an alpha-alumina monohydrate of one density may not be equivalent in density to another alpha-alumina monohydrate with respect to the hydrotreating process referred to herein. Alpha-alumina monohydrate particularly suitable for use herein is one having an average bulk density of n.

3 0.4-0.5 g / cm. The preferred procedure is to use a mixture of alpha-alumina monohydrate, in particular a mixture of alpha-alumina monohydrate with an average bulk density of n.

3 0.7-0.9 g / cm and alpha alumina monohydrate with an average bulk density of about 0.2-0.3 g / cm, taking advantage of the catalytic properties of the higher density alumina and the bonding properties of the lower density alumina to provide a product with suitable durability as well as improved activity. In any case, it is recommended to combine the alpha-alumina monohydrates in a ratio to obtain a mixture having the above-mentioned average bulk density of about 0.4 to 0.5 g / cm -1.

The finely divided refractory inorganic oxide is mixed with a peptizing agent and a sufficient amount of water to obtain a mixture characterized by a loss of impregnation of about 50-70% and preferably about 55-65% at 900 ° C. The peptizing agent is suitably a weak acid such as formic acid, acetic acid, propionic acid and the like, although strong acids such as sulfuric acid, hydrochloric acid and especially nitric acid are preferable. Typically, the peptizing agent is mixed with the finely divided inorganic oxide as its aqueous solution to provide at least partial of the required water content of the mixture.

The shear mixing conditions referred to herein are substantially those used in the art to achieve uniform dispersion of the paste or paste components. Generally, a shear mixing device is used comprising a plurality of blades or blades rotating in adjacent planes about a common axis, with a cutting or grinding effect due to the smallest possible gap between the rotating blades, blades and sidewalls and / or blades and one or more fixed cutting bars. Shear mixers are typically designed to maintain the entire mixture in close contact with the rotating blades or blades to take full advantage of the shear effect. The power supply per unit mass is a suitable measure of the intensity or severity of the mixing operation for the particular mixture. For example, an energy supply corresponding to about 22 watt hours per kg of dry refractory inorganic oxide in the mixture of about 0.5-5 minutes (corresponding to a power supply of about 260-2600 W / kg) has been found to provide an intensity of or a shear mixing operation of suitable severity which results in uniform dispersion of the components of said mixture.

62960

It is generally recognized that catalysis involves a mechanism that is particularly known for its unpredictability. Minor changes in the manufacturing process often lead to unexpected improvement of the catalyst product. The improvement may be due to an indeterminate and minor change in the physical properties and / or composition of the catalyst product, which produces a new composition that is difficult to define and manifests only as a result of substantially improved activity, selectivity and / or stability to one or more chemical reactions. In the present case, for the mixture of the present invention, the shear mixing operation described above is performed to achieve a substantially uniform dispersion of the components of said mixture and there is little, if any, visible improvement in dispersion as the severity of the shear mixing operation is increased. An increase in the severity of the measure would therefore prove inappropriate. However, it has been found that when the severity of the shear mixing operation is increased as disclosed herein, a substantial improvement in the catalytic activity of the final product occurs, especially when a hydrotreating catalyst is used in conjunction with a Group VIA and Group VIII metal component. Thus, the mixture described in accordance with the present invention is maintained under shear mixing conditions, the intensity of said shear mixing being characterized by an energy supply corresponding to about 33-260 watt hours per kg of dry refractory inorganic oxide in said mixture for about 0.5-5 minutes and in a preferred embodiment, the mixture is maintained under shear mixing conditions, the intensity of which is characterized by an energy supply corresponding to about 33-130 watt hours per kg of dry refractory inorganic oxide contained in said mixture, for about 1-3 minutes.

The extrusion operation is conveniently performed with a commercial extruder. For example, the paste is continuously processed through a screw rotating through the cylinder and pressed through a perforated plate at one end of the cylinder. The extrudate can be cut into pieces of the desired length prior to drying and calcination with a rotating knife as the extrudate bursts from the torn plate. Alternatively, the compact can be crushed into random pieces of length during the drying and calcination process. In any case, the compact is dried and calcined, drying usually taking place at a maximum temperature of about 120 ° C for 1-24 hours and calcination preferably taking place in an oxidizing atmosphere 62960, such as air at a temperature of about 315-650 ° C for about 2-4 hours. within an hour.

As mentioned above, the extruded product of this invention is particularly useful in connection with the Group VIA and Group VIII metal component as a hydrotreating catalyst. The Group VIA and Group VIII metal component may be combined with the extrudate in any suitable manner, including coextrusion and / or impregnation. For example, a Group VIA metal compound and a Group VIII metal compound can be dry blended with a finely divided refractory inorganic oxide and further treated according to the method of the present invention. Molybdenic anhydride or molybdenic acid are particularly suitable Group VIA metal compounds, and cobalt carbonate is a particularly suitable Group VIII metal compound for dry blending with finely divided refractory inorganic oxide. Other suitable metal compounds of group VIA, i. molybdenum, tungsten and chromium compounds include molybdenic acid, ammonium molybdate, ammonium chromate, chromium acetate, chromium chloride, chromium nitrate, tungstic acid, etc. Other Group VIII metal compounds that may be used, i. compounds of iron, nickel, cobalt, platinum, palladium, rhodium, ruthenium, osmium and iridium include nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, cobalt nitrate, cobalt disulfate, ferrinitrate, ferric sulfate, ferric sulfate, platinum chloride.

The extruded product of this invention, with or without the coextruded Group VIA and Group VIII metal component combined with it, is preferably impregnated with Group VIA and Group VIII metal component 11a by conventional impregnation techniques to provide a final combination containing about 4-30% by weight of Group VIa metal and about 1-10% by weight of Group VIII metal. Absorption can be accomplished by a conventional technique in which the compacts are soaked, dipped, suspended, or otherwise immersed in the impregnation solution under conditions that adsorb the soluble compound containing the desired catalytic component. A particular absorption technique has been found to be particularly advantageous in promoting the desired physical properties of the final catalyst. Thus, the impregnation of the metal components of group VIA and group VIA takes place preferably from a common aqueous solution of their soluble compounds, for example from an ammoniacal solution of molybdenic acid and cobalt nitrate 7 62960. Furthermore, the impregnation is preferably carried out using the smallest possible volume of impregnation solution, which is compatible with the uniform distribution of the catalytic components on the rebelled press bodies. One preferred method involves the use of a steam jacketed rotary dryer. The compression pieces are immersed in an impregnating solution in a dryer and drummed therein by means of a rotary movement of the dryer, the volume of the compression pieces thus treated being initially between about 0.7 and 1.0 times the volume of the impregnation solution. Evaporation of the solution in contact with the press bodies is carried out by supplying steam to the dryer jacket. Evaporation is further facilitated by continuously purging the dryer using a stream of dry gas, suitably air or nitrogen. The impregnated bodies thus dried are then calcined in an oxygen-containing atmosphere at the above-mentioned temperature of about 315-650 ° C for about 2-4 hours.

When the Group VIA and Group VIII metal components are combined with a refractory inorganic oxide extrusion by coextrusion and impregnation, it is recommended to add about 10-40% by weight of said components and more preferably about 20-30% by weight by coextrusion technique and add the remainder of said components by impregnation.

The following examples are provided to illustrate the improvement resulting from the implementation of a preferred embodiment of the present invention and are not to be construed as an unreasonable limitation on the broad scope of the invention as set forth in the appended claims.

Example I

Alpha-alumina monohydrate (Catapal SB) with an average bulk density of about 0.79 g / cm 3 was mixed with powdered alpha-alumina monohydrate (Kaiser Medium) with an average bulk density of about 0.23 g / cm 3. cm to give a mixture with an average bulk density of approximately 0.45 g / cm, of which 95% was filterable through a 105 micron micrograph. The alumina mixture was then dry blended with molybdenic acid and cobalt carbonate and a 5% aqueous nitric acid solution was added to form an extrudable paste. The mixture obtained in this example was subjected to vigorous shear mixing for 1 minute, during which time the energy supply corresponded to about 14 watts to 62,960 hours per kg of alumina in said mixture. The cobalt carbonate and molybdenic acid were then coextruded with alumina as a paste characterized by a 55-60% annealing loss at 900 ° C. The resulting compact was dried and calcined in air for 1 hour at about 345 ° C and for another 2 hours at about 595 ° C. The calcined compact, which was crushed into pieces about 3.2 mm long, was then impregnated with a common ammonia-containing solution of cobalt nitrate and molybdenic acid prepared by mixing an aqueous solution of molybdenum acid and ammonium hydroxide with aqueous cobalt nitrate hexahydrate and ammonium hexahydrate. The extrudates were immersed in a solution which was then evaporated to dryness. The impregnated compact was then first calcined at about 330 ° C for 1 hour in air containing 22% steam, and then at about 510 ° C for 2 hours in air. The calcined product contained 3.2% by weight of cobalt and 12.9% by weight of molybdenum, with 75% of said metals coming from the coextrusion step and 25% from the impregnation step.

Example II

The product of this example was prepared essentially as described in the previous example except that 50% of the cobalt and molybdenum components were incorporated into the product during the coextrusion step and the remaining 50% were incorporated by the impregnation step. The product contained a total of 3.1% by weight of cobalt and 13.0% by weight of molybdenum.

Example III

In this example, the extrudate was again prepared essentially as described in the previous examples, with the exception that only 25% of the cobalt and molybdenum components came from the coextrusion step and the remaining 75% from the impregnation step. In this example, the extrudate contained a total of 3.35% by weight of cobalt and 13.5% by weight of molybdenum.

Example IV

A mixture of alpha alumina monohydrate was prepared essentially as described in the previous examples. A 5% by weight aqueous solution of nitric acid was added to the mixture, and the mixture was subjected to a strong shear mixing operation as in the above examples. The resulting paste having a 55-60% annealing loss at 900 ° C was extruded, dried and calcined, all according to the above examples. The calcined bodies were then impregnated with a common ammonia-containing solution of 62960 molybdenic acid and cobalt nitrate prepared by mixing an aqueous solution of molybdenic acid and ammonium hydroxide with an aqueous solution of cobalt nitrate hexahydrate and ammonium hydroxide. The pieces were immersed in a solution which was then evaporated to dryness. The bodies were then calcined in air containing 22% steam for about 1 hour at about 33 ° C and another 2 hours at 510 ° C. The catalyst product contained 3.3% by weight of cobalt and 13.7% by weight of molybdenum, all from the impregnation process.

Example V

The alpha-alumina monohydrate mixture described above was dry blended with finely divided molybdenum oxide and cobalt carbonate. A 5% aqueous solution of nitric acid was added and the resulting mixture was subjected to a normal shear mixing operation for 1 minute, the energy supply in this case corresponding to about 22 watt hours per kg of alumina contained in the mixture. The resulting paste with a 55-60% annealing loss at 900 ° C was extruded, dried and calcined as described. The calcined compact was then impregnated with a common ammonia-containing solution of molybdenic acid and cobalt nitrate prepared by mixing an aqueous solution of molybdenic acid and ammonium hydroxide with an aqueous solution of cobalt nitrate hexahydrate and ammonium hydroxide. The extrudates were immersed in a common solution, which was then evaporated to dryness. The impregnated extrudates were then calcined as described. The calcined product contained 2.9% by weight of cobalt and 11.3% by weight of molybdenum, 75% of said metals coming from the coextrusion step and 25% from the impregnation step.

Example VI

The extruded catalyst of the present invention was prepared in substantially the same manner as in the previous example, including a normal shear mixture with an energy input of n in 1 minute.

22 watt hours per kg of alumina contained in the mixture except that in this case 50% of the cobalt and molybdenum components were incorporated into the catalyst during coextrusion and the remaining 50% were incorporated during the impregnation step. The catalyst product contained a total of 2.24% by weight of cobalt and 10.6% by weight of molybdenum.

10 62960

Example VII

In this example, the extrudate was again prepared in substantially the same manner as in Example V, including a normal shear mix with an energy input of about 22 watt hours per kg of alumina in 1 minute except that in this case only 25% of the cobalt and molybdenum components were combined with the catalyst during the coextrusion step. while 75% was combined during the absorption phase. In total, the catalyst product contained 3.65% by weight of cobalt and 13.4% by weight of molybdenum.

Example VIII

The alpha-alumina monohydrate mixture of the previous examples to which a 5% by weight aqueous solution of nitric acid had been added was subjected to a normal shear mixing procedure for 1 minute. The energy supply in this case corresponded to about 22 watt hours per kg of alumina - a normal shear mixing operation. The obtained paste with a loss on ignition of 55-60% at 900 ° C was extruded, dried and calcined as in the previous examples. The calcined compact was then impregnated with a common ammonia-containing solution of molybdenic acid and cobalt nitrate prepared as described above. The calcined pieces were immersed in this solution, which was then evaporated to dryness. The impregnated bodies were then calcined in air for about 1 hour at 400 ° C and another 2 hours at 595 ° C as described above. The calcined product contained 3.0% by weight of cobalt and 10.3% by weight of molybdenum.

The catalysts described above were evaluated for desulfurization of a vacuum gas oil boiling in the range of 315-565 ° C and containing 2.6% by weight of sulfur. In all cases, the catalyst was placed as a solid bed in a vertical tubular reactor maintained at a pressure of 5.2 MPa and 385 ° C. Vacuum gas oil was fed over the catalyst at a liquid flow rate of 3.2 times the volume per hour with about 320 standard cubic meters of hydrogen per cubic meter of feedstock. The reactor effluent was separated into a liquid and gas phase in a high pressure separator at 93 ° C and the liquid phase was treated on a stripping column to separate the light fractions. Four two-hour trial periods were performed, each separated from the 10-hour line-excluded period. The liquid stripper bottom fraction from each test period was analyzed for sulfur and the arithmetic mean of the four test periods 62960 was used to determine catalyst activity relative to the standard reference catalyst used under the same conditions containing 2.5% by weight cobalt and 8.7% by weight molybdenum 1/6 mm: n with alumina balls. Relative activity was calculated for the desulfurization rates of the test catalyst and the reference catalyst.

Example IX

In this example, an extruded product was prepared essentially as described in the previous examples. 25% of the metal components were the result of the coextrusion step and the remaining 75% were the result of the impregnation step. However, in this example, nickel and molybdenum components were used, with the resulting product containing 3.1% by weight Ni and 11.5% by weight Mo. The relative activity of the catalyst in question was 134.

The results obtained for the catalysts of Examples I, II, III, IV, V, VI, VII, VIII and IX are shown in Table I.

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With respect to the results listed, it is apparent that the intensity of the shear-mixing operation described herein has a decisive and beneficial effect on the catalytic activity of the final product. It is also apparent that of the catalysts prepared under high shear mixing conditions, those catalysts have a significant additional improvement in activity in which about 10-40% by weight of the metal components, cobalt and molybdenum are coextruded with alumina and about 90-60% by weight are impregnated on its surface. .

The present invention therefore further comprises an extruded mixture containing from about 1 to 10% by weight of Group VIII metal and from about 4 to 30% by weight of Group VIA metal and prepared by a process in which finely divided refractory inorganic oxide is mixed together. a metal compound, a Group VIA metal and a peptizing agent to form a mixture characterized by a weight loss of about 50-70% upon ignition at 900 ° C, the concentrations of said Group VIII metal compound and the Group VIA metal compound being sufficient to form about 10-40 % by weight of Group VIII and Group VIA metal components from the final extruded mixture; maintaining said mixture under shear mixing conditions, the intensity of said shear mixing being characterized by an energy supply corresponding to about 33-260 watt-hours per kg of dry refractory inorganic oxide contained in said mixture for about 0.5-5 minutes; extruding the obtained paste and drying and calcining the compact; impregnating the calcined compact with amounts of the Group VIII metal compound and the Group VIA metal compound to provide a final extruded combination containing about 1-10% by weight of the Group VIII metal and about 4-30% by weight of the Group VIA metal; and drying and calcining the resulting mixture in an oxidizing atmosphere.

Claims (10)

A process for preparing an extruded catalyst, comprising mixing powdered, refractory, inorganic oxide with a metal compound from group VIA and with a metal compound from group VIII in lateral conditions to obtain a dry mixture containing from 4 to 30% by weight. % of the metal from group VIA and 1-10% by weight of the metal from group VIII, liquid peptic acid and water are added to the mixture to obtain a moist paste which is extruded and cut into particles, dried and calcined, characterized in that catalyst particles with increased activity is produced, whereby the moist paste containing water in such amounts to form a paste whose annealing loss during calcination at 900 ° C is 50-70% by weight is mixed under cutting mixing conditions with such force that the energy input is 33-260 Wh / kg of dry oxide in the mixture, for a period of 0.5-5 minutes. Process according to Claim 1, characterized in that the strength of the cutting mixture is characterized by the energy input, which corresponds to 33-130 Wh / kg dry oxide in the mixture for a period of 1-3 minutes. 3. Process according to claim 1 or 2, characterized in that the refractory inorganic oxide is alumina and especially alpha alumina monohydrate. Process according to claim 3, characterized in that the average weight density of the alpha alumina monohydrate is 0.4-0.5 g / cm. 5. A process according to any one of claims 1-4, characterized in that the refractory inorganic oxide is a mixture containing alpha alumina monohydrate having an average solubility of 0.7-0.9 g / cm 3 and alpha aluminum 3 oxide monohydrate with mean weight density of 0.2-0.3 g / cm, while the mean weight density of the mixture is 0.4-0.5 g / cm 3. Method according to any of claims 1-5, characterized in that sufficient levels of the metal compound from the group Vili and from the metal compound from group VIA are present to obtain 20-30% by weight of metal components from group VIII and from group VIA to the final extruded mixture.