CS232705B2 - Production method of ejected catalyst - Google Patents

Description

BACKGROUND OF THE INVENTION The invention relates to a process for the production of an extruded catalyst, preferably for use in the hydrogenation desulphurisation of heavy fuel oils, in which a finely divided refractory inorganic oxide, a peptizing agent and the necessary amount of water are mixed to form a mixture having a weight loss at 900C C 50 to 70 ° C, whereupon the paste obtained is extruded, cut into particles and calcined.

It is well known that sulfur oxides and minor amounts of other sulfur compounds are major atmospheric contaminants. The harmful effect of these sulfur-based pollutants is manifested, for example, by the occurrence of cardiorespiratory diseases and eye inflammation and leads to a reduction in the amount of sulfur dioxide ¹ discharged into the atmosphere, particularly in densely populated areas.

It has been found that a substantial proportion of the sulfur oxides present in the atmosphere result from the combustion of petroleum products and it has therefore been proposed to limit the sulfur compounds content of heavy fuel oils intended for combustion in densely populated areas. However, the supply of heavy fuel oils with suitably low sulfur content is insufficient to meet current demand, and there is an increasing need to develop improved desulfurization processes for treating available fuel oils with relatively high sulfur content.

Desulphurization technology currently involves a hydrogenated-desulphurization treatment using hydrogenated-desulphurization catalysts while still developing catalysts with higher selectivity and / or efficiency under less demanding reaction conditions; in this way, the hydrogenation cracking of the treated heavy fuel oils can be avoided.

The reaction conditions generally include a temperature of 95 to 425 ° C, with a preferred temperature of 315 to 425 ° C. In the hydrogenation desulfurization reaction, a hydrogen pressure of 0.7 to 14 MPa is used, and hydrogen is fed into the process in a mixture with recirculated hydrogen, thereby ensuring a hydrogen consumption of 28.3 to 1430 m ³ per 0.1587 m ³ hydrocarbon feed. The sulfur-containing feed is treated with hydrogen on the catalyst at an hourly liquid space velocity of 0.5 to 0.5

20 May

The above drawbacks are largely eliminated by the process for producing the extruded catalyst. preferably usable in the hydrogenation desulphurization of heavy fuel oils, in which a fine-grained refractory inorganic oxide, a peptizing agent and a necessary amount of water are mixed at a temperature of 900 ° C to a mass loss of 50 to 70 ° / o to form a mixture which whereupon the paste obtained is extruded, cut into particles, dried and calcined, characterized in that said paste components are mixed for 0.5 to 5 minutes under shear mixing conditions, the intensity of said shear mixing corresponding to an energy input of 33.3 up to 266.6 Wh per kg of dry refractory inorganic oxide contained in said mixture.

The paste components are preferably mixed for 1 to 3 minutes under shear mixing conditions, the intensity of said shear mixing corresponding to the energy input

33.3 to 133.3 Wh per kg of dry refractory inorganic oxide contained in said mixture.

Preferably, 1 to 10% by weight of metal of the eighth subgroup of the periodic chemical element and 4 to 30% by weight of metal of the sixth subgroup of the Periodic Chemical Element are admixed with the catalyst, 10 to 40% The periodic chemical elements are mixed with the refractory inorganic oxide, the peptizing agent and water before impregnating the calcined extrudate before shear mixing and extrusion and the remaining amount of metals of the eighth and sixth subsets of the periodic chemical elements.

Preferably, alumina is used as the refractory inorganic oxide.

Preferred alumina is alpha-alumina monohydrate, preferably having an average bulk density of 0.4 to 0.5 g. cm ^-3 .

It is also possible to use a mixture of alpha-alumina monohydrate with an average bulk density of 0.7 to 0.9 g / cm @ ³ and alpha-alumina monohydrate with an average bulk density of 0.2 to 0.3 g as alpha alumina. cm ³ , the mixture having an average bulk density of 0.4 to 0.5 g. cm ^-3 .

Preferably, the peptizing agent and the refractory inorganic oxide are mixed with a metal compound of the eighth sub-group and a metal compound of the sixth sub-group of the Periodic Table of the Chemicals in an amount necessary. to achieve a metal content of the eighth minor and sixth minor subgroups of the Periodic Table of Chemical Elements in the resulting extrudate of 20 to 30% by weight.

Cobalt is preferably used as the metal of the eighth sub-group of the Periodic Table of the Chemicals.

Molybdenum is preferably used as the metal of the sixth sub-group of the Periodic Table of the Chemicals.

Preferably, cobalt carbonate or molybdic acid is mixed with the refractory inorganic oxide and the peptizing agent.

An advantage of the process according to the invention is that the catalyst obtained in this way has a higher efficiency than the prior art similar catalysts.

In the following, the process of the invention will be described in more detail.

In the process of the invention, the peptizing agent is first mixed with the finely divided refractory inorganic oxide and the necessary amount of water to form a mixture which, when fired at 900 ° C, has a weight loss of 50 to 70%.

The term "fine-grained" includes particles with a mean diameter of less than 150 µm, such as particles obtained as a microsieve with a mesh size of 105 μτη. The refractory inorganic oxide may be, for example, alumina, silica, zirconia, boron oxide, chromium oxide, magnesium oxide, titanium dioxide, or mixtures thereof, such as a mixture of alumina and silica, a mixture of alumina and zirconia and a mixture of alumina and chromium oxide.

The alumina is preferably an alpha-alumina monohydrate of the bohemite structure, which is available in various densities. However, alpha-alumina monohydrate of some density is not as suitable for the process of the invention as alumina monohydrate of other density. A particularly suitable alpha-alumina monohydrate has an average bulk density of 0.4 to 0.5 g. cm, ^-3 . It is preferred to use mixtures of alpha-alumina monohydrate with an average bulk density of 0.7 to 0.9 g / cm @ ³ and alpha-alumina monohydrate with an average bulk density of 0.2 to 0.3 g. cm &^lt; ^{3 &gt}; which has the advantage of catalytic; properties of a denser alumina and, secondly, an advantage of the bonding properties of a less dense alumina and which thus provides a more durable and more efficient catalyst. In any case, it is preferable to combine the alpha alumina inonohydrates of said bulk densities in such a ratio as to obtain an average bulk density of 0.4 to 0.5 g.cm ^-5 .

The finely divided refractory inorganic oxide is admixed with the peptizing agent and water in an amount necessary to form a weight loss composition on firing at a temperature of 90 ^° C to 50 ^° C to 50 ^° C, preferably 55 to 65%. The peptizing agent is preferably a weak acid such as acid, formic, acetic acid, propionic acid, although it is preferable to use a strong acid; acids such as sulfuric acid, hydrochloric acid and especially nitric acid.

Typically, the peptizing agent is mixed with a fine-grained refractory oxide in the form of an aqueous solution of the peptizing agent to provide at least a portion of the desired water content of the mixture.

The shear mixing conditions used in the process of the invention are generally those used to achieve uniform dispersion of the individual components of the paste. Typically, a shear mixer is used having a plurality of vanes rotating in parallel planes about a common shaft, with a shear or spread effect resulting from minimal clearance between the rotating vanes and the side inner walls of the container in which the mixer is located, and / or blades and at least one stationary shear bar.

Typically, the shear mixing compositions are designed to maintain the entire volume of the mixture in close proximity to the rotating blades, thereby taking full advantage of the shearing effect. The energy input per unit of compound is dependent on the desired mixing intensity for the particular mixture.

For example, it has been found that already an energy input equivalent to 33.3 Wh per kg of dry refractory inorganic oxide present in the mixture for 0.5 to 5 min. provides shear mixing of an appropriate intensity to obtain uniform dispersion of the components of said mixture.

It is generally known that catalysis proceeds according to yet not fully understood mechanisms. Often small variations in the operating conditions during catalyst production lead to an unexpected increase in the efficiency of the catalyst obtained. An improvement in the quality of the catalyst may result from a difficulty in determining the physical properties and / or composition of the catalyst, these changes being apparent only from the improved catalyst quality, in particular from its increased activity, selectivity and / or stability.

The shear mixing is carried out in the process according to the invention until a substantially uniform dispersion of the individual components of the paste is achieved, the quality of the dispersion practically independent of the intensity of the shear mixing. Therefore, increasing the intensity of shear mixing would seem unnecessary. However, it has been found that when the shear mixing intensity increases, this results in a substantial increase in the catalytic efficiency of the catalyst obtained, particularly in the case of a catalyst comprising metals of the sixth and eighth subgroups of the Periodic Table of the Chemicals. Therefore, the process according to the invention uses shear mixing, the intensity of which corresponds to an energy input equivalent to 33.3 to 266.6 Wh per 1 kg of the dry refractory inorganic oxide contained in the mixture and having a duration of 0.5 to 5 minutes. In a preferred embodiment of the process of the present invention, the paste components are maintained under shear mixing conditions having an energy input of 33.3 to 133.3 Wh per kg of dry refractory inorganic oxide contained in the mixture and having a duration of 1 to 3 minutes.

The extrusion is carried out in a conventional extruder. The paste is continuously fed through the screw conveyor to the extruder die through which it is then extruded. The extrudate can be cut into particles of desired length using a rotary knife before drying and calcination and immediately after leaving the extrusion die.

The extrudate can also break into particles of random length during drying and calcining. In any case, the extrudate is dried and calcined, and drying is usually carried out at a temperature of up to 120 ^{° C.} C for 1 to 24 hours and calcination is preferably carried out in an oxidizing atmosphere, such as air, at a temperature of 315 to 650 ° C for 2 to 4 hours.

As already mentioned, the catalyst obtained by the process of the invention and containing metals of the sixth to eighth subgroups of the Periodic Table of the Chemicals is particularly suitable as a catalyst useful in hydrogenation processes.

The metals of the sixth and eighth subgroups of the Periodic Table of Chemical Elements may be incorporated into the catalyst either by mixing them into the catalyst prior to mixing and extruding the paste and / or impregnating the already extruded catalyst with these metals.

Thus, for example, it is possible to dry-mix a finely divided inorganic oxide metal compound of the sixth and eighth subgroups of the Periodic Table of the Chemicals. For the dry mixing with finely divided refractory inorganic oxide, suitable metal compounds are the sixth subgroup of the Periodic Table of the Elements, molybdenum oxide and molybdenic acid. Equally advantageously, the compounds of the eighth sub-group of the Periodic Table of the chemical elements of cobalt carbonate may be used.

Other suitable metal compounds of the sixth subgroup of the Periodic Table of the Elements are ammonium molybdate, ammonium chromate, ammonium acetate, chromium chloride, chromium nitrate and tungstic acid.

. Other suitable metal compounds of the eighth sub-group of the Periodic Table of the Elements are iron, nickel, cobalt, platinum, palladium, rhodium, ruthenium, osmium and iridium compounds, especially nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, cobalt nitrate, ferric nitrate, ferric sulfate, platinum (II) chloride and palladium (II) chloride.

The catalyst extrudate, which optionally already contains part of the metals of the sixth and eighth subgroups of the Periodic Table of Chemicals that have been added to the paste prior to extrusion, is impregnated with the sixth and eighth subgroups of the Periodic Table of Chemicals a catalyst comprising 4 to 30% by weight of metal of the sixth sub-group of the Periodic Table of the Chemicals and 1 to 10% by weight of metal of the eighth sub-group of the Periodic Table of the Chemicals.

The impregnation is carried out by conventional methods in which the extrudate particles are soaked, suspended or otherwise immersed in an impregnating solution under conditions in which a soluble compound of the desired metal is adsorbed to said extrudate particles.

Some impregnation techniques are particularly advantageous to achieve the desired physical properties of the final catalyst. Thus, it is preferable to impregnate the metal compounds of the sixth and eighth subgroups of the periodic system of chemical elements from an aqueous ammoniacal solution of their soluble compounds, for example molybdic acid or nickel nitrate. Furthermore, impregnation is better performed using a minimum volume of impregnating solution, resulting in a more even distribution of the compound of said metals on the calcined extrudate particles.

A preferred impregnation method involves the use of a rotary dryer with a steam heated jacket. The extrudate particles are immersed in the impregnating solution present in the drier and rolled therein as a result of the rotary movement of the driers, the particle size of the trudate being initially equal to 70 to 100% of the impregnating solution volume. Evaporation of the impregnating solution in contact with the extrudate particles is carried out by means of steam conducted in the dryer shell. Evaporation is further facilitated by continuously purging the dryer with a stream of dry gas, preferably air or nitrogen. The impregnated particles thus dried are then calcined in an oxygen-containing atmosphere at 315 to 650 ° C for 2 to 4 hours.

When the metals of the sixth and eighth subgroups of the Periodic Table of Chemical Elements are incorporated into the paste prior to extrusion and impregnation, it is preferred to incorporate 10 to 40, preferably 20 to 30%, by weight of the total amount of said metals. is incorporated into the catalyst by said impregnation.

Example 1

Alpha-alumina monohydrate with a bulk density of 0.79 g. cm ^-3 was mixed with powdered alpha-alumina monohydrate having a bulk density of 0.23 g. cm ^-3 to obtain a mixture with an average bulk density of 0.45 g. cm ³ and 95% of the particles of this mixture pass through a microsieve with a mesh size of 105 µm. This alumina mixture was then mixed with molybdic acid, cobalt carbonate and 5% aqueous nitric acid to form an extrudable paste. The resulting mixture was vigorously sheared for 1 minute, the energy input at that time being equivalent to 68.5 Wh per kg of alumina contained in the mixture. The cobalt carbonate and molybdic acid were thus co-extruded with alumina in the form of a paste indicated by a weight loss on firing at 900 ° C of 50 to 60%.

The resulting extrudate was dried and calcined in air for 1 hour at; temperature of 345 ° C and for a further 2 hours at 595 ° C.

The calcined extrudate, which was cut lengthwise into 3.2 mm particles, was then impregnated with an ammoniacal solution of cobalt nitrate and molybdic acid, prepared by mixing an aqueous solution of molybdic acid and ammonium hydroxide with an aqueous solution of cobalt nitrate hexahydrate and ammonium hydroxide.

The impregnation was carried out by immersing the extrudate particles in the solution, which was then evaporated to dryness in the presence of the extrudate particles. The impregnated extrudate particles were then calcined first at 330 ° C for 1 hour in air containing 22% water vapor and then at 510 ° C for 2 hours with air. The calcined product contained 3.2% by weight of cobalt and 12.9% by weight of molybdenum, 75% of which were incorporated into the catalyst by admixing prior to extrusion and 25% of the metals were incorporated into the catalyst by impregnation.

Example 2

The catalyst was prepared in this example as in the previous example except that 50% of molybdenum and cobalt were admixed to the paste prior to extrusion and the remaining 50% of the metals were incorporated into the catalyst by impregnation. The catalyst contained a total of 3.1% by weight of cobalt and 13% by weight of molybdenum.

Example 3

In this example, the catalyst was again prepared as described in the preceding examples except that only 25% of cobalt and molybdenum was incorporated into the catalyst by admixing prior to extrusion and the other 75% of these metals were incorporated into the catalyst by impregnation. The extruded product contained 3.35% by weight of cobalt and 13.5% by weight of molybdenum.

Example 4

The alpha alumina monohydrate mixture was prepared as in the previous examples. To this mixture was added a 5% by weight solution of nitric acid and the mixture was vigorously sheared under the conditions of the previous

2 7 0: 5 examples. The resulting paste, which exhibited a 55-60% weight loss on firing at 900 ° C, was extruded, dried, calcined and cut as in the previous examples. The calcined particles were then impregnated with an ammonia solution of molybdic acid and cobalt nitrate, prepared by mixing an aqueous solution of molybdic acid and ammonium hydroxide with an aqueous solution of cobalt nitrate hexahydrate and ammonium hydroxide. The particles were immersed in this solution and the solution was evaporated to dryness in their presence. The particles were then calcined in air containing 22% water vapor for 1 hour at 330 ^° C and then for a further 2 hours at 510 ^° C.

The catalyst obtained contained 3.3% by weight of cobalt and 13.7% by weight of molybdenum. All metals were incorporated into the catalyst by impregnation. Example 5

The above-described mixture of alpha-alumina monohydrate was dry blended with finely powdered molybdenum oxide and cobalt (II) carbonate. A 5% aqueous nitric acid solution was then added to the resulting mixture, and the resulting mixture was sheared for 1 minute at an energy input equivalent to 22.2 Wh per kg of alumina contained in the mixture. The resulting paste, showing a weight loss of 55 to 60% at firing at 900 ° C, was extruded, dried and calcined as described above. The calcined extrudate was then impregnated with an ammoniacal solution of molybdic acid and cobalt nitrate, prepared by mixing an aqueous solution of molybdic acid and ammonium hydroxide with an aqueous solution of cobalt nitrate hexahydrate and ammonium hydroxide. The impregnation was carried out by immersing the extruded particles in the solution and evaporating them to dryness in the presence of the particles. The impregnated extrudate particles were then calcined as described above.

The calcined product contained 1.9% by weight of cobalt and 11.3% by weight of molybdenum, 75% of which were incorporated into the catalyst by admixing prior to extrusion and 25% of the metals were incorporated by impregnation.

Example 6

The extruded catalyst was prepared in the same manner as in the previous example, including shear mixing with an energy input of 22.2 Wh per kg of alumina contained in the mixture for 1 minute 3 except that in this case 50 percent of cobalt and molybdenum were incorporated into the catalyst by mixing by extrusion and the remaining 50% is introduced into the catalyst by impregnation. The catalyst contained a total of 2.24% by weight of cobalt and 10.6% by weight of molybdenum.

Example 7

In this example, the extrudate was again prepared in the same manner as in Example 5, including shear mixing with an energy input equivalent to 22.2 Wh per kg of alumina for 1 minute, except that only 25% of cobalt and molybdenum was admixed to the catalyst before. by extrusion, while 75% of the cobalt and molybdenum were so impregnated into the catalyst by impregnation. In total, the catalyst contained 3.65 weight percent cobalt and 13.4 weight percent molybdenum.

Example 8

The alumina-alumina monohydrate mixture of the preceding examples was mixed together with the aqueous nitric acid solution for 1 minute. The energy input in this case was equivalent to 22.2 Wh- per kg of alumina present in the mixture. The resulting pasty-like paste, showing a 55-60% loss in weight at firing to 900 ° C, was extruded, dried and calcined as in the previous examples. The calcined extrudate was then impregnated with an ammonia solution of molybdic acid and cobaitme-nitrate prepared as described above. The impregnation was carried out by immersing the calcined catalyst particles in the solution and evaporating them to dryness in the presence of the particles. The impregnated particles were then calcined successively in air for 1 hour at 400 ° C and then for a further 2 hours at 595 ° C. The refined product contained 3% by weight of cobalt and

10.3% by weight of molybdenum.

The activity of the catalysts obtained in the preceding examples was tested in the desuuration of a gas oil boiling in the range of 315 to 565 ° C and containing 2.6% by weight of sulfur. The catalyst was arranged in the form of a fixed bed in a vertical tubular reactor maintained at a pressure of 60 bar and a temperature of 385 ^° C. The gas oil was metered through the catalyst at an hourly space velocity of 3.2 in a mixture with 51 m ^{3 of} hydrogen per 0.159 m ^{3 of} feed oil. The reactor effluent was separated into a liquid and gaseous phase in a high-pressure separator at a temperature of 93 ^° C and the liquid phase was treated in a stripping column to separate the light fractions. Four two-hour test runs were performed; there was always a 10-hour break between these runs. The liquid bottoms from the stripper column from each run were analyzed11

327 of the sulfur content and the arithmetic mean of the four test runs were used to calculate the catalyst performance relative to the reference standard catalyst used under the same conditions, the standard catalyst containing 2.5% by weight of cobalt and 8.7% by weight of molybdenum. incorporated into 1.6 mm diameter alumina beads. The relative activity was calculated as the ratio of the desulfurization activity of the test catalyst to the desulfurization activity of the reference catalyst. The values obtained for the catalysts prepared according to Examples 1 to 8 are shown in the following table.

TABLE

The catalyst of Example no. 1 Mixing: energetic power / weight of the mixture (Wh.kg-i) 68.5 Addition of metals: before extrusion (%) 75 impregnation (%) 25 Bulk density (g cm cm ³ ) 0.75 Particulate density (g. cm ^-3 ) 1.30 Specific surface area (m ² .g ^-1 ) 249 Pore volume (cm ^3. G ¹ ) 0.48 Pore diameter (nm) 7.2 Metals contained in the catalyst Cobalt (° / Weight) 3.2 Molybdenum (% by weight) 12.9 Relative efficiency 146 Mixing: energetic power / weight of the mixture (Wh.kg-i) 22.2 Addition of metals: before extrusion (% j 75 impregnation (% j 25 Bulk density (g. Cm ^-3 ) 0.73 Particulate density (g. cm- ³ ) 1,27 Specific surface area (m ^2. G ^_1 ) 279 Pore volume (cm ^3. G ^-1 j 0.48 Pore diameter (nm) 7.2 Metals contained in the catalyst Cobalt, (% by weight) 2.9 Molybdenum (% by weight) 11.3 Relative efficiency 1.06

As shown in the table above, the shear mixing intensity has a significant effect

2 3 4 68.5 68.5 68.5 50 25 0 50 75 100 ALIGN! 0.74 0.72 0.78 1.39 1.34 1.52 279 270 236 0.44 0.47 0.38 6.6 7.0 6.8 3.1 3.35 3.3 13.0 13.5 13.7 148 191 162 22.2 22.2 22.2 50 25 0 50 75 100 ALIGN! 0.73 0.81 0.73 1.32 1.46 1.31 301 225 259 0.48 0.42 0.49 6.4 6.9 8.1 , 2.24 3.65 3.0 10.6 13.4 10.3 117 126 100 ALIGN! He still has better efficiency when

10% to 40% of the catalyst activity of the obtained catalyst is incorporated into the catalyst. It will also be appreciated that the catalyst is prepared under intensive shear mixing of cobalt and molybdenum by admixing prior to extrusion and 90 to 60% by weight of these metals by impregnation.

Claims (12)

SUBJECT A process for the production of an extruded catalyst, preferably for use in the hydrogenation desulfurization of heavy fuel oils, in which a fine-grained refractory inorganic oxide, a peptizing agent and the necessary amount of water are mixed to form a mixture which has a loss on firing at 900 ° C 50 to 70% by weight, whereupon the paste obtained is extruded, cut into particles, dried and calcined, characterized in that: OF THE INVENTION said paste components are mixed for 0.5 to 5 minutes under shear mixing conditions, the intensity of said shear mixing corresponding to the energy input 33.3 to 266.6 Wh per kg of dry refractory inorganic oxide contained in said mixture. 2. The process of claim 1 wherein the paste components are mixed for 1 to 3 minutes under shear mixing conditions, wherein the shear mixing intensity corresponds to an energy input of 33.3 to 133.3 Wh per kg of dry refractory inorganic oxide contained therein. in said mixture. 3. The process of claim 1, wherein from about 1% to about 10% by weight of metal of the eighth subgroup of the Periodic Table of Chemicals is admixed with the catalyst, and from about 10% to about 40% by weight of the total amount of metals of the eighth and sixth subsets of the periodic chemical system are mixed with the refractory inorganic oxide, peptizing agent and water before shear mixing and extrusion, and the calcined extrudate is impregnated with the remaining metals of the eighth and sixth subsets. 4. Process according to claim 1, characterized in that alumina is used as the refractory inorganic oxide. 5. A process according to claim 4, wherein the alumina is an alpha alumina monohydrate. 6. A process according to claim 5, wherein the alpha alumina monohydrate is an alpha alumina monohydrate having an average bulk density of 0.4 to 0.5 g. cm ' ³ . 7. A process according to claim 5, wherein the alpha alumina is a mixture of alpha alumina monohydrate having an average bulk density of 0.7 to 0.9 g. Cm @ ³ and alpha alumina monohydrate having an average bulk density. 0.2 to 0.3 g. cm ^-3 , the mixture having an average bulk density of 0.4 to 0.5 g. cm · ³ . 8. A method according to any one of claims 3 to 7, comprising mixing the peptizing agent and the refractory inorganic oxide with a metal compound of the eighth sub-group and a metal compound of the sixth sub-group of the Periodic Table of Chemical Elements. subgroups of the periodic system of chemical elements in the resulting extrudate of 20 to 30% by weight. 9. A process according to any one of Claims 3 to 8, wherein cobalt is used as the metal of the eighth sub-group of the Periodic Table of Chemical Elements. 10. A method according to any one of Claims 3 to 9, wherein molybdenum is used as the metal of the sixth sub-group of the Periodic Table of Chemical Elements. 11. A process according to any one of Claims 3 to 9, wherein cobalt carbonate is mixed with the refractory inorganic oxide and the peptizing agent. 12. The process of claim 3, wherein molybdenic acid is mixed with the refractory inorganic oxide and the peptizing agent.