JPS6336291B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a catalyst composition used in the catalytic cracking of hydrocarbons, and more specifically, it has a high cracking activity and a high yield of not only gasoline fractions but also middle distillates such as kerosene and diesel oil. The present invention relates to a method for producing a catalyst composition that can be produced at a high rate. For catalytic cracking of hydrocarbons, silica-alumina,
Heat-resistant inorganic oxides such as silica-magnesia, silica-zirconia, and alumina-boria, compositions in which crystalline aluminosilicate zeolite is dispersed in these inorganic oxides, and clay minerals such as kaolin added to these compositions. have traditionally been used as catalysts. Since the main purpose of catalytic cracking of hydrocarbons is usually the production of gasoline, catalysts that have high cracking activity and can obtain a gasoline fraction with a high octane number in a high yield are used as catalysts. Catalysts with high selectivity are preferred. In this sense, catalysts in which crystalline aluminosilicate zeolite is dispersed in a silica-based matrix such as silica-alumina or silica-magnesia have been used. It is said that the catalyst for catalytic cracking of hydrocarbons preferably has excellent stability against heat and steam and wear resistance in addition to the above-mentioned cracking activity and gasoline selectivity. In the catalytic cracking process of hydrocarbons, it is customary to regenerate a catalyst that has been poisoned by carbonaceous precipitation, and then subject the regenerated catalyst to the catalytic cracking reaction again. The process involves stripping the adhering hydrocarbons with steam and then burning the carbonaceous material on the poisoned catalyst in the presence of oxygen. Therefore, if the thermal and steam stability of the catalyst is insufficient, the activity of the catalyst will be impaired during regeneration, and the regenerated catalyst will have significantly lower cracking activity and gasoline selectivity than the fresh catalyst. It is. Also,
Most modern catalytic cracking processes commonly use fluidized bed reactors, so if the catalyst does not have sufficient wear resistance, the catalyst will be pulverized in the fluidized bed and lost to the outside of the system. This is because it also contributes to impairing the decomposition activity and gasoline selectivity of the catalyst. In view of these circumstances, the present inventors have developed a catalyst composition in which alumina, which can be detected as crystalline by X-ray diffraction, is blended into a silica-based matrix such as silica-alumina, and crystalline aluminosilicate zeolite is further dispersed. was previously proposed as a catalyst for catalytic cracking that has excellent cracking activity and gasoline selectivity, as well as stability against water vapor and heat, and wear resistance (see Japanese Patent Application Laid-open No. 152548/1983). The present inventors further improved the previously proposed catalyst and continued research to develop a catalyst for catalytic cracking that is highly selective for the production of middle distillates such as kerosene and gas oil. By using air-flow calcined alumina as described below as the alumina that can be detected as crystalline by the method, and by incorporating kaolin into the catalyst, intermediate distillation can be achieved without impairing the features of the catalyst proposed earlier. It has been discovered that it is possible to impart selectivity to the catalyst for the production of fractions. Therefore, the method for producing a catalyst for catalytic cracking according to the present invention involves contacting aluminum hydroxide produced by the Beyer method with hot air at 350 to 700°C for a period of 5 seconds or less, to obtain air-flow calcined alumina, kaolin, and the like. It is characterized by spray drying an aqueous slurry containing a precursor of a silica-based matrix and a crystalline aluminosilicate zeolite. According to the knowledge obtained by the present inventors, in order to improve the selectivity for the production of middle distillates, both air-flow calcined alumina and kaolin can be blended into a silica-based matrix in which crystalline aluminosilicate zeolite is dispersed. This is essential, and the desired selectivity cannot be sufficiently improved by blending only one of them. Although the theoretical basis for this is not necessarily clear, by using air-flow calcined alumina and kaolin together, it is possible to provide the catalyst with pores that allow easy diffusion of hydrocarbon molecules, while suppressing over-decomposition of hydrocarbons. It is estimated that the activity of the crystalline aluminosilicate zeolite can be fully exhibited, and as a result, the production amount of not only gasoline fractions but also middle distillates such as kerosene and diesel oil is increased. Incidentally, the catalyst obtained by the method of the present invention has a diameter of
It has pores of 1000 Å to 3000 Å (based on mercury intrusion method). The airflow calcined alumina used in the present invention is produced by rapidly dehydrating aluminum hydroxide (gibbsite) produced by the Beyer method by contacting it with hot air at 350 to 700°C, preferably 550 to 650°C, for a short time. Obtainable. In this case, the contact time with the hot air is extremely important and is usually less than 5 seconds, preferably less than 1 second. This rapid dehydration produces minute cracks in gibbsite without destroying the hexagonal plate-shaped crystal matrix of gibbsite.
This allows highly active alumina to be obtained. Furthermore, this air-flow calcined alumina has
As introduced in No. 91595, it is identified as x-alumina by X-ray diffraction method. The kaolin used in the present invention is preferably kaolinite, which has hexagonal plate-shaped crystals like gibbsite. According to the method of the present invention, the above-mentioned air-flow calcined alumina, kaolin, silica-based matrix precursor and crystalline aluminosilicate zeolite are made into an aqueous slurry, and this is spray-dried in a conventional manner to produce the desired catalytic cracking catalyst. can be obtained. As a precursor of silica matrix,
The aqueous slurry contains air-calcined alumina, kaolin, and crystalline aluminosilicate zeolite dispersed in a silica-based matrix precursor, as silicic acid liquid, silica hydrosol, silica-alumina hydrogel, silica-magnesia hydrogel, etc. are commonly used. It can be prepared by The amount of airflow calcined alumina added is 10 to 10% of the weight of the final catalyst composition.
30%, the amount of kaolin added is the same 30-50%, and the amount of crystalline aluminosilicate added is the same 3-40%.
It is preferable that Reference example (manufacture of airflow calcined alumina) Aluminum hydroxide (Al ₂ O ₃ 3H ₂ O) manufactured by the Beyer method is placed in a calcining tube where hot air at 650°C is flowing for a contact time of 2 seconds. Air flow calcined alumina was obtained. This airflow calcined alumina was identified by X-ray diffraction as x-alumina crystals, and its composition was Al ₂ O ₃ .0.5H ₂ O. Comparative Example 1 Commercially available No. 3 water glass was diluted to prepare a water glass solution with an SiO ₂ concentration of 11.2%. Separately, a 10.5% aluminum sulfate solution was prepared. This water glass solution and aluminum sulfate solution were added at 20/min, 10/min, respectively.
The gel was prepared by continuous mixing for 10 minutes at a rate of 10 minutes. This mixed gel was aged at 65°C for 3.5 hours,
The pH was stabilized at 5.8 with water glass. The air-flow calcined alumina obtained in the above reference example was mixed into this gel at a concentration of 20% based on the weight of the final catalyst.
Catalyst A was obtained by spray drying at a temperature of .degree. Comparative Example 2 A gel prepared in the same manner as Comparative Example 1 was divided into three parts, and one part was spray-dried as it was to obtain Catalyst B. Kaolin and bentonite were added to the remaining two in amounts of 20% based on the weight of the final catalyst, and the catalysts were spray-dried. Catalyst C was added with kaolin, and Catalyst D was added with bentonite. Example 1 Commercially available No. 3 water glass was diluted and SiO ₂ concentration was 12.73%.
A water glass solution of was prepared. Separately, sulfuric acid with a concentration of 25% was prepared. Silica hydrosol was prepared by continuously mixing this water glass solution and sulfuric acid at a rate of 20/min and 5.65/min for 10 minutes, respectively. This silica hydrosol was divided into two parts, and one part contained kaolin and the air-flow calcined alumina obtained in the reference example, each having a weight of 55% and 10%, respectively, based on the weight of the final catalyst.
%, and a water suspension slurry of rare earth-exchanged Y-type zeolite with a concentration of 30% in advance is mixed so that the zeolite content is 15% based on the weight of the final catalyst, and this mixture is heated to a hot air temperature. After spray drying at 220°C, catalyst E was obtained by washing and drying. Kaolin and air-flow calcined alumina were added to the remaining silica hydrosol so that their respective weights were 45% and 20% based on the weight of the final catalyst,
Furthermore, in the same manner as in the case of Catalyst E, zeolite was added and spray-dried to prepare Catalyst F. Comparative Example 3 Kaolin was added to the silica hydrosol prepared in the same manner as in Example 1 so that the weight of the final catalyst was 65%, and a rare earth-exchanged Y-type zeolite water suspension slurry with a concentration of 30% was added. The zeolite content in the final catalyst was added to 15%, and the mixture was spray-dried, washed, and dried to prepare catalyst G. Example 2 A silica hydrosol was prepared in the same manner as in Example 1. Separately, after ammonium ion exchange with the sodium type phasiasite by a conventional method,
The product was calcined at 550°C for 3 hours, and the calcined product was again subjected to ammonium ion exchange and then calcined in a moist state at 600°C for 3 hours to prepare a hydrogen-type zeolite. Divide the silica hydrosol into two parts,
First, kaolin and the air-flow calcined alumina of the reference example were added so that their weights in the final catalyst were 50% and 10%, respectively, and the above hydrogen-type zeolite water suspension slurry, which had been adjusted to a concentration of 30%, was added to the final catalyst. The catalysts were mixed so that the zeolite content in the catalyst was 20%, and the mixture was spray-dried at a hot air temperature of 220°C, washed, and dried to obtain catalyst H. Follow the same procedure to get the remaining 1
Catalyst I was prepared using two silica hydrosols with kaolin, flash calcined alumina and zeolite contents of 40%, 20% and 20%, respectively, based on the weight of the final catalyst. Comparative Example 4 Kaolin was added to the silica hydrosol prepared in the same manner as in Example 1 so that the weight of the final catalyst was 60%, and the same type of hydrogen-type zeolite water suspension slurry as that used in Example 2 was added to the final catalyst. Catalyst J was prepared by spray drying a mixture in which the zeolite content in the catalyst was 20%, followed by washing and drying. Comparative Example 5 The air-flow calcined alumina of the reference example was added to the silica hydrosol prepared in the same manner as in Example 1, and the weight of the final catalyst was
A hydrogen-type zeolite water suspension slurry of the same kind as that used in Example 2 was added so that the zeolite content in the final catalyst was 20%, and the mixture was spray-dried, washed, and then dried. Catalyst K was prepared. Example 3 2086g of sodium aluminate (Al ₂ O _{3
A solution was prepared by adding 958 g of sodium hydroxide (Na 2 O} content 37.8%) with stirring. After adding 7176 g of silica sol (SiO ₂ content 30%) having a silica particle size of 50 Å to 500 Å to this solution while stirring, stirring was stopped and the solution was allowed to stand at room temperature for 20 hours. Next, add this mixture
It was heated in a 95°C water bath for 2 hours, then taken out from the water bath and cooled to room temperature. To the obtained slurry, 1345 g of silica sol (SiO ₂ content 30%) was added again with stirring and heated in a 95° C. water bath for 10 days, and the solid content in the liquid was filtered and washed. The obtained solid substance was confirmed to be highly pure faujasite by X-ray diffraction method. Further, the surface area of this faujasite as determined by the BET method was 685 m ² /g, and the oxide molar ratio of the faujasite as determined by chemical analysis was as follows. 1.02Na ₂ O・Al ₂ O ₃・5.5SiO ₂・9.2H ₂ O After ammonium ion exchange of this sodium type phasiasite by a conventional method, 3
After firing for an hour, the fired product was subjected to ammonium ion exchange again, and then heated again for 600 hours while still containing moisture.
The mixture was calcined at ℃ for 3 hours to obtain hydrogen type zeolite. Next, kaolin was added to the silica hydrosol prepared in the same manner as in Example 1 so that the weight of the final catalyst composition was 50%.
Also, the air-flow calcined alumina of the reference example was mixed so that the weight of the final catalyst composition was 10%, and the 30% slurry of the hydrogen type zeolite was added so that the zeolite content in the final catalyst composition was 20%. %. The mixture thus obtained was spray-dried, washed, and dried again to obtain catalyst L. Comparative Example 6 Kaolin was added to the silica hydrosol prepared in the same manner as in Example 1 so that the weight of the final catalyst composition was 55%, and air-flow calcined alumina of Reference Example was added to the silica hydrosol so that the weight of the final catalyst composition was 5%. A hydrogen-type zeolite slurry similar to that used in Example 2 was mixed so that the zeolite content in the final catalyst composition was 20% by weight, and the mixture was spray-dried, washed, and dried. Catalyst M was obtained. Comparative Example 7 To the silica hydrosol prepared in the same manner as in Example 1, kaolin was added so that the weight of the final catalyst composition was 20%, and air-flow calcined alumina of the reference example was added so that the weight of the final catalyst composition was 40%. A hydrogen-type zeolite slurry of the same kind as that used in Example 2 was mixed so that the zeolite content in the final catalyst composition was 20% by weight, and this mixture was spray-dried, washed, and dried. A catalyst N was obtained. Comparative Example 8 Alumina having a composition of Al ₂ O ₃ .0.1H ₂ O obtained by firing aluminum hydroxide (Al ₂ O ₃ .3H ₂ O) produced by the Beyer method at 850°C for 10 seconds was treated with the alumina of the present invention. Example 3 except that it was used instead of airflow calcined alumina
Catalyst O was obtained in exactly the same manner. Catalyst performance test example 1 Each catalyst A~ obtained in the above comparative example and example
Thermal and steam stability tests and decomposition activity tests were conducted on O. The stability test described above tested the catalyst at a temperature of 760°C in an air stream containing 55% water vapor.
After treatment for 12 hours, the surface area and pore volume were measured by calcining at 600℃ for 2 hours, and the residual value was calculated by dividing the measured values by the surface area and pore volume of the catalyst before steam treatment and heat treatment. It was evaluated based on the percentage. In the activity test, the catalyst was subjected to steam treatment and heat treatment in the same manner as in the stability test. Clark oil was used as the raw material oil, and the reaction conditions were a reactor temperature of 492°C, a WHSV of 8 hr ^-1 , and a catalyst/stock oil weight ratio of 5. The results are shown in Table 1 along with the composition of each catalyst. As is clear from Table 1, catalyst E of the present invention,
F, H, I, and L have lower LCO/H than other catalysts.
The high CO ratio indicates that these catalysts have excellent selectivity for the production of middle distillates. Although catalysts K and N also have a high LCO/HCO ratio, the amount of coke produced is considerably larger than that of the catalyst of the present invention.

【table】

[Table] Catalyst Performance Test Example 2 The decomposition activities of Catalysts J and H were evaluated in relation to WHSV. Test Example 1 except that both catalysts were pretreated in the same manner as in Test Example 1, and the WHSV was changed.
The decomposition activity was measured under the same reaction conditions. The results are shown in Table-2. As can be seen from Table 2, Catalyst H of the present invention exhibits high selectivity for the production of middle distillates even if the conversion rate increases or decreases due to changes in WHSV.

【table】

Claims (1)

[Claims] 1 Contains air-flow calcined alumina obtained by contacting aluminum hydroxide produced by the Bayer method with hot air at 350 to 700°C for a period of 5 seconds or less, a precursor of kaolin and silica matrix, and crystalline aluminosilicate zeolite. A method for producing a catalyst composition for hydrocarbon decomposition, which comprises spray-drying an aqueous slurry.