Preparation method of catalytic cracking catalyst

Abstract

The invention relates to a preparation method of a catalytic cracking catalyst. According to the method, the NaY molecular sieve raw powder and halogen-containing gas are contact to perform gas phase ion exchange reaction; the sodium reduction and the ultra-stabilization of the NaY molecular sieve raw powder are completed in one step; the low-sodium high-silica-alumina-ratio molecular sieve is prepared. According to the method, different kinds of clay raw ores are compounded and are treated by high-concentration acid to obtain acid active composite clay; then, the low-sodium high-silica-alumina-ratio molecular sieve, the acid active composite clay, bonding agents, rare earth and decationized water are mixed and pulped; then, spraying granulation is performed; roasting and curing are performed; washing and drying are not needed; a finished product of the catalytic cracking catalyst is obtained. The catalytic cracking catalyst has the advantages that the olefin content in the gasoline can be obviously reduced; the light oil yield is improved; the preparation flow process of the catalyst is short; no ammonia and no nitrogen are discharged.

Description

technical field [0001] The present invention relates to the technical field of preparation of oil refining catalysts, in particular to a method for preparing catalytic cracking catalysts, and more specifically to an ultra-stable molecular sieve prepared by a gas-phase ion exchange method as an active component and a composite acid active clay as an activation carrier , providing a catalyst preparation method for catalytic cracking with no ammonia nitrogen discharge, short process flow, high silicon, low sodium and high stability. [0002] technical background [0003] As we all know, the petroleum refining industry is an important pillar of the national economy. Its industrial chain is long, its products cover a wide range, and it is closely related to people's lives. The most important refining method in the petroleum refining process is catalytic cracking technology. 70% of the gasoline, 40% of diesel, and 40% of propylene in my country's daily needs come from catalytic cra...

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Problems solved by technology

It can be seen that in this method, the molecular sieve concentration in the reactor is high, the bed density is higher, and the molecular sieve is in a dense phase state with silicon tetrachloride in the pipeline, and the mass transfer and heat transfer effect is poor, which will cause different properties of the product; in addition, The silicon tetrachloride gas is not diluted by the carrier gas, and the high-concentration silicon tetrachloride gas contacts with the molecular sieve particles, the reaction is stronger and the crystal form is greatly damaged, resulting in serious collapse of the molecular sieve structure, a sharp drop in product crystallinity, and a large amount of release The heat cannot be taken away by the carrier gas, which may easily cause local overheating of the molecular sieve bed; at the same time, after the reaction, the molecular sieve is directly mixed with the substrate and water for beating without washing, so that the Na + , NH 4 + , SO 4 2- Harmful ions such as ions re-enter molecular sieves and catalysts; and after the silicon tetrachloride tail gas reacts with lye in the absorption tower, it is directly discharged as waste water, which will cause great damage to the environment

[0037] CN103785437A, CN103785438A, CN103787352A, CN104549445A, on the basis of the above method, increase the washing process of the molecular sieve after the reaction, but there are still poor mass and heat transfer effects, different properties of the product, local overheating of the reaction, and direct discharge pollution of salty wastewater environmental issues

In recent years, there has been little research on the support of semi-synthetic catalysts. At the same time, based on reasons such as technical secrecy, there are few reports on the conditions and processes of chemical modification of the support and clay. Therefore, it is necessary to carry out more detailed research on this. Now The preparation process of some semi-synthetic molecular sieve catalytic cracking catalysts also needs to be greatly optimized and improved

[0041] CN1044772A treats single clay sepiolite as a cracking catalyst carrier after being treated with dilute hydrochloric acid or nitric acid, but the mother liquor after nitric acid treatment and the filtrate after the catalyst is washed with ammonium sulfate contain a large amount of ammonia nitrogen, which causes greater pressure for environmental protection and sewage treatment

In fact, such a high sulfuric acid concentration and acid treatment temperature will cause great damage to the crystal structure of kaolinite, resulting in a decrease in the thermal stability and hydrothermal stability of the catalyst (as can be seen from its micro-reaction activity data)

In addition, the clay is treated with such a high concentration of sulfuric acid, so that the sulfate radical content in the modified clay increases significantly (from 0.54wt% to 0.70wt%), which may cause the sulfate radical in the catalyst to exceed the standard (the sulfate radical content in the undisclosed catalyst in the patent )

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