Modified Y molecular sieve and preparation method thereof

Abstract

The invention discloses a modified Y molecular sieve and a preparation method thereof, which have the following properties: the silicon-aluminum ratio of the bulk phase is 10-70, wherein the silicon-aluminum ratio of the surface layer is 7-30, and the silicon-aluminum ratio of the surface layer is lower than the silicon-aluminum ratio of the bulk phase Ratio 5~40, wherein the surface layer refers to the thickness range from the outer surface of the molecular sieve to the inside of 5~400nm; the unit cell constant of the modified Y molecular sieve is 2.425~2.455nm; the specific surface area of ​​the modified Y molecular sieve is 600~900m2 / g, the pores Content 0.20~0.70ml / g; infrared acid content 0.3~1.5mmol / g. The preparation method of the modified Y molecular sieve of the present invention is as follows: the Y molecular sieve after ammonium exchange is subjected to primary dealumination treatment, rapid drying, carbon deposition reaction, high-temperature roasting treatment, and then secondary dealumination treatment, drying, and charcoal burning treatment, A modified Y molecular sieve is obtained. The silicon-aluminum ratio of the surface layer of the molecular sieve of the invention is lower than that of the bulk phase, and has broad application prospects in the hydrocracking reaction process.

Description

technical field [0001] The invention relates to a modified Y molecular sieve and a preparation method thereof. Background technique [0002] Hydrocracking technology has the characteristics of strong adaptability to raw materials, great flexibility in production operations and product plans, and good product quality. It can directly convert various heavy and low-quality feedstocks into high-quality jet fuel, diesel, and lubricating oil base materials that are urgently needed by the market. As well as chemical naphtha and tail oil steam cracking raw materials for ethylene production, it has become one of the most important heavy oil deep processing processes in modern oil refining and petrochemical industries, and has been increasingly widely used at home and abroad. The heart of the hydrocracking process is the hydrocracking catalyst. Hydrocracking catalyst is a typical dual-function catalyst, which has dual functions of hydrogenation and cracking. Among them, the hydrogen...

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Problems solved by technology

[0003] At present, modified Y molecular sieve is the most widely used in hydrocracking process. The conventional treatment method has uniform distribution of silicon and aluminum inside and outside the molecular sieve, and uniform distribution of acid centers. When the silicon aluminum ratio of Y molecular sieve is reduced, the acid center density of Y molecular sieve is increased, and the The temperature sensitivity is improved, but at the same time, the secondary cracking is also greatly increased, and the hydrogen consumption is greatly increased

However, when the Y molecular sieve is subjected to advanced treatment and the acid density is too low, the temperature-raising sensitivity of the catalyst is poor.

[0004] CN200710158784.0 discloses a hydrocracking catalyst containing Y molecular sieve and its preparation method. In this invention, Y-type molecular sieve is obtained after hydrothermal treatment with a mixed aqueous solution of aluminum salt and acid, and the temperature-raising sensitivity of the prepared catalyst is Higher, but at the same time, the secondary cracking during the heating process increases significantly, and the hydrogen consumption increases significantly, which is not conducive to the stable operation of the industrial hydrocracking unit during the heating process

[0005] CN200810012212.6 discloses a hydrocracking catalyst carrier and its preparation method. The hydrocracking catalyst prepared by the invention has poor temperature raising sensitivity

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