A kind of modified ZSM-5 molecular sieve catalyst and preparation method thereof

Abstract

The invention discloses a preparing method of a modified ZSM-5 molecular sieve based catalyst.The preparing method comprises the following steps that firstly, modification preparation of an Ag / ZSM-5 molecular sieve is carried out, wherein an equivalent-volume impregnation method is adopted, a silver nitrate solution and a ZSM-5 molecular sieve are mixed evenly according to the Ag loading amount of 1-10wt%, room-temperature impregnation is carried for 10 h, and the mixture is dried to the constant weight at 85 DEG C, roasted for 5 h at 550 DEG C, and then cooled to the room temperature; secondly, modification preparation of an I-Ag / ZSM-5 molecular sieve is carried out, wherein the equivalent-volume impregnation method is adopted, an iodine-containing speciation solution and the Ag / ZSM-5 molecular sieve obtained in the first step are mixed evenly according to the loading amount of 1-10wt%, room-temperature ultrasonic impregnation is carried for 10-30 min first, then conventional impregnation is carried out for 2-12 h, and the mixture is dried to the constant weight at 50-105 DEG C.By means of the preparing method of the modified ZSM-5 molecular sieve based catalyst, the low-temperature conversion rate of methyl alcohol can be increased, the low-carbon olefin selectivity can be improved, and the service life is long.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method of a modified ZSM-5 molecular sieve catalyst. Background technique [0002] ZSM-5 molecular sieve is a kind of SiO 4 and AlO 4 A zeolite microporous molecular sieve composed of tetrahedrons and having a three-dimensional cross network straight channel structure. Because of its good hydrothermal stability, large specific surface area and strong shape-selective catalytic function, it has been widely used in coal-based methanol production of low-carbon olefins (MTO) technology. [0003] Due to the large pores and strong surface acidity of ZSM-5 molecular sieve, the industrial application usually needs to modify the molecular sieve. At present, ZSM-5 molecular sieves are mainly modified by various methods such as impregnation or doping of various metal elements, acid-base or high-temperature hydrothermal desilication and dealumination. A...

AI Technical Summary

Problems solved by technology

However, the higher reaction temperature in industrialization not only increases the unit energy consumption of the product, but also accelerates the formation of carbon deposits, resulting in rapid deactivation of the catalyst and the need for frequent regeneration, further increasing the production cost of the product

It can be seen that the existing MTO process has shortcomings such as high reaction temperature, high energy consumption per unit of product, easy carbon deposition and deactivation of the catalyst, and frequent regeneration.