Method for preparing ZnO-Al2O3@ZSM-5 core-shell structured catalyst

Abstract

The invention discloses a method for preparing a ZnO-Al2O3@ZSM-5 core-shell structured catalyst. The method comprises the steps: preparing ZnO-Al2O3 powder; and proportioning raw materials, i.e., n(TEOS), n(NaAlO2), n(TPAOH) and n(H2O) according to a mole ratio of (40 to 360): 1: 19: 4015, sequentially adding NaAlO2, TPAOH and TEOS into deionized water with stirring, carrying out uniform stirringcontinuously, carrying out aging for 3h with stirring at room temperature to form a sol system, adding ZnO-Al2O3 powder into the system according to a core-shell mass ratio, i.e., ZnO-Al2O3: ZSM-5 of(1: 4) to (4: 1), carrying out uniform stirring continuously, carrying out a hydrothermal reaction for 36 to 48 hours at the temperature of 170 DEG C to 190 DEG C in a homogeneous reactor, cooling reacted substances to room temperature, carrying out centrifugation, carrying out washing with deionized water, carrying out washing with anhydrous ethanol, carrying out drying for 12h at the temperature120 DEG C, carrying out roasting for 3h at the temperature 500 DEG C to 600 DEG C, thereby preparing the ZnO-Al2O3@ZSM-5 core-shell structured catalyst. The catalyst prepared by the method can be used for simultaneously improving conversion ratio of carbon dioxide and selectivity of low-carbon olefins in a two-step method process for preparing the low-carbon olefins from methanol through CO2 hydrogenation.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and specifically relates to a ZnO-Al 2 o 3 The preparation method of @ZSM-5 core-shell structure catalyst. Background technique [0002] Zinc-aluminum (ZnO-Al 2 o 3 ) The two-component catalyst is CO 2 Catalytic hydrogenation synthesis methanol process is a kind of metal oxide catalyst with strong anti-sintering stability and anti-sulfur ability and good effect. ZSM-5 molecular sieve is made of SiO 4 and AlO 4 Microporous silica-alumina molecular sieves with tetrahedral units interlaced to form a three-dimensional intersecting channel structure are widely used in methanol catalytic cracking because of their rich and adjustable B-acid properties, high specific surface area and unique shape-selective function of microporous products. Low Carbon Olefin Process (MTO). Accordingly, a bifunctional core-shell catalyst was prepared by coupling metal oxides and acidic molecular sieves,...

AI Technical Summary

Problems solved by technology

However, the active components of existing composite catalysts are randomly distributed, and the structure only provides an open reaction environment. More importantly, the distribution structure with traditional nano-copper particles as the active component has extremely poor anti-sintering stability and cannot effectively solve the problem of CO 2 CO in the two-step process of hydrogenation and methanol to light olefins 2 The hydrogenation synthesis of methanol process and methanol catalytic conversion to light olefins process require different reaction formation and dissociation conversion environmental conditions, resulting in the poor catalytic effect of existing composite catalysts