Preparation method of gamma-Al2O3@CuO-ZnO@ZSM-5 double-core-shell catalyst

Abstract

The invention discloses a preparation method of a gamma-Al2O3@CuO-ZnO@ZSM-5 double-core-shell catalyst. The preparation method comprises the following steps: preparing gamma-Al2O3@CuO-ZnO powder; according to a molar ratio of raw materials, namely n(TEOS), n(NaAlO2), n(TPAOH) and n(H2O), of (40-360):1:19:4015, sequentially adding NaAlO2, TPAOH and TEOS into deionized water while stirring, continuously stirring uniformly, stirring and aging at room temperature for 3h to form a sol system, adding the gamma-Al2O3@CuO-ZnO powder into the system according to a core-shell mass ratio of gamma-Al2O3@CuO-ZnO to ZSM-5 of 1:2 to 2:1, continuing stirring uniformly, performing a hydrothermal reaction in a homogeneous reactor at 170-190 DEG C for 24-48h (at a rotating speed of 4r / min), cooling to room temperature, centrifuging, washing by using deionized water, washing by using anhydrous ethanol, drying at 120 DEG C for 12 h, and roasting at 500-600 DEG C for 3h to obtain the gamma-Al2O3@CuO-ZnO@ZSM-5 double-core-shell catalyst. The catalyst prepared by the preparation method provided by the invention can simultaneously increase the carbon dioxide conversion rate and the low-carbon olefin selectivity in a two-step technology in which the low-carbon olefin is prepared from methanol through CO2 hydrogenation.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a γ-Al 2 o 3 Preparation method of @CuO-ZnO@ZSM-5 double core-shell catalyst. Background technique [0002] Copper zinc aluminum (CZA, CuO-ZnO-Al 2 o 3 ) three-component copper-based catalyst is the current CO 2 Catalytic hydrogenation synthesis of methanol is the most widely used catalyst with good effect. ZSM-5 molecular sieve is made of SiO 4 and AlO 4 A microporous silica-alumina molecular sieve with tetrahedral units interlaced to form a three-dimensional intersecting channel structure. Because of its rich and adjustable B-acid properties, high specific surface area and unique shape-selective function of microporous products, it is widely used in the process of methanol catalytic cracking to light olefins (MTO). Coupling metal oxides and acidic molecular sieves to prepare bifunctional composite catalysts and apply them to CO 2 In the two-step process of ...

AI Technical Summary

Problems solved by technology

It can be seen that the existing research adopts the co-precipitation method and roasts Cu(OH) at 400 °C. 2 -Zn(OH) 2 -Al(OH) 3 Precursor, Al(OH) present 3 The dehydration decomposition is not complete, resulting in the carrier effect of γ-Al 2 o 3 The surface chemical properties are not obvious, and the reactivity is low

At the same time, the active components of the existing bifunctional composite catalysts are randomly distributed, and the structure only provides an open reaction environment, which cannot effectively solve the problem of CO 2 CO in the two-step process of hydrogenation and methanol to light olefins 2 Hydrogenation methanol synthesis 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 dual-function catalysts