Method for preparing gamma-Al2O3@CuO-ZnO@SAPO-34 dual-core-shell catalyst

Abstract

The invention discloses a method for preparing a gamma-Al2O3@CuO-ZnO@SAPO-34 dual-core-shell catalyst. The method comprises the steps: preparing gamma-Al2O3@CuO-ZnO powder; and proportioning raw materials, i.e., Al2O3, P2O5, SiO2, MOR and H2O according to a mole ratio of 1.0: 0.8: 0.6: 2.5: 80, sequentially adding pseudo-boehmite, ethyl orthosilicate and a template agent, i.e., morpholine into anorthophosphoric acid solution with stirring, carrying out uniform stirring continuously, carrying out aging for 24h with stirring at room temperature to form a sol system, adding gamma-Al2O3@CuO-ZnO powder into the system according to a core-shell mass ratio, i.e., gamma-Al2O3@CuO-ZnO: SAPO-34 of (1: 2) to (2: 1), carrying out uniform stirring continuously, then, transferring the mixture into a reactor, carrying out hydrothermal crystallization for 24 to 48 hours at the temperature of 190 DEG C to 210 DEG C, carrying out cooling, carrying out filtering, carrying out washing with deionized water until washing water is neutral, carrying out baking for 6h at the temperature of 105 DEG C, and carrying out roasting for 3h at the temperature of 500 DEG C to 600 DEG C, thereby preparing the gamma-Al2O3@CuO-ZnO@SAPO-34 dual-core-shell 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, in particular to a γ-Al 2 o 3 Preparation method of @CuO-ZnO@SAPO-34 dual 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. SAPO-34 molecular sieve is made of SiO 4 , AlO 4 and PO 4 A microporous silicoaluminophosphate molecular sieve with three kinds of 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 ...

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