ZSM-5 Molecular Sieves: Preparation from Coal Gasification Slag and Performance in Methanol to Aromatics

doi:10.15541/jim20260049

Abstract

Abstract: Coal gasification slag (CGS), rich in silicon and aluminum species, represents a potential raw material for the preparation of molecular sieves. However, the traditional activation method of silicon and aluminum species in CGS has the problems of high energy consumption, significant pollution and substantial cost. In this study, CGS was activated by sub-molten salt method at low temperature, and then ZSM-5 molecular sieve was synthesized by hydrothermal method with activated CGS as raw material, and its methanol to aromatics (MTA) performance was evaluated. The results showed that the suitable activation conditions for the synthesis of ZSM-5 zeolite by CGS activated by sub-molten salt were as follows: CGS/NaOH mass ratio of 1 : 1.2, alkali concentration of 6.10 mol/L, activation time of 3 h, and activation temperature of 200 ℃. The suitable crystallization conditions for the synthesis of ZSM-5 molecular sieve by activating CGS are as follows: the synthesis system of pH 11, crystallization temperature of 160 ℃, crystallization time of 72 h, and the molar ratio of tetrapropyl ammonium bromide (TPABr)/SiO₂ of 0.1. The ZSM-5 molecular sieve synthesized has good crystallinity, complete skeleton and regular morphology. The Zn/H-ZSM-5 catalyst was prepared by ion exchange and equal volume impregnation of the synthesized ZSM-5 zeolite. The results of MTA performance evaluation showed that the methanol conversion of Zn/H-ZSM-5 catalyst reached 100% in the range of 400-500 ℃ and 5-10 h^-1. With the increase of reaction temperature, the selectivity of aromatics increased firstly and then decreased. With the increase of mass space velocity, the selectivity of aromatics gradually decreased. The reaction temperature of 450 ℃ and the mass space velocity of 5 h^-1 are the suitable temperature for MTA reaction on Zn/H-ZSM-5 catalyst. At this time, the methanol conversion rate reached 100% and the aromatics selectivity was 45.0%, showing good MTA performance and application potential. This study can provide a new pathway for the green and efficient synthesis of molecular sieves using CGS.

Key words: coal gasification slag, ZSM-5 molecular sieve, sub-molten salt activation, catalyst, methanol to aromatics

CLC Number:

TQ426

CHEN Zhiping, DUAN Zhenyang, YU Haoshan, ZHOU Wenwu, YANG Zhiyuan, ZHOU Anning. ZSM-5 Molecular Sieves: Preparation from Coal Gasification Slag and Performance in Methanol to Aromatics[J]. Journal of Inorganic Materials, DOI: 10.15541/jim20260049.

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