Effect of Brønsted acid of Y zeolite on light arene formation during catalytic upgrading of coal pyrolysis gaseous tar

Abstract

Catalytic upgrading of coal pyrolysis gaseous tar is one of the promising techniques for the efficient conversion and utilization of tar. The heavy arene in tar can effectively convert into light arene, such as benzene, toluene, ethylbenzene, xylene and naphthalene (BTEXN). Therefore, a series of acid modified Y-type zeolites were prepared by ammonium exchange method, and the effect of Brønsted acid in zeolite and coal rank on the distribution of tar was investigated in this study. The XRD, N2 adsorption, and pyridine-FTIR analysis results show that the structure of the acid-modified zeolite has not changed, but the content of the medium Brønsted acid changed significantly. The yield of BTEXN produced in the catalytic upgrading of three different rank coal pyrolysis gaseous tar (one is lignite, the other two are bituminous coal) is up to 3.2 times, 2.8 times and 1.7 times that of the raw coal pyrolysis, respectively. The increase in the acidity of medium Brønsted acid greatly contributes to the conversion of heavy arene to BTEXN. For different coal samples, the performance of the catalyst is closely related to its Brønsted acid amount and Brønsted/Lewis ratio. And the textural properties of the zeolite also have an important influence on its catalytic performance.