Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a ＂molecular engineering＂ process to realize directional co...Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a ＂molecular engineering＂ process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method ofp-xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para-selective technical process. If constructing p-xylene as the single target product, the major challenge to develop para-selective toluene methylation is to improve the p-xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield ofp-xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards coveting external acid sites by surface modification to get short ＂micro-tunnels＂ with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para-methyl group.展开更多
基金Acknowledgements We would like to greatly acknowledge the financial support from the National Natural Science Foundation of China （NSFC, Grant No. 21403303） and Major Research Plan of NSFC （No. 91434102）.
文摘Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a ＂molecular engineering＂ process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method ofp-xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para-selective technical process. If constructing p-xylene as the single target product, the major challenge to develop para-selective toluene methylation is to improve the p-xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield ofp-xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards coveting external acid sites by surface modification to get short ＂micro-tunnels＂ with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para-methyl group.
