One-Step Production of Ethylbenzene from Ethane and Benzene on the PtZnPr/ZSM-5 Catalyst

A one-step process for the production of ethylbenzene from ethane and benzene was used to overcome the issues of high energy consumption and long process flow in the conventional two-step reaction consisting of ethane dehydrogenation followed by benzene/ethylene alkylation. On this basis, a metal-acid dual-active center catalytic model (PtZnPr/ZSM-5) was proposed, with Pt species providing the metal dehydrogenation active centers, Zn and Pr as auxiliaries, and ZSM-5 providing the acid active centers. The alkylation reaction on ZSM-5 pulls the ethane dehydrogenation reaction on Pt by consuming its intermediate product, ethylene, thereby coupling the two reactions. Experiments showed that reducing the spatial distance between the dual active centers enhanced the catalytic activity. The addition of Zn and Pr auxiliaries to Pt/ZSM-5 effectively enhanced the dispersion of metals, while reducing the adsorption activity of ethyl species by the Pt active center and inhibiting the formation of coke precursors. The analysis of acid strength and Brønsted acid sites of the zeolite catalysts revealed that the addition of Zn and Pr auxiliaries resulted in a decrease in the presence of strong acid sites, thereby contributing to the catalyst's extended lifetime. Additionally, it was observed that the introduction of Pr led to an augmentation of Brønsted acid sites, which play a pivotal role as active sites in the alkylation reaction. This augmentation assists in facilitating benzene conversion and consequent rate enhancement. Ultimately, a high benzene conversion of close to 17% was achieved, and the catalyst life was improved by over 6.5 times compared with Pt/ZSM-5.