In a recent development, academicians from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, including Academician Zhongmin Liu, Researcher Yingxu Wei, Researcher Zhengxi Yu, and Associate Researcher Jingfeng Han, have made significant strides in elucidating the reaction mechanism and product distribution control of molecular sieve catalyzed coupling reactions. The findings have been published in the "Journal of the American Chemical Society."
Molecular sieve shape-selective catalysis stands as a prime example of host-guest chemistry. The catalytic conversion of methanol using molecular sieves provides an alternative route for manufacturing basic petrochemical products from non-petroleum resources. Presently, the industrialization of processes that selectively and effectively convert methanol into olefins, aromatics, gasoline, and other products has been successfully achieved.
In this study, building upon a profound understanding of the methanol-to-olefin process, the team established a methanol-toluene coupling reaction system and delved into its reaction mechanism. Through various experimental and characterization techniques, the team revealed and optimized the regulatory role of toluene in the reaction system. The research uncovered that the introduction of toluene as a reactant forms a flowing aromatic hydrocarbon pool consisting of lightly methylated benzene, submethylated cyclopentadiene/cyclohexadiene, and their protonated products. This regulation of the methanol conversion reaction pathway tends to favor ethylene production. Furthermore, combining theoretical calculations, the team constructed a comprehensive network for the methanol-toluene coupling reaction.
Through a combined regulation strategy, this work simultaneously controls the selectivity of products such as olefins and aromatics, achieving high selectivity for ethylene, propylene, p-xylene, and other high-value-added products on a single molecular sieve bed layer. Ethylene and propylene can further produce polyethylene and polypropylene, while downstream products of ethylene glycol and terephthalic acid from p-xylene can be used for polyester production. This efficient coupling route holds significant guidance for the synthesis of polyolefins and polyesters in the polymer industry. Moreover, the establishment of combined regulation strategies provides a model case for the joint production of various target chemicals in complex catalytic processes. Based on this strategy, an industrial demonstration unit for methanol coupling is currently under construction, with prospects for widespread application and promotion in large-scale methanol coupling industrial processes.
Related paper information: https://doi.org/10.1021/jacs.3c12087
