Monodentate Formate‐Mediated Toluene Methylation to Xylene at Low Temperature Using Formic Acid and Hydrogen
Abstract
Abstract The industrial methanol–toluene methylation process for xylene production faces a challenge of lowering the reaction temperature while suppressing the side reaction of methanol to hydrocarbons. This depends on the low‐temperature formation of the methoxy intermediate required for methylation. Here, we establish a route for methoxy formation in which formic acid (FA) hydrogenates via a metastable monodentate formate intermediate. With the GaZrO x –ZSM‐5 catalyst, Ga–H bonds act as a “placeholder”, enabling FA adsorption as a monodentate formate rather than a stable bridged formate. At 300 °C and 3.0 MPa, toluene conversion reaches 13.9% with 77.6% xylene selectivity, outperforming established routes. Kinetic isotope effect experiments revealed that Ga‐based catalysts show a secondary isotope effect, whereas non‐Ga catalysts exhibit an inverse isotope effect. Density functional theory calculations indicated that the monodentate formate was more susceptible to hydrogenation which then facilitated methylation. This work provides a competitive route for xylene production from toluene under mild conditions using sustainable FA and H 2 .
Article Details
Authors (14)
Jiachang Zuo
State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols‐Ethers‐Esters College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
Chong Liu
Department of Chemistry and Biochemistry
Bilyu Hong
State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols‐Ethers‐Esters College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
Qiongjin Jiang
State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols‐Ethers‐Esters College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
Zhenyu Yang
Jia Liu
Wen Zhou
Yingjie Lai
State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials
Tom Backhouse
Johnson Matthey Public Limited Company London EC4A 4AB UK
Linmin Ye
State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols‐Ethers‐Esters College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China
Yongjin Luo
Fujian Key Laboratory of Pollution Control and Resource Reuse College of Environmental and Resource Sciences Fujian Normal University Fuzhou 350007 China
Wei Zhuang
Han Xu
Youzhu Yuan
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering