Cu/Sn-β Catalyst Enabling the One-Step Synthesis of Methyl Acetate from Methanol Alone via Dehydrogenation Coupling
Qiang Nie, Jiaqi Si, Chao Meng, Tian Lan, Weidong Sun, Guofeng Zhao, Ye Liu, Yong Lu
Abstract
Methyl acetate (MA) can be directly synthesized via a methanol dehydrocoupling reaction, which is attractive but urgently calls for a groundbreaking catalyst. Herein, we report a Cu/Sn-β system with Sn–Cu synergistic catalysis, enabling the one-step MA synthesis from methanol alone. Over the 3Cu/Sn-β-30 (Si/Sn molar ratio of 33, Cu loading of 3 wt %), a maximum MA space–time yield of 1.4 molMA kgcat–1 h–1 is obtained with 4.1% methanol conversion and 56.4% MA selectivity at 220 °C. Electron transfer from Cu species to framework-confined Sn occurs and thus increases and stabilizes Cu+ sites. Lewis-acidic Sn(framework)/Cu+ pairs, with the assistance of Cu0 dehydrogenation, can transform a methanol molecule into bridged-adsorbed CH2O*. The C–C coupling of CH2O* with CH3O* on another Sn site proceeds to form CH3CHO* by leaving H on Cu+ and O (C–O bond cleavage of CH3O*) on that Sn site. The CH3CHO* subsequently condenses with CH3O* adsorbed on the Cu0 site to form MA.