title: Mechanistic insight into the formation of acetic acid from the direct conversion of methane and carbon dioxide on zinc-modified H-ZSM-5 zeolite.
abstract: Methane and carbon dioxide are known greenhouse gases, and the conversion of these two C1-building blocks into useful fuels and chemicals is a subject of great importance. By solid-state NMR spectroscopy, we found that methane and carbon dioxide can be co-converted on a zinc-modified H-ZSM-5 zeolite (denoted as Zn/H-ZSM-5) to form acetic acid at a low temperature range of 523-773 K. Solid-state (13)C and (1)H MAS NMR investigation indicates that the unique nature of the bifunctional Zn/H-ZSM-5 catalyst is responsible for this highly selective transformation. The zinc sites efficiently activate CH4 to form zinc methyl species (-Zn-CH3), the Zn-C bond of which is further subject to the CO2 insertion to produce surface acetate species (-Zn-OOCCH3). Moreover, the Brønsted acid sites play an important role for the final formation of acetic acid by the proton transfer to the surface acetate species. The results disclosed herein may offer the new possibility for the efficient activation and selective transformation of methane at low temperatures through the co-conversion strategy. Also, the mechanistic understanding of this process will help to the rational design of robust catalytic systems for the practical conversion of greenhouse gases into useful chemicals.
authors: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University , Lanzhou, Gansu 730000, P.R. China.
authors: Jian-Feng
authors: JF
authors: Wu
authors: Si-Min
authors: SM
authors: Yu
authors: Wei David
authors: WD
authors: Wang
authors: Yan-Xin
authors: YX
authors: Fan
authors: Shi
authors: S
authors: Bai
authors: Chuan-Wei
authors: CW
authors: Zhang
authors: Qiang
authors: Q
authors: Gao
authors: Jun
authors: J
authors: Huang
authors: Wei
authors: W
authors: Wang
mesh_terms: D019342:Acetic Acid / Q000138:chemical synthesis* / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D017641:Zeolites / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D017641:Zeolites; D002245:Carbon Dioxide; D015032:Zinc; D008697:Methane; D019342:Acetic Acid