Effect of carburising agent on the preparation of molybdenum carbides by plasma and their catalytic HDO of o-cresol

Abstract

Abstract In this paper, molybdenum carbides have been prepared by DBD plasma using mixtures of H2 and CH4. C2H4 or C3H8 with different hydrocarbon/H2 successfully, and characterized by XRD, XPS, Raman, CO2-TPO and H2-TPD. The results of XRD show that the different carburising agents and C/H2 have little influence on β-Mo2C particles size at input power 40 W. Carburising with a mixture of H2 and C2H4 gives rise to ƞ-MoO1 − x and then deeply carbonized to β-Mo2C, while when using CH4 or C3H8 as the carbon source, MoO2 is directly carbonized to β-Mo2C. Besides, the kind of carburising agents has no effect on the input power of synthetic β-Mo2C (40 W). XPS, Raman and CO2-TPO characterization revealed the effect of carburising agents and hydrocarbon /H2 on the amount of carbon deposition during the surface of the β-Mo2C. Under the same C/H2, the surface of Mo2C-E has the lowest carbon deposition, while the carbon deposition on the surface of Mo2C-M is highest, and with the increasing of hydrocarbon /H2 of the same carburising agent, the carbon deposition on the surface increases. Mo2C-M, Mo2C-E and Mo2C-P were evaluated in the hydrodeoxygenation of o-cresol, using a stainless-steel tubular reactor. The results showed that the Mo2C-E (C2H4/H2 = 1/8) shows the better catalytic performance and the toluene yield is over 80%, which can be attributed to the more active sites and the lower carbon deposition, and this result is consistent with the result of H2-TPD.