Catalytic conversion of cellulose into ethylene glycol over nickel-promoted tungsten carbide

Abstract

In our previous work, we reported that Ni-promoted tungsten carbide functioned as a highly active and selective catalyst for cellulose conversion. The catalytic performance was largely dependent on the support used. With active carbon as the support, the maximum yield of EG was about 61%. However, when a mesoporous carbon or a SBA-15 as the support, the maximum yield of EG was increased up to 75%.2,3 In this work, we further studied the effect of preparation method, specifically, the impregnation sequence of Ni and W, on the catalytic performance in cellulose conversion. For this purpose, a series of Ni-promoted W2C catalysts were prepared by a post-impregnation method and evaluated for the catalytic conversion of cellulose into ethylene glycol. Quite different from our previously reported Ni-W2C/AC catalysts which were prepared by the co-impregnation method, the introduction of nickel by the post-impregnation method did not cause catalyst sintering but resulted in the re-dispersion of tungsten component, which was identified by characterization using XRD, TEM, and CO chemisorption. The highly dispersed Ni-promoted W2C catalyst was found to be very active and selective for the cellulose conversion into ethylene glycol, with 100% conversion of cellulose and 73.0% yield of ethylene glycol. The underlying reason was attributed to the much better dispersion of active sites on the catalyst. With this post-impregnation method, we also prepared a series of other transition metals promoted tungsten carbide catalysts, and found that Ru-promoted tungsten carbide gave a comparable activity and selectivity to Ni-promoted one for the production of ethylene glycol from cellulose.