Influence of CS2 on performance of Ni2P/SiO2 for deoxygenation of methyl laurate as a model compound to hydrocarbons: Simultaneous investigation on catalyst deactivation

Abstract

The effect of CS2 on the performance of Ni2P/SiO2 for the deoxygenation of methyl laurate as a model compound to hydrocarbons was investigated. To explore the catalyst deactivation, the fresh and used catalysts were characterized by N2 sorption, XRD, HRTEM, 31P MAS NMR, XPS, ICP-AES and TG-DTA. For comparison, we also investigated the performance of Ni12P5/SiO2 and the effects of H2O and CO on the property of Ni2P/SiO2. At 300°C, 3.0MPa and WHSV of 5h−1, Ni2P/SiO2 continuously deactivated during 28h in the absence of CS2, which is mainly ascribed to the carbonaceous deposit as well as the surface restructuring of Ni2P due to H2O. The presence of CS2 accelerated the deactivation of Ni2P/SiO2 in the initial stage (about first 10h), whereas the catalyst activity did not change obviously in the latter 18h. Also, the presence of CS2 remarkably promoted the decarbonylation reaction and the formations of undecene and dodecene, which were more obvious with higher CS2 concentration. Interestingly, the Ni2P phase was transformed to Ni12P5 in the presence of CS2, which did not take place in the absence of CS2. We propose that the effect of CS2 on the performance of Ni2P/SiO2 is mainly ascribed to the formation of the surface nickel phosphosulfide phase on bulk Ni12P5. In addition, water was detrimental to the catalyst stability.