Methyl palmitate hydrodeoxygenation over silica-supported nickel phosphide catalysts in flow reactor: experimental and kinetic study

BACKGROUND The search for alternative sources of fuels is crucial for sustainable development now and in the near future. Biomass attracts much attention as an environmentally friendly, green and CO2-neutral source of fuels. Hydrodeoxygenation (HDO) of fatty acid-based feedstocks such as nonedible vegetable oil, waste cooking oil and animal fat is a versatile technology for producing efficient fuels. HDO schemes are often contradictory and have different numbers of stages. In the work reported, a highly active nickel phosphide catalyst was obtained and methyl palmitate (MP) HDO kinetic modelling was carried out to elucidate the HDO reaction scheme. RESULTS The effect of reduction temperature (400-600 degrees C) on the catalytic properties of the catalyst in MP HDO was evaluated and the most active catalyst (after reduction at 450 degrees C) was used in the kinetic experiments. The experimental data were collected in a wide range of MP conversion. The reaction scheme of MP HDO was elucidated by means of mathematical modelling which was specified by successive consideration of the experimental results of HDO selectivities at low MP conversions (1-10%), additional experiments of alcohol HDO (dodecanol-1 as an analogue for hexadecanol-1) and analysis of gas-phase products. CONCLUSIONS In accordance with the results obtained, both hydrolysis of MP and hydrogenolysis of C bond OCH3 bond should be considered for describing the conversion of MP to intermediate compounds. This finding could explain the synergetic effect of acid and metal centres, which has been reported in the literature on aliphatic ester HDO, and justify the higher activity of bifunctional catalysts in this reaction. (c) 2019 Society of Chemical Industry