Activity of Ni/CeO2 catalyst for gasification of phenol in supercritical water

An effective Ni/CeO2 catalyst prepared by the polyol reduction method for degrading phenol into CH4, H2 and CO2 in supercritical water (SCW) was developed. About 80% carbon gasification efficiency can be achieved at 525 °C and 60 min with 5 wt% phenol, 0.098 kg/m3 water density and 0.5 g Ni/CeO2/g phenol catalyst, forming CH4 and H2 as the main gaseous products. Comparison study indicated that the efficiency of present Ni/CeO2 catalyst was about 20% higher than that of a commercial catalyst, i.e., Ni/SiO2Al2O3 from Sigma-Aldrich with 65 wt%Ni, at a reaction conditions of 500 °C and 30 min. The characterization analyses of BET, TPR, XRD, XPS and TEM indicated that there was a NiCe alloy formed in Ni/CeO2, which could be important to enhance the activities of the carbon gasification efficiencies and gas yields. A kinetic modelings were conducted and the results showed that the lnA and the activation energy (Ea) of gasification were 7.1 ± 0.5 and 58.1 ± 3.2 kJ/mol for the gaseous product, and were 2.6 ± 0.9 and Ea is 36.6 ± 5.6 kJ/mol for the char formation, respectively. The present Ni-based-metal Ni/CeO2 catalyst is cheaper and has a potential application for the gasification to convert phenol into gases fuels in SCW process.