Supercritical water synthesized Ni/ZrO2 catalyst for hydrogen production from supercritical water gasification of glycerol

Abstract

Catalysts are crucial to promote the technical feasibility of supercritical water gasification (SCWG) for H2 production from wet biomass, yet catalysts prepared by conventional methods normally encounter sintering problems in supercritical water. Herein, a series of ZrO2-supported Ni catalysts were tried to be prepared by supercritical water synthesis (SCWS) and evaluated for SCWG in terms of activity and property stability. The SCWS was conducted at 500 °C and 23 MPa using metal nitrates as starting materials. Effect of precursor concentration on property and catalytic performance of the SCWS-prepared catalysts for SCWG of 20 wt% glycerol were systematically studied. XRD, SEM-EDS, TEM and TGA were applied for catalyst characterization. Results verified the successful obtaining of Ni/ZrO2 nanocatalysts with Ni crystals of 30–70 nm and ZrO2 crystals of ~11 nm by the SCWS process, which were found to be active on the WGSR for SCWG to increase the H2 yield as high as 155%. Importantly, the SCWS-prepared Ni/ZrO2 catalysts exhibited excellent property stability and anti-coking ability for SCWG of glycerol.