Study on CO2 reforming of methane to syngas over Al2O3-ZrO2 supported Ni catalysts prepared via a direct sol-gel process

Ni-based catalysts supported on Al2O3-ZrO2 (Ni/Al2O3-ZrO2) were prepared by a direct sol-gel process with citric acid as the gelling agent. The evaluation of the catalyst prepared for methane reforming with CO2 was carried out with thermal gravimetric analysis (TGA), infrared spectroscopy (IR), X-ray diffraction (XRD), microscopy analyses (SEM and TEM), temperature-programmed reduction (TPR) and in a micro-reactor system. The catalytic performance for CO2 reforming of methane to synthesis gas in a continuous-flow micro-reactor under atmospheric pressure was investigated. TGA, IR, XRD and microscopy analyses show that the Ni particles have a nanostructure of around 5 nm and are uniformly dispersed on the Al2O3-ZrO2 support, which exists as an amorphous phase. Catalytic tests using CO2 reforming of methane to synthesis gas show that the catalytic activity increases with increasing metal loading, and the 20Ni/Al2O3-ZrO2 (0.2 Ni/Al molar ratio) catalyst has excellent activity and stability, compared with that of the Al2O3 supported Ni catalyst, with 91.9% conversion of CO2 and 82.9% conversion of CH4 Over 50h at 1073 K, atmospheric pressure, hourly space velocity of 11, 200 ml gcat(-1) h(-1) and CH4:CO2:N-2 of 2:2:1. The excellent catalytic activity and stability is attributed to the very highly and uniformly dispersed small metallic Ni particles, the reducibility of the Ni oxides and an interaction between metallic Ni particles and the support Al2O3-ZrO2. (C) 2004 Elsevier Ltd. All rights reserved.