Study on CO 2 reforming of methane to syngas over Al 2O 3–ZrO 2 supported Ni catalysts prepared via a direct sol–gel process

Abstract

Ni-based catalysts supported on Al 2O 3–ZrO 2 (Ni/Al 2O 3–ZrO 2) 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 CO 2 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 CO 2 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 Al 2O 3–ZrO 2 support, which exists as an amorphous phase. Catalytic tests using CO 2 reforming of methane to synthesis gas show that the catalytic activity increases with increasing metal loading, and the 20Ni/Al 2O 3–ZrO 2 (0.2 Ni/Al molar ratio) catalyst has excellent activity and stability, compared with that of the Al 2O 3 supported Ni catalyst, with 91.9% conversion of CO 2 and 82.9% conversion of CH 4 over 50 h at 1073 K , atmospheric pressure, hourly space velocity of 11 , 200 ml gcat - 1 h - 1 and CH 4:CO 2: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 Al 2O 3–ZrO 2.