Biogas upgrading to syngas by combined reforming using Ni/CeO2–Al2O3 with bimodal pore structure

Abstract

Ni/CeO2–Al2O3 with bimodal porous structure and two different CeO2 concentrations (low: 5 wt% and high: 15 wt%) were prepared by the refluxed co-precipitation method and characterized by N2 physisorption, XRD, TPR, H2-TPD, and CO2-TPD. Catalysts were tested in combined steam and dry reforming of methane (CSDRM) at atmospheric pressure, 600°C–700 °C and CH4: CO2: H2O = 1: 0.48: 0.8, in order to prepare synthesis gas with H2:CO ratio of 2:1. The catalytic activity decreases with increasing ceria content, the best catalyst being Ni/CeO2(5 wt%)-Al2O3. The good activity obtained for Ni/CeO2(5 wt%)-Al2O3 is a consequence of the more intimate contact of ceria with alumina, providing higher metal-support interaction, but also of the higher dimensions of larger pores which contribute to the better targeting of the reagents to the catalytic sites. In the used catalysts, the ceria presence better preserved the bimodal porous structure and decreased the carbon deposition by ∼70%.