Study on Methanation Performance of Biomass Gasification Syngas Based on a Ni/Al2O3 Monolithic Catalyst

摘要

The structure of a Ni/Al_(2)O_(3) monolithic catalyst after methanation reaction and its methanation performance were studied by taking analogue syngas of biomass gasification H_(2)/CO/N_(2) as feed gas when the temperature ranged from 250 to 550 °C, and the weight hourly space velocity (WHSV) was between 6000 and 14,000 mL g~(–1) h~(–1). The Ni/Al_(2)O_(3) catalysts using cordierite honeycomb ceramics as the substrate were prepared by dipping and sol–gel methods. The results show that the Ni/Al_(2)O_(3) catalyst prepared by the dipping method (DIP-Ni/Al_(2)O_(3)) has better methanation performance than the Ni/Al_(2)O_(3) catalyst prepared by the sol–gel method (SG-Ni/Al_(2)O_(3)) through many tests such as TEM, BET, XRD, H_(2)-TPD, H_(2)-TPR, and TG analysis. The DIP-Ni/Al_(2)O_(3) catalyst exhibits the best methanation performance at 400 °C when the molar ratio of H_(2), CO, and N_(2) is 3/1/1 and the WHSV is 10,000 mL g~(–1) h~(–1). Under this condition, the CO conversion and CH_(4) selectivity are 98.6 and 90.9%, respectively. In addition, the methanation performance of the DIP-Ni/Al_(2)O_(3) catalyst is relatively more stable, and the CO conversion and CH_(4) selectivity were basically maintained at around 90% within the experimental WHSV range. The influence of Ni content on the methanation performance of the DIP-Ni/Al_(2)O_(3) catalyst can be seen in the order from high to low of methanation performance: 15% Ni, 20% Ni, and 10% Ni, and the maximum values of CO conversion and CH_(4) selectivity reach 96.8 and 96%, respectively, at 400 °C for 15% Ni/Al_(2)O_(3).