H2S-resistant CeO2-NiO-MgO-Al2O3 LDH-derived catalysts for steam reforming of toluene

Recently, biomass gasification has garnered a lot of attention due to its potential to produce hydrogen-rich syngas. In this research paper, H2S resistant catalysts for steam reforming of toluene as a model tar compound is studied on CeO2-NiO-MgO-Al2O3 (Ce-NMA) hydrotalcite-derived catalysts synthesized by homogeneous urea hydrolysis. A family of Ce-NMA catalysts were synthesized with different Ce loading: 0Ce-NMA, 5Ce-NMA, 10CeNMA, 15Ce-NMA and 20Ce-NMA. Among all the catalysts, the performance of the catalysts improved up to 15CeNMA, which showed the most stable performance in the presence of H2S poison. The H2-TPR and XPS showed that the presence of ceria improved the reducibility of the catalysts by facilitating electron transfer to nickel. 15Ce-NMA gave a conversion of 82%, whereas 20Ce-NMA showed a 96% toluene conversion. However, the recovery of 15Ce-NMA was very quick (30-45min) as against that of 20Ce-NMA, which deactivated to 40% conversion and took 2 h to recover the performance. The XPS of reduced catalysts showed that Ni0/Ni2+ ratio constantly increased with increasing ceria loading due to the Ce3+/Ce4+ redox pairs, which aided the reduction of Ni2+ to Ni0. The TG/DTA analysis revealed that the highest amount of carbon was formed over 0Ce-NMA and 20Ce-NMA, meaning Ce loading was only effective till a certain amount. 15Ce-NMA demonstrated lower carbon deposition as compared to 0Ce-NMA and 20Ce-NMA. Raman analysis revealed that the type of carbon varied in the 20Ce-NMA. The graphitic carbon decreased till 15Ce-NMA but suddenly increased in 20Ce-NMA, leading to higher carbon deposition and lower activity in the catalyst.

Automated summary

In this study, H2S resistant catalysts for steam reforming of toluene were investigated on CeO2-NiO-MgO-Al2O3 (Ce-NMA) catalysts with varying Ce loadings. Among all the catalysts, 15Ce-NMA showed the most stable performance in the presence of H2S poison and demonstrated lower carbon deposition compared to others. XPS analysis revealed that the presence of ceria improved the reducibility of the catalysts by facilitating electron transfer to nickel.