Preparation, Characterization And Application Of Ordered Mesoporous Ni-based Catalysts In CH₄/CO₂Reforming To Syngas

Nowadays, the consumption of fossil fuels increased continuously and rapidlywith growing world population and industrialization, which further causes severalproblems, such as CO2emissions and the greenhouse gas effect. Therefore, thedevelopment and utilization of clean and renewable energy have paid widespreadattention all over the world. Hydrogen is considered to be an ideal clean energy source,which is widely used in aerospace, transportation, electronics, oil refining, metallurgyand other fields. CH4/CO2reforming to produce syngas (CO2+CH4=2CO+2H2, ΔH0(298K)=247kJ·mol-1) had received considerable attention from both economical andenvironmental viewpoint in recent years. However, the main obstacle preventing fromlarge scale industrialization is the rapid deactivation of the catalysts due to carbondeposition and aggregation of active metals, so that the key problem to be solved is todesign an appropriate catalyst with high catalytic activity and stability.In our work,2D-hexagonal mesoporous MAS-9and3D-worm-like mesoporousKIT-1were used as supports, and a series of LaxNiyOz/MAS-9and10Ni-mCeO2/KIT-1catalysts were prepared by sol-gel method. We studied the effectof different reaction temperature and La/Ni molar ratio on catalytic activity overLaxNiyOz/MAS-9catalysts. At the same time, the influence of different loadingamount of CeO2on catalytic performance over10Ni-mCeO2/KIT-1catalysts was alsoinvestigated. Supports and catalysts were characterized by BET, XRD, FT-IR,ICP-MS, H2-TPR, TG/DSC and HRTEM techniques.Under the condition of an atmospheric pressure at850°C and gas hour spacevelocity (GHSV) of3.2×104mL·g-1·h-1, the conversion of CH4and CO2overLaNi2Ox/MAS-9catalyst were100%, the selectivity of H2and CO were95%and99%,respectively. In addition, the stability test of LaNi2Ox/MAS-9catalyst at850°C for145h revealed that the conversion of CO2(100%), the selectivity of H2(95%) and CO(99%), with H2/CO ratio of0.96as well as carbon yield (ca.1%) almost kept constantalthough conversion of CH4slightly decreased to94%. Small-angle XRD andHRTEM results indicated that the mesoporous structure of MAS-9still kept intactafter145h CH4/CO2reforming. Therefore, LaNi2Ox/MAS-9was an excellent catalystof CO2/CH4reforming with high catalytic activity, stability and strong ability to coke-resistance.The catalytic results of10Ni-mCeO2/KIT-1catalysts suggested that the catalyticactivity and the ability of carbon resistance improved with a moderate amountaddition of CeO2, which was related with redox properties of CeO2. However, excessaddition of CeO2caused opposite result probably due to the acidity of CeO2.