Synthesis,characterization Of Ni-based Meso-& Micro-porous Catalysts And Application In CO₂ Reforming Reaction Of CH₄ & Biomass

Nowadays,the utilization of CO₂ is one of the interesting topics in order to minimize its concentration in the atmosphere and to produce hydrogen and syngas because the continuous emissions of CO₂ caused greenhouse effect and global warming,which are responsible for atmospheric pollution.Therefore,the effective usage of CO₂ is valued in many aspects,especially in methane dry reforming reaction?MDR?for the production of syngas?H₂/CO?with widespread utilization.However,the deactivation of catalyst is one of the main obstacles for industrial application in the hydrogen and syngas production.In this work,various types of Ni-based catalysts doped by La,Mg,Co,CaO and CeO₂ were prepared.The effect of these modified catalysts on catalytic activity was studied in methane dry reforming reaction and biomass?corncob?dry reforming reaction.The main conclusions of experimental work are given as follows:A series of Ni-Co based catalysts doped with different wt% ratios of Mg/La supported on MSU-S were synthesized by a sol-gel method.Various characterization techniques such as N2-physisorption,H₂-TPR,FT-IR,H₂-TPD,CO₂-TPD,HRTEM,XRD,O₂-TPO and TG/DSC were used to investigate structural properties and catalytic activities of the catalysts.The dispersion of Ni particles in the mesoporous structure of MSU-S was confirmed by UV,XRD and HRTEM studies.H₂-TPR and UV-vis results indicated the presence of strong interaction between support and nickel particles.The catalytic activity for syngas production was studied at different GHSV and different temperatures at atmospheric pressure.The results of BET,HRTEM and FTIR illustrated that mesoporous structure of x Mg/La yCozNi/MSU-S catalyst was almost preserved during DRM reaction.Two types of coking were determined on the surface of catalyst by TG/DSc and O₂-TPO results.3La2Co7Ni/MSU-S performed the best with highest catalytic performance and stability with low coking after 50 h.xCeO₂yNi/MCM-22 catalysts with weight% ratios?CeO₂: Ni 0:9,4:9,8:9,12:9?were synthesized by a sol-gel technique.The activity of catalyst illustrated that presence of CeO₂ suppressed carbon deposition and enhanced production of hydrogen during CO₂/CH₄ reforming reaction with GHSV of 2.4× 104 mL g-1h-1 at 700-750 oC at atmospheric pressure.The H₂-TPR studies revealed the strong interaction between HO-Si-groups of MCM-22 and nickel particles.The 8CeO₂ 9Ni/MC M-22 catalyst performed the best at 750 oC due to presence of oxygen in CeO₂ which promoted C-H bond activation and the removal of deposited carbon.CaO doped Ni/ MCF were synthesized by a sol-gel technique and conventional incipient wetness impregnation method.The XRD results verified that CaO and Ni particles were highly dispersed on the surface of catalyst.The Ni: CaO ratio was adjusted for enhancement of metal particle dispersion in order to increase the catalytic activity and anti-coking.The catalytic performance was evaluated for CH₄/CO₂ reforming at 700-750 oC with GHSV of 24000 mL g-1 h-1.The results demonstrated that the catalyst synthesized by a sol-gel method exhibited superior catalytic activity,stability and anticoking properties than the catalyst synthesized by incipient wetness impregnation method.Among all catalysts,9CaO 9Ni/MCF showed the best catalytic performance with 93% CH₄ and 99% CO₂ conversions within 100 h.A series of 0-12CeO₂.9Ni/MCM-22 catalysts were prepared by a sol-gel method and their catalytic activity was estimated for hydrogen production in the corncob?biomass?/CO₂ dry reforming reaction.The presence of CeO₂ in nickel-based MCM-22 catalyst resulted in the enhancement of catalytic activity as the oxygen species can adsorb CO₂ and react with carbon formed on the surface of catalyst during corcob/CO₂ reforming reaction.The 4%CeO₂ 9Ni/MC M-22 catalyst performed the best,exhibiting excellent catalytic activity at different temperatures.