Preparation Of One-dimensional SiO₂ Nanotube Confined Nickel-based Catalyst And Its Application In Methane Dry Reformin

Due to development needs,the environmental problems and energy shortages brought about by the use of fossil fuels worldwide cannot be ignored.Prompting people to look for alternative new energy sources,natural gas is considered to be the most potential alternative due to its abundant reserves.The main component of natural gas is methane,which can be converted into more valuable chemicals and liquid fuels.With the continuous improvement of the world’s industrialization,the carbon dioxide content in the air continues to increase year by year,and the reduction of carbon dioxide in the world is very serious.Methane carbon dioxide reforming is currently one of the most promising processes for converting two greenhouse gases,CH₄ and CO₂,into syngas and promoting CO₂utilization.However,a major challenge of inexpensive and highly active Ni-based catalysts for DRM reactions is their susceptibility to sintering and carbon deposition issues.This paper focuses on the study of Ce/Ni and Mo/Ni bimetallic confined catalysts,and a series of bimetallic Ce/Ni bimetallic confined catalysts in Si O₂nanotubes were synthesized by precipitation method and coating method.By adding urea to adjust the p H value of Niphy NTs solution,the Niphy NTs surface adsorption ability is enhanced.Finally,Mo/Ni catalyst was synthesized by precipitation method and coating method.TEM,XRD,N₂-adsorption and desorption,H₂-TPR,XPS,H₂-chemisorption,and fresh catalysts were used for characterization.Secondly,the specific activity of catalysts is compared under harsh conditions,and the catalysts with better activity and stability are selected for long-term stability test.TEM,XRD and TGA were used to evaluate the carbon deposition of the catalyst.The mechanism of DRM reaction was studied by in-situ diffuse reflectance Fourier transform（In-situ DRIFTS）.Finally,the sulfur resistance of 20Ce/Ni@Si O₂ and Mo/Ni@Si O₂ catalysts with H₂S was studied.The results mainly include that the bimetallic x Ce/Ni@Si O₂ catalyst has a higher activity of reforming methane with carbon dioxide than Ni@Si O₂ catalyst without Ce.In particular,the conversion of CH₄ and CO₂ remained stable at 76.3%and 80.1%under the long-term test of 20Ce/Ni@Si O₂ at 700 ^oC for 80 h,respectively.This is because the catalyst has higher sintering resistance,higher surface Ni and oxygen vacancy concentration,and higher carbon deposition resistance.The mechanism of CO₂ activation through Ce O₂ and H*was revealed by the study of transposition infrared diffuse reflectance.For Mo/Ni@Si O₂ catalyst,the conversion rates of CH₄and CO₂ remain 78.8%and 79.1%in 100 h,and the weight loss is only 7.6%.Through the sulfur resistance study,the performance of the catalyst decreases gradually after the addition of H₂S,and finally deactivates.