Preparation Of Nano-nickel-supported Cerium Oxide-based Catalyst And Application In Micro Tubular SOFC

Propane partial oxidation reforming is one of the most mature hydrogen production methods in modern industrialization.Propane can undergo partial oxidation reforming under the catalysis of high-temperature catalysts to produce synthesis gas with H₂as the main component.SOFC is an all-solid structure cell that can directly convert chemical energy in fuel into electrical energy.Because the exothermic properties of partial oxidation reforming meet the needs of SOFC high-temperature operation,new requirements have been put forward for the combined application of partial oxidation reforming of propane and solid oxide fuel cells at this stage,which has also triggered a research boom among scientific researchers.Ni-Al₂O₃catalysts are the most commonly reported non-noble metal catalysts,but Ni-supported catalysts are prone to carbon deposition during the reaction process.When coupled with SOFC for a long time,they tend to cause the anode material to lose activity.For this reason,in this paper,the CeO₂was prepared by hydrothermal synthesis method,and Ni-CeO₂catalyst was prepared by sol-gel method.The catalyst was used for the propane POX test,the preparation method,the active component loading and reforming temperature on catalytic performance were studied.The results show that the catalytic reforming performance is the best when the sol-gel method is used,the nickel loading is10%and the reforming temperature is 600℃,and the hydrogen yield is about 220μmol g_cat^-1s^-1.In addition,the reusability of the catalyst was explored,and it was found that calcining the catalyst at 600℃in an air atmosphere can remove the carbon deposits on the catalyst.Thermo gravimetric analysis shows that as the number of reforming increases,the amount of catalyst carbon deposition is decreasing.This may be due to the occurrence of inter-carbon materials during multiple reforming/calcination processes.The NiO-YSZ anode of the solid oxide fuel cell was prepared by the extrusion molding method,and the electrolyte（YSZ）,the cathode separator（GDC）and the cathode（LSCF）were sequentially coated on the outer surface of the anode tube by the dip coating method.A SEM was used to analyze the microscopic morphology of the cells section and the inner surface of the anode.The fuel cell test system was used to test the cell,and the influence of operating temperature and fuel flow rate on the performance of the SOFC was studied.The results show that as the temperature increases,the maximum power density of the SOFC increases,and the impedance decreases.The maximum power density reaches 0.67 W cm^-2at 700°C.In addition,COMSOL MULTIPHSICS（?）software was used to build a two-dimensional model of a SOFC supported by the anode.Through the simulation of the anode fuel channel,it is found that the H₂content at the anode entrance is the highest,and the electrochemical reaction is the most active.Through the simulation of the current density of the anode channel,it is found that the current density distributed around the anode current collector is the largest,and the current density distribution has a certain relationship with the degree of electrochemical reaction.Coupling the Ni-CeO₂catalyst with a micro tubular SOFC,at 700℃,directly using reformed gas as fuel,the maximum power density of the cell measured is 0.57 W cm^-2,which is greater than the case of using 20% H₂ under the same conditions.At the same time,under the long-term use of reformed gas test conditions,the cell performance remained for 48-h without significant degradation.SEM analysis of the SOFC anode after long-term use revealed that the anode structure gradually became loose from the outlet（Rc）to the inlet（Ra）.In addition,the carbon deposits generated at different parts of the anode were analyzed.The carbon deposited at the inlet and outlet was amorphous carbon,but the carbon deposited at the anode outlet was carbon fiber.The effect of taking electricity from the middle of the anode is far greater than taking electricity from the inlet.For one thing,the longest current path in the middle current collecting mode is only half of the current path in the inlet and outlet current collecting modes,for another thing,a large amount of carbon deposits may also affect the efficiency of inlet collection.