CeO2晶粒尺寸调控镍基催化剂高压甲烷干重整抗积碳性能的机制研究OA

[Purposes]High-pressure dry reforming of methane(DRM),as a key technology for direct production of high-pressure syngas,improves overall energy efficiency by more than 40%com-pared with that of atmospheric systems.However,carbon deposition under high-pressure conditions severely restricts its industrial application.[Methods]In this study,CeO2 modification strategies via co-precipitation(CP)and impregnation(I)methods were comparatively investigated,revealing the crucial role of CeO2 crystallite size in anti-coking performance of a hydrotalcite-derived Ni-based cata-lyst(Ni/MgAl2O4-MgO).[Results]Comprehensive characterization techniques including BET,O2-TPO,XRD,and CO2-TPD demonstrate that the co-precipitation derived NiCe/MgAl2O4-MgO(C)catalyst exhibits larger CeO2 crystallites(10.98 nm)and formation of CeAlO3(XRD 2θ=33.1°)caused by the combination of Ce³⁺ with Al in MgAl2O4,which disrupts the original support structure and leads to severe Ni sintering.In contrast,the impregnation-derived NiCe/MgAl2O4-MgO(I)catalyst restricts the CeO2 crystallite size to 5.13 nm,resulting in small-sized,low-crystallinity CeO2 particles while maintaining a high specific surface area(153.864 m2/g).This superior structure enhances the CO2 adsorption capacity by 4.5 times(CO2-TPD)and reduces the proportion of graphitic carbon from 86.1%to 24.7%(O2-TPO-MS).A 72 h high-pressure stability test confirmes that the deactivation rate of the impregnated catalyst is only 12.93%,significantly lower than that of the co-precipitation catalyst(25.97%)and the unmodified system(27.54%).[Conclusions]This study elucidates that CeO2 crystallite size is one of the core factors governing the differential catalytic performance,provid-ing a new paradigm for the design of high-pressure DRM catalysts.