Dip-coating Preparation Of Monolithic Fiber@γ-Al₂O₃ For Structured Design Of Ni-based Catalysts Adopted In Dry Reforming Of Methane

Concerns about the depletion of petroleum reserves and considering the chemical recycling of CO2 to fuels/chemicals has provided particular impetus for worldwide exploration on the dry reforming of methane (DRM), which can convert both abundant methane and carbon dioxide into syngas feedstock for many downstream processes such as Fischer-Tropsch synthesis and methanol synthesis. Recently, structured catalyst and catalytic reactors (SCRs) receive great attentions in the process intensification for the heterogeneous catalysis especially for the strongly endo-/exo-thermic reactions such as the DRM, due to the improved hydrodynamics in combination with the enhanced heat/mass transfer. Development of a high-performance monolithic structured catalyst for the DRM with enhanced heat transfer is particularly desirable but is a new challenging area. To accomplish this goal, monolithic fiber@γ-Al2O3 has been developed via dip-coating strategy and subsequently utilized as support to load Ni catalysts for the DRM.Thin-sheet sinter-locked three-demensional network structure consisting of 15-32 vol%nickel/copper (Ni/Cu) microfibers (diameter:8μm) and 68-85 vol% voidage has been utilized as substrate. Alumina oxide is then placed onto the surface of fibers by dip-coating method using Akl2O3 sol-gel. This approach is working effectively and efficiently to fabricate high-quality Fiber@Al2O3 media, which provide a unique combination of high surface area, excellent thermal conduction, homogenous distribution and good flexibility. The effects of the Al2O3 sol-gel parameters including concentration, pH value and aging time, substrate pretreatment, and impregnation technology, on the quality of as-prepared Fiber@Al2O3 media with respect of Al2O3 loading, uniformity and robustness, have been investigated systematically in order to identify an optimal dip-coating fabrication condition. In addition, substrate pre-coating assistant dip-coating fabrication methods have been proposed, being working efficiently.The as-prepared Fiber@Al2O3 media have been characterized with respect of textural property, composition, geometry and morphology features, by means of several modern characterization techniques such as SEM, BET and EDS. Fiber@Ni/Al2O3 catalysts, with or without CeO2 additives, are developed by highly dispersing Ni (Ni and CeO2) onto the Al2O3 washcoats glued on the metal fibers via incipient wetness impregnation method. The obtained monolithic catalysts are examined in the DRM, showing visible promotion effect compared to the traditional particulate Ni-based catalysts. Note that the Cu-fiber@Ni-CeO2/Al2O3 is found to be a promising DRM catalyst with good activity and carbon resistance.