Study On The Selectivity, Regeneration Rate And Deactivation Energy Of Nickel-catalyzed Hydrogenolysis Of Aryl Ethers

With the development of society and the rapid development of human civilization,the problem of energy shortage has become a problem that restricts the further development of human society and economy and the sustainable use of resources.Lignin,which has a polymer structure in many biomass resources,has high energy,and lignin has not been converted into high-value products on a large scale.Therefore,it has gradually attracted people's attention,and has been developed and used as a chemical raw material.The development of lignin degradation technology has become the focus of research.This thesis attempts to study the reduction degradation of lignin from the aspect of hydrogenolysis technology,focusing on the performance and stability of nickel-based materials in the process of heterogeneous hydrogenolysis and reduction of lignin.The specific research contents of this thesis are as follows:1. Ordered mesoporous Ni?OMNi?and non-ordered mesoporous Ni?NMNi? catalysts were synthesized by a hard templating approach using SBA-15 and fumed silica?Aerosil 200?,respectively.The behaviour of unsupported mesoporous Ni metal in the selective cleavage of a model aryl ether was investigated to explore the effects of catalyst pore morphology on selectivity,sorption,and stability of the metal.Compared to NMNi and NPNi,OMNi shows enhanced selectivity for phenol.For all Ni catalysts,phenol is the main species that poisons the surface,however,its hydrogenation at ca.205?leads to regeneration.OMNi is more readily regenerated than either NMNi or NPNi,making it promising as a catalyst for lignin valorization.2. Using KIT-6 ordered mesoporous silica as a template,ordered mesoporous nickel ?meso Ni?was successfully synthesized by the hard template method.The synthesized meso Ni was subjected to X-ray diffraction?XRD?,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?,H₂ programmed temperature reduction?TPR?,energy dispersive X-ray spectrometer?EDX?,and N₂adsorption-desorption technology,Characterized the mesoporous structure of the synthesis catalyst,with the required high surface area?84.2 m²/g?.Compared with commercial catalyst Raney Ni,meso Ni shows better catalytic cracking activity for lignin model compounds?benzylphenyl ether,BPE?in flow reactor systems,and has high aromatics The selectivity also shows a higher regeneration rate,which is confirmed by studies of deactivation and regeneration mechanisms in flow reaction systems at high temperature and pressure.At the same time,the substances adsorbed on the surface of mesoporous nickel were analyzed.Phenol may be the main adsorbent.The excellent catalytic hydrogenolysis performance of meso Ni comes from its unique mesoporous structure,which has a high specific surface area and a large number of nickel active sites.The excellent catalytic performance of the catalyst provides a broad prospect for improving the use of lignin.