Study On The Effect Of Pore Structure On Metal Embedded In The Porous Carbon-coated Monolithic Catalyst

Currently,monolithic catalysts are the most widely used catalysts around the world.We have conducted a long-term research on the monolithic catalyst based on porous carbon coating,and created a mosaic catalyst with monolithic metal porous carbon coating which is different from the traditional preparation method.The interaction between the active component and the porous carbon coating was completely changed,attributed to the active component embedded in the porous carbon coating through the new prepared method.The characterization results showed that the active components with the uniform particle size and were uniformly dispersed on the surface of porous carbon coating.At the same time,the active components are very stable.It can be used without pre-reduction,and exhibit excellent catalytic activity,selectivity and stability in the catalytic hydrogenation reaction.However,the inlaid metal porous charcoal coated monolithic catalyst is not perfect either.For example,because the active component is embedded in the porous carbon,if the carbon material fails to form a porous carbon structure or fails to form a porous carbon structure,the active component coated in it will greatly limit its catalytic performance,thereby Reduced utilization of active components.The study found that the carbonization temperature is the main factor affecting the formation and development of the porous carbon structure.Increasing the carbonization temperature was beneficial for the formation and development of the porous carbon structure.But,the agglomeration of the active components and the collapse of the porous carbon structure were occurred at a higher carbonization temperature.Therefore,it is necessary to study the further improvement of porous carbon structure,which was prepared via other physical-chemical methods at a lower carbonization temperature.And at the same time,the performance of monolithic catalysts coated with metal porous carbon coating was also studied in a wider catalytic hydrogenation reaction.In this paper,furfuryl alcohol resin was selected as the precursor of porous carbon coating,transition metal nickel was used as active ingredient,cordierite honeycomb ceramic was acted as carrier,and a series of monolithic catalysts with inlaid nickel porous carbon coated honeycomb ceramics were prepared through polymerization,coating,curing,carbonization and other steps.Furthermore,the pore structure of the porous carbon coating was adjusted by adding pore-expanding agents and microwave radiation.On this basis,the physical-chemical properties of monolithic catalyst was characterized by the N2-physical adsorption,TG,XRD,TEM,XPS,Raman spectroscopy,FT-IR,XRF,elemental analysis,TPD and other characterization methods,and the performance of the monolithic catalyst was evaluated in the continuous catalytic hydrogenation of aryl nitro-compounds.The main research results obtained are as follows:(1)When polyethylene glycol(PEG)was used as a pore-expanding agent,the development of a porous carbon structure could be promote by a moderate amount of medium-molecular-weight PEG.This result was manifested by an increase in the BET specific surface area of the porous carbon coating and an increase in the micropore and mesopore pore volume,which is beneficial for the exposure of nickel metal embedded in the porous carbon coating.In the selective p-chloronitrobenzene hydrogenation,with n-butanol as the solvent,the PEG-modified nickel inlaid porous carbon coated honeycomb ceramic monolithic catalyst showed more excellent catalytic performance.(2)When the cured monolithic catalyst is modified by microwave radiation,treatment at medium microwave output power(200 W)and short time(1.5 min)can promote the development of porous carbon structure,which is shown by the BET ratio of porous carbon coating The surface area is increased and the pore volume of micropores and mesopores is increased,which helps to expose more nickel metal embedded inside the porous carbon coating.In the selective hydrogenation of p-chloronitrobenzene with n-butanol as the solvent,the monolithic nickel-coated porous carbon-coated honeycomb ceramic monolithic catalyst modified by microwave radiation treatment showed more excellent catalytic performance.However,too high microwave output power or too long microwave processing time will cause irreversible damage to the porous carbon structure.(3)Nickel-embedded porous carbon coated honeycomb ceramic monolithic catalyst was also suitable for the hydrogenation reaction of sodium p-nitrobenzoyl glutamate with water as a solvent.Compared with the nickel-supported porous carbon-coated honeycomb ceramic monolithic catalyst,the nickel-embedded monolithic catalyst showed higher catalytic activity,stability,and ease of operation.