Preparation Of Mesoporous Carbon Supported Solid Acids And Bases And Their Pyrolytic Properties For Cellulose

Biomass are the only resources on the planet that can be regenerated and can be converted into liquid fuels.Their development and utilization are of great concern.Catalytic pyrolysis technology has been widely studied as a relatively efficient biomass thermochemical conversion technology.But the components of thermal pyrolytic products are extremely complex,and the reaction process is also affected by many factors?e.g.,reaction temperature,the heating rate,the type of catalyst,the content of various components of biomass,etc.?.How to catalytically convert biomass into high value-added chemicals or required chemical intermediates is still a scientific problem.This paper focuses on the role of mesoporous carbon-supported solid acid or alkaline catalysts in the pyrolysis reaction of cellulose,and the selectivity of high value-added chemicals of furfural and hydroxyacetone.From the two aspects of the catalyst preparation and the catalytic pyrolysis mechanism of cellulose,systematic experiments were conducted and the following conclusions were mainly drawn:Carbon and silicon composites were synthesized by a method of three component co-assembly.Solid acid catalysts X/MC?X=AlCl₃,FeCl₃,ZnCl₂?and solid base catalysts X/MC?X=Na₂CO₃,NaOH,K₂CO₃,KOH?were prepared by over impregnation.BET analyses showed that the mesoporous rate of these catalysts was about 80%,The catalysts were successfully characterized by using XRD,SEM and EDX methods.The catalytic effect of the catalyst is related to the metal content of the outer surface and the load in the channels.When hydroxy acetone was the desired product,the catalytic efficiency had following reder:NaOH/MC>Na₂CO₃/MC?KOH/MC>K₂CO₃/MC.With the increase of the concentration of alkaline impregnation solution,the catalytic efficiency of NaOH/MC and K₂CO₃/MC increased first and then decrease.The best impregnating solution concentration for catalyst NaOH/MC and K₂CO₃/MC was 0.35 mol/L,while the best impregnation solution concentration for catalyst Na2CO3/MC and KOH/MC required further study.When furfural was the desired product,the order of the catalytic efficiency was:AlCl₃/MC>ZnCl₂/MC?FeCl₃,and the best impregnating solution content for AlCl₃/MC was 0.25 mol/L,The catalytic efficiency of ZnCl2/MC and FeCl3/MC changed little.According to the analysis of pyrolysis mechanism with fast catalytic pyrolysis products on cellulose,it is known that the addition of carbon materials can reduce the production of anhydrous sugar and increase the products of low molecular weight within a certain range.Acidic catalysts can reduce the content of anhydrous sugar in a certain extent,and the content of furan compounds increased significantly;while the alkaline catalysts can reduce the content of anhydrous sugar on a large scale,small molecule compounds increased significantly,mainly promoting the production of straight chain aldehyde and ketone generated.