Synthesis And Catalytic Properties Of Granular Carbon-base Solid Acids

Biodiesel has become a traditional fossil fuel alternative fuel that has received much attention in recent years due to its non-toxic,renewable and degradable properties.The raw materials are mainly derived from animal and vegetable oils.Under the action of a catalyst,triglycerides in animal and vegetable oils will be transesterified with methanol or ethanol to form the corresponding alkyl ester mixture.Therefore,the key to the successful preparation of biodiesel lies in the choice of catalyst.Homogeneous catalysts are currently widely used,which has the problems of long time-consuming steps such as neutralization,separation and purification,which is not conducive to environmental friendliness.In recent years,heterogeneous acid catalysts have been extensively studied due to the advantages of simple product separation and purification,no pollution,etc.However,most of the solid acid catalysts currently used in biodiesel synthesis reactions have leaching problems.Most carbon-based solid acids are powdery,with fine particles and uneven distribution.After use,separation and recovery are difficult,resulting in catalyst loss and failure.Achieve large-scale industrialization.Based on the above problems,this paper proposes a green,economical and feasible method to prepare particulate carbon-based solid acid to solve the problem of difficult separation in subsequent treatment,and takes the catalytic performance of oleic acid and methanol esterification reaction as the guide to study the catalyst preparation conditions,Dosage,methanol/oil molar ratio and other factors affect its catalytic performance.The main research content includes the following three parts:(1)Using aspen,pine and tung wood as carbon sources,carbonized at high temperature to form granular carbon-based intermediates,and then sulfonated to prepare three different biomass granular carbon-based solid acids.By optimizing the reaction conditions of carbonization and sulfonation,comparing the compressive strength performance of the three catalysts,the best carbon-based solid acid was selected as the aspen granular carbon-based solid acid.The characterization of the structure and morphology of the aspen granular carbon-based solid acid was applied to the esterification reaction of oleic acid and methanol.The experimental results show that the catalyst has high catalytic activity and conversion rate for the synthesisof biodiesel over 90%.(2)On the basis of aspen-based carbon-based solid acid,asphalt doping was performed before and after carbonization,two different types of asphalt-doped granular carbon-based solid acid were prepared,and the element distribution of the two carbon-based solid acids was explored.Differences in apparent morphology,functional group structure and porosity.After optimizing the carbonization temperature and esterification conditions,it was found that the pitch particulate carbon-based solid acid doped after carbonization had higher esterification reactivity and the conversion rate exceeded 98%.In addition,the catalyst prepared by the method has better stability,and the esterification conversion rate after five cycles is still more than 90%.(3)A new granular carbon-based solid acid is prepared by carbonization-sulfonation method infiltrating raw materials of poplar wood with epoxy resin.A novel particulate carbon-based solid acid is used to catalyze the esterification of oleic acid and methanol to prepare biodiesel.The effect of reaction conditions on the conversion of oleic acid was studied.The results show that the epoxy resin-immobilized granular carbon-based solid acid,which is cheap and easy to prepare,exhibits excellent catalytic activity,has good recycling performance,and the esterification rate can still reach 80% after repeated use.