Controllable Preparation And Application Of Uniform Porous Carbon-based Solid Sulfonic Acid

A solid acid catalyst is defined as a kind of solid material that can supply protons or accept electrons.Compared with liquid acids,solid acids have many advantages such as easy separation of products,adjustable structure and acidity,and high catalytic activity,so that solid acid catalysts have attracted the attention of many researchers.In both domestic and foreign countries,various solid acid catalysts have been studied in depth,and great progress has been made in the development of synthetic methods and different types.At present,there are hundreds of solid acid catalysts.According to the composition and properties of catalysts,there are zeolite molecular sieves,acid-functionalized silicas,heteropoly acids,metal oxides,metal organic frameworks(MOFs),acidic ion-exchange resins and sulfonated carbon materials,etc.Due to the low acid density,small pore diameter and low surface area of the traditional solid sulfonic acid catalysts,it is not suitable for the preparation of biodiesel.In this thesis,we have prepared three types of solid sulfonic acid catalysts with different carbon precursors,and discussed the influences of calcination temperature and dosage of sulfuric acids on pore size distribution and acid density of the resultant materials,which have great influences on the performance in esterification of high fatty acids.For the materials prepared from an amino acid carrying sulfonic groups,we also explored the adsorption performance toward basic organic pollutants.The main research contents include:(1)Using biomass sucrose as a carbon source,inorganic salt sodium chloride as a pore making agent,sulfuric acid as the sulfonating agent,we successfully synthesized a kind of porous carbon sulfonic acid catalyst with homogeneous and uniform particle sizes and good sphericity by a spray drying combined with post-sulfonation method.Under the optimal conditions(sulfonation temperature 150 oC,sulfonation time 24 h),the obtained catalysts have interconnected hierarchical pore channels,high specific surfaces up to 828 m2/g and high strong acid density of 1.019 mmol/g.The catalyst has excellent catalytic performance and stability in the esterification of oleic acid.The conversion of oleic acid is up to 97.01 % with the sample SN-150C-24 h as the catalyst,and the conversion of oleic acid remains above 82 % after being used for five times.Compared with the commercial sulfonated resin and molecular sieves,the porous carbon based sulfonic acid catalyst prepared in this work has obvious advantages in the esterification of high fatty acids.(2)A mesoporous sulfonated resin catalyst was synthesized by one-step process using phenolic resin as a substrate material,surfactant F127 and silica source TEOS as pore forming agents and sulfuric acid as the sulfonating agent.The material has a good specific surface and large pores.The density of sulfonic acid group is up to 0.995 mmol/g,and the internal structure is made up of many small nanospheres.The pore channels are developed,which is beneficial for esterification of long chain high fatty acids.(3)A new type of solid sulfonic acid catalyst was obtained by using a small amount of sodium chloride as pore forming agent,a kind of amino acid with sulfonic acid group(Taurine)as substrate material and ozone as an oxidant.The catalyst has a good specific surface and a high sulfonic group density,and has excellent performance in the adsorption and separation of alkaline pollutants,such as aniline.