Screening Of Catalysts And Determining Of Process Conditions For Synthesis Of Epichlorohydrin From Glycerol

With increasing need of epichlorohydrin (ECH) and application of glycerol which isproduced by biodiesel as by-product, the process of synthesise ECH from glycerol isbecoming a hotspot of research.The technology of synthesise ECH from glycerol contains two processes which arechlorination and cyclizing. In this paper, the screening of catalysts and the determining ofprocess conditions for chlorination and cyclizing are studied. The methods for qualitativeand quantitative analysising of dichlorohydrin (DCP) and ECH include ebulliometry、IRand GC, the conversion rate of glycerol is determined by UV-VIS spectrophotometry andsodium periodate oxidation.By screening of one-component carboxylic acids, the adipic acid shows the bestcatalytic effect. Among the compound catalysts, inorganic acid and dehydrants are addedinto the reaction respectively with adipic acid. It is proved that the inorganic acid couldnot play a catalytic role. However, the dehydrants of acetonitrile and acetic anhydride canmake the yield increased obviously. More specifically, the yield for DCP has increased5.47%by using adipic acid and acetonitril than the adipic acid. The adipic acid and aceticanhydride also make the yield increased2.8%. But considering the harm of acetonitrileitself, adipic acid and acetic anhydride are determined as the suitable catalysts.Through single factor experiment, the most optimal process conditions forchlorination are determined. When the temperature of reaction is115℃, the time ofreaction is5h, the amount of catalyst is7.5%(w/w) of glycerol, the mass ratio of adipicacid to acetic anhydride is3:2and the ventilation flow of HCl is200mL/min, the yieldfor DCP reaches69.5%and conversion rate of glycerol is99.77%under these conditions.In the cyclizing reaction, the influence of NaOH、Ca(OH)2、KOH and Na2CO3onthe yield for ECH are mainly considered. It is concluded that when the alkali forcyclizing is NaOH, n(NaOH):n(DCP) is1.1:1, the temperature of reaction is40℃and thetime of reaction is20~25min, the yield for ECH can reach above74%.