Choride-Tin(â…¡) Salt Collaborative Catalyzing Biomass Conversion To Methyl Lactate

The research found that the salts of tin(Ⅳ)(tin chloride) or tin(Ⅱ)(tin dichloride, tin methylsulfonate and tin benzyl sulfonate etc) combining with imidazolium chloride could form excellent catalysts, which catalyzes the conversion of carbohydrates to methyl lactate in methanol. The catalysts composed of tin(Ⅱ) methanesulfonate and ionic liquid could catalyze methyl lactate synthesis reactions from carbohydrates, such as sucrose, glucose, fructose, starch, cotton fiber and so on. Except for the low methyl lactate yield of10%obtained in the cotton cellulose reaction, more than35%methyl lactate yields were obtained in all the other carbohydrate reactions. The highest methyl lactate yield of70%was obtained for fructose.In the presence of tin(Ⅱ) methanesulfonate and1-ethyl-3-methyl imidazolium chloride ([EMIM]Cl), sucrose was converted to methyl lactate.51%of methyl lactate yield was obtained in methanol at130℃within2h of reaction. The dialkyl imidazolium chlorides exhibited relatively good promotion effect for the conversion of sucrose catalyzed by tin methanesulfonate catalyst, while no promotion effect was detected to the dialkyl imidazolium sulfates or methyl sulfates.64%of methyl lactate yield was obtained in the reaction of sucrose under optimum conditions when1,1’-methlene-3,3’-dimethyl bisimidazolium dichloride was used.In the presence of tin(Ⅱ) methanesulfonate and1-ethyl-3-methyl imidazolium, starch was converted to methyl lactate in a yield of over40%at180℃within8h of reaction. Comparing the results when dialkyl imidazole sulfates, dialkyl imidazole methyl sulfates and dialkyl imidazole chloride were used, we found that only imidazole salts with chlorine anion shows relatively good promotion effects on tin (Ⅱ) methanesulfonate catalyst. The highest methyl lactate yield was obtained when1,1’-methlene-3,3’-dimethyl di-imidazole dichloride was used as catalyst.45%methyl lactate yield was obtained in the reaction of starch at180℃within8h of reaction.In the investigation, we also observed that the combination of NH4Cl-SnCl2was very active to catalyze the conversion of carbohydrate to methyl lactate. When sucrose was used (in the12ml stainless steel reactor), up to45%of methyl lactate yield was obtained. When carrying out the conversion reaction for sucrose in continuous feeding model in a10L reactor, the yield of methyl lactate was70%and10%respectively. Under the same condition,51%of methyl lactate yield and19%of lactic acid yield were obtained for the catalytic conversion of.glucose in continuous feeding model in a10L reactor.When industrial starch was used as feedstock and NH4Cl-SnCl2was used as the catalyst, reaction was carried out in a10L batch reactor, resulting in41%of methyl lactate yield and 18%of lactic acid yield at160℃for8h. The same procedure was repeated when corn starch was used as feedstock,40%of methyl lactate yield and13%of lactic acid yield were obtained.