Study On The Catalyst And Route For The Synthesis Of Glyoxylic Acid From Methyl Glycolate

A novel route for the synthesis of glyoxylic acid from methyl glycolate and its catalyst were studied.In the synthesis process,the Fe-Co binary oxide acts as catalyst catalyzing the air oxidation of methyl glycolate and the hydrolysis of methyl glyoxylate.The effects of catalyst composition,calcination and catalytic reaction conditions on the synthesis of glyoxylic acid from methyl glycolate were investigated.The main findings are as follows:The effects of molar ratio of Fe/Co on the physicochemical and catalytic properties of Fe-Co binary oxide catalysts were studied.The results showed that compared with single Co₃O₄ and Fe₂O₃,Fe-Co binary oxides have large specific surface area,good reducibility,large surface acidity and adsorbed oxygen.With the increase of the molar ratio of Fe/Co,the surface atomic ratio of Co³⁺/Co²⁺and the content of O_defef took on a volcano variation trend.With the increase of Fe/Co molar ratio,the conversion of methyl glycolate and the selectivity of glyoxylic acid showed a"volcanic"trend with the increase of Fe/Co molar ratio,and the conversion and selectivity reached the maximum when the molar ratio of Fe/Co was 12/8.The effect of calcination temperature on the performance of the catalyst was studied.With the increase of calcination temperature,the specific surface area of the catalysts decreased sharply,the reduction temperatures shifted to the high temperature region,the surface acidity and atomic ratio of Co³⁺/Co²⁺and the amount of O_defef decreased gradually.At the reaction conditions of 200^oC,1 atm and GHSV=1740 h^-1,taken Fe₁₂Co₈ catalyst as an example,the conversion of methyl glycolate by Fe₁₂Co₈ calcinated at 300 ^oC was 48%,the conversion of methyl glycolate by Fe₁₂Co₈ calcinated at 600 ^oC was 10%.The effect of reaction conditions on the performance of the catalyst was investigated.The conversion of methyl glycolate was increased by increasing the reaction temperature,but the methyl glycolate was overoxidized to CO₂ at too high temperature.With the increase of Fe/Co molar ratio,the critical temperature of overoxidation of the catalyst decreases(from 230 ^oC of Fe₁Co₈ to 205^oC of Fe₁₆Co₈).The conversion of methyl glycolate increased with the increase of the molar ratio of oxygen to methyl glycolate,and remained stable when the molar ratio reached 1.0.At the reaction conditions of 200 ^oC,1 atm and GHSV=1740 h^-1,the conversion of methyl glycolate over Fe₁₂Co₈ catalyst is 76%,the selectivity of glyoxylic acid is 70%,the selectivity of methyl glyoxylate is 30%and the yield of glyoxylic acid is 53.2%.The results show that it is feasible to synthesize glyoxylic acid from methyl glycolate using Fe-Co binary oxide catalyst.