Study On Pentaerythritol Green Synthesis Process

Traditional preparation method of pentaerythritol has fully developed, but there is a large amount of organic pollutants in waste water and vast amounts of by-products — formate which has not market.The purpose of this paper is to explore green synthesis process of pentaerythritol.In this thesis,the triethylamine was used as catalysts for aldol condensation reaction.Then Raney — Ni was selected to be hydrogenation catalyst,and the organic solvent is ethyl alcohol.The consequent was affected by the reaction time, reaction temperature, the raw material ratio,the amount of triethylamine,and concentration of raw materials in the aldol condensation reaction stage.Reaction time, temperature, pressure, catalyst dosage and reaction solvent in catalytic hydrogenation stage was investigated.The results indicated that, the optimum conditions was as follows: reaction temperature was 60 ?,reaction time was 1h,reaction concentration of raw material was18%,triethylamine and formaldehyde mole ratio was 0.15:1,acetaldehyde and formaldehydethe molar ratio was 0.3:1 in the aldol condensation reaction stage;reaction pressure was 3MPa,reaction temperature was 110?,reaction time was4 h,the amount of catalyst was 14%,solvent was ethanol in catalytic hydrogenation stage.Under the optimum reaction conditions,The highest yield of pentaerythritol was48.23%.The recovery problem of triethylamine ? raney-Ni ? ethanol was investigated.When triethylamine was recycled,The unreacted raw materials were also recycled.But we didn't find the right separation method,recovery rate of triethylamine was only 43% or so. When we used Regenerate Raney-Ni in these processes, the rate of pentaerythritol recover.Ethanol solvent can be completely recycled and ethanol have high purity. when the recovered ethanol was used in the experiment,the rate of pentaerythritol was not affected.