Study On Hydrogenation Of Fatty Acid Methyl Ester And 2-ethylhexenal With Thermoregulated Transfer Catlysts

At present, the hydrogenation reaction popularly uses cuprum, chromium, zinc, ferrum and thulium oxide catalysts . The drawback is the reaction of the heterogeneous catalysis, the existence of mass transfer and diffusion resistance, high temperature and pressure , short catalyst life, recycling and re-use problems and other issues, in particular the loss of chromium and other heavy metals can cause a particularly serious problem of environmental pollution. In order to solve those problems thermoregulated transfer catalysts are used in hydrogenation of fatty acid methyl ester and 2-ethylhexenal.In this paper four kinds of thermoregulated phosphine ligands: fatty alcohol polyoxyethylene ether 1,2-phenylene phosphate ester (OPGPP), methoxy polyethylene glycol diphenylphosphine(MGPPE), tri-methoxy polyethylene glycol phosphine(TMPGP), and fatty alcohol polyoxyethylene ether diphenyl phosphate ester (TAPEP) were prepared and characterized by FT-IR and 1HNMR. Then the cloud point of these four kinds of ligands were mensurated by extrapolation, the results were 103℃, 112℃, 107℃and 106℃respectively, showed that all the prepared phosphine ligands had thermoregulated function.The prepared thermoregulated phosphine ligands were respectively reaction with palladium chloride by in-situ synthesis, obtained three kinds of thermoregulated transfer catalysts (PdCl2/OPGPP, PdCl2/MGPPE and PdCl2/TAPEP). These catalysts were used in the hydrogenation of oleic acid methyl ester, the PdCl2/OPGPP showed excellent catalytic activity. The optimum reaction conditions for hydrogenation of oleic acid methyl ester were obtained as follows: reaction temperature 200℃, hydrogen pressure 7MPa, the amounts of palladium chloride occupy oleic acid methyl ester 0.12%, n(palladium chloride):n(OPGPP)=1:10, reaction time 4h. Under the above conditions, the OH·V of products was 114 and the I·V of products was 25. The cycle performance of catalyst was investigated. When the composite catalytic system was repeatedly used four times,the OH·V of products was 102 and the I·V of products was 27.The complex of TMPGP and palladium chloride was used as the catalyst in the hydrogenation of fatty acid methyl ester. The optimum reaction conditions for hydrogenation of fatty acid methyl ester were obtained as follows: reaction temperature 200℃, hydrogen pressure 7MPa, the amounts of palladium chloride occupy fatty acid methyl ester 0.12%, n(palladium chloride):n(TMPGP) 1:10, reaction time 6h. Under the above conditions, the OH·V of products was 163 and the I·V of products was 0. The cycle performance of catalyst was investigated. When the composite catalytic system was repeatedly used five times, the OH·V of products was 140 and the I·V of products was 3.The complex of TMPGP and palladium chloride was used as the catalyst in the hydrogenation of 2-ethylhexenal to produce 2- ethylhexanol. The optimum reaction conditions for hydrogenation of fatty acid methyl ester were obtained as follows: reaction temperature 200℃, hydrogen pressure 7MPa, the amounts of palladium chloride occupy fatty acid methyl ester 0.18%, n(palladium chloride):n(TMPGP)= 1:10, reaction time 8h. Under the above conditions, the conversion of 2-ethylhexenal was 86% and the yield of 2- ethylhexanol was 84%. The cycle performance of catalyst was investigated. When the composite catalytic system was repeatedly used five times, the conversion of 2-ethylhexenal was 76% and the yield of 2- ethylhexanol was 74%.Through above-mentioned study, thermoregulated transfer catalysts were successfully applied to hydrogenation of fatty acid methyl ester and 2-ethylhexenal. Based on all the study in this paper catalysts in hydrogenation of fatty acid methyl ester and 2-ethylhexenal will be extended in the future.