The Research Of Catalyst For Synthesizing Esters By The Diol Through One-pot Method

It is valuable research direction that Esters with high added value was synthesized by the diol through One-pot Method,But there is a disadvantage of low efficiency of catalyst.Though consulting literature we found that the catalytic effect of gold catalyst on the synthesis of esters by alcohols was excellent.Then on this basis,we explored that CeO₂-cube supported gold nanoparticle on the catalytic performance of 1,3-propanediol oxidative esterification.We found a kind of hydrotalcite supported nano Au in synthesis of ester through One-pot Method is highly active.The main content of this paper is as follows:?1?Au nanoparticles supported on CeO₂ nanocubes were successfully prepared by a deposition-precipitation method and tested for the oxidative transformation of1,3-propanediol.We studied the different parameters which may affect catalytic performance,such as dosage of urea,the calcination temperature of CeO₂ nanocubes,the calcination temperature of Au/CeO₂-cube,Au loading,the loading temperature.And the catalyst was characterized by ICP,HRTEM,TEM,XRD,NH3-TPD,CO2-TPD,TPR and XPS.The optimized preparation conditions of Au/CeO₂-cube were obtained as follows: the mass ratio of urea/ceria 6,the calcination temperature of CeO₂ nanocubes400 ?,the calcination temperature of Au/CeO₂-cube 200 ?,Au loading 1.5%,the loading temperature 80 ?.In the condition of 100 ?,p?O2?=2 MPa,the mole of1,3-propanediol /Au 75.5 and the reaction time 4 hours,the results show that the conversion of 1,3-propanediol was 97.5% and the selectivities to methyl3-hydroxypropionate and dimethyl malonate were 90.1% and 6.1%,respectively.Using the calcination temperature of the used catalyst of 200 ? with the calcination time of 2h could remove the toxic substances on the surface of the catalyst with circulation use of four times,and the catalytic performance of the regenerated 1% Au/CeO₂-cube decreased slightly.This was mainly owned to the Au particle size in the process of catalytic reaction due to growing up.It was found that the suitable interaction of Au?2.0-4.0 nm?and CeO₂ and the suitable amount and strength of the acidic and basic sites were favorable for the oxidative esterification.A possible reaction mechanism had also been proposed for the selective oxidative ersterification of 1,3-propanediol to synthesize3-hydroxy methyl propionate and dimethyl malonate on the Au/CeO₂-cube catalysts.?2?Magnesium-Aluminum hydrotalcite?HT?supported gold catalysts were prepared by the sol-immobilisation method and used in the methanol esterificationreaction of 1,3-porpanediol.We studied the different parameters which may affect catalytic performance,such as the calcination temperature of HT,the calcination temperature of Au/ HT.And the catalyst was characterized by ICP,TEM,XRD,XPS.The optimized reaction conditions were obtained as follows: the calcination temperature of HT 150 ?,the calcination temperature of Au/ HT 150 °C and catalyst activities of1% Au/HT during four reaction cycles.In the condition of 100 °C,p?O2?=2 MPa,the mole of 1,3-propanediol /Au 113.2 and the reaction time 4 hours,the results show that the conversion of 1,3-propanediol was 96.2% and the selectivities to methyl3-hydroxypropionate and dimethyl malonate were 94.9% and 3.1%,respectively.A possible reaction mechanism had also been proposed.?3?Gold catalysts with zinc magnesium aluminum hydroxide and zinc magnesium aluminum oxide or hydrotalcite as the carrier were prepared by the sol-immobilisation method and used in the synthesis delta-Valerolactone reaction of 1,5-Pentanediol.And the catalyst was characterized by ICP,TEM.We found the content is around 1% and gold particle size at about 3 nm.And Au/Al2O3 and Au/MgAl?3:1?-HT of the deltaValerolactone selectivity were greater than 99%,and Au/MgAl?3:1?-HT of catalytic activity is the largest.In alcohol mole ratio of gold of 200:1,through optimizing the reaction conditions are: reaction temperature is 110 ?,the reaction time of 2 h when the delta-lactone yield 67.9%.