Study On The Catalyst For Ethanol Synthesis From Syngas

As an important basic chemical raw material,ethanol is widely used in chemical industry and other fields.As a part of the coal chemical industry,the development of syngas chemical has a significant effect on the applications for clean coal resources.Both of the methanol modified and Fischer-Tropsch modified catalysts,prepared by co-precipitation,impregnation or combination of the two methods,were studied for the synthesis of ethanol from syngas,and characterized by BET,H2-TPR,CO-TPD,CO₂-TPD,XPS and XRD for assessment of the impact of supports and additives on the structure and morphology.After screening,Cu was determined as the active component.The results indicated basic support MgO was more advantageous for ethanol synthesis than other supports,such as Al2O3,ZrO₂ and SiO₂.The appropriate molar ratio of Cu/MgO was 1:1.For Cu/MgO catalyst,the ability of carbon chain growth and space time yield of C₂₊OH increased with the addition of Mn.On one hand it increased the surface area of catalysts and the dispersion of Cu,Mg species,on the other hand it increased the number and intensity of basic sites.Under the condition of Mn/Cu=0.3,the selectivity ratio of C₂₊OH to C1OH and the space time yield of C2H5OH increased from 0.08 to 0.31 and 2.69 g·?kgcat·h?-1 to 5.65 g·?kgcat·h?-1.The C₂₊OH synthesis capacity was limited on Mn/Cu/MgO catalyst.Co modified Mn/Cu/MgO catalyst,were prepared by co-precipitation method.With the addition of Co,Co2Mg and MnCo2O4 phase was formed,which facilitated the dispersion of the Cu,Mn and Mg species.When the addition amount of Co molar ratio of Co to Cu was 0.3,the selectivity ratio of C₂₊OH to CiOH and the space time yield of C₂₊OH increased from 0.31 to 3.12 and 15.83 g/?kg·h?to 50.32 g/?kg·h?,respectively,compared with the catalyst without Co.The characterization and performance evaluation of the catalysts showed that the addition of promoter Co remarkably promoted the carbon insertion ability,which will eventually improve the selectivity of C₂₊OH in this reaction.