Study On Selective Dehydration Of BDO Catalyzed By Doped CeO₂

1,4-butanediol（BDO）is a platform chemical which can be obtained from green regeneration resources through fermentation.Developing the downstream high value-added derivatives of BDO is the key to extend the industrial chain and expand the profitability of enterprises.Selective catalytic dehydration of BDO can produce 3-butene-1-ol（BTO）.BTO is an intermediate chemical with wide application and high added value.The synthesis of BTO by conventional routes can not meet the requirements of commercial production.The preparation of BTO catalysts by selective dehydration of BDO is a necessary step to realize the commercial production of this process.A series of CeO₂,MO_X/CeO₂ and Co₃O₄-Ce-Zr catalysts were prepared.Firstly,different precipitants were explored to prepare CeO₂.On the basis of the optimum preparation method of CeO₂,Fe,Co,Ni,Cr,Mn doped CeO₂ were used.Furthermore,CeO₂-ZrO₂ solid solutions with different molar ratios were prepared,and Co₃O₄ was loaded on CeO₂-ZrO₂ solid solutions.The performance of catalysts was evaluated in the micro reactor.The physicochemical properties of the catalysts were characterized by XRD,BET,H₂-TPR,SEM,TEM,NH₃-TPD,CO₂-TPD and XPS.The main conclusions are as follows:The results showed that the CeO₂ catalyst prepared with ammonia as precipitant had more CeO₂（111）crystal faces,and the effect was the best.On the basis of the above,a series of MO_x/CeO₂ catalysts prepared by impregnation method had been found that the doping of Co₃O₄ increased the ratio of Ce³⁺,increasing the defect and oxygen vacancy ratio on the crystal surface,and improving the activity of BDO selective dehydration.The preparation conditions of Co₃O₄-CeO₂ were optimized.On the basis of the above,a series of MO_x/CeO₂ catalysts prepared by impregnation method had been found that the defect and oxygen vacancy ratio on the crystal surface and the activity of BDO selective dehydration could be increased and improved after doping of Co₃O₄increased the ratio of Ce³⁺.It was found that when the Co₃O₄ content was 5%（mass fraction）and the calcination temperature was 800°C,the catalyst showed good performance,and the BTO selectivity could reach 70.50%.ZrO₂ catalyst also had good performance in this reaction.Therefore,cerium zirconium composite oxide catalysts with different molar ratios and Co₃O₄-Ce-Zr catalysts were explored.The results showed that the catalyst with the molar ratio of cerium to zirconium of 3:1 had the best selective dehydration performance for BDO.The catalyst with Co₃O₄showed outstanding catalytic performance,with BDO conversion of80.16%and BTO selectivity of 72.53%.The addition of Co₃O₄ and ZrO₂were also increased the acid content of the catalyst,the redox ability of the surface and the ratio of oxygen vacancy.From the characterization test results,it could be inferred that under the condition of acidity and basicity and oxidation-reduction properties,the oxidation-reduction mechanism could more reasonably explain the results of selective dehydration to BTO.