One-step Selective Oxidation Of Methanol To Dimethoxymethane Over Bifunctional Catalysts

The synthesis of one-step selective oxidation of methanol to dimethoxymethane,eliminating the methanol oxidation into formaldehyde sections and larger savings in equipment investment.In recent years,it has been widely concerned about the research of catalysts for this kind of chemical reactions.In this paper,a series of bifunctional catalysts with both redox and acid centers were prepared.After the experimental study of its catalytic activity,V₂O₅-Zr O₂/SO₄^2-ispreferred.Applicationof XRD,FT-IR,NH₃-TPD,H₂-TPR,XPS,SEM,TEM,EDX and N₂ adsorption and desorption of V₂O₅-Zr O₂/SO₄^2-have been characterized,determine their surface morphology,composition and structure(molecular formula:Zr₆V_2.5SO₁₈).According to the results of the characterization:The catalyst at a calcination temperature of 450°C,500°C,and 550°C.The higher catalystic activity of the three catalysts was surely related to the V₂O₅ crystalline dispersed on their surface.Among them,the V₂O₅/Zr O₂-773K possessed stronger acidic property and highly specific surface.As a result,V₂O₅/Zr O₂-773K presented excellent catalytic activity for the oxidation of methanol,which was attributed to the V₂O₅crystalline existing on the surface achieving redox active sites,higher acidic nature and increased specific surface area.The conversion of methanol was 38.0%and the selectivity of methylal was90.5%under the catalyst calcination temperature was 500?,the reaction temperature was 200?,the methanol inlet was 0.05 m L·min^-1,the oxygen inlet was 5 m L·min^-1,the nitrogen inlet was 15 m L·min^-1.Roasting promotes the interaction between sulfate and surface oxides,forming a strong acid center,which greatly improves the surface acidity without reducing the redox properties.It is precisely because of the acidic center and the role of oxidation and reduction in order to promote the activation of methanol and oxygen in the pressure of 1 MPa and the temperature of 200?.The selectivity to DMM at all the time remained at about 90%when using the catalyst V₂O₅/Zr O₂.In addition,we studied the stability of the catalyst,and discussed the possible reasons for deactivation of the catalyst.