B2O3改性Na2CO3催化剂用于甲醇脱氢制无水甲醛

以B₂O₃为助催化剂，采用研磨混合法改性Na₂CO₃催化剂，在固定床反应器中催化甲醇脱氢制备无水甲醛，考察催化剂的组成和反应条件等对催化反应的影响，采用XRD、TG-DTG、N₂吸附-脱附、SEM和CO₂-TPD等对催化剂进行表征。结果表明，以B₂O₃为助催化剂采用机械研磨混合法改性的Na₂CO₃催化剂，增加了催化剂的比表面积，在(10～30) nm增加了大量的孔道，平均孔径达18.44 nm，比表面积为1.65 m²·g^-1，且B₂O₃分布均匀，改性后的催化剂碱性降低，在催化甲醇脱氢制备无水甲醛的反应中，催化活性明显高于Na₂CO₃催化剂，表明B₂O₃改性Na₂CO₃催化剂能提高甲醇转化率和甲醛选择性。在B₂O₃/Na₂CO₃催化剂中B₂O₃质量分数为30%、甲醇进料质量分数为26%、反应温度为650 ℃和甲醇重时空速为2.94 h^-1条件下，甲醇转化率达59.97%，甲醛选择性达83.28%。

Methanol dehydrogenation to anhydrous formaldehyde over boron oxide-modified sodium carbonate catalyst

Na2CO3 catalyst was modified by B2O3 and was used for methanol dehydrogenation to formaldehyde in a fixed-bed flow reactor under the atmospheric pressure.The effects of catalyst composition,reaction temperature,weight hourly space velocity were investigated.The catalyst was characterized by XRD,TG-DTG,nitmgen adsorption-desorption,SEM and CO2-TPD.The results showed that B2O3 promoter was highly and evenly dispersed on the surface of Na2CO3,and the specific surface area and the pore structure of B2O3/Na2CO3（30％） catalyst was improved;the pore channels were increased largely in pore diameter （10-30） nm,average pore size was 18.44 nm and specific area was 1.65 m2 · g-1.The basicity of B2O3/Na2CO3 （30％） catalyst was decreased.The activity of B2O3/Na2CO3 （30％） catalyst was significantly higher than that of pure Na2CO3 catalyst in the reaction of methanol dehydrogenation to anhydrous formaldehyde,which indicated that B2 O3 modification was beneficial to the enhancement of methanol conversion and the selectivity to formaldehyde.Methanol conversion and the selectivity to formaldehyde were 59.97％ and 83.28％,respectively,under the optimum reaction condition as follows：B2 O3 30％ of B2O3/Na2CO3 catalyst mass,methanol feed mass fraction 26％,reaction temperature 650 ℃ and methanol weight hourly space velocity 2.94 h-1.