Cr2O3-Co3O4／SiO2对十八醇氧化生成十八酸反应的催化性能

 制备了一系列不同Cr／Co比例的Cr2O3－Co3O4／SiO2催化剂，并用XRD，FT－IR和BET等手段对催化剂进行了表征；考察了催化剂对十八醇氧化生成十八酸反应的催化性能，及反应条件（反应温度和反应时间）对催化性能的影响，确定了最佳反应条件．结果表明，金属硝酸盐在773K焙烧后转变成相应的氧化物并负载于二氧化硅上．Cr2O3－Co3O4／SiO2催化剂对十八醇氧化反应有很高的催化活性，十八酸选择性最高可达99．93％，收率可达52．44％．Cr2O3－Co3O4／SiO2催化剂的活性明显高于单一的Cr2O3／SiO2或Co3O4／SiO2催化剂

Oxidation of Octadecanol to Octadecanoic Acid over Cr2O3-Co3O4/SiO2 Catalyst

A series of Cr_2O_3-Co_3O_4/SiO_2 catalyst with different Cr/Co ratios was prepared by impregnation method. The catalyst samples were charaterized by XRD, FT-IR and BET techniques. The characteristic peaks of Cr_2O_3 and Co_3O_4 can be observed in both XRD patterns and FT-IR spectra. The specific surface area, the pore volume and the pore diameter of Cr_2O_3-Co_3O_4/SiO_2 catalyst become smaller owing to the metal oxides loaded on the inner surface of silica. It is reported that the effects of reaction conditions on catalytic performance of Cr_2O_3-Co_3O_4/SiO\-2 for the oxidation of octadecanol to octadecanoic acid are based on the high conversion of ocadecanol over Cr_2O_3/SiO_2 catalyst and the high selectivity for octadecanoic acid over Co_3O_4/SiO_2 catalyst. The yield of octadecanoic acid tended to rise with the time on stream and reached 52.44% after reaction for 8 h. There was no further increase in the yield of octadecanoic acid with time prolonged, because long-time running might lead to decarboxylation of some carboxylic acid. The reaction temperature is an important factor for this reaction. The temperature below 403 K is favorable for the formation of octadecanoic acid, but at temperature higher than 403 K, the yield of octadecanoic acid undergoes declining also owing to decarboxylation. Under appropriate conditions, Cr_2O_3-Co_3O_4/SiO_2 can be a highly effective catalyst for oxidation of octadecanol with yield of 52.44% and selecivity of 99.93% for octadecanoic acid.