硅藻土负载Dawson型磷钨酸铯的制备、表征及催化氧化合成己二酸

以硅藻土为载体,采用浸渍法制备出CsxH6-xP2W18O62·nH2O/硅藻土催化剂。对催化剂进行FT IR、XRD、SEM、NH3 TPD及N2吸附 脱附表征。将该催化剂用于催化H2O2氧化环己酮合成己二酸,并考察了Cs离子取代度和CsxH6-xP2W18O62·nH2O负载量对催化活性的影响。结果表明,30%Cs3H3P2W18O62/硅藻土的催化活性最高。采用正交设计方法得到对己二酸收率影响由大到小的因素依次为H2O2用量、反应时间、反应温度、催化剂用量,最佳工艺条件为催化剂用量占环己酮质量分数51%、n(C6H10O)/n(30%H2O2)=1/5、反应温度105℃、反应时间50 h,此时己二酸的收率为853%,纯度为999%。30% Cs3H3P2W18O62/硅藻土具有良好的稳定性,重复使用5次,己二酸收率仍可达701%。

Preparation,Characterization of CsxH6-xP2W18O62·nH2O/Diatomite and Its Catalytic Application for Adipic Acid Synthesis

Cs_xH_6-xP₂W₁₈O₆₂·nH₂O/Diatomite catalysts were prepared by impregnation method and characterized by FT IR, XRD, SEM, NH3 TPD and N2 adsorption desorption techniques. The prepared catalysts were then used in the oxidation of cyclohexanone to adipic acid with H2O2. The effects of Cs ion exchange degree and loading amount of CsxH6-xP2W18O62·nH2O on the catalytic behavior of CsxH6-xP2W18O62·nH2O/Diatomite were investigated, showing that Cs3H3P2W18O62·nH2O/Diatomite with Cs3H3P2W18O62·nH2O loading amount of 30% exhibited the best catalytic activity. According to the influence degree from large to small, the factors affecting the yield of adipic acid were in the order of H2O2 quantity, reaction time, reaction temperature and catalyst dosage, which was the conclusion of orthogonal experiments, and the obtained optimal reaction conditions were the mass fraction of catalyst to cyclohexanone of 51%, n(C6H10O)/n(30%H2O2)=1/5, reaction temperature of 105℃ and reaction time of 5 h, under which the yield and purity of adipic acid were 853% and 99%, respectively. 30%Cs3H3P2W18O62·nH2O/Diatomite also showed good catalytic stability with the adipic acid yield still of 701% after 5 recycle times, and was easily removed from the system after reaction.