Catalytic oxidation of carbazole by t-butyl hydroperoxide over Mo catalysts
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摘要: 以油溶性过氧化叔丁醇(TBHP)为氧化剂，采用钼（Ⅵ）类催化剂，对油品中性质稳定的氮化物咔唑进行了催化氧化研究。考察了钼催化剂及其载体对咔唑氧化的影响。结果表明，在无负载条件下，乙酰丙酮钼（MoO2(acac)2）的催化活性略高于三氧化钼（MoO3）；经弱酸性树脂（D113）负载后，MoO3催化活性显著提高；三种载体（Al2O3、树脂D113和树脂D751）均能提高钼催化剂的活性，使咔唑转化率达到65%以上，其中MoO3/Al2O3催化活性最高。杂金属Ni和Co的加入导致MoO3/Al2O3催化活性降低。其次，进行了氧化反应选择性研究，实验发现在反应液中含有二苯并噻吩时，TBHP/MoO3/D113能优先氧化咔唑；而TBHP/MoO3/D751对咔唑和二苯并噻吩具有近似的氧化活性。最后根据光谱数据对咔唑系列产物的结构进行了初步推测。Abstract: Catalytic oxidation of carbazole (CAZ) was investigated using oil-soluble t-butyl hydroperoxide (TBHP) as oxidant and Mo(VI) complexes as catalyst. The influences of various factors on CAZ conversion were probed including ligand, supporter and other metals Ni and Co involving. The results show that without supporter molybdenum acetylacetonate (Mo(VI)) has higher activity than MoO3 because of its solubility in hydrocarbon. All supporters, Al2O3, weakly acidic cation exchange resin (D113) and weakly acidic chelating cation exchange resin (D751), can promote the activity of MoO3. Incorporation of Ni and Co metals can reduce the activity of MoO3/Al2O3. It is also found that in the presence of dibenzothiophene (DBT), TBHP/MoO3/D113 presents a higher oxidation selectivity of CAZ, while TBHP/MoO3/D751 has a similar oxidation activity to CAZ and DBT. The structure of CAZ oxidation product was speculated according to the spectrum data.
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