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首页> 外文期刊>Chemistry central journal >The highly selective oxidation of cyclohexane to cyclohexanone and cyclohexanol over VAlPO 4 berlinite by oxygen under atmospheric pressure
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The highly selective oxidation of cyclohexane to cyclohexanone and cyclohexanol over VAlPO 4 berlinite by oxygen under atmospheric pressure

机译：大气压下氧在VAlPO 4 berinite上高选择性地将环己烷氧化为环己酮和环己醇

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Background: The oxidation of cyclohexane under mild conditions occupies an important position in the chemical industry. A few soluble transition metals were widely used as homogeneous catalysts in the industrial oxidationof cyclohexane. Because heterogeneous catalysts are more manageable than homogeneous catalysts as regardsseparation and recycling, in our study, we hydrothermally synthesized and used pure berlinite (AlPO4) and vanadiumincorporated berlinite (VAlPO4) as heterogeneous catalysts in the selective oxidation of cyclohexane with molecular oxygen under atmospheric pressure. The catalysts were characterized by means of by XRD, FT-IR, XPS and SEM.Various infuencing factors, such as the kind of solvents, reaction temperature, and reaction time were investigatedsystematically.Results: The XRD characterization identifed a berlinite structure associated with both the AlPO4 and VAlPO4 catalysts.The FT-IR result confrmed the incorporation of vanadium into the berlinite framework for VAlPO4. The XPS measurement revealed that the oxygen ions in the VAlPO4 structure possessed a higher binding energy than those in V2O5,and as a result, the lattice oxygen was existed on the surface of the VAlPO4 catalyst. It was found that VAlPO4 catalyzedthe selective oxidation of cyclohexane with molecular oxygen under atmospheric pressure, while no activity wasdetected on using AlPO4. Under optimum reaction conditions (i.e. a 100 mL cyclohexane, 0.1 MPa O2, 353 K, 4 h, 5 mgVAlPO4 and 20 mL acetic acid solvent), a selectivity of KA oil (both cyclohexanol and cyclohexanone) up to 97.2%(with almost 6.8% conversion of cyclohexane) was obtained. Based on these results, a possible mechanism for theselective oxidation of cyclohexane over VAlPO4 was also proposed.Conclusions: As a heterogeneous catalyst VAlPO4 berlinite is both high active and strong stable for the selectiveoxidation of cyclohexane with molecular oxygen. We propose that KA oil is formed via a catalytic cycle, which involvesactivation of the cyclohexane by a key active intermediate species, formed from the nucleophilic addition of the lattice oxygen ion with the carbon in cyclohexane, as well as an oxygen vacancy formed at the VAlPO4 catalyst surface.
机译：背景：环己烷在温和条件下的氧化在化学工业中占有重要地位。几种可溶性过渡金属在环己烷的工业氧化中被广泛用作均相催化剂。由于非均相催化剂在分离和回收方面比均相催化剂更易于管理，因此在我们的研究中，我们在大气压下通过水热合成并使用纯柏林铁（AlPO4）和钒结合的柏林铁（VAlPO4）作为非均相催化剂，用分子氧选择性氧化环己烷。通过XRD，FT-IR，XPS和SEM对催化剂进行了表征，系统地研究了各种影响因素，如溶剂的种类，反应温度，反应时间等。傅立叶变换红外光谱（FT-IR）结果证实钒被掺入了用于VAlPO4的硅藻土骨架中。 XPS测量表明，VA1PO4结构中的氧离子具有比V2O5中更高的结合能，结果，晶格氧存在于VA1PO4催化剂的表面。发现在大气压力下，VA1PO4催化了分子氧对环己烷的选择性氧化，而使用AlPO4则未发现活性。在最佳反应条件下（即100 mL环己烷，0.1 MPa O2、353 K，4 h，5 mg VAlPO4和20 mL乙酸溶剂），KA油（环己醇和环己酮）的选择性高达97.2％（几乎为6.8）获得％的环己烷转化率。基于这些结果，提出了环己烷在VAlPO4上选择性氧化的可能机理。结论：作为多相催化剂，VAlPO4硅藻土既具有高活性，又具有很强的稳定性，可用于分子氧对环己烷的选择性氧化。我们建议，KA油是通过催化循环形成的，该循环涉及通过关键活性中间物质激活环己烷，该中间活性物质是晶格中氧离子与环己烷中碳的亲核加成反应，以及在VAlPO4处形成的氧空位。催化剂表面。

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