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首页> 外文期刊>RSC Advances >Molybdenum oxide/gamma-alumina: an efficient solid acid catalyst for the synthesis of nopol by Prins reaction
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Molybdenum oxide/gamma-alumina: an efficient solid acid catalyst for the synthesis of nopol by Prins reaction

机译：氧化钼/γ-氧化铝：一种有效的固体酸催化剂，可通过Prins反应合成Nopol

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Prins condensation of beta-pinene with paraformaldehyde was carried out over MoOx/gamma-Al2O3 catalyst in liquid phase. MoOx/gamma-Al2O3 catalysts with different loadings were synthesized by impregnation method and characterized by XRD, N-2 sorption, NH3-TPD, UV-DRS, TEM and SEM. The surface area, TEM and UV-DRS measurements reveal complete coverage of alumina support by MoOx was achieved between 9 and 11 wt% loading in which the molybdenum is present as octahedral and tetrahedral species in the form of a monolayer domain and small clusters of MoOx. The effect of MoOx loading and calcination temperature of the catalysts on total acidity and catalytic activity in the Prins reaction were correlated. The total surface acid density of MoOx/gamma-Al2O3 increased with an increase in MoOx loading until 11 wt% and further loading decreased the acidity. Among the different supports, ZrO2, TiO2, SiO2 and Nb(2)O5, gamma-Al2O3 exhibited the best performance. The influence of solvent on the Prins reaction in terms of dielectric constant, acceptor and donor number was investigated. Solvents with both AN and DN in the range of 10 to 20 were suitable to facilitate the reaction. The effect of reaction temperature, catalyst amount, reactant mole ratio and reusability of the catalyst for the Prins reaction were investigated. The 11 wt% MoOx loaded on g-Al2O3 showed the best performance with 96% beta-pinene conversion with 86% nopol selectivity.
机译：β-O烯与低聚甲醛在MoOx /γ-Al2O3催化剂上进行液相缩合反应。通过浸渍法合成了不同负载量的MoOx /γ-Al2O3催化剂，并通过XRD，N-2吸附，NH3-TPD，UV-DRS，TEM和SEM对其进行了表征。表面积，TEM和UV-DRS测量表明，MoOx可以完全覆盖氧化铝载体，负载量为9至11 wt％，其中钼以单面域和小簇MoOx的形式存在于八面体和四面体物种中。关联了MoOx的负载量和催化剂的煅烧温度对Prins反应中总酸度和催化活性的影响。 MoOx /γ-Al2O3的总表面酸密度随MoOx负载的增加而增加，直至达到11 wt％，而进一步的负载则降低了酸度。在不同的载体中，ZrO2，TiO2，SiO2和Nb（2）O5，γ-Al2O3表现出最好的性能。从介电常数，受体和给体数的角度研究了溶剂对Prins反应的影响。 AN和DN均在10至20范围内的溶剂适合于促进反应。研究了反应温度，催化剂用量，反应物摩尔比和催化剂对Prins反应的可重复使用性的影响。负载在g-Al2O3上的11 wt％MoOx以96％的β-beta烯转化率和86％的Nopol选择性表现出最佳性能。

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