Cadmium oxide supported on silica is a highly active and selective bifunctional catalyst for the clean synthesis of p-cymene using dehydroisomerization of cyclic monoterpenes such as α-pinene, β-pinene, limonene, α-terpinene, γ-terpinene, and terpinolene. The dehydroisomerization occurs via acid-redox bifunctional catalysis at the gas-solid interface involving isomerization of monoterpenes to p-menthadienes on acid sites of silica support followed by p-menthadiene dehydrogenation to p-cymene on oxo-metal sites of CdO. The less reactive bicyclic monoterpenes, such as α-pinene and β-pinene, give 91–95% p-cymene yields at 325–375 °C, whereas more reactive monocyclic monoterpenes, such as limonene, α-terpinene, γ-terpinene, and terpinolene, give a 100% yield at 200–250 °C. To the best of our knowledge, CdO/SiO₂ has the highest efficiency in monoterpene-to-p-cymene dehydroisomerization among the catalysts reported so far. The catalyst was characterized by BET, TGA, XRD, DRIFTS, H₂-TPR, and ICP–OES.

二氧化硅负载的氧化镉是一种高活性和选择性双功能催化剂，用于清洁合成对伞花烃，使用环状单萜如α-蒎烯、β-蒎烯、柠檬烯、α-萜品烯、γ-萜品烯和萜品油烯的脱氢异构。脱氢异构化通过气-固界面处的酸-氧化还原双功能催化发生，涉及单萜在二氧化硅载体的酸性位点上异构化为对-薄荷二烯，然后对-薄荷二烯在 CdO 的含氧金属位点上脱氢为对-甲基异丙基苯。反应性较低的双环单萜，如 α-蒎烯和 β-蒎烯，在 325-375 °C 下对甲基异丙基苯的产率为 91-95%，而反应性较高的单环单萜，如柠檬烯、α-萜品烯、γ-萜品烯、和萜品油烯，在 200–250 °C 下的产率为 100%。据我们所知，CdO/SiO ₂在目前报道的催化剂中单萜制对伞花烃脱氢异构效率最高。通过 BET、TGA、XRD、DRIFTS、H ₂ -TPR 和 ICP-OES 对催化剂进行了表征。