A bifunctional catalyst, comprising GaZr oxide and SAPO-34 zeolite, manifests enhanced catalytic activity in CO hydrogenation to light olefins; nonetheless, the comprehensive analysis of the pivotal role played by the underlying structure of ZrO in Ga-Zr oxide has not been investigated. Herein, different crystalline structures of ZrO were prepared by the co-precipitation method and adopted as a support to deposit Ga to obtain ZrO with different ratios of monoclinic ZrO (-ZrO) to tetragonal ZrO (-ZrO) in GaZr oxides for CO hydrogenation to light olefins. Various characterizations demonstrated that the interface between Ga and the mixed phase of (-) ZrO produces more oxygen vacancies which favors the adsorption and activation of CO, and the larger specific surface area and stronger H adsorption and dissociation capacity promote CO conversion. Interestingly, the GaZr oxide with high -ZrO content exhibits superior catalytic activity than the GaZr oxide with high content of -ZrO. The highest light olefins yield (9.0%) and selectivity (77.9%) (CO free) with 27.9% CO conversion was achieved. DRIFT spectra further elaborated that the GaZr oxides with different ZrO crystalline phases follow the same reaction pathway to hydrogenate CO first to HCOO* and then to CHO* on GaZr oxide surface. While compared with sole ZrO, the introduction of Ga significantly promotes the hydrogenation of HCOO* to CHO*, acting as a crucial reaction intermediate that subsequently diffuses into SAPO-34 pores to enhance the desired light olefins selectivity.

中文翻译：

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ZrO2晶相对GaZr氧化物氧空位及其CO2加氢制低碳烯烃性能的影响

由GaZr氧化物和SAPO-34沸石组成的双功能催化剂在CO加氢制轻质烯烃中表现出增强的催化活性；然而，尚未对Ga-Zr氧化物中ZrO的基础结构所起的关键作用进行全面分析。本文采用共沉淀法制备了不同晶型结构的ZrO，并以Ga为载体沉积Ga，得到GaZr氧化物中单斜晶系ZrO(-ZrO)与四方晶系ZrO(-ZrO)不同比例的ZrO，并进行CO加氢制备轻质烯烃。各种表征表明，Ga与(-)ZrO混合相之间的界面产生更多的氧空位，有利于CO的吸附和活化，更大的比表面积和更强的H吸附和解离能力促进CO转化。有趣的是，具有高-ZrO含量的GaZr氧化物表现出比具有高-ZrO含量的GaZr氧化物优异的催化活性。实现了最高的轻质烯烃产率 (9.0%) 和选择性 (77.9%)（不含 CO），CO 转化率为 27.9%。 DRIFT光谱进一步阐述了具有不同ZrO晶相的GaZr氧化物遵循相同的反应路径，在GaZr氧化物表面上首先将CO氢化成HCOO*，然后氢化成CHO*。与单独的 ZrO 相比，Ga 的引入显着促进了 HCOO* 氢化为 CHO*，充当关键的反应中间体，随后扩散到 SAPO-34 孔中，以提高所需的轻质烯烃选择性。