AbstractThe oxide–zeolite (OXZEO) catalyst design concept has been demonstrated in an increasing number of studies as an alternative avenue for direct syngas conversion to light olefins. We report that face‐centered cubic (FCC) MnGaOx‐Spinel gives 40 % CO conversion, 81 % light olefins selectivity, and a 0.17 g gcat−1 h−1 space‐time yield of light olefins in combination with SAPO‐18. In comparison, solid solution MnGaOx (characterized by Mn‐doped hexagonal close‐packed (HCP) Ga2O3) with a similar chemical composition gives a much inferior activity, i.e., the specific surface activity is one order of magnitude lower than the spinel oxide. Photoluminescence (PL), in situ Fourier‐transform infrared (FT‐IR), and density functional theory (DFT) calculations indicate that the superior activity of MnGaOx‐Spinel can be attributed to its higher reducibility (higher concentration of oxygen vacancies) and the presence of coordinatively unsaturated Ga3+ sites, which facilitates the dissociation of the C−O bond via a more efficient ketene–acetate pathway to light olefins.
摘要氧化物-沸石(OXZEO)催化剂设计理念已在越来越多的研究中得到证实,可作为合成气直接转化为轻质烯烃的替代途径。我们报告说,面心立方(FCC)MnGaOx-Spinel 与 SAPO-18 结合使用,可实现 40% 的 CO 转化率、81% 的轻质烯烃选择性以及 0.17 g gcat-1 h-1 的轻质烯烃时空产率。相比之下,化学成分相似的固溶体 MnGaOx(特征为掺锰的六方紧密堆积(HCP)Ga2O3)的活性要低得多,即比表面活性比尖晶石氧化物低一个数量级。光致发光(PL)、原位傅立叶变换红外(FT-IR)和密度泛函理论(DFT)计算表明,MnGaOx-尖晶石之所以具有更高的活性,是因为它具有更高的还原性(更高浓度的氧空位)和存在配位不饱和的 Ga3+ 位点,这有利于通过更有效的酮-乙酸途径解离 C-O 键,生成轻质烯烃。