<br>深入了解 CuZnAl 催化剂对 CO 加氢制醇的结构敏感性,Fuel

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深入了解 CuZnAl 催化剂对 CO 加氢制醇的结构敏感性
Fuel ( IF 6.7 ) Pub Date : 2022-04-26 , DOI: 10.1016/j.fuel.2022.124265
Penglong Jia ₁ , Yongjun Liu ₁ , Rui Yang ₁ , Peng Luo ₁ , Wei Huang _{1,

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Affiliation

CO 加氢的催化转化是 Cu 基催化剂上的结构敏感反应。区分 Cu 基催化剂在甲醇合成和乙醇/C2+OH 合成中的结构分化和可能的反应途径非常重要。在此，评估了四种类型 CuZnAl 催化剂的活性，并研究了它们的结构差异。在固定床反应器中直接应用固液分离后，通过完全液相（CLP）法制备的 CuZnAl 催化剂（CZA）也显示出合成乙醇和高级醇（C2+OH）的能力，在 10.6% 的 CO 转化率下，C2+OH 在液体产物中的选择性高达 31.6%。然而，商用甲醇合成催化剂（CMC）的 CO 转化率最高（28.2%），C2+OH 选择性最差（7.8%）。通过ICP、XRD、CO-TPD、N2O吸附、XPS、SEM、TEM和原位漂移技术表征后，发现Cu的分散和暴露的Cu表面积对CO转化率有显著影响。乙醇和 C2+OH 的选择性与 Cu 的大小和分布、结构特征以及 Cu 和 Al 的化学环境有关。原位 DRIFTS 表明 CHxO* 物种可以在不同的 CuZnAl 催化剂上形成。然而，形成的 CHxO* 物质将在 CMC 催化剂上快速氢化以产生甲醇，而该步骤在 CZA 催化剂上被抑制。此外，仅在 CZA 催化剂上观察到桥式吸附 CO，这有利于形成 CHx 中间体，从而导致乙醇和高级醇的形成。

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Insight into the structural sensitivity of CuZnAl catalysts for CO hydrogenation to alcohols

The catalytic conversion of CO hydrogenation is a structure-sensitive reaction over Cu-based catalyst. It is very important to distinguish the structural differentiation and possible reaction pathway of Cu-based catalysts in methanol synthesis and ethanol/C2+OH synthesis. Herein, the activity of four types of CuZnAl catalysts is evaluated, and their structural differentiation is investigated. The CuZnAl catalyst (CZA) prepared by a complete liquid-phase (CLP) method after solid–liquid separation directly applied in the fixed bed reactor also shows the ability to synthesize ethanol and higher alcohols (C2+OH), with the selectivity of C2+OH in liquid product reaching up to 31.6% at the CO conversion of 10.6%. However, commercial methanol synthesis catalyst (CMC) displays the highest CO conversion (28.2%) and the poorest C2+OH selectivity (7.8%). After characterized by ICP, XRD, CO-TPD, N2O adsorption, XPS, SEM, TEM and in-situ DRIFTS techniques, it is discovered that the dispersion of Cu and the exposed Cu surface area significantly influences CO conversion. The selectivity of ethanol and C2+OH is related to the size and distribution of Cu, the architectural feature, and the chemical environment of Cu and Al. In-situ DRIFTS indicates that CHxO* species can be formed over different CuZnAl catalysts. However, the formed CHxO* species will be rapidly hydrogenated to produce methanol on CMC catalyst, while the step is inhibited on CZA catalyst. Additionally, a bridge-type adsorbed CO is only observed on CZA catalyst, which is beneficial for the formation of CHx intermediates, leading to the formation of ethanol and higher alcohols.

更新日期：2022-04-26

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