Selective Vapor-Phase C1-Elongation of Methanol and Ethanol with H2 and CO2 by Tailoring Active Sites Immobilized in UiO-66-Type Metal Organic Frameworks

甲烷、甲醇、甲酸或一氧化碳等氯代化合物已经可以通过二氧化碳和氢气的多相催化选择性地生成。然而，含有一个以上C原子的分子，除了乙醇之外，到目前为止只能作为二氧化碳氢化产物分布中的一个组分获得，气相中有H2。这是因为很难同时控制C-C-形成和二氧化碳加氢。考虑到这一挑战，该项目打算在二氧化碳、氢气和脂肪醇(甲醇、乙醇)的气流中特别形成一个C-C键。以这种方式，选择性地合成了C1-细长羧酸或各自的醇。为此，将使用以UIO-66型金属-有机骨架为基础的固体催化剂，在其上固定金属原子或团簇。该项目遵循三个明确的目标：1)展示用H2和甲醇或乙醇进行气相无卤化二氧化碳加氢生成C1-拉长羧酸或醇；2)从MOF框架和固体催化剂中固定的金属原子或簇合物的单独作用了解反应机理；3)调整固体催化剂，例如通过改变活性中心或其周围的配位环境，以提高对特定的C1-拉长羧酸或其相应的醇的选择性。达到这三个目标可能最终允许从气体进料中除去醇，从而开辟了一条新的途径，用于在气相中通过直接二氧化碳氢化生成更高级的(C2+)羧酸和醇

C1-compounds such as methane, methanol, formic acid or carbon monoxide can already be formed selectively via heterogenous catalysis by CO2 hydrogenation with H2. Molecules containing more than one C atom, however, can with the exception of ethanol so far only obtained as one component in a distribution of products from CO2 hydrogenation with H2 in the gas phase. This due to the difficulty to simultaneously control C-C-formation and CO2 hydrogenation. Given this challenge, this project intends to form specifically one C-C bond in a gas stream of CO2, H2 and an aliphatic alcohol (methanol, ethanol). In this way, the C1-elongated carboxylic acid or the respective alcohol is synthesized selectively. To this end, solid catalysts based on UiO-66-type metal-organic frameworks, on which metal atoms or clusters are immobilized, will be used. The project follows three definite objectives: 1) demonstration of the formation of the C1-elongated carboxylic acid or alcohol by gas-phase halide-free CO2 hydrogenation with H2 and methanol or ethanol; 2) understanding of the reaction mechanism from the individual roles of both the MOF framework and the immobilized metal atoms or clusters within the solid catalyst; 3) tailoring of the solid catalysts, e.g., by changing the active sites or the coordination environment around it, to drive the selectivity towards either a specific C1-elongated carboxylic acid or its corresponding alcohol. Meeting these three objectives may ultimately allow for a removal of the alcohol from the gas feed, thus opening a new path for the selective formation of higher (C2+) carboxylic acids and alcohols from direct CO2 hydrogenation with H2 in the gas phase