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

点击翻译按钮获取中文摘要

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