Reaction Network Analysis of the Ruthenium-Catalyzed Reduction of Carbon Dioxide to Dimethoxymethane

Abstract

Due to the growing interest in dimethoxymethane (DMM) as formaldehyde synthon and fuel additive, new and more efficient routes toward the formaldehyde analog are being investigated. One approach is the reductive transformation of carbon dioxide using a ruthenium phosphine catalyst and a Lewis acid additive in methanol. In the present work, we investigated the underlying reaction network, consisting of several intermediates, equilibria and side products, through in situ IR spectroscopy. We determined rate constants and activation parameters for the hydrogenation steps. Their temperature-dependent differences can be used to influence the product selectivity in this catalysis. To favor DMM formation, the acetalization equilibrium and especially the amount of water formed were identified as promising optimization opportunities. Simulation of concentration profiles on the basis of the proposed kinetic model enables the prediction of experimental product distributions for various reaction parameters, demonstrating the power of reaction network analysis for process optimization.