Computational Investigation of the Catalytic Hydrodeoxygenation of Propanoic Acid over a Cu(111) Surface

Abstract

Cu-based alloy catalysts have recently been investigated experimentally for the hydrodeoxygenation (HDO) of biomass-derived organic acids. Here, the HDO of propanoic acid (PAc) has been studied over Cu(111) by mean-field microkinetic modeling based on parameters obtained from first-principles calculations. Models were developed for the gas- and liquid-phase HDO in condensed water and 1,4-dioxane. In agreement with experimental observations, the gas-phase PAc conversion rate is low at 573 K and increases in liquid water by 1 order of magnitude. In all reaction environments, the decarboxylation mechanism is dominant at low hydrogen partial pressures less than 0.1 bar, and the C–COO bond dissociation is the rate-controlling elementary step. This observation contrasts with the rate-controlling step identified over most group VIII metal surfaces, which is the C–OH bond dissociation in the decarbonylation mechanism. At high hydrogen (H2) partial pressures greater than 10 bar, the HDO of PAc produces propionaldehyde that can readsorb and further react through decarbonylation to produce C2 alkane products, which is conceptually different from the low H2 partial pressure scenario. At high H2 partial pressures, the initial hydrogenation at the carbonyl carbon of PAc becomes the rate-controlling elementary step.

Machine Learning Accelerated First-Principles Study of the Hydrodeoxygenation of Propanoic Acid

“…We have previously studied the HDO of propionic acid over five transition metal surfaces, including Pt(111), 72 Pd(111), 73 Cu(111), 74 Rh(111), 75 and Ru(0001). 76 New data for Ag(111), Re(0001), Pd(100), and Ni(111) were generated for this study.…”

Systematic Search for Thermal Decomposition Pathways of Formic Acid on Anatase TiO2 (101) Surface**

“…For this purpose, an efficient and exhaustive reaction path search method has been desired. Over the past two decades, a variety of automated reaction path search and kinetic analysis methods have been developed [34–56] . Some of these, such as the growing string method, [50] Gaussian process regression, [51] microkinetic simulation, [52–55] and the stochastic surface walking neural network method, [56] have been applied to reactions on clean metal surfaces.…”

“…Over the past two decades, a variety of automated reaction path search and kinetic analysis methods have been developed [34–56] . Some of these, such as the growing string method, [50] Gaussian process regression, [51] microkinetic simulation, [52–55] and the stochastic surface walking neural network method, [56] have been applied to reactions on clean metal surfaces. However, extensive exploration of reaction paths on oxide surfaces, especially considering defects, has been limited, probably due to their higher complexity compared to clean surfaces.…”