In this short review, we highlight the recent advances in methane conversion processes at high and low temperatures. Methane conversion processes are of great importance in achieving a crude-oil independent supply of energy, fuels and chemicals for the future. Direct conversion of methane into chemicals and fuels has been often considered as the "holy grail" of current catalysis research due to the unreactive nature of methane, which makes targeted chemical transformations to fuels and chemicals very challenging. We discuss the progress in developing heterogeneous catalytic and electrocatalytic systems to overcome this challenge. We conclude by providing a perspective on the future of this area of research.

Selective removal of oxygen from biomass-derived polyols is critical toward bridging the gap between biomass feedstocks and the production of commodity chemicals. In this work, we show that earth-abundant molybdenum oxide based heterogeneous catalysts are active, selective, and stable for the cleavage of vicinal C–O bonds in biomass-derived polyols. Catalyst characterization (Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)) shows that partially reduced MoO x centers are responsible for C–O bond cleavage and are generated in situ by hydrogen dissociated atoms over palladium (Pd) nanoparticles. We find that the support, TiO2, facilitates communication between the hydrogen dissociating metal and dispersed MoO x sites through hydrogen spillover. Reactivity studies using a biomass-derived model substrate (1,4-anhydroerythritol) show the effective removal of vicinal hydroxyls over MoO x -Pd/TiO2 producing tetrahydrofuran with >98% selectivity at 29% conversion. Catalyst stability is demonstrated upon cycling. These studies are critical toward the development of low-cost heterogeneous catalysts for sustainable hydrodeoxygenation of biobased polyols to platform chemicals.

The position of aluminum atoms in ion-exchanged zeolites is known to affect the reactivity of active sites. In this work, we used density functional theory (DFT) calculations to systematically quantify the effect of the Al-atom position within the α-ring of Zn-exchanged MFI (Zn-MFI) on the activation of methane. Our DFT results indicate that the most stable configuration for the Zn-exchanged cluster of the α-ring is obtained when the Al atoms are located at the T11-T2 crystallographic sites. For each Al-atom configuration, we analyzed the reaction pathways for methane activation. Our results suggest that the activation of methane yields the formation of a Brønsted acid site, which can be formed at an oxygen atom within the α-ring or at an oxygen atom that lies outside the α-ring, and that the lowest reaction energy for methane activation is obtained when the Brønsted acid site is formed at the oxygen atom in which the highest occupied molecular orbital of the isolated cluster is located. Furthermore, our results indicate that the partial atomic charge of the Zn atom within the α-ring of MFI can be correlated with the transition-state energy of methane activation, which ranges from 87 to 131 kJ/mol depending on the location of Al atoms. The fundamental studies conducted in this work contribute to the elucidation of essential parameters and correlations, based on electrostatic and electron density, for the activation of methane on Zn-MFI zeolites.

Hydrodeoxygenation chemistries play a key role in the upgrading of biomass‐derived feedstocks. Among these, the removal of targeted hydroxyl groups through selective C−O bond cleavage from molecules containing multiple functionalities over heterogeneous catalysts has shown to be a challenge. Herein, we report a highly selective and stable heterogeneous catalyst for hydrodeoxygenation of tartaric acid to succinic acid. The catalyst consists of reduced Mo5+ centers promoted by palladium, which facilitate selective C−O bond cleavage, while leaving intact carboxylic acid end groups. Stable catalytic performance over multiple cycles is demonstrated. This catalytic system opens up opportunities for selective processing of biomass‐derived sugar acids with a high degree of chemical functionality.