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Proton exchange membrane water electrolysis is a promising technology to produce green hydrogen from renewables, as it can efficiently achieve high current densities. Lowering iridium amount in oxygen evolution reaction electrocatalysts is critical for achieving cost-effective production of green hydrogen. In this work, we develop catalysts from Ir double perovskites. Sr

Small amounts of manganese oxide incorporated on MgO enhanced C 2+ hydrocarbon selectivity during the oxidative coupling of methane (OCM). Both C 2+ selectivity and CH 4 conversion were also improved by adding alkaline metal halides. Dosing CH 2 Cl 2 pulses into the CH/ 4 O 2 feed stream over alkali promoted Mn MgO catalysts led to an improvement in the yield to C 2+ hydrocarbons. The extent of this effect and the stability of the alkali phases were found to depend on the type of promoter. Photoelectron spectroscopy (XPS) revealed that all the used catalysts retained important amounts of chlorine in the form of Cl − ions, and simultaneously manganese was oxidized to Mn 4+ . In the light of quantitative XPS data, a redox mechanism consisting of the decomposition of halocompound at catalyst surface through formation of an oxyhalide of the type MnO 2−x2 Cl/ x has been proposed. The different patterns for CH 4 conversion and C 2+ selectivity indicate a key role of the alkali promoter and its distribution on the surface, on the formation of this Cl-containing species.

This review summarizes different catalytic options for the production of syngas and hydrogen starting from simple hydrogen-containing molecules. Particular attention is given to new direct catalytic alternatives in natural gas conversion. Improvements in syngas technology are discussed, including partial oxidation, autothermal reforming, combined reforming and carbon dioxide reforming, and the energy efficiencies of direct and indirect methane conversion are compared. Processes, issues and practical difficulties are discussed with academic and applied efforts presented in parallel. It is emphasized that most of the ongoing research related to the direct processes is at the exploratory stage while technology utilizing indirect approach has advanced to semi-works and initial commercialization plants. The new emerging processes based on partial oxidation features are unique for syngas generation. Further enhancement of such processes plus improvements in other second generation technologies and advances in direct processes are anticipated to provide additional, new attractive paths to the chemical conversion of natural gas. Similarly, on board generation of hydrogen-rich gaseous fuels either for spark ignition engines or for coupled-fuel-cells electric engines is discussed within the scope of both partial oxidation and catalytic decomposition of methanol. A concept based in the thermochemical water splitting, which provides a renewable portable fuel from water in the form of H2, is also presented. Above all, as the chemistry involved in most of these catalytic alternatives takes place under extreme conditions, highly stable catalysts and engineering concepts are being developed.