Production of carbon monoxide and hydrogen from methanol using a ruthenium pincer complex: a DFT study

To understand the mechanism of the dehydrogenation of methanol to CO and H2 catalyzed by a ruthenium pincer complex, a density functional theory (DFT) study has been conducted on two different cycles which differ in the substances entering the cycle (methanol (cycle 1) versus methoxymethanol (cycle 2)). Our calculated results show that both cycles consist of three stages: dehydrogenation of alcohol to aldehyde (stage I); hydrogen formation (stage II); and decarbonylation with the regeneration of the catalyst (stage III). The energy barriers of the rate-determining steps for cycles 1 and 2 are 49.6 and 28.5 kcal mol-1, respectively. Thus cycle 2 is more energetically feasible. For stage III of cycle 2, our results did not support the mechanism proposed in the experiment (CO release occurs prior to decarbonylation). Instead, we suggested and examined an alternative pathway, that is, decarbonylation occurs prior to CO release. The mechanistic insights gained in the present paper could be beneficial for further designing of these kinds of reactions.

Catalytic Hydrothermal Deoxygenation of Stearic Acid with Ru/C: Effects of Alcohol- and Carboxylic Acid-Based Hydrogen Donors

Catalytic hydrothermal processing is a promising technology for the production of biofuels used in transportation to alleviate the energy crisis. An important challenge for these processes is the need for an external supply of hydrogen gas to accelerate the deoxygenation of fatty acids or lipids. It follows that in situ-produced hydrogen can improve process economics. This study reports on the use of various alcohol and carboxylic acid amendments as sources for in situ hydrogen production to accelerate Ru/C-catalyzed hydrothermal deoxygenation of stearic acid. Addition of these amendments significantly increases yields of liquid hydrocarbon products, including the major product heptadecane, from stearic acid conversion at subcritical conditions (330 °C, 14-16 MPa during the reaction). This research provided guidance for simplifying the catalytic hydrothermal process of biofuel production, making the production of the desired biofuel in one pot possible without the need for an external H₂ supply.

Quick-EXAFS and Raman monitoring of activation, reaction and deactivation of NiCu catalysts obtained from hydrotalcite-like precursors

The understanding of phase transformation upon activation, reaction and deactivation of catalysts is of prime importance for tailoring catalysts with better performances. Herein we combined Quick-EXAFS and Raman spectroscopies in operando conditions through the monitoring of reaction products by mass spectrometry in order to study in depth active species and deactivating ones for Ethanol Steam Reforming reaction. Quick-EXAFS data analyzed by multivariate analysis allows one to determine the nickel and copper species involved during the activation of a Ni-Cu hydrotalcite-like precursors. Upon reaction and regeneration monitoring, Raman spectroscopy combined with mass spectrometry highlights the side products formed upon ESR leading to the formation of amorphous coke species encapsulating active metallic species and inducing catalyst deactivation. The coke encapsulation of active species was demonstrated by the simultaneous observation of oxidation of nickel and copper as soon as the amorphous coke was burnt by the oxidative regeneration treatment. Formation of filamentous coke species is also confirmed as causing little impact in catalyst deactivation.

Glycerol Production and Transformation: A Critical Review with Particular Emphasis on Glycerol Reforming Reaction for Producing Hydrogen in Conventional and Membrane Reactors

Glycerol represents an emerging renewable bio-derived feedstock, which could be used as a source for producing hydrogen through steam reforming reaction. In this review, the state-of-the-art about glycerol production processes is reviewed, with particular focus on glycerol reforming reactions and on the main catalysts under development. Furthermore, the use of membrane catalytic reactors instead of conventional reactors for steam reforming is discussed. Finally, the review describes the utilization of the Pd-based membrane reactor technology, pointing out the ability of these alternative fuel processors to simultaneously extract high purity hydrogen and enhance the whole performances of the reaction system in terms of glycerol conversion and hydrogen yield.

Rational design of ethanol steam reforming catalyst based on analysis of Ni/La2O3 metal–support interactions

Ni/La₂O₃ nanocatalyst with strong interactions, compared to Ni/SiO₂, generated higher H₂ yield by suppressing the methanation reaction and coke deposition.

Plasmon-mediated photothermal conversion by TiN nanocubes toward CO oxidation under solar light illumination

Titanium-nitride (TiN) nanocubes were decorated with platinum nanoparticles via a wet-chemistry route to yield TiN-supported Pt catalysts (Pt/TiN).

Towards a methanol economy based on homogeneous catalysis: methanol to H2 and CO2 to methanol

The possibility to implement both the exhaustive dehydrogenation of aqueous methanol to hydrogen and CO2 and the reverse reaction, the hydrogenation of CO2 to methanol and water, may pave the way to a methanol based economy as part of a promising renewable energy system. Recently, homogeneous catalytic systems have been reported which are able to promote either one or the other of the two reactions under mild conditions. Here, we review and discuss these developments.

Hierarchically structured catalysts for cascade and selective steam reforming/hydrodeoxygenation reactions

A hierarchically structured catalyst with combined steam reforming and hydrodeoxygenation active sites is reported to efficiently upgrade the pyrolysis vapors of lignocellulosic biomass via size-exclusion.

A first-principles investigation of oxygen reduction reaction catalysis capabilities of As decorated defect graphene

Arsenic adsorbed double vacancy defect graphene systems are found to demonstrate excellent electrocatalytic properties for oxygen reduction reaction via high affinity towards four electron process.