Hydrogen: Trends, production and characterization of the main process worldwide

One of the most attractive routes for the production of hydrogen or syngas for use in fuel cell applications is the reforming and partial oxidation of hydrocarbons. The use of hydrocarbons in high temperature fuel cells is achieved through either external or internal reforming. Reforming and partial oxidation catalysis to convert hydrocarbons to hydrogen rich syngas plays an important role in fuel processing technology. The current research in the area of reforming and partial oxidation of methane, methanol and ethanol includes catalysts for reforming and oxidation, methods of catalyst synthesis, and the effective utilization of fuel for both external and internal reforming processes. In this paper the recent progress in these areas of research is reviewed along with the reforming of liquid hydrocarbons, from this an overview of the current best performing catalysts for the reforming and partial oxidizing of hydrocarbons for hydrogen production is summarized.

Advances in reforming and partial oxidation of hydrocarbons for hydrogen production and fuel cell applications

Undoubtedly, hydrogen (H2) is a clean feedstock and energy carrier whose sustainable production should be anticipated. The pyrolysis of biomass or waste plastics and the subsequent reforming over base (transition) or noble metals supported catalysts allows reaching elevated H2 yields. However, the catalyst used in the reforming step undergoes a rapid and severe deactivation by means of a series of physicochemical phenomena, including metal sintering, metallic phase oxidation, thermal degradation of the support and, more notoriously, coke deposition. This review deals with the currently existing alternatives at the catalyst and reactor level to cope with catalyst deactivation and increase process stability, and then delves with the fundamental phenomena occurring during this catalyst deactivation. An emphasis is placed on coke deposition and its influence on deactivation, which depends on its location, chemical nature, morphology, precursors or formation mechanism, among others. We also discuss the challenges for increasing the value of the carbon materials formed and therefore, enhance process viability.

Coke formation and deactivation during catalytic reforming of biomass and waste pyrolysis products: A review

This Review describes recent advances in the design, synthesis, reactivity, selectivity, structural, and electronic properties of the catalysts for reforming of a variety of oxygenates (e.g., from simple monoalcohols to higher polyols, then to sugars, phenols, and finally complicated mixtures like bio-oil). A comprehensive exploration of the structure–activity relationship in catalytic reforming of oxygenates is carried out, assisted by state-of-the-art characterization techniques and computational tools. Critical emphasis has been given on the mechanisms of these heterogeneous-catalyzed reactions and especially on the nature of the active catalytic sites and reaction pathways. Similarities and differences (reaction mechanisms, design and synthesis of catalysts, as well as catalytic systems) in the reforming process of these oxygenates will also be discussed. A critical overview is then provided regarding the challenges and opportunities for research in this area with a focus on the roles that systems of ...

Catalytic Reforming of Oxygenates: State of the Art and Future Prospects.

Solid oxide fuel cells (SOFCs) are a rapidly emerging energy technology for a low carbon world, providing high efficiency, potential to use carbonaceous fuels, and compatibility with carbon capture and storage. However, current state-of-the-art materials have low tolerance to sulfur, a common contaminant of many fuels, and are vulnerable to deactivation due to carbon deposition when using carbon-containing compounds. In this review, we first study the theoretical basis behind carbon and sulfur poisoning, before examining the strategies toward carbon and sulfur tolerance used so far in the SOFC literature. We then study the more extensive relevant heterogeneous catalysis literature for strategies and materials which could be incorporated into carbon and sulfur tolerant fuel cells.

Strategies for carbon and sulfur tolerant solid oxide fuel cell materials, incorporating lessons from heterogeneous catalysis

Hydrogen production from ethanol is regarded as a promising way for energy sustainable development, which is undergoing an explosive growth over the last decade. Besides operating conditions, hydrogen yield greatly dependent on the nature of metal and the support selected. To date, Rh based catalysts proved to be the most active systems due to the fact that Rh possessed the greatest capacity toward C–C bond cleavage. Support also played a critical role in terms of hydrogen selectivity and stability. MgO, CeO2 and La2O3 etc were evidenced as suitable supports because of their basic characteristic and/or redox capacity. A detailed analysis based on the spectroscopic technique revealed that reaction pathways proceeded along a mono-functional or bi-functional mechanism according to the types of active metal and support. Ethanol dehydrogenation and/or dehydration reaction mainly occurred on the support, and the diffusion/transformation of the intermediates took place at the metal–support interface. Meanwhile, active metal accelerated the decomposition reaction. The observed catalyst deactivation was normally assigned to the coke formation, active metal sintering and/or oxidation as well as the impurity in crude bio-ethanol. Hence, the scope of this review is to address the present progress in ethanol reforming for hydrogen production including catalyst development and the analysis of the reaction mechanism and kinetics in order to shed light on the design of high efficient catalyst systems and the fundamental understanding of ethanol conversion at the molecular level.

Hydrogen production from ethanol reforming: Catalysts and reaction mechanism

Hydrogen production from ethanol steam reforming over Rh/CeO2 catalyst

The invention provides a metal surface treatment agent composed of aqueous solution or aqueous emulsion containing ionic liquid. The metal surface treatment agent comprises the ionic liquid, silicate or silane coupling agent, water-soluble chitin or chitosan, corrosion inhibitor, stabilizer, pH modifier, wetter, coalescing agent, antioxidant, ethanol and water, the ionic liquid is room-temperature ionic liquid consisting of nitrogenous heterocyclic compound cations and inorganic or organic anions, one or more of nanoscale titanium dioxide, zirconium oxide or zirconium fluoride is uniformly mixed into the silicate or silane coupling agent by the weight equivalently accounting for 3%-25% of that of the silicate or silane coupling agent. A chemical conversion coating is formed on a metal surface by the metal surface treatment agent, can inhibit corrosion of the metal surface, and has a fine coating performance. The metal surface treatment agent is used for treating cold-rolled plates, galvanized plates and aluminum plates, and the metal surface treated by the metal surface treatment agent has the coating adhesion force equivalent to that of a metal surface treated by a phosphorus-containing metal surface treatment agent.

Metal surface treatment agent

Steam reforming of propane over a novel Ir/Ce0.75Zr0.25O2 catalyst was investigated. Various techniques such as X-ray diffraction (XRD), temperature-programmed reduction (TPR), high resolution transmission electron microscopy (HRTEM), and oxygen storage capacity (OSC) etc were used to characterize the as-prepared catalysts in order to elucidate the catalyst structure-performance relationship. The doping of ZrO2 into the CeO2 lattice greatly improved the redox property of the CeO2 by creating more surface oxygen vacancies. Stability test revealed that the Ir/Ce0.75Zr0.25O2 sample exhibited rather stable catalytic behavior for 65 h time-on-stream without obvious deactivation, which was assigned to the efficient prevention of the sintering of the highly dispersed Ir particles through the strong interaction between Ir and CeO2 support and to the significant resistance to coke deposition due to the excellent OSC of Ce0.75Zr0.25O2 support.

Hydrogen production from propane steam reforming over Ir/Ce0.75Zr0.25O2 catalyst

A novel Nb2O5 catalyst with the highly single crystallinity and well aligned nanorods was successively synthesized by hydrothermal method and presented promising catalytic behavior for lactic acid synthesis from glucose. Notably, the sample was easily separated and reused without the obvious deactivation. It might shed light on an alternative process for lactic acid production instead of conventional fermentation.

Dazhi Wang

Papers

Hydrogen production from ethanol reforming: Catalysts and reaction mechanism

Hydrogen production from ethanol steam reforming over Rh/CeO2 catalyst

Metal surface treatment agent

Hydrogen production from propane steam reforming over Ir/Ce0.75Zr0.25O2 catalyst

Lactic Acid Production from Glucose Over a Novel Nb2O5 Nanorod Catalyst