Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

Hydrogen is considered to be the most viable energy carrier for the future. Producing hydrogen from ethanol steam reforming would not only be environmentally friendly but also would open new opportunities for utilization of renewable resources, which are globally available. This paper reviews the current state of the steam reforming process of ethanol, examines different catalysts, and, finally, makes a comparative analysis. Different catalysts have been used for the steam reforming of ethanol. Depending on the type of catalysts, reaction conditions, and the catalyst preparation method, ethanol conversion and hydrogen production vary greatly. It was observed that Co/ZnO, ZnO, Rh/Al2O3, Rh/CeO2, and Ni/La2O3−Al2O3 performed the best, in regard to the steam reforming of ethanol. Currently, hydrogen production from ethanol steam reforming is still in the research and development stage.

Current status of hydrogen production techniques by steam reforming of ethanol : A review

Hydrogen is a promising energy carrier in future energy systems. However, storage of hydrogen is a substantial challenge, especially for applications in vehicles with fuel cells that use proton-exchange membranes (PEMs). Different methods for hydrogen storage are discussed, including high-pressure and cryogenic-liquid storage, adsorptive storage on high-surface-area adsorbents, chemical storage in metal hydrides and complex hydrides, and storage in boranes. For the latter chemical solutions, reversible options and hydrolytic release of hydrogen with off-board regeneration are both possible. Reforming of liquid hydrogen-containing compounds is also a possible means of hydrogen generation. The advantages and disadvantages of the different systems are compared.

Chemical and Physical Solutions for Hydrogen Storage

A review on reforming bio-ethanol for hydrogen production

Hydrogen production reactions from carbon feedstocks: fossil fuels and biomass.

Bio-ethanol steam reforming on Ni/Al2O3 catalyst

Oxide-supported noble metal catalysts were tested in the preferential oxidation of carbon monoxide (PROX) reaction in the temperature range between 50 and 300 °C. Both the influence of the noble metal nature (Pt, Ir, Pd), the support physical and chemical properties (redox, acidity, basicity) and the reaction conditions (oxygen stoichiometry) on the catalyst activity and selectivity was evaluated. Platinum and iridium were shown to be the most active and selective catalysts in the whole temperature range compared with palladium. Furthermore, noble metals supported over ceria-based oxides were shown to be active and selective, especially at low temperature. Additionally, it was observed that the higher the molar fraction in ceria in the oxide, the higher the activity and the selectivity in the PROX reaction. Ceria, with the highest oxygen mobility at the oxide surface, was shown to be the best support. Accordingly, on simple oxides (CeO2, SiO2–Al2O3, Al2O3, SiO2, La2O3 and MgO), the induced mobility of the oxygen atoms at the surface of the support determined elsewhere, well correlated with the basicity of the support, was shown to be one key parameter for the performances of the catalysts in the PROX reaction. Finally, the formation of water (hydrogen oxidation) at high temperature and high oxygen excess was shown to be responsible for the increasing activity of the catalysts in the conversion of CO to CO2 via the water gas shift reaction (WGSR).

/pdf/noble-metal-catalysts-for-the-preferential-oxidation-of-zzm7kt428w.pdf

Noble metal catalysts for the preferential oxidation of carbon monoxide in the presence of hydrogen (PROX)

The steam reforming reaction of hydrocarbons and organic fuels, in general, is followed by a two-stage reaction of water gas shift, which allows increasing the hydrogen yield and a final purification step for CO removal to use hydrogen in an ammonia plant or a PEM fuel cell. This paper is focused on the CO Preferential Oxidation, CO PROX (or CO selective oxidation in excess hydrogen) reaction, considered as the simplest and cost effective process to achieve the less than 10 ppm CO. The objective of this paper is to review the performances of noble metals (Pt, Ru, Rh, Pd), gold and transition metal oxides catalysts in this reaction. Although the results reported are largely influenced by the experimental conditions (reactant flow composition, mass of catalyst, duration of experiment …) a comparison of advantages and drawbacks for each type of catalysts is proposed in terms of activity and selectivity as well as of CO2 and H2O influences. A special attention will be paid to copper-doped ceria catalysts which appear to be very active and selective in a range of temperatures appropriate for fuel cell application. The performances, the stability and the low cost of these formulations compared to noble metal-based catalysts make them very attractive for an industrial application.

Fernando Mariño

Papers

Bio-ethanol steam reforming on Ni/Al2O3 catalyst

Noble metal catalysts for the preferential oxidation of carbon monoxide in the presence of hydrogen (PROX)

Preferential Oxidation of Carbon Monoxide in the Presence of Hydrogen (PROX) over Noble Metals and Transition Metal Oxides: Advantages and Drawbacks

Hydrogen production from steam reforming of bioethanol using Cu/Ni/K/γ-Al2O3 catalysts. Effect of Ni

Hydrogen from steam reforming of ethanol. characterization and performance of copper-nickel supported catalysts