Thanh-Binh Truong

Autothermal methanol reforming for hydrogen production in fuel cell applications

Fuel cell powered electric cars using on-board methanol reforming to produce a hydrogen-rich gas represent a low-emissions alternative to gasoline internal combustion engines (ICE). In order to exceed the well-to-wheel efficiencies of 17% for the gasoline ICE, high-efficiency fuel cells and methanol reformers must be developed. Catalytic autothermal reforming of methanol offers advantages over endothermic steam-reforming and exothermic partial oxidation. Microreactor testing of copper-containing catalysts was carried out in the temperature range between 250 and 330°C showing nearly complete methanol conversion at 85% hydrogen yield. For the overall process a simplified model of the reaction network, consisting of the total oxidation of methanol, the reverse water-gas shift reaction, and the steam-reforming of methanol, is proposed. Individual kinetic measurements for the latter two reactions on a commercial Cu/ZnO/Al2O3 catalyst are presented.

Low-temperature catalytic partial oxidation of hydrocarbons (C1-C10) for hydrogen production

Abstract The catalytic partial oxidation of hydrocarbons to provide hydrogen for fuel cells, mobile or stationary, requires high temperatures (900°C), multireactors and incurs the highest incremental costs for the gasoline fuel processor. New experimental data between 500°C and 600°C, supported by equilibrium calculations, show that hydrogen with low carbon monoxide concentrations can be produced from liquid and gaseous hydrocarbons, thus simplifying the reactor chain. Low sulphur refinery feeds (C 4 –C 6 , C 4 –C 10 ), simulated natural gas (C 1 –C 3 ) and single compounds are used and safety procedures discussed. Results from laboratory reactors with 1 wt % rhodium on mixed oxide catalysts show that hydrogen rates of 43,000 l H 2 / h / l reactor (power density 129 kWth / l reactor) are produced with RON =95 feeds . However, the cost and availability of rhodium limit the catalyst rhodium content to 0.1 wt % when 31,100 l H 2 / h / l reactor were measured. Optimisation and reactor scale-up for heat management is in progress.

The autothermal partial oxidation kinetics of methanol to produce hydrogen

The kinetics of autothermal methanol partial oxidation are investigated to produce hydrogen for fuel cell systems. Two reactor systems are used to determine the kinetic parameters under isothermal conditions. The originally supposed six-reaction system (dimethyl ether formation, methanol decomposition, water gas shift, steam reforming, methanol partial oxidation (POX), hydrogen total oxidation) could be simplified, because the water gas shift reaction is slow in comparison to the others and the total oxidation of hydrogen is mass transfer limited with the commercial copper/alumina catalyst used. Previously determined kinetic data for methanol decomposition [7] were also used to facilitate the evaluation of the kinetic data. Respective activation energies in kJ/mol are 117, 76, –, 81 and 65 (POX), with the standard deviations of 6–24%. Turnover frequencies at 250°C for the POX reaction were calculated from copper surface area measurements. They were the same order of magnitude (460 min−1) as literature values 1. , 11. . Under non-isothermal “hotspot” operation, hydrogen production rates were 10000–13000 litresH2/hour/litre reactor volume(lrv), which is equivalent to 30–39 kWth/lrv, providing significant power densities from the fuel processor. Hydrogen yields of 72% or 2.2 moles of hydrogen per mole methanol feed, with 1–2% CO in the exit gas, were measured.

Fuels for fuel cells: Requirements and fuel processing

Abstract: Polymer electrolyte and solid oxide are the two fuel cell types (PEFC, SOFC) under development in Switzerland. The very distinct operating temperatures of 80 °C (PEFC) and 800–950 °C (SOFC) impose fundamentally different requirements upon the nature of the fuel; normally purified H2 for the former (CO trace) and usually synthesis gas for the latter (H2, CO as main constituents). Apart from stored hydrogen, the most relevant fuels are primary hydrocarbons (natural gas, biogas, liquids,…), that then need processing (chemical conversion, cleaning) up to a level compatible with the fuel cell catalysts. These processes are briefly reviewed. Fuel compositions with an emphasis on impurities are given. Two application examples from Swiss RD are presented: gasoline conversion to high purity H2 for PEFC and contaminated biogas processing for SOFC. Keywords: Biogas · Fuel impurities · Fuel processing · Partial oxidation · Reforming

85 High selectivity preferential oxidation (PROX) catalysts for CO removal from hydrocarbon derived reformates for PEM fuel cells

Preferential oxidation (prox) catalysts for CO removal are important for the reformer-PEM fuel cell system. For ruthenium on promoted alumina catalysts, both high selectivity (99.9%) CO removal and low (<5%) hydrogen conversions were measured with synthetic reformates, typical of hydrocarbon partial oxidation (pox) products. Optimum excess air ratios (λO2) and wide operating windows for gas hourly space velocities (GHSV) were defined. A two step reaction mechanism based on chloride in the support, redox properties of ruthenium and onstream observations is suggested. XPS analyses of fresh and deactivated catalysts (860 to 1700 hours) support the proposal. With hydrocarbon derived reformates, the selectivity was maintained only for gaseous hydrocarbons (C1–C3). Reformates from liquids e.g. isooctane, platformate, allowed 99.9% CO removal but H2 conversions rose to 17%, even with an active carbon adsorbent. Optimisation of catalyst and process parameters is required.