Stefano Cavallaro

Ethanol steam reforming in a molten carbonate fuel cell. A preliminary kinetic investigation

Abstract The decomposition of ethanol to COx and H2 was investigated under a wide range of operating conditions. High pressure reduces H2, CO and CO2 production, while high temperature produces the opposite effect. At T

Hydrogen produced from ethanol for internal reforming molten carbonate fuel cell

Ethanol is proposed as alternative fuel for the indirect internal reformer of molten carbonate fuel cells (IIR-MCFCs). At MCFCs working conditions (T ¼ 923 K and P ¼ 1 bar), both Rh- and Co-based catalysts have been tested using diluted ethanol/water mixture. The steam/ carbon ratio of the feed was selected close to 4.2 mol/mol, in the aim to simulate the composition of ethanol/water mixture produced from biomasses. A good performance on Rh-based catalysts was reached for a sample containing 5 wt.% of Rh on Al2O3, while Co-based catalysts were suitable only for higher loading of active phase (i.e. 20 wt.%). The supports influence has been also investigated as well as different behavior was been found as a function of their nature. In fact, while Rh (5 wt.%) doped Al2O3 seems to be stable and active catalyst, the Co (20 wt.%)/Al2O3 decays in short time because of coke deposition. The MgO represents a more suitable support for Co catalyst because of its lower acidity with respect to Al2O3. Samples of Co (20 wt.%)/MgO catalysts have been found more stable than Co/ Al2O3 (low coke formation) and reached performance levels comparable to that of Rh/Al2O3. Although Co/MgO required higher contact times than Rh/Al2O3, to be used in IIR-MCFCs, it represents an interesting and cheaper alternative to noble metal (Rh). # 2001 Elsevier Science B.V. All rights reserved.

Steam reforming of ethanol on Ni/MgO catalysts: H2 production for MCFC

Abstract H2 production by ethanol steam reforming in simulating molten carbonate fuel cell (MCFC) conditions was explored. Ni/MgO catalysts exhibit very high selectivity to H2 and CO2 as a consequence of their low tendency to promote carbon monoxide methanation and ethanol decomposition reactions. Coke formation is strongly depressed due to the benefits induced by the use of basic carrier which positively modify the electronic properties of supported Ni.

Ethanol steam reforming in a molten carbonate fuel cell: a thermodynamic approach

The economy of the world energy sources is showing interest in the utilization of oxygenated products whose purpose is to improve the storage and the transfer of hydrogen as a non-polluting fuel with a high heat power density. An interesting field of utilization of these products is represented by the fuel cell systems for production of electricity. In this respect, the use of the water/ethanol mixture has been investigated as an alternative fuel for molten carbonate fuel cells. Some thermodynamic calculations have been carried out by a mathematical model to determine the energy and mass balances for a water/ethanol fuelled molten carbonate fuel cell. The thermodynamic efficiencies determined for this system have been correlated with the main operative parameters that give some interesting findings indicating encouraging aspects on the utilization of these systems to the production of electricity and heat. Lastly, attractive operative conditions have been determined and compared with that of a molten carbonate fuel cell with methane direct internal reforming.

Light alcohols/methane fuelled molten carbonate fuel cells: a comparative study

The configuration of internal reforming has been successfully applied in molten carbonate fuel cells (MCFCs), allowing a flexibility in fuel use unfeasible for other kind of fuel cells, which operate at lower temperatures. On this basis, a theoretical study able to provide useful information on the use of ethanol, methanol or methane as fuel in MCFCs has been carried out. The paper reports the most significant results obtained from this comparative analysis, which allows clear evaluations about the energetic suitability of each examined fuel. This study, developed by the support of a mathematical model, gave as main results the chemical, electrical and thermal power densities obtainable by each raw fuel and evidenced the limits or gains arising from the variation of the MCFCs operative parameters. Leaving out the economical point of view, ethanol present some advantages (natural availability, storage and handling safety, heat distribution on the catalyst, etc.) compared with the other fuels.

Hydrogen Production by Steam Reforming of Ethanol: A Two Step Process

A two-layer fixed-bed catalytic reactor for hydrogen production by steam reforming of ethanol is proposed. In this reactor ethanol is first converted to acetaldehyde over a Cu-based catalyst and then acetaldehyde is converted to a hydrogen-rich mixture over a Ni-based catalyst. It is shown that the use of such type of reactor prevents coke formation and provides hydrogen yields closed to equilibrium.

Syngas and electricity production by an integrated autothermal reforming/molten carbonate fuel cell system

Abstract The feasibility and the overall process economy of an integrated system of molten carbonate fuel cell (MCFC) and autothermal reformer (ATR) have been studied. The ATR–MCFC performance has been evaluated in terms of pressure, inlet rates of oxygen and steam, current density and cell configuration (indirect or direct). The process, carried out close to the MCFC basic conditions (T=923 K), can be alternatively addressed to the main production of syngas or electricity by means of the inlet operative parameters that strongly influence the outlet composition and the overall thermal balance. A better heat compensation (but a small syngas/electricity production) corresponds to a greater oxygen content in the inlet stream (O2/H2O/CH4=0.6/2/6/1), while the H2 residual is a complex function of the current density and of the O2/H2O/CH4 relative ratios. A total gases pressure in the ATR compartment higher as that into the anodic housing can be hypothesised for a direct ATR–MCFC equipped with a ceramic membrane that strongly improves the cell performance.

Alkylation of toluene with methanol on zeolites. The role of electronegativity on the chain or ring alkylation

Abstract Catalysed alkylation of toluene with methanol on zeolites proceeds in two different ways, depending upon the nature of the zeolite, and gives rise to ethylbenzene-styrene and/or xylenes. The results indicate that the activity and selectivities are dictated by the acidity and electronegativity of the zeolites with the most electropositive ones producing ethylbenzene and styrene and the most electronegative catalysing formation of xylenes.

Alkali effect on the MCFC-internal reforming catalyst life

Abstract An investigation on the interaction between the internal reforming catalyst (1.6 mm pellets of Ni/MgO) and the electrolyte has been carried out on a 94 cm2 molten carbonate monocell operated in a direct internal reforming geometry at 923 K, with a S/C ratio equal to 2.5 and a GHSV of 600 h−1. Tape-cast electrodes and a hot-pressed LiAlO2 tile (55 wt% of Li/K carbonates) have been used. Tests have been performed under controlled conditions and catalyst activity determined by gas-chromatographic analysis of the exit anode gases. The distribution of Li, K, Ni, Cr, Fe and Mg has been determined on the fresh and spent components by AAS and the presence of C has been analysed by DTG. Optical observations and porosimetric analysis have shown the presence of a thin glassy layer of KOH on the external surface of the catalyst, from which some preliminary interpretation on the IR catalyst deactivation mechanism has been derived.

Feedstocks for biodiesel production

Abstract: Globally dominating feedstocks for biodiesel production nowadays are mainly rapeseed, soybean, sunflower and palm oils; animal fats (tallow) and recycled frying oils are minor contributors. This chapter describes the main characteristics of the major and minor first-generation foodstocks for biodiesel production and the short- to medium-term prospects of second-generation, non-edible feedstocks (in particular Jatropha and algae) and various highly acidic, low-quality oils for the same purpose. Biodiesel outlooks are differing geographically as a result of the prevailing agronomic and climatic conditions. Important developments can be observed in various parts of the world.