• Energy Research

A series of Ni catalysts supported on La Ce O mixed oxides with different Ni content (Ce1-3xLa2xNixO2-?, x = 0.10; 0.20 and 0.25) prepared by combustion synthesis, was tested in tri-reforming reaction of simulated biogas. The influence of O2/CH4, CH4/CO2 molar ratios in the reaction stream has been evaluated caring out the reaction at 800 oC, under a fixed gas hourly space velocity (GHSV = 31,000 h-1). The highest catalytic activity was obtained with the Ce0.70La0.20Ni0.10O2-? sample that showed high stability (CH4, CO2 conversion rates and the H2/CO molar ratio in the reformed gas were 1.56 mmol/s gNi, 0.56 mmol/s gNi and 1.57, respectively) under an average biogas composition (CH4/CO2 = 1.5). No carbon deposition was detected after 150 h of reaction. The characterizations of the samples have highlighted that Ni and La ions were partially incorporated into CeO2 framework, cubic fluorite structure of CeO2 support was retained also at high level of doping. Ni metal phase in close contact with La2O3-CeO2 matrix coupled with Ni2+ with high cationic character appeared to be responsible of the catalytic activity and stability of the catalysts.

Polymer electrolyte fuel cell (PEFC) offers the possibility of generating power with high efficiency and low emissions for mobile and stationary applications. A very crucial factor to use the PEFC-based engine for transportation purposes is the choice of fuel and fuel processor, proper for a realistic, on-board, employment. This paper covers the in-progress activities performed by CNR-ITAE on experimental studies of the autothermal reforming of propane on a proprietary ceria-supported platinum catalyst: this study represents the first step of a project oriented for the development of a compact and reliable fuel processor, fed by LPG, to be used in a PEFC vehicle. The main issues that should be satisfied by the hydrogen generator will be high fuel conversion, stable performance for repeated start-up and shut-down cycles, capability to process different hydrocarbons, etc. In this respect, the CO preferential oxidation step has also been studied by the performance analysis of commercial Pt/Al2O3 and Ru/Al2O3 catalysts (Engelhard Co.). © 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

[object Object]

Biogas, a renewable source of CH4 and CO2, is used for hydrogen generation by tri-reforming reaction; the reaction is a combination of CO2 reforming, steam reforming and partial oxidation of CH4 in a single catalytic step.Several Ni/La-Ce-O mixed oxides, prepared by combustion synthesis, were used as catalysts. The experimental tests, carried out with synthetic biogas at 800°C with a gas hourly space velocity (GHSV) of 30000 h-1, were aimed to study the influence of different parameters (amount of La doping, Ni load and feed composition) on the catalysts activity and stability. The synergic effect of nickel-lanthana-surface oxygen vacancies of ceria influences the samples activity.

The performance of a Pt/CeO2 catalyst as packed bed, coated on monolith and as selfstructured bed has been evaluated during C3H8 oxidative steam reforming. Structured bed, prepared by a new aqueous tape casting method, combining high total porosity (80%) with a self-supported channel structure, offers a better and more efficient control of heat and mass transfer along the catalytic bed, showing, especially at high gas hourly space velocity (300000 h-1), better performance in terms of fuel conversion, hydrogen production and low by-products formation coupled with an economy of the catalyst of about to 43% with respect to the traditional packed bed system.

The transition toward a "Hydrogen Economy" could ensure significant advantages in terms of energetic efficiency and environmental impact, with reduced production of greenhouse gases. In the near term, considering the actual lack of infrastructure for H2 storage and distribution, equipments operating with FCs fed with H2 or H2-rich gases produced by reforming of available fossil (Natural Gas, LPG, Diesel, etc..) and renewable (biogas, bioethanol) fuels represent a valid and interesting alternative to actual energy generation systems [1,2]. Additionally, large-scale central production will depend on market volumes to evolve in order to compensate for the capital expenditures of building up capacity. Thus, distributed production of hydrogen/syngas via smaller reformer, integrated with different fuel cell systems (SOFC, PEM), is viewed as an attractive near option for stationary. Combined Heat and Power System (CHPS). Moreover, the reforming of fossil fuels could represent a practical option to create H2 filling stations realized with on-site fuel processor (FP) units fed with distribuited fuels already present on the road [3]. The key requirements for a fuel processor include rapid start-up, good dynamic-response to follow the change in hydrogen demand, high fuel conversion, small size and weight, simple design (construction and operation), stable performance for repeated start-up and shut-down cycles, maximum thermal integration, low cost and maintenance, high reliability and safety. In addition, the design of robust, low cost, highly performing and relatively fuelflexible catalysts is also required. In this regards, structured reactors, such as microchannels, ceramic or metallic monoliths and foams, show a number of advantages, like, compactness, high power densities, high mass specific powers, low catalyst request, lower pressure drop and improved heat and mass transfer, compared to conventional technology such as packet beds [4]. In this work, the performances of structured catalysts, based on 1.5wt%Rh/CeO2 coated on cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm) and alumina foams (20, 30, 40 ppi, diameter 1 cm, length 1.5 cm) were investigated and compared towards Steam Reforming (SR) and Oxy Steam Reforming (OSR) of different fuels (CH4, Biogas, n-dodecane). The structured supports were lined by combining the Solution Combustion Synthesis (SCS) for the deposition of ceria oxide, with the Wet Impregnation Technique (WIT) for the loading of active metal. The deposition process was repeated several times until reaching the desired and equal amount (? 0.180mg) of catalytic layer over all the supports [5]. The final structured catalysts, showed in Fig. 1, were characterized by SEM, EDX-mapping, TEM and XRD techniques; in addition, Rh/CeO2 catalyst in powder form was also prepared by the same procedure and characterized by XRD, TPR and CO chemisorption analysis. Pressure drop and catalytic layer loss tests have been evaluated. Both monolith and foam catalysts have shown comparable results in terms of uniform thin coating (thickness between 20-30 ?m), high mechanical strength (negligible weight loss ? 0.4% on total weight of the sample after ultrasonic treatment) with low pressure drop of the monolith respect the foam. The different reforming experiments were conducted in a fixed-bed quartz reactor (?i = 1 cm) at atmospheric pressure. The overall operating conditions are summarized in table 1. A first series of tests were carried out only with monolith catalysts to identify the optimum conditions in terms of S/C for SR, S/C and O/C for OSR for each fuel at fixed intermediate WSV and temperature. A second series of tests were carried out to compare the catalytic performance of foam and monolith catalysts varying the temperature and the WSV.

Sorbents for CO2 capture have been prepared by wet impregnation of a commercial active carbon (Ketjen-black, Akzo Nobel) with two CO2-philic compounds, polyethylenimine (PEI) and tetraethylenepentamine (TEPA), respectively. The effects of amine amount (from 10 to 70wt.%), CO2 concentration in the feed, sorption temperature and gas hourly space velocity on the CO2 capture performance have been investigated. The sorption capacity has been evaluated using the breakthrough method, with a fixed bed reactor equipped with on line gas chromatograph. The samples have been characterized by N2 adsorption-desorption, scanning electron microscopy and energy dispersive X-ray (SEM/EDX). A promising CO2 sorption capacity of 6.90 mmol/gsorbent has been obtained with 70wt.% of supported TEPA at 70°C under a stream containing 80vol% of CO2. Sorption tests, carried out with simulated biogas compositions (CH4/CO2 mixtures), have revealed an appreciable CO2 separation selectivity; stable performance was maintained for 20 adsorption-desorption cycles.

L'OR4 è composto dai seguenti 4 WP: WP4.1 - Trattamento dei combustibili low carbon per l'alimentazione di celle a combustibile; WP4.2 - Ausiliari per applicazioni navali basati sull'uso di celle SOFC; WP4.3 - Ausiliari per applicazioni navali basati sull'uso di celle HT-PEFC; WP4.4 - Progettazione, realizzazione e dimostrazione di un sistema integrato reformer e cella a combustibile.