Studies on reaction rate and effectiveness factor of noble metal catalysts for fuel processing

Abstract

The fuel reforming technology for fuel cell applications has been a challengeable issue because of strict requirements such as high efficiency, compact structure and low cost. As an effort to fulfill the requirements, various noble metal-based catalysts have been developed for the fuel processing including autothermal reformer and water-gas shift (WGS) reactor. In this study, the noble metal catalysis in autothermal reformer and water gas shift reactor was investigated by experimental methods and numerical modeling. After selecting catalysts of noble metals on mixed oxides, the activity of the catalysts and the properties of the catalysis for each reaction were tested preliminarily. Furthermore, reaction rates were measured with a scouting reactor excluding all the effects of transports limitations. Kinetic parameters of relevant model equations were estimated by a nonlinear regression method. Using the reaction rate equations with the estimated parameters, the reactors were modeled with focus on the effects of transport phenomena inside catalyst particles and between particles and fluid. The utilization of material of the catalysts was quantitatively predicted by the simulation. For Autothermal reforming (ATR), assuming two-step reaction pathway, steam reforming (SR) reaction rate was measured over platinum supported on a cerium-gadolinium oxide. A reaction equation from a literature successfully fitted the data. The reaction equation with the adjusted parameters was used for SR section modeling. According to the simulation results, the intraparticle transport resistance (mass) and interphase transport resistances (mass and heat) are significant in SR section of ATR. Platinum supported on cerium-zirconium oxide was selected as a WGS catalyst. The catalysts were prepared with three different metal loadings, and the activities of the catalysts were tested. Activation energies estimated from the results of experiments agreed well with the literature values....