A kinetic analysis of the partial oxidation of C3H8 over a 2% Rh/Al2O3 catalyst in annular microreactor

In this paper, we report a detailed kinetic investigation of C3H8 catalytic partial oxidation (CPO) over a Rh/alpha-Al2O3 catalyst. We applied an isothermal microreactor to collect kinetically relevant data with the aim of identifying the prevalent kinetic dependences and extending our C-1 molecular kinetic scheme to the description of the C3H8 CPO process. The kinetic study consisted of CPO and steam reforming tests with diluted feeding mixtures in a wide range of temperature, composition and space velocity. The experimental results showed that H-2 and CO are formed through consecutive steps of total oxidation and steam reforming of the fuel. The syngas composition is also affected by the water gas shift reaction, as well by the methanation of COx. In analogy with CH4 CPO, the rate of total oxidation of C3H8 and the rate of steam reforming of C3H8 were found to be proportional to the concentration of fuel, but independent from the concentration of the co-reactant. The rate of the forward water gas shift reaction was found to be first order dependent on H2O and independent from CO, while the rate of methanation was assumed to be proportional to H-2 partial pressure. A preliminary micro-kinetic analysis showed that C3H8 adsorption likely involves the formation of CHx intermediates with x <= 2. (C) 2012 Elsevier B. V. All rights reserved.