(600ca) A Density Functional Theory Study of Methanol Steam Reforming Catalyzed by Cobalt Based Materials

Hydrogen-based fuel cells are a promising substitute to fossil fuels for both energy storage and automotive fuel. Methanol steam reforming (MSR) is an ideal approach to produce hydrogen on site for vehicles where the storage and transportation of hydrogen is costly. Currently many metals such as Cu, Pd, Co, and Rh are found to be capable of catalyzing the MSR reaction; however they often have at least one of these following problems: low reaction rate; low selectivity to carbon dioxide; carbonization on surface of catalyst during reaction. In our study we investigated the reaction pathway of MSR on the cobalt (0001) surface using Density Functional Theory (DFT). We examined the adsorption of reactants, products, and intermediates that are along the MSR reaction pathways suggested by previous studies. For each species we determined the most stable structure and based on this information we have constructed a free energy diagram for the reaction pathways for reforming methanol on Co(0001) surface. We have also used the nudged elastic band (NEB) method to determine the transition states and energy barriers for important elementary steps to study the kinetics, especially for the competing steps that effect product selectivity. We will discuss the implications of our calculations to experimental results and other DFT studies of MSR on other metal surfaces.