- 5:03 PM

Comparative Catalysis Testing and Competing Mechanisms in Methanol Reforming

Sam D. Jones and Helena Hagelin-Weaver. Chemical Engineering, University of Florida, Bldg 723, Gainesville, FL 32611

Automobiles powered by hydrogen fuel cells which can be run on renewable energy sources are emerging as an environmentally friendly alternative to internal combustion engines. In order to be economically feasible and safe for the consumer, hydrogen must be generated from a liquid fuel on board the vehicle. Currently, copper and mixed metal oxides are used to catalyze the reaction of methanol and steam to produce hydrogen. Additional work investigating the relationship between surface and structural characteristics of copper catalysts and their catalytic activity is needed to improve the catalysts used in this type of reforming. Our research is built on existing knowledge of rational catalyst design and focuses on fabrication of nano-scale crystal structures on the catalyst surface by employing new precursor materials to maximize both hydrogen production and CO2/CO selectivity. The use of nanoparticle oxide supports has the potential to afford a degree of control over the catalyst structure that has not been previously attainable using more traditional precursor materials. Furthermore, since nanoparticles exhibit size-dependent properties it is also possible that the newly developed catalysts have unique catalytic properties. The aim of this research is to develop catalyst fabrication techniques which will result in catalysts that can withstand a wide range of operating conditions and extended time on stream compared to commercially available methanol reforming catalysts. Recent work into the relationship between the reaction network in the steam reforming of methanol and the chemical composition of the catalyst in use has yielded some surprising results. It has been found that by manipulating the amount of active phase in the catalyst (Cu) different products once only present as intermediates can be isolated. This grants a considerable degree of insight into the reaction network. Information as to the rate determining step in the reaction can also be inferred. Specifically, formaldehyde has long been proposed as an intermediate in the reaction between methanol and water, but there has been a notable lack of information in the literature as to what determines the rate of formaldehyde production and its subsequent oxidation to the desired products of H2 and CO2. Recent work performed with nano-structured reforming catalysts has shed some light into this element of the reforming reaction. Additional surface analysis including XPS and BET measurements have been used to investigate how the physical and electronic structure of the catalysts is altered in the reforming reaction. The focus of this presentation will be on the performance of nano-structured catalysts compared to a common commercially available reforming catalyst and also on the structural and chemical relationships between different nano-structured catalysts with varying concentrations of copper