Thin Films, Surfaces, and Coatings
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Materials Engineering and Sciences Division
Poster Session: Materials Engineering & Sciences (08A - Polymers)
Monday, November 11, 2019 - 3:30pm to 5:00pm
Supported noble metal catalysts are widely used for chemical production, energy conversion and environment protection, and understanding the underlying nature of the size-dependent and support-dependent catalytic reaction rate is of crucial importance to guide the catalyst design and optimization. The intrinsic rate of a catalytic reaction can be expressed as the quantity (number) of the active sites (i.e., NT), which is a function of the shape and size of the nano metal particle, times the quality (activity) of the ones (i.e., TOF), depending on the electronic property of the active sites. We propose a method to decouple the structural and electronic effects, so to identify the dominate active site and descriptor for the catalytic activity. For a given catalyst shape, we do multi-faceted kinetics analysis and modeling the size-dependent surface sites, to discriminate the dominant active sites by using nano metals of different sizes but similar electronic properties. It is shown to be applicable for the supported noble metal catalysts for hydrolytic dehydrogenation of ammonia borane, CO/glycerol oxidation, propylene epoxidation and acetylene hydrogenation. By using nano metal particles with similar sizes to exclude the size effects, the metal binding energy/partial charge, which is easily determined by experiments and can be finely tuned by using different supports and dopants, is identified as a descriptor for the catalytic activity. A new kinetics rate equation is therefore formulated, which includes the catalyst structural parameters of the catalyst (i.e., the number of catalyst active sites and the descriptor), and therefore can be used to guide the design and optimization of the catalyst.