Enhancing Four-Carbon Olefin Production from Acetylene over Copper Nanoparticles in Metal-Organic Frameworks.

Four-carbon olefins, such as 1-butene and 1,3-butadiene, are important chemical feedstocks for the production of adhesives and synthetic rubber. These compounds are found in the C4 fraction of "green oil" products that can arise during the hydrogenation of acetylene. Here, we demonstrate that control of catalyst structure increases the yield and productivity of these important olefins with a family of catalyst materials comprised of Cu nanoparticles (CuNPs) bound within the pores of Zr-based metal-organic frameworks. Using carbon monoxide as a probe molecule, we characterize the surfaces of these catalytic CuNPs with diffuse reflectance infrared Fourier transform spectroscopy, revealing that the electronic structure of the CuNP surfaces is size dependent. Furthermore, we find that as CuNP diameter decreases, the selectivity for C4 products increases, and that lowering the stoichiometric ratio of H2/acetylene improves selectivity and productivity of the catalyst.