Reactive Metal-Biopolymer Interactions for Semihydrogenation of Acetylene

Biopolymer chitosan have large amount of hydroxyl and amino groups which can interact with metal and modify physicochemical properties at interfaces, ideal as supports in catalytic systems. Here we show the catalytic system that leverages reactive metal-biopolymer interactions for selective hydrogenation of acetylene, which represents one of the most important reactions in petrochemical industry. ~100% conversion and ~90% selectivity to ethylene can be achieved at 90 oC. In situ DRIFTS identifies the di-σ adsorption of acethylene over metal sites, which competes favorably with ethene adsorption, resulting in high selectivity. Quantum-chemical simulations suggest that the perpendicular mode of Chitosan adsorption via the NH2 group is energetically favorable on Pd(111) compared to others by ~0.6 eV. Compared with pristine Pd(111), *C2H4 is favorable to desorb into the gas phase rather than further hydrogenation over Pd/CTS due to the lowering of the electronic d-states of Pd upon adsorption of Chitosan.