Hydrogenation of Propyne in Palladium-Containing Polyacrylic Acid Membranes and Its Characterization

Abstract

In this contribution, catalytically active membranes based on poly(acrylic acid) networks containing palladium nanoparticles are presented as a suitable catalyst for a gas-phase hydrogenation reaction. The palladium particles were prepared in sizes of a few nanometers from Pd(OAc)2 in the presence of a block copolymer in organic solutions with reducing agents such as NaBH4 or LiAlH4. After the metal dispersion had been mixed with a polymer dispersion with a defined amount of poly(acrylic acid), catalytically active membranes were obtained by cross-linking the dispersion with a difunctional epoxide. Membranes with defined porosities and amounts of palladium were characterized for their catalytic activity. The partial hydrogenation of propyne to propene was chosen as the model reaction. To benchmark the activity and selectivity of the prepared membranes, the hydrogenation was also studied in a fixed-bed reactor filled with similar amounts of commercially available porous or egg-shell catalysts. Simulations of the reaction in membranes were performed using numerical tools in order to distinguish between kinetic and mass-transfer control of the reaction.