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.

Membrane Reactors: Advanced Systems for Intensified Chemical Processes

“…Porous polymeric membranes made of polyacrylic acid (PAA) have been functionalized with Pd nanoparticles [42]. The effects of the membrane porosity, the catalyst loading and the reactant mixture flow rate on the catalytic properties of these membranes have been investigated in the gasphase partial hydrogenation of propyne to propylene (Eq.…”

“…PAA membranes loaded with Pd nanoparticles have also been used for the selective hydrogenation in liquid phase of various unsaturated substrates in a flow-through catalytic membrane reactor operating at 323 K and 40 bar of hydrogen pressure [42].…”

Adsorption Processes for the Synthesis of Catalytically Active Metal Nanoparticles in Polymeric Matrices

“…Such hybrid materials prevent NP agglomeration and need no stabilizing ligands, which makes the NP more active in the catalytic reactions [9,10]. The choice of hypercrosslinked polymer matrices is limited to porous membranes based on polyacrylic acid crosslinked by a difunctional epoxide [13][14][15] and hypercrosslinked polystyrene (HPS).…”

Experimental strategies for increasing the catalyst turnover number in a continuous Heck coupling reaction

“…A lot of research has been done to heterogenize TMCs with different techniques such as encapsulation, interphase chemistry, phase-tagging for biphasic catalysis or ionic liquids and various techniques for the immobilization of molecular catalysts on solid or colloidal supports [4]. For example, Gröschel et al [5], employed a catalytically active membrane based on poly(acrylic acid) networks containing palladium nanoparticles for the partial hydrogenation of propyne. In order to test the long term stability a membrane was kept under constant reaction conditions for about 6 days (reactants flow rate of 20 mL.min -1 and temperature of 298 K) and a conversion and selectivity of about 50% and 88% were obtained, respectively (TON data not presented).…”