Preparation and evaluation of Pd membrane on supports activated by PEG embedded Pd nanoparticles for ATR membrane reactor

Abstract

Stresses and formation of voids are the main origins of pinholes in palladium (Pd) composite membranes at high temperatures. The stresses are associated with the Pd layer-substrate interaction and the formation of the voids is due to the gas bubble trapped inside the deposits. Pd embedded polyethylene glycol (PEG) was used during the activation step of the electroless plating (ELP) method. Also, multiple plating and annealing steps were employed to suppress void formation. Three plating and annealing steps rendered the prepared Pd membrane quite dense and defect-free. The surface roughness of modified support was found to play a crucial role in the stability of the Pd membrane. The resulting membrane showed an infinite selectivity for H2/Ar with H2 flux of 1-6.6 m3 m-2 h-1. Besides, H2 permeate flux kept constant and the separation factor of H2/Ar over infinite for 240 h at different temperatures, indicating the high potential of the prepared membrane for H2 purification. Furthermore, membrane reactor experiments showed the CH4 conversion is about 15 % higher than that in the traditional reactor at the same condition.