Asymmetric ceramic hollow fibres applied in heterogeneous catalytic gas phase reactions

The present work provides a summary of the state of the art of using asymmetric ceramic hollow fibres as substrates for inorganic dense membranes and/or catalysts, in the development of new hollow fibre reactors for heterogeneous catalytic gas phase reactions. Three different hollow fibre reactor designs were studied; a hollow fibre membrane reactor (HFMR), a catalytic hollow fibre micro-reactor (CHFMR) and a catalytic hollow fibre membrane micro-reactor (CHFMMR). The performance of the HFMR, CHFMR and CHFMMR in different reactions such as methanol steam reforming (MSR), dry reforming of methane (DRM) and water gas shift (WGS) was compared with that of a traditional fixed-bed reactor configuration. A Pd-based membrane (thickness of approximately 5 μm) was deposited on the outer surface of the asymmetric ceramic hollow fibres using an electroless plating technique, in the development of both the HFMR and CHFMMR. The Pd-based membranes showed high H2 permeability (image at T = 450 °C and ΔP = 1 bar) and infinite H2 selectivity under the different reaction conditions studied. The catalyst was deposited on the walls of finger-like region of the asymmetric ceramic hollow fibres by the sol–gel Pechini method, in the development of the CHFMR and CHFMMR. The CHFMMR, which showed a performance 2.5 times higher than that in a traditional fixed-bed reactor, is proposed as a key step in the intensification of heterogeneous catalytic gas phase processes by integration of membrane-reactor and micro-reactor technologies.