Nickel hollow fiber membranes for hydrogen separation from reformate gases and water gas shift reactions operated at high temperatures

Abstract

High temperature H2-selective membranes can be applied as the membrane reactor for pure hydrogen production by catalytic reforming of alcohols or hydrocarbons. Conventional Pd-based membranes are limited for this purpose due to the low thermal stability, significant hydrogen embrittlement, quick poisoning by other impurity species and high material cost. In this work, metallic nickel (Ni) hollow fiber membranes with thin wall thickness and optimal microstructure were fabricated by the dry-wet spinning and sintering technique, and employed for H2 separation from the model reformate mixtures containing CO2, CO, H2O and H2S at elevated temperatures up to 1000 °C. The prepared Ni hollow fiber membranes possess 100% H2-permselectivity, only allowing for the hydrogen in the reformate mixtures to permeate through under experimental conditions. In the presence of CO, CO2 and H2O (vapor), the hydrogen recovery from reformate mixtures may be noticeably influenced due to the water gas shift reaction (WGS: CO + H2O ? CO2 +H2). Multiple cycling operation and long-term tests were conducted, indicating that the Ni hollow fiber membranes have good cycling operation performance and high resistance to CO, CO2, H2O and H2S poisoning at high temperatures. The excellent thermal and chemical stability as well as the high permeation performance make the Ni hollow fiber membranes great potentials in advanced applications such as the portable hydrogen sources or the large-scale hydrogen production from coal gasification.