Copper based materials for water-gas shift equilibrium displacement

Abstract

Water-gas shift reaction and sorption enhanced water-gas shift were studied over Cu-CeO2 and Cu-HTlc catalysts in the temperature range between 125 and 295 degrees C. The catalysts were characterized by N-2 sorption, XRD, H-2-TPR and SEM techniques. Among the tested catalysts, copper supported on polyhedral ceria nanoparticles showed the highest activity, achieving 87.6% CO conversion. High dispersion of copper was identified as a catalyst property required for high WGS activity. During SE-WGS tests using either a multilayer arrangement of Cu-CeO2 catalyst and K-HTlc sorbent, or Cu promoted hydrotalcite hybrid catalyst, nearly 70 mol% H-2 was obtained in the product gas stream during the initial transient period. Elevated pressure and surplus of steam in the feed increased the sorption capacity of K-HTlc, resulting in delayed CO2 breakthrough. On the other hand, dilution of feed stream with inert gas (He) resulted in a dramatic decrease of sorbent's capacity leading to an early CO2 breakthrough.