The production of pure hydrogen usually requires its extraction from a gas mixture. In fact, one of the critical stages related to the use of hydrogen as an energy carrier is the development of efficient and competitive techniques that separate hydrogen from other by-products such as steam, hydrocarbons, carbon dioxide and other gases. Among different technologies, dense ceramic membranes are promising candidates for separation and purification of H2 in a non-galvanic mode. In this context, mixed ionic and electron conductors (MIEC) oxides incorporate hydrogen into their lattice as charge protonic defects which means that, theoretically, they are 100% selective towards hydrogen separation. Furthermore, the properties of these oxides (i.e. working temperatures, durability) endow membranes that could be directly integrated into industrial processes or used in the so-called catalytic membrane reactors. Recently, BaCe0.65Zr0.20Y0.15O3-? (BCZ20Y15) and Ce0.85M0.15O2-? (M = Y and Gd) dual-phase membranes were explored by our group reaching hydrogen permeability values among the highest ever reported for bulk MPEC membranes. [1] However, long-term stability and degradation mechanisms are critical issues for these systems. The working conditions are really challenging: H2 purification is carried out at high temperatures in harsh reducing environments containing H2O, CO, CO2, and sulphides. In these conditions, undesired phenomena such as structural changes, cation diffusion, mechanical modifications or chemical reactions could occur damaging the membranes transport performances. This work focuses on the chemical and mechanical stability of BCZ20Y15-doped ceria composites for hydrogen separation membranes. BCZ20Y15-MDC15 composites were exposed to different environments at high temperatures and then characterized by means of XRD and SEM techniques. The scope of this study is to evaluate the stability behavior of these composites under atmospheres that simulate practical membrane separation conditions. [1] E. Rebollo, C. Mortalò, S. Escolástico, S.Boldrini, S. Barison, J. M. Serra, and M. Fabrizio, Energy and Environmental science 8, 3675-3686, (2015)
BaCe0.65Zr0.20Y0.15O3-d-Ce0.85M0.15O2-d (M: Y, Gd) ceramic membranes under syn-gas atmospheres
E Rebollo;M Fabrizio
2017
Abstract
The production of pure hydrogen usually requires its extraction from a gas mixture. In fact, one of the critical stages related to the use of hydrogen as an energy carrier is the development of efficient and competitive techniques that separate hydrogen from other by-products such as steam, hydrocarbons, carbon dioxide and other gases. Among different technologies, dense ceramic membranes are promising candidates for separation and purification of H2 in a non-galvanic mode. In this context, mixed ionic and electron conductors (MIEC) oxides incorporate hydrogen into their lattice as charge protonic defects which means that, theoretically, they are 100% selective towards hydrogen separation. Furthermore, the properties of these oxides (i.e. working temperatures, durability) endow membranes that could be directly integrated into industrial processes or used in the so-called catalytic membrane reactors. Recently, BaCe0.65Zr0.20Y0.15O3-? (BCZ20Y15) and Ce0.85M0.15O2-? (M = Y and Gd) dual-phase membranes were explored by our group reaching hydrogen permeability values among the highest ever reported for bulk MPEC membranes. [1] However, long-term stability and degradation mechanisms are critical issues for these systems. The working conditions are really challenging: H2 purification is carried out at high temperatures in harsh reducing environments containing H2O, CO, CO2, and sulphides. In these conditions, undesired phenomena such as structural changes, cation diffusion, mechanical modifications or chemical reactions could occur damaging the membranes transport performances. This work focuses on the chemical and mechanical stability of BCZ20Y15-doped ceria composites for hydrogen separation membranes. BCZ20Y15-MDC15 composites were exposed to different environments at high temperatures and then characterized by means of XRD and SEM techniques. The scope of this study is to evaluate the stability behavior of these composites under atmospheres that simulate practical membrane separation conditions. [1] E. Rebollo, C. Mortalò, S. Escolástico, S.Boldrini, S. Barison, J. M. Serra, and M. Fabrizio, Energy and Environmental science 8, 3675-3686, (2015)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
