A Simple EAM Potential for Hydrogen-Selective Palladium Based Membranes for Biomass Derived Syngas Processing

摘要

Biomass offers the potential to economically produce hydrogen via gasification from an abundant and renewable feedstock. When hydrogen is produced from a biomass gasifier, it is necessary to purify it from syngas streams containing components such as CO, CO_2, N_2, CH_4, and other products. Therefore, a challenge related to hydrogen purification is the development of hydrogen-selective membranes that can operate at elevated temperatures and pressures, provide high fluxes, long operational lifetime, and resistance to poisoning while still maintaining reasonable cost. Palladium based membranes have been shown to be well suited for these types of high-temperature applications and have been widely utilized for hydrogen separation. Palladium's unique ability to absorb a large quantity of hydrogen can also be applied in various clean energy technologies, like hydrogen fuel cells. In this paper, a fully analytical interatomic Embedded Atom Potential (EAM) for the Pd-H system has been developed, that is easily extendable to ternary Palladium based hydride systems such as Pd-Cu-H and Pd-Ag-H. The new potential has fewer fitting parameters than previously developed EAM Pd-H potentials and is able to accurately predict the cohesive energy, lattice constant, bulk modulus, elastic constants, melting temperature, and the stable Pd-H structures in molecular dynamics (MD) simulations with various hydrogen concentrations. The EAM potential also well predicts the miscibility gap, the segregation of the palladium hydride system into dilute (α) and concentrated (β) phases.