(354j) Understanding Facilitated Transport of Hydrogen in Polybenzimidazole Containing Palladium Nanoparticles Using an Integrated Experimental and Modeling Approach

Authors: 
Zhu, L., University at Buffalo, The State University of New York
Lin, H., University at Buffalo, The State University of New York
Yin, D., University at Buffalo, The State University of New York
Konda, S., University at Buffalo, The State University of New York
Swihart, M. T., University at Buffalo, The State University of New York

Membrane
technology is an energy-efficient and low-cost approach for pre-combustion CO2
capture and H2 purification in the integrated gasification combined
cycle (IGCC) processes. Conventional membranes are based on rigid polymers with
strong size sieving ability, such as
poly[2,2’-(m-phenylene)-5,5’-bisbenzimidazole] (PBI) that provides high H2/CO2
diffusion selectivity. In this study, we demonstrate enhanced H2
sorption and diffusion in PBI films with embedded palladium (Pd) nanoparticles,
which have strong affinity towards H2. Pd nanoparticles with uniform
diameters of 6 - 8 nm are prepared via a hot-injection colloidal synthesis. The
loading of Pd nanoparticles in PBI increases H2 sorption by almost
1,000 times, and at high Pd loadings, the Pd nanoparticles may form fast
channels allowing the H2 molecules to jump from one particle to
another and thus increasing the effective H2 diffusivity.  For
example, adding 70 wt.% Pd in PBI increases H2 permeability from 25
to 70 Barrers, and H2/CO2 selectivity from 13 to 29 at
150 °C. Such performance is above the Robeson’s upper bound for H2/CO2
separation, demonstrating the potential of these new materials for industrial H2/CO2
separation. The gas transport in these PBI-Pd nanocomposites is being modeled using
computational fluid dynamics (CFD)  to elucidate the mechanisms for the facilitated
H2 transport. This presentation will also discuss the visualized microstructure
of the nanocomposites and provide a unified view of the H2 and CO2
transport in the nanocomposites using an integrated experimental and simulation
approach.