Hydrogen Uptake Kinetics of 1,4-Bis(phenylethynyl)benzene (DEB) Rubberized Coating on Silicone Foam Substrate.

The hydrogen uptake kinetics of 1,4-bis(phenylethynyl)benzene, or DEB, mixed with palladium (Pd) on activated carbon in a rubber matrix coating on top of a porous silicone foam substrate are investigated. First, isothermal isobaric hydrogenation experiments were performed under different temperatures and H2 pressures to extract the uptake kinetics. The H2 uptake models based on the measured kinetic parameters were then employed to investigate/simulate the performance of the getter under dynamic application environments. The actual hydrogenation characteristics in this type of getter are multifaceted and involve actual H2 concentration in the getter matrix, micrometer-scale diffusion of atomic hydrogen away from Pd sites, precipitation of hydrogenated DEB crystals at the coating surfaces, and mobility of fresh DEB molecules. The kinetic analysis/modeling methodology described in this report can serve as a template for other gas-solid reactions as well. Besides possessing a good hydrogen capacity and excellent performance, this type of rubberized getter also offers some unique advantages over traditional solid getter: flexible structure and protection of the Pd catalyst from exposure to the environment.