Increased hydrogen spillover by gaseous impurity: The Benson–Boudart method for dispersion revisited

A new bridge-building technique was used for facilitating H spillover on metal doped adsorbents for hydrogen storage at room temperature. By preadsorbing 1.0×10−3 atm1.0×10−3 atm of CH4 on Pt/AX-21 (superactivated carbon), the adsorbed amount of hydrogen increased by ∼100% at 1 atm and 25 °C, attributed to the adsorbed CH4 serving as bridges for spillover. We conclude that the Benson–Boudart method can provide a good assessment for the dispersion of metals supported on Al2O3 (and zeolites). For carbon and SiO2 supports, even with pure H2, spillover leads to overestimates of dispersion, and any small amounts of gaseous impurities could lead to much greater overestimates.