Hydrogen adsorption on porous silica

A number of MCM-41 samples were produced with different ageing times and zinc dopant levels. Hydrogen adsorption experiments performed at 77 K on pure MCM-41 samples showed a maximum excess wt% uptake of 2.01%. Samples were doped with Zn in the Si:Zn ratio of 50:1, 25:1 and 10:1. These samples showed an increase in dd-spacing in their XRD patterns, suggestive of Zn incorporation into the structure but resulting in a decrease in long range pore ordering and surface area with increasing Zn content. Two of the three doped samples showed an increase in H2H2 adsorbed per unit surface area suggestive of increased interaction strength. However, definitive confirmation is difficult due to degradation of the pore structure and surface area. Adsorption at room temperature was minimal, being 0.1 wt% or below.