Sol-Gel Processed Cobalt-Doped Methylated Silica Membranes Calcined under N 2 Atmosphere: Microstructure and Hydrogen Perm-Selectivity

Methyl-modified, cobalt-doped silica (Co/MSiO ) materials were synthesized by sol-gel technique calcined in N atmospheres, and membranes were made thereof by coating method. The effects of Co/Si molar ratio ( ) on the physical-chemical constructions of Co/MSiO materials and microstructures of Co/MSiO membranes were systematically investigated. The gas permeance performance and hydrothermal stability of Co/MSiO membranes were also tested. The results show that the cobalt element in Co/MSiO material calcined at 400 °C exists not only as Si-O-Co bond but also as Co O and CoO crystals. The introduction of metallic cobalt and methyl can enlarge the total pore volume and average pore size of the SiO membrane. The activation energy ( ) values of H , CO , and N for Co/MSiO membranes are less than those for MSiO membranes. When operating at a pressure difference of 0.2 MPa and 200 °C compared with MSiO membrane, the permeances of H , CO , and N for Co/MSiO membrane with = 0.08 increased by 1.17, 0.70, and 0.83 times, respectively, and the perm-selectivities of H /CO and H /N increased by 27.66% and 18.53%, respectively. After being steamed and thermally regenerated, the change of H permeance and H perm-selectivities for Co/MSiO membrane is much smaller than those for MSiO membrane.