Formation of a three-dimensional mesostructured cobalt smectite during deposition-precipitation functionalization of mesoporous SBA-15

摘要

SBA-15 has been functionalized with cobalt by the deposition-precipitation procedure and the obtained samples have been characterized by XRD,N2-sorption,SEM,TPR and ICP-AES.Cobalt stevensite,which is a type of clay material belonging to the smectite group,is formed at the internal surface of the SBA-15 particles during the procedure,without altering the size or shape of the particles.The obtained samples exhibit the XRD peaks characteristic for cobalt stevensite and also the(100)peak typical for mesoporous materials.Due to the structural re-organization of amorphous silica into crystalline stevensite at the silica surface,the pore walls are contracting.This pore wall contraction causes the micropores in the parent SBA-15 sample to expand,thereby transforming these micropores into mesopores.The obtained cobalt stevensite samples therefore have a three-dimensional structure with interconnected mesopores,which was verified by the observed N2-sorption isotherms of type IVb.