Mesoporous synthetic clays: synthesis, characterization, and use as HDS catalyst211 supports

摘要

Mesoporous synthetic clays (MSCs) are obtained when polymer-containing silicate211u001egels are hydrothermally crystallized to form layered magnesium silicate hectorite 211u001eclays containing polymers that are incorporated in situ. Polyvinylpyrrolidone of 211u001eseveral average molecular weights ranging from 10K to 1.3M, in gel loadings 211u001evarying from 5-30 wt%, were used. The organic polymer template molecules were 211u001eremoved from synthetic polymer-clay complexes via calcination. Pore radii, 211u001esurface areas, and pore volumes of the resulting porous inorganic networks were 211u001ethen measured. For the most part there is a direct correlation between both PVP 211u001emolecular weight and polymer loading on the diameter of the average pore. In 211u001eaddition to conventional techniques, the polymer-clay materials were also 211u001echaracterized by small angle x-ray scattering to ascertain the disposition of the 211u001epolymeric matrix. The MSC materials after calcination were examined as potential 211u001esupports for hydrodesulfurization (HDS). They were loaded with a bimetallic Co/Mo 211u001ecatalyst system for comparison with a commercial Co/Mo alumina catalyst. 211u001eDibenzothiophene (DBT) diluted with hexadecane (0.75 wt% S) was utilized as a 211u001eliquid feed for the HDS tests. This feed was chosen as a deep HDS test of a heavy 211u001emodel oil. The pore diameters of the MSC catalysts were found to have a strong 211u001eeffect on both the HDS activity and selectivity.