Kinetics of adsorptive desulfurization over alkaline-treated Beta zeolite

When molecular size of an adsorbate is as large as the pore size of molecular sieves, the adsorbate can enter into the pore structure and thus the pore size of molecular sieves is a critical factor in determining adsorption performance. To improve adsorbate selectivity and diffusion, Beta molecular sieves were modified by alkaline treatment of NaOH solution. The treated Beta molecular sieves were characterized by analytical techniques of BET, TEM, FT-IR, XRD and NH3-TPD to investigate the alkaline treatment process on crystal structure, surface acidity and pore structure. Adsorption desulfurization showed that both adsorption quantity and adsorption rate of alkaline-treated Beta molecular sieves were improved obviously. Especially the adsorption of large-kinetic-sized dibenzothiophene reached to 5.06 mg·g-1. The kinetics of adsorbing dibenzothiophene on Beta molecular sieves was a pseudo-2nd-order adsorption process. After alkaline treatment, rate constants of both adsorption and molecular diffusion inside pores were increased significantly, which in turn improved mass transfer of diffusion inside porous structures and desulfurization efficiency of sulfur compounds. © All Right Reserved.