Continuous synthesis of mesoporous Y zeolites from normal inorganic aluminosilicates and their high adsorption capacity for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT)

Abstract

Mesoporous Y composites which exhibit both crystallized micropores and large mesopores with narrow mesopore diameter distributions and controlled pore diameters were successfully synthesized. The composite is synthesized through an elaborate design of the SiO2@cationic surfactant cetyltrimethylammonium bromide (SiO2@CTAB) micelle swelled by an appropriate amount of 1,3,5-trimenthylbenzene (TMB); it is subsequently fabricated from the condensing of the Y zeolite precursors, which contain Y zeolite seeds, on the mesoscale micelle followed by a hydrothermal crystallization process. The effect of synthesis conditions such as the amounts of CTAB, TMB and TEOS added to the synthesis system on the physicochemical properties of the obtained products was examined. The as-synthesized materials were carefully characterized by employing XRD, N2 adsorption–desorption, SEM, TEM and pyridine-adsorbed FTIR techniques. The mesoporous Y zeolite exhibited both the typical diffraction characteristics of Y zeolites in the wide-angle XRD pattern, and the typical diffraction characteristics of a narrowly dispersed mesopore structure in the small-angle XRD pattern is successfully synthesized for the first time. Finally, the adsorption capacity for DBT and 4,6-DMDBT by samples with different mesopore diameters were assessed by a batch method. Sample MY-0.5C-0.35T-0.9B showed the highest capacity for adsorbing DBT in model diesel, and sample MY-0.5C-0.35T-1.5B showed the highest capacity for adsorbing 4,6-DMDBT in model diesel. Most importantly, sample MY-0.5C-0.35T-1.5B showed the highest adsorptive rate for both DBT and 4,6-DMDBT, which is at least 10 times faster than that of sample MY-0C-0.35T-0B because of the elimination of the diffusion limitation.