Chemical Liquid Deposition Modified ZSM-5 Zeolite for Adsorption Removal of Dimethyl Disulfide

A series of ZSM-5 zeolites were prepared through a chemical liquid deposition (CLD) method and used for adsorption removal of dimethyl disulfide (DMDS) from methyl tert-butyl ether (MTBE). The structural properties and acidity were characterized, and the proper deposition amount and calcination temperature have been accessed. N-2 adsorption test and X-ray photoelectron spectroscopy (XPS) results show that methylsilicone oil is deposited on the external surface and narrows the pore size of the zeolite. NH3-temperature-programmed desorption (NH3-TPD) and modified Hammett indicator titration results indicate that the acid sites on the external surface are eliminated while acid sites in the channel are not influenced significantly. Both the pore structure and acidity play important roles in determining the sulfide adsorption process. The optimal modification condition was found as a deposition amount of 30% and a calcination temperature of 500 degrees C. Adsorption isotherms were also conducted in both parent and CLD-modified ZSM-5 adsorbents. The DMDS adsorption capacity of CLD-modified adsorbent is 8.24 mg/g, which is almost 6 times higher than that of the parent ZSM-5 sample.