The adsorption properties of organic sulfur compounds on zeolite-based sorbents impregnated with rare-earth metals

Dimethyl disulfide (DMDS) and dimethyl sulfide (DMS) are non-polar, stable, organic sulfur compounds found in liquefied petroleum gas, and their oxidation in the atmosphere results in the formation of tropospheric sulfur dioxide, which is subsequently converted into sulfuric acid, as the main factor of acid rain. In the present study, adsorption processes were devised based on the use of modified zeolite impregnated with rare-earth metals (Ce, La or Pr) for the adsorption of DMDS and DMS, and their sorption capacities were compared with that of commercial zeolite [Zeolite-Y, Ultra Stable Y(USY)]. The adsorption capacities of adsorbents were tested using a micro liquid flow reactor at room temperature. USY impregnated with cerium oxide (UC-10) had excellent DMDS and DMS adsorption capacities as compared with the other adsorbents tested. It was found that impregnation of USY with rare-earth metal such as Ce improved the sulfur adsorption capacity of zeolite. The form of the Ce promoter impregnated into USY was determined by FT-Raman spectroscopy. Adsorbents were characterized by X-ray fluorescence spectrometer, X-ray diffraction, and BET and the results obtained are discussed.