چكيده به لاتين
Demercaptanization and dehydration improve the quality of the final liquefied petroleum gas ( LPG) and therefore are of great important operations in natural gas refinery. Among different technologies, adsorption using solid sorbents is known as one of the most efficient process. The Faujasite zeolite is highly desired for desulfurization of fuels because of their many beneficial properties, such as physical and hydrothermal stabilities, non-toxicity, high surface areas, their tuneable selectivity regarding polar molecules, good regenerability, and good cost-benefit ratios; nevertheless, there have been many efforts to enhance properties by preparing nanosized and hierarchically structured zeolites. Herein, the Y-Microzeolite (Y-MZ), Y-Nanozeolite (Y-NZ), Y-NZ/MCM-41 composite and Poly pyrrole-functionalized Y-NZ/MCM-41 composite with low (Y-NZ /MCM-41/PPY1) and high loading(Y-NZ/MCM-41/PPY2) were prepared as viable options for investigation the nanosized and hierarchically structured zeolites onto adsorption of Ethyl-Mercaptan(Et-mercaptan) from liquefied petroleum gas(LPG) by means of providing high pore diameters, high surface areas, high mass transfer properties and high reactivity. The synthesized materials were studied via XRD, SEM, EDX, FT-IR, TGA and BET methods. The experimental column breakthrough curves studies underline the potential of these material for removal of Et-Mercaptan from LPG on the basis of Et-Mercaptan sorption capacity, stability and regenerability. Under the experimental conditions explored, the adsorption capacities of adsorbents for Et-mercaptan decreased in the sequence: Y-NZ > Y-NZ/MCM-41/PPY1> Y-MZ >Y-NZ/MCM-41> Y-NZ/MCM-41/PPY2 which were 159, 115, 70, 46 and 20 mg/g, respectively. Compared to investigated adsorbents, Y-NZ adsorbent has high capacities for Et-Mercaptan adsorption from LPG and being stable to multiple regeneration cycles under temperature of 350 °C during 5h, while Y-NZ /MCM-41/PPY1 composite with relatively high adsorption capacities being not stable to multiple regeneration cycles under temperature desorption and some undesirable reactions, e.g., decomposition of PPY were performed onto the composite. The nature of ethyl-mercaptan adsorption and the impact of multiple adsorption−desorption cycles on the adsorbents have been studied using FT-IR.
Also, the potential of Y-NZ modified with single Cu, Ce, La cations, as well as Cu-Ce and Cu-La for removal of Et-Mercaptan from LPG.were investigated. The results show that the exchanged samples have higher performances in terms of adsorption capacity compared to the untreated zeolite, that adsorbs about 172, 157, 164, 184, 173 and 147 mg/g for Cu/Y-NZ, Ce/Y-NZ, La/Y-NZ, La-Cu/Y-NZ, Ce-Cu/Y-NZ and Y-NZ, respectively. Y-MZ and Y-NZ were compared to remove moisture from gas.The results showed that he Y-NZ have higher performance in terms of adsorption capacity compared to the Y-MZ, that adsorbs about 22.2 and 15.4 g/g, respectively. These nanostructures were recovered at 350 ° C under nitrogen atmosphere for 5 hours.
