Studied On Synthesis And Adsorption Desulfurization Performance Of ZSM-5/KIT-6Composite Molecular Sieves

In this work, in order to deeply reduce the contents of thiophenic sulfur compounds,novel supports and high-performance adsorbents were prepared. The research contents areas follows.Firstly, Zeolite ZSM-5was synthesized by the hydrothermal method using silicasolas silica source, NaAlO2as Alumina source and TPABr as template. The optimal synthesisconditions of Zeolite ZSM-5were: TPABr/SiO2=0.047, OH-/SiO2=0.17, H2O/SiO2=26,SiO2/Al2O3=75and crystallization time of72h. Secondly, a novel ZSM-5/KIT-6(ZK)composite molecular sieves, containing the bimodal pore (micropore and mesopore)distributions, was synthesized. In this system, a triblock copolymer PEO20-PPO70-PEO20(P123) and an n-butanol were used as a co-template, the nanocrystal clusters of the zeoliteZSM-5precursors were added into the template solution. Meanwhile, the addition amountand the crystallization time of the precursors, and pH values were invesitigated.Furthermore, the synthesized samples were characterized by several methods includingX-ray diffraction (XRD), scanning electron microscopy (SEM), transission electronmicroscopy (TEM), magic angle spinning nuclear magnetic resonance (27Al MAS NMR),Fourier transform infrared spectrometer (FTIR) and N2physical adsorption/desorption.The XRD analysis showed that the sample appeared similar mesoporous characteristicdiffraction peaks with those of the KIT-6and its microporous characteristic diffractionpeaks were the same as those of the zeolite ZSM-5. And, the N2adsorption resultsapproved that the composite material was provided with a typical mesoporous adsorptionisotherms and a pore size distributioncurve. its BET surface area, pore volume and pore size were620.6m2·g-1,0.71cm3·g-1and6.1nm, respectively. Furthermore, FTIR patterns, SEM images and27Al MAS NMRpatterns agreed that the synthesized sample was the micro-mesopore composite molecularsieves instead of the mechanical mixtures of ZSM-5and KIT-6.In this work, desulfurization adsorbents were prepared by the solid-state ionexchange method. In addition, the desulfurization performances of the adsorbents, using athiophene solution as a model gasoline, were investigated by a fixed-bed dynamic sorption technique. The evaluation results showed that the desulfurization performances of ZKadsorbents had an obviously advantage over those of ZSM-5and KIT-6adsorbents. Also,the results indicated that the optimum intoducting content of the nickel ions was10%, thebreakthrough adsorption capacity of sulfur was0.204mmol/g and the saturated adsorptioncapacity was0.367mmol/g, while the optimum introducting content of cuprous ions was5%, the breakthrough adsorption capacity and the saturated adsorption capacity were0.145mmol/g and0.243mmol/g, respectively.