Study Of Synthesis Of Binderless Zeolite And Preparing Of Low Aromatic Solvent Oil By Adsorption Of Naphtha

Due to the problem of high content of aromatics and poor environmental performance with domestic solvent oil, suitable process should be developed in order to produce low aromatic or dearomatic solvent oil. The desorptiom oil derived from the adsorption separation process of naphtha can be used to produce multiple brands of solvent oil. In this paper, adsorbent with high performance was prepared and used for the adsoption separation of naphtha on a fixed bed adsorption device.Firstly, binderless zeolite 5A was synthesized through the hydrothermal treatment of silica gel particles, which was prepard by using oil forming method. The optical ratio of raw material is n(NaAlO2):n(SiO2):n(NaOH):N(H2O)=2:1:1:40. Furthermore, the reaction condition is found as follows:solidation at room temperature for 7 days, aging at 50℃ for 2h and crystallization at 100℃ for 3h. The adsorption capacity for n-hexane is 0.118g/g and the mechanical strength is 12.4N. The results of liquid phase adsorption kinetics indicate that n-paraffins have higher diffusion rate on the binderless zeolite 5 A than that on the zeolite with binder.Secondly, the crystallization kinetics of zeolite 5A from silica gel particles wasinvestigated. The results show that zeolite A gradually transforms to hydrosodalite as the crystallization time increases. With as increase of alkalinity, both the crystallization of zeolite A and its transformation to hydrosodalite can be accelerated. As a result, it can be concluded that the crystallization of zeolite A on the silica gel particles is controlled by the surface conversation of aluminosilicate gel rather than the diffusion in the particles.Thirdly, the adsorption separation performance of synthesized binderless zeolite 5 A was studied on the fixed bed adsorption device and compared to zeolite 5A with binder. The results show that at the adsorption temperature of 300℃, space velocity of 98h-1, the adsorption capacity of binderless zeolite 5 A is 0.132g/g, which is 18.9% larger than that of zeolite 5A with binder.Finally, the desorption oil was successfully cut into four solvent oil products:pentane foamer, extracting solvent oil No.6, rubber solvent No.120 and solvent oil No.140.