The Effect Of Pore Size Modification Of Zeolite Y On The Adsorption Desulfurization

In the past years, deep desulfurization of transportation fuels has become an urgent worldwide issue with increasingly stringent environmental regulations and the growing awareness of environmental protection. Although hydrodesulfurization (HDS) has been widely used in industry, the activity of the present catalyst and the existing operating conditions can not meet the requirements of ultra-deep desulfurization of transportation fuels.Adsorption desulfurization has attracted increasing attention due to mild reaction conditions, low operating costs and deep desulfurization without affecting the properties of transportation fuels. Microporous zeolite has been widely investigated in adsorption desulfurization. However, there is no systematic research on the effect of micropre filling effect arising from the microporous pore on adsorption desulfurization. In this dissertation, microporous Y zeolite was treated with chemical method to modify its pore structure, the influence of the treatment conditions on the pore structure was studied, and the effect of pore size modification on the acidity of the adsorbents and the adsorption modes of different adsorbates was also investigated. This dissertation aimed to clarify the influence of the micropre filling effect on the selective adsorption desulfurization with competitors.The pore size modification of zeolite Y can be achieved by sequential EDTA-NaOH treatment. After ion-exchanging, the adsorbents were obtained. The adsorbent DA6-ATl-AW-Ce, which displayed newly created mesopores but the same microporous volume as CeY, showed nearly the same desulfurization performance as CeY. The reason is that, compared with CeY, the micropre filling effect of DA6-ATl-AW-Ce is almost unchanged. The adsorbent meso-CeY with mesopores developed at the cost of micropores in zeolite Y presented better desulfurization performance when adsorbing benzothiophene. Moreover, the addition of competitor (toluene or cyclohexene) into model gasolines containing thiophene resulted in a moderate decline in the sulfur removal over meso-CeY, while a sharp one over CeY. The reason is that, compared with CeY and DA6-ATl-AW-Ce, the mocroporosity of meso-CeY was to some extent destroyed, and hence, the micropre filling effect of meso-CeY was weakened, and in this case, the direct S-Ce interaction became dominant. However, meso-AgY and AgY showed nearly the same desulfurization performances. This phenomena can be explained by the same adsorption mode, π complexation of the three adsorbates on Ag ions, though the micropore filling effect of meso-AgY is weakened compared with AgY.Uniformly dispersed La2O3/SBA-15adsorbents were prepared by wet impregnation and solid-state grinding methods, respectively, and the adsorption desulfurization performances were evaluated with fixed-bed reactor with benzothiophene. The results showed that there were thresholds and no acid sites were obseved when La2O3was dispersed on SBA-15with the two different methods. La2O3/SBA-15can adsorb a certain amount of benzothiophene, but competitive adsorption occurs when benzothiophene coexists with toluene.