New Kaolin Desulfurization Catalysts And Adsorbents

A novel catalyst with high selectivity for sulfur reduction in FCC and a new desulfurization adsorbent with high adsorption capacity were developed. The details can be summarized as follows.Kaolin in-situ crystallization catalyst prepared via an in-situ crystallization method was modified by vanadium. The catalysts with different contents of vanadium were characterized by X-ray powder diffraction and specific surface area test. According to the results of experiment, we can find that vanadium destroys the crystal structures of catalysts slightly.The Kaolin in-situ crystallization catalyst was evaluated in a fixed fluid bed (FFB) reactor and characterized by pyridine-adsorption Fourier transformed infrared (FTIR) analyses. Comprehensively considered from the FFB evaluated results and the sulfur reduction ability, the catalyst modified by 0.45 wt.% of vanadium would perform the best, and the sulfur reduction rate is 25.5%. Compared with DOS, the sulfur reduction rate and conversion of the catalyst modified by 0.45 wt.% of vanadium increase about 5% and 2%, respectively. Combined with the FTIR analysis, the weak Lewis acidity of the catalyst enhances, and the sulfur reduction rate increases with increasing vanadium content.Three sorbents (CrNaY,MnNaY,CoNaY) were prepared by an aqueous ionic exchange technique to introduce three kinds of transition metal ions (Cr³⁺, Mn²⁺ and Co²⁺) into the in-situ crystallization NaY zeolite . The sorbents were characterized by X-ray powder diffraction and specific surface area test, and the nonaqueous solution back titration method is used for the determination of surface acidity of sorbents. The behaviors in adsorptive desulfurization of model gasoline were aslo investigated. The results show that CrNaY performs the best. Under the condition of 93℃, adsorption time of 1 h and mass ratio of adsorbent to oil ratio of 0.5, 70.03% of the removal rate of thiophene for CrNaY can be obtained. And the desulfurization performance enhances with the increase of the surface acidity of sorbents.The waste FCC catalyst was modified by HC1 with various concentrations. Then, the modified waste FCC catalysts were characterized by X-ray powder diffraction and specific surface area test. The results show that the waste FCC catalyst treated by HC1 with a concentration of 8% performs the best, which has the strongest intensity of X-ray diffraction peaks and the biggest special surface area(217.13 m²/g) and pore volume(0.208 ml/g).The 8% HCl modified waste FCC catalyst, the waste FCC catalyst added a certain quantity of acid modified kaolin and the waste FCC catalyst added a certain quantity of alkaline modified kaolin were evaluated in a FFB reactor. The results indicate that the activity of the waste FCC catalyst can be improved by the three different treatments. After the above treatments, the conversions of the waste FCC catalysts increase and all of the catalysts have a certain sulfur reduction ability. The waste FCC catalyst added a certain quantity of alkaline modified kaolin has the best cracking performance with a conversion increase of 7.1%, and the 8% HCl modified waste FCC catalyst has the best desulfurization ability with a sulfur reduction rate of 16.3%.