【作者】 曹占国；

【导师】 刘民； 郭新闻； 王祥生；

【作者基本信息】 大连理工大学 ， 工业催化， 2011， 硕士

【摘要】 为保护环境,世界各国对发动机燃料的组成相继提出了严格的限制,以降低有害物质的排放。生产低硫、高辛烷值的清洁汽油己成为当今炼油技术进步的重要课题。我国FCC汽油一般占成品汽油总和的70%以上,采用常规的加氢脱硫催化剂,在加氢改质过程中会导致FCC汽油烯烃严重饱和,造成辛烷值大量损失。因此,我国迫切需要开发具有高选择性的加氢脱硫催化剂。纳米HZSM-5具有独特的孔道结构和较大的外表面积,可以增强活性组分的分散度和负载量,提高目的产物的选择性和收率。本文采用水热处理对纳米HZSM-5分子筛进行改性,通过XRD、NH3-TPD、N2-吸附等表征手段研究了改性后分子筛的物性变化；在此基础上,将活性组分Co、Mo负载在水热处理后的分子筛上,考察了其在FCC汽油中的选择性加氢脱硫性能,并在模型化合物中比较了催化剂对不同硫化物的脱除情况。最后探索了螯合剂EDTA改性对CoMo/HZSM-5催化剂在FCC汽油中选择性加氢脱硫性能的影响。主要得到如下结论：1.随着水热处理温度的提高,纳米HZSM-5分子筛比表面积降低,酸量减少,酸强度变弱,同时孔体积变化不大,分子筛保持了良好的MFI拓扑结构。2.采用活性组分Co、Mo对水热处理后的纳米HZSM-5催化剂进行改性,考察了催化剂在全馏分FCC汽油中的选择性加氢脱硫性能。结果表明,随着水热处理温度的提高,催化剂的加氢脱硫性能受到抑制,烯烃饱和活性却得到改善；反应温度提高,催化剂脱硫活性增强,烯烃饱和程度加剧；增大空速有利于催化剂保烯烃,而不利于脱硫。CoMo改性的600℃水热处理纳米HZSM-5分子筛,其反应后产品油族组成基本不变,汽油辛烷值损失△RON<1,表现出较好的选择性加氢脱硫性能。经过水热处理并负载活性组分CoMo的纳米HZSM-5系列催化剂对噻吩和苯并噻吩具有良好的脱除能力,但当处理温度高于700℃时,催化剂对二者的脱除能力严重下降,不利于脱硫；该系列催化剂对苯并噻吩的脱除效果要好于对噻吩的脱除。3.采用EDTA对CoMo/HZSM-5催化剂进行改性,考察了其在FCC汽油中选择性加氢脱硫性能的变化。结果表明,EDTA改性后的催化剂加氢脱硫性能得到明显改善,但烯烃饱和程度加剧,辛烷值损失严重,未能达到脱硫保辛烷值的目的；改变工艺条件,催化剂的烯烃饱和活性和加氢脱硫活性不能达到一个好的平衡,无法实现高效选择性加氢脱硫。要达到高选择性的加氢脱硫,还必须进一步改善催化剂性能。更多还原

【Abstract】 To protect the environment, the motor fuel compositions have been limited strictly to reduce emissions of harmful substances in the world. Production of low sulfur, high reaserch octane number(RON) clean gasoline has become an important issue of refining technological progress. Fluid catalytic cracking(FCC) gasoline of the total gasoline usually accounts for more than 70% in China. The process using traditional hydrodesulfurization catalyst will lead to the serious saturation of olefins in FCC gasoline, causing significant loss of RON. Therefore, our country needs urgently to develop high selective hydrodesulfurization catalyst.Nano-HZSM-5 has a unique pore structure and larger surface area, which can enhance the dispersion of active components and the loading amount and improve the selectivity and yield of target product in the reaction. In this article, nano-HZSM-5 zeolites had been modified by hydrothermal treatment, the physical properties of the modified catalysts were characterized. On this basis, the selective hydrodesulfurization performance of HZSM-5 zeolites after hydrothermal treatment and loading active component Co, Mo were investigated for FCC gasoline upgrading. The hydrodesulfurization performance of the catalysts for thiophene was compared with that of benzothiophene. Finally, the selective hydrodesulfurization performance of CoMo/HZSM-5 catalysts modified with chelating agent EDTA was also studied. Conclusions from the experiments were summarized mainly as follow:1. With hydrothermal treatment temperature increased, the surface area and the acid amount of the nano-HZSM-5 catalyst decreased and the weak acid strength and pore volume changed little. HZSM-5 zeolite maintained a good MFI topology after hydrothermal treatment.2. The selective hydrodesulfurization performance of HZSM-5 zeolites after hydrothermal treatment and loading active component Co, Mo were investigated in the full range FCC gasoline. The results showed that the hydrodesulfurization activity of modified catalysts was inhibited, but olefin saturation activity was improved with hydrothermal treatment temperature increased. As reaction temperature increased, the desulfurization activity and olefin saturation of the catalyst increased; The increase of WHSV was helpful for keeping olefin contents, but not beneficial to the desulfurization activity of the catalysts. The modified catalyst after hydrothermal treatment at 600℃and loading active component Co, Mo had better selective hydrodesulfurization performance than other catalysts, which the composition of reaction product is essentially as the same as raw oil and its RON loss was less than 1.The HZSM-5 catalysts after hydrothermal treatment and loading active component Co, Mo had good desulfurization activity for thiophene and benzothiophene. However, when the hydrothermal treatment temperature was over 700℃, the catalytic activity for them declined seriously. The desulfurization activity of these serial catalysts for benzothiophene is better than that of thiophene.3. The selective hydrodesulfurization performance of the CoMo/HZSM-5 catalys modified with chelating agent EDTA was investigated in FCC gasoline upgrading. The results showed that the catalyst after modified by EDTA can not meet the purpose of desulfurization and maintaining RON of FCC gasoline for its desulfurization activity significantly improved, but the olefin saturation degree aggravated and its RON loss was serious. The olefin saturation activity and HDS activity can not reach a good balance with the change of process conditions. To achieve high selectivity hydrodesulfurization performance, the catalytic activity of the catalysts must be further improved.更多还原