【作者】 张学军；

【导师】 王宗贤；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2008， 博士

【摘要】 石油资源的短缺和环保法规的日益严格,使石油产品的有效利用和清洁生产倍受关注。加氢裂化作为重油高效催化转化和唯一可直接生产符合欧IV清洁油品标准的加氢技术,开发和应用加氢裂化多产优质中间馏分油（煤油和柴油）型催化剂,一直是石油化工领域的热点之一。目前制备具有适宜酸性、多级孔道结构分子筛和高活性加氢组分是提高加氢裂化催化剂重油转化能力、活性和中间馏分油选择性的关键。本文通过吸收分子筛改性、加氢活性相及介孔材料的最新研究结果,致力于这些关键问题的解决,旨在形成加氢裂化多产中间馏分油分子筛和催化剂“量体裁衣”设计。论文着重研究了大孔改性Y分子筛、催化新材料介孔Al-SBA-15/Y分子筛复合材料的制备及重油加氢裂化性能。系统考察了酸性载体、W-Ni加氢金属组分对催化剂表面性质和催化性能的影响,研究了W-Ni系加氢裂化催化剂的加氢活性相,考察了加氢裂化多产中间馏分油催化剂的重油加氢裂化性能及中间馏分油选择性影响因素。并采用X-射线衍射（XRD）、氮气吸附、透射电镜（TEM）、傅立叶变换红外光谱（FT-IR）、热重-差热分析（TG-DTG）等表征手段,对分子筛和催化剂的结构和性质进行了分析。主要内容包括:详细研究了化学和水热处理过程对Y分子筛骨架结构、表面性质和孔结构的影响,探讨了不同化学-水热处理方法Y分子筛二次孔的形成机理和形成规律,采用XRD、氮气吸附、TEM、FT-IR等技术对Y分子筛改性后的产物进行了详细的表征。采用新型化学-水热处理方法制备出了总孔容为0.688mL/g,二次孔孔容为0.548ml/g的大孔改性Y分子筛。以大庆减压馏分油为原料、>350℃馏分油单程转化率为75v%,考察了以大孔改性Y分子筛为载体加氢裂化催化剂的重油加氢裂化性能。研究结果表明,以新型化学-水热处理方法制备出的大孔改性Y分子筛为主要裂化组分的加氢裂化催化剂,具有优异的催化性能,生产中间馏分油的选择性高达80.82%,中间馏分油收率高达64.86 wt%。在中等酸性条件下,采用两步法制备了介孔Al-SBA-15/Y分子筛系列复合材料,考察了复合分子筛材料的酸性稳定性,初步探讨了复合分子筛材料的形成机理,并用不同尺度的异丙苯和三异丙探针分子考察了分子筛的酸催化反应性能,同时考察了以介孔Al-SBA-15/Y分子筛为载体加氢裂化催化剂的重油加氢裂化性能。研究结果表明,新型微孔-介孔Al-SBA-15/Y复合分子筛加氢裂化催化剂,同时具备了高水热稳定SBA-15分子筛的均一介孔结构和微孔Y分子筛的酸性特点,在不同尺码探针分子的酸催化反应中,表现出较高的裂化性能;在重油加氢裂化反应中,对大分子烃显示出优异的催化转化能力,可显著降低尾油的BMCI值。以大孔改性Y分子筛或介孔Al-SBA-15/Y分子筛复合材料与γ-Al₂O₃、无定形硅铝混合作为催化剂载体,Ni-W为加氢活性组分,考察了酸性组分、Ni/（Ni+W）原子比和助剂对催化剂表面性质和裂化性能的影响。制备了具有适宜酸性、孔结构和高加氢活性的加氢裂化多产中间馏分油催化剂,并用XRD、氮气吸附、SEM、FT-IR、NH₃-TPD等技术对催化剂进行了表征。结果表明,催化剂的酸类型以L酸中心为主,B酸中心较少,主要为弱酸和中强酸。催化剂中2～4nm的孔结构占催化剂总孔容的85%以上,并在2～4nm和4～10nm呈双峰分布。W-Ni加氢活性金属组分在加氢裂化催化剂上分散较好,W-Ni加氢活性金属组分的硫化物,在400～850℃（尤其是400～700℃）易还原。以大庆减压馏分油为原料、>350℃馏分油单程转化率为75v%,考察了加氢裂化多产中间馏分油催化剂的活性稳定性和耐氮性。研究结果表明,在1800hr活性稳定性试验中,加氢裂化多产中间馏分油催化剂的中间馏分油选择性大于82%,催化剂的失活速率小于0.013℃/天;在1000hr耐氮性考察试验中,催化剂中间馏分油选择性大于78%,具有很好的活性稳定性、耐氮性和重油加氢裂化性能。更多还原

【Abstract】 Petroleum resource shortage and recent strict environmental regulations have brought more attention to effective utilization of petroleum products and clean fuel processes and technologies. Hydrocracking is a kind of effective catalytic process for heavy oil conversion and the only technology that can produce clean fuels to meet the Euro IV emission standard. The development and utilization of hydrocracking catalysts for maximizing high quality middle distillates is one of the hot topics in petrochemical industry. The key issue for improving heavy oil conversion ability, activity and middle distillate selectivity of catalysts is to develop the hydrocracking catalysts with suitable acidity, hierachical pore structure zeolites and higher hydrogenation activity components. Based on the latest research results of zeolite modification, hydrogenation active phase characterization and mesoporous material synthesis, the target of this thesis is to achieve a tailored design for hydrocracking catalysts producing maximum middle distillates. Modified large pore Y zeolite and novel catalytic material mesoporous Al-SBA-15/Y zeolite composites were first prepared. Then heavy oil hydrocracking performance of both zeolites and the influences of an acid support and the W-Ni hydrogenation active components on catalyst surface properties and catalytic performance were studied. The W-Ni hydrogenation active phases of catalysts and the influential factors on heavy oil hydrocracking performance and middle distillate selectivity of hydrocracking catalysts were also investigated. Structure and properties of zeolites and catalysts were characterized by XRD, N2 adsorption, TEM, FT-IR, and TG-DTG. The main results are as follows:The effects of chemical and hydrothermal treatment methods on Y zeolite framework structure, surface acidity and pore structure during large pore Y zeolite modification procedures were studied. The forming mechanism and forming rules of secondary pores in Y zeolites were discussed. The modified products were then characterized by XRD, N2 adsorption, TEM and FT-IR techniques. Modified large pore Y zeolites with total pore volume of 0.688mL/g and mesopore volume of 0.548mL/g were prepared by novel chemical-hydrothermal treatment methods. Heavy oil hydrocracking performance of the catalyst using modified large pore Y zeolites as support was evaluated by using Daqing VGO (Vaccum Gas Oil) as feedstocks in a pilot hydrogenation unit at a conversion of 75v%. The hydrocracking performance evaluation results revealed that the catalyst using modified large pore Y zeolite prepared by novel method achieved a middle distillate selectivity of 80.82% and a middle distillate yield of 64.86wt%, which showed that the catalyst had more excellent catalytic performance than that using modified Y zeolite prepared by traditional method.Mesoporous Al-SBA-15/Yzeolite composites were prepared by a two-step method in moderate acid media and their forming mechanism was discussed. Examined were their acidity stability under different hydrothermal treatment processes, acid catalysis reaction performance using probe molecules of different size, and the catalytic performance of the catalyst using as-prepared materials for hydrocracking heavy oil. The forming mechanism of Al-SBA-15/Yzeolite composites was investigated. Mesoporous Al-SBA-15/Yzeolite composites were characterized by N2 adsorption, XRD and TEM techniques. The catalytic cracking reaction results revealed that Y/Al-SBA-15 composites possessed high catalytic activities in the cracking of both small (cumene) and large molecules (TIPB), which might be related to some large pores and strong acidic sites in the Y/Al-SBA-15 composites. More importantly, for the hydrocracking of vacuum gas oils, the lower BMCI value of the tail oil showed that Y/Al-SBA-15 composite catalysts have significantly superior performance on the conversion of large hydrocarbon molecules.Hydrocracking catalysts for maximizing middle distillates were prepared using modified large pore Y zeolite or mesoporous Al-SBA-15/ Y composites as main acid components,γ-Al2O3 and amorphous silica-alumina as carrier, and Ni-W as catalytic active phases. The effects of acid components, Ni/( Ni+W ) atomic ratio and promoters on catalyst surface properties and hydrogenation activity were examined and characterized. Characterization results of hydrocracking catalysts for maximizing middle distillates showed that the catalyst acidity types were mainly L acid sites with few B acid sites by Py-IR, and more weak acid sites and less strong acid sites at 150-400℃by NH3-TPD. The proportion of catalyst pore size of 2-4 nm was more than 85%, and the pore size exhibited bimodal distribution at 2-4 nm and 4-10 nm by N2 adsorption. W-Ni hydrogenation active components showed excellent dispersion on the hydrocracking catalyst by XRD and SEM-EDS. Hydrogenation active phases were W-Ni sulfide species, which were the reduction phases at 400 - 850oC (especially 400 - 700oC) by O2-TG characterization.The catalyst performance was evaluated by both 1800hr activity and stability test and 1000hr nitrogen tolerance test using Daqing VGO as feedstocks in the pilot hydrogenation unit at a conversion of 75v%. The deactivation rate of the catalyst was 0.013℃/day, and middle distillate selectivity was over 82% and 78% respectively, showing the catalyst’s good activity and stability, as well as good nitrogen tolerance performance and heavy oil catalytic performance.更多还原