柠檬酸引入方式对CoMo/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用改进溶胶-凝胶法制备的TiO_2-Al_2O_3作复合载体,制备不同柠檬酸引入方式改性的CoMo/TiO_2-Al_2O_3加氢脱硫催化剂。利用低温N_2吸附-脱附、XRD、SEM和H_2-TPR等对催化剂进行表征,并采用固定床反应器对催化剂加氢脱硫性能进行评价。结果表明,后处理法制备的催化剂比表面积相对较大,孔道结构较好,活性金属组分以无定形形态均匀分散在载体表面,一定程度上减弱了其与载体间的相互作用;该催化剂可以延缓Co硫化,并且络合生成较多易于硫化还原的Mo物种,利于MoS_2在催化剂表面的堆叠,生成更多的Co-Mo-S(Ⅱ)活性相,因而相应的CoMo催化剂对噻吩加氢脱硫转化率显著提高。     

改性Ni/Al_2O_3催化蒽醌加氢反应的研究

以Al_2O_3为载体,La、Ce或Zr为改性剂,Ni作为活性组分,制备了一系列改性的Ni/Al_2O_3催化剂,并通过蒽醌加氢反应系统地评价了催化剂的反应活性,发现La、Ce改性的催化剂,其加氢活性得到显著的增加。活性最好的催化剂为La_5-Ni_(40)/Al_2O_3,氢效为3.96g·L~(-1)。采用XRD、H_2-TPR、BET等方法对La_5-Ni_(40)/Al_2O_3的表面结构进行了一定的表征分析,发现加入La元素能促进活性组分Ni的分散,提升了其加氢性能。实验得出催化剂的最佳焙烧温度和还原温度分别为600℃和550℃,既保证了催化剂具有适当的孔道结构,同时也改善了活性组分Ni的分散度。     

噻吩硫化物催化加氢脱硫研究进展

以焦炉煤气中噻吩转化为切入点,综述了噻吩加氢脱硫反应的催化机理和催化剂研究进展,着重概述了催化剂中活性组分、载体和助剂等对催化剂催化性能的影响。噻吩加氢脱硫反应的催化机理中Co-Mo-S模型被更多人接受。过渡金属及其氮化物、碳化物与磷化物因其廉价与高活性而被广泛用作催化剂的活性组分,复合载体因克服单一载体缺陷更具应用前景,展望了焦炉煤气二级加氢工艺中噻吩加氢脱硫催化剂的发展方向。     

Ni2P/TiO2的制备、表征及其加氢脱硫反应性能

利用程序升温还原方法合成了Ni2P／TiO2催化剂，采用H2-TPR、XRD、XPS等技术对样品的结构和性质进行了表征，研究了催化剂对噻吩的常压加氢脱硫反应性能。结果表明，在TiO2为载体的负载型催化剂上，Ni2P为主要活性相，无明显的单质Ni相；与Ni2P／SiO2相比，Ni2P／TiO2催化剂对噻吩常压加氢脱硫反应有较高的转化率以及良好的稳定性，噻吩稳定转化率达到了36％左右。     

磷对MoNi/γ-Al2O3加氢处理催化剂性能的影响

采用分步浸渍法制备了不同磷含量的MoNiP/γ- Al2O3加氢预处理催化剂.采用TPR、HRTEM和XPS技术对催化剂进行表征,以噻吩和喹啉为模型化合物,考察催化剂的加氢脱硫和加氢脱氮活性.结果表明,磷与活性组分相互作用形成新Mo - Ni -O-P相,增加了低温还原峰面积,使还原峰峰顶温度升高.磷的引入提高了活性金属组分的硫化度,使催化剂的MoS2片晶层数更多,片层长度更长,有助于噻吩和喹啉克服空间位阻吸附在活性中心位上;但过量磷会使MoS2发生团聚,降低活性中心位数目,不利于提高催化剂活性.添加适量磷对催化剂表面和活性相进行有限度的改变,使催化剂具有最佳的脱硫和脱氮活性.     

Au-Pd/TiO2-Al2O3催化剂的加氢脱硫性能研究

采用溶胶凝胶(sol-ge1)、共沉淀(CP)和沉积沉淀(DP)法制备了介孔TiO2-Al2O3复合载体(简称复合载体);以噻吩加氢脱硫(HDS)为探针反应,考察了复合载体制备条件对负载型Au-Pd催化剂噻吩HDS反应性能的影响;并采用X射线衍射进行表征.结果表明,不同温度焙烧的TiO2一Al2O3复合载体都具有介孔结构,其中773 K焙烧制得的TiO2一Al2O3复合载体的比表面积和孔容较大,B酸中心较多;以乙醇还原的Au-Pd/TiO2-Al2O3催化剂的加氢脱硫活性较好.乙醇还原的Au-Pd/TiO2-Al2O3催化剂中Au-Pd之间及活性组分与载体之间的相互作用较强,形成AuxPdy合金的晶粒较小,活性组分的分散度和活性表面积较大,反应活化能较低,这些均有利于催化剂活性的提高.     

磷对MoNi/γ-Al2O3加氢处理催化剂性能的影响

采用分步浸渍法制备了不同磷含量的MoNiP/γ-Al₂O₃加氢预处理催化剂。采用TPR、HRTEM和XPS技术对催化剂进行表征,以噻吩和喹啉为模型化合物,考察催化剂的加氢脱硫和加氢脱氮活性。结果表明,磷与活性组分相互作用形成新Mo-Ni-O-P相,增加了低温还原峰面积,使还原峰峰顶温度升高。磷的引入提高了活性金属组分的硫化度,使催化剂的MoS₂片晶层数更多,片层长度更长,有助于噻吩和喹啉克服空间位阻吸附在活性中心位上;但过量磷会使MoS₂发生团聚,降低活性中心位数目,不利于提高催化剂活性。添加适量磷对催化剂表面和活性相进行有限度的改变,使催化剂具有最佳的脱硫和脱氮活性。     

MoS2基催化剂加氢脱硫反应活性相和作用机理研究进展

加氢脱硫工艺在清洁油品生产过程中发挥着重要作用，而MoS₂基催化剂是加氢脱硫的主要催化剂，因此对MoS₂基催化剂活性相和催化反应机理的深入研究有助于从原子层面上对催化剂进行优化设计。本文首先介绍了国内外有关MoS₂基催化剂活性相形貌结构的研究，着重探讨了硫化气氛、助剂和载体类型对活性相结构的影响，以及现有表征技术在MoS₂基催化剂活性相形貌结构研究中所面临的挑战，总结了不同条件下活性相的微观结构特征；同时，从MoS₂基催化剂的活性相组成和结构角度分析了噻吩的加氢脱硫机理，发现了加氢脱硫活性与催化剂微观结构之间的紧密联系；最后展望了理论计算在设计和开发高效加氢脱硫催化剂过程中的重要指导作用。     

碳基载体石油馏分加氢脱硫催化剂研究进展

总结了以活性炭、碳纳米管、介孔碳、石墨烯等碳基材料为载体的加氢脱硫催化剂的研究进展。与常规Al₂O₃基载体催化剂相比,碳基载体催化剂比表面积大,活性金属的分散性好,活性金属-碳表面间的相互作用弱,有利于形成高活性的Ⅱ类活性相。以二苯并噻吩及4,6-二甲基二苯并噻吩等含硫有机物为处理对象,碳基载体加氢脱硫催化剂总体上具有比Al₂O₃基载体催化剂更高的加氢脱硫催化活性。为满足碳基载体加氢脱硫催化剂的工业应用要求,需要降低制备成本,并针对催化体系的特点进行孔结构优化及表面改性,同时,还需要加强对碳基加氢催化剂加氢脱硫反应机理和动力学方面的研究,以促进催化剂与工艺技术的进步。     

CoMo/Al_2O_3-SiO_2催化剂原位红外光谱研究

采用原位红外光谱技术,以CO作为探针分子研究了加氢脱硫CoMo/Al2O3-SiO2催化剂的活性吸附位的变化规律。原位硫化温度范围为300~550℃,获得了CoMo/Al2O3-SiO2催化剂的MoS(2110cm2-1)和CoMoS(2070cm-1)活性相在增加硫化温度过程中的转变规律。在CoMo/Al2O3-SiO2催化剂中,当载体中SiO2含量逐渐增加时,能够显著改变催化剂活性相的相对强度变化,表明载体中加入适量的SiO2能够显著改变加氢脱硫CoMo/Al2O3-SiO2催化剂的载体与活性金属(Co和Mo)的相互作用,从而提高金属在加氢催化剂载体上的分散性能,产生更多活性吸附位。     

TiO2-coated on Al2O3 support prepared by the CVD method for HDS catalysts

Mo---Co or Mo---Ni catalysts supported on alumina (Al₂O₃) have been widely used for hydrodesulfurization (HDS) of heavy petroleum fractions. In order to enhance the catalytic activities for HDS, a composite type support (TiO₂-Al₂O₃) prepared by the chemical vapor deposition (CVD) method has been studied. We found that Mo catalyst supported on TiO₂-Al₂O₃ showed much higher catalytic activity for HDS of dibenzothiophene derivatives than the catalysts supported on Al₂O₃.     

Ti-modified alumina supports prepared by sol–gel method used for deep HDS catalysts

The typical physico-chemical properties and their hydrodesulfurization activities of NiMo/TiO₂-Al₂O₃ series catalysts with different TiO₂ loadings were studied. The catalysts were evaluated with a blend of two kinds of commercially available diesels in a micro-reactor unit. Many techniques including N₂-adsorption, UV–vis DRS, XRD, FT-Raman, TPR, pyridine FT-IR and DRIFT were used to characterize the surface and structural properties of TiO₂-Al₂O₃ binary oxide supports and the NiMo/TiO₂-Al₂O₃ catalysts. The samples prepared by sol–gel method possessed large specific surface areas, pore volumes and large average pore sizes that were suitable for the high dispersion of nickel and molybdenum active components. UV–vis DRS, XRD and FT-Raman results indicated that the presence of anatase TiO₂ species facilitated the formation of coordinatively unsaturated sites (CUS) or sulfur vacancies, and also promoted high dispersion of Mo active phase on the catalyst surfaces. DRIFT spectra of NO adsorbed on the pure MoS₂ and the catalysts with TiO₂ loadings of 15 and 30% showed that NiMo/TiO₂-Al₂O₃ catalysts possessed more CUS than that of pure MoS₂. HDS efficiencies and the above characterization results confirmed that the incorporation of TiO₂ into Al₂O₃ could adjust the interaction between support and active metals, enhanced the reducibility of molybdenum and thus resulted in the high activity of HDS reaction.     

Support Effects on Thiophene Hydrodesulfurization over Co-Mo-Ni/Al2O3 and Co-Mo-Ni/TiO2-Al2O3 Catalysts

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.     

焙烧及还原条件对Ni2P/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用溶胶-凝胶法制备了TiO₂-Al₂O₃复合载体, 以柠檬酸(CA)为络合剂采用浸渍法制备了Ni₂P负载的TiO₂-Al₂O₃复合载体催化剂, 并用 X 射线衍射(XRD)、N₂吸附比表面积(BET)测定技术对催化剂的结构和性质进行了表征, 考察了载体焙烧温度、催化剂焙烧温度、还原温度、还原压力对其进行的二苯并噻吩(DBT)加氢脱硫(HDS)性能的影响。结果表明, 升高载体焙烧温度有利于催化剂表面上活性物种的分散, 但焙烧温度过高会导致催化剂烧结, 适宜的载体焙烧温度为550℃。当还原温度为500～550℃时, 磷化镍主要以Ni₁₂P₅相形式存在, 且随着还原温度的升高, Ni₁₂P₅的衍射峰强度逐渐增强, 还原温度为700℃时, 可得到单一的Ni₂P物相。载体焙烧温度为550℃, 催化剂焙烧温度为500℃, 还原温度为700℃, 常压还原制备的Ni₂P/TiO₂-Al₂O₃催化剂具有最好的活性。在360℃、3.0MPa、氢油体积比500、液时体积空速2.0h^-1的条件下, 反应4h时, DBT转化率为99.5 %。     

制备条件对Ni2P/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用溶胶-凝胶法制备了TiO₂-Al₂O₃复合载体, 以柠檬酸为络合剂, 浸渍法制备了负载型Ni₂P/TiO₂-Al₂O₃催化剂前体, 程序升温H₂还原法制备了Ni₂P/TiO₂-Al₂O₃催化剂, 并用 X 射线衍射(XRD)、N₂吸附比表面积(BET)测定技术对催化剂的结构和性质进行了表征, 考察了浸渍方法、Ni/P摩尔比、Ni₂P负载量对其进行的二苯并噻吩(DBT)加氢脱硫(HDS)性能的影响。结果表明, 当Ni/P比低于1:1时, 能得到单一的Ni₂P物相;当Ni/P比为2:1时, 开始出现Ni₃P物相。采用Ni/P比为1:1、Ni₂P负载量为30%、采用共浸渍方法制备的Ni₂P/TiO₂-Al₂O₃催化剂具有最好的活性, 在360℃、3.0MPa、氢油比500 (体积比)、液时体积空速2.0h^-1的条件下反应4h时, 二苯并噻吩转化率为99.5%。     

Maya crude hydrodemetallization and hydrodesulfurization catalysts: An effect of TiO2 incorporation in Al2O3

Hydrotreating of Maya heavy crude oil over high specific surface area CoMo/TiO₂–Al₂O₃ oxide supported catalysts was studied in an integral reactor close to industrial practice. Activity studies were carried out with Maya crude hydrodesulfurization (HDS), hydrodemetallization (HDM), hydrodenitrogenation (HDN), and hydrodeasphaltenization (HDAs) reactions. The effect of support composition, the method of TiO₂ incorporation, and the catalyst deactivation are examined. Supported catalysts are characterized by BET specific surface area (SSA), pore volume (PV), pore size distribution (PSD), and atomic absorption. It has been found that sulfided catalysts showed a wide range of activity variation with TiO₂ incorporation into the alumina, which confirmed that molybdenum sulfided active phases strongly depend on the nature of support. The pore diameter and nature of the active site for HDS, HDM, HDN, and HDAs account for the influence of the large reactant molecules restricted diffusion into the pore, and/or the decrease in the number of active sites due to the MoS₂ phases buried with time-on-stream. The textural properties and hysteresis loop area of supported and spent catalysts indicated that catalysts were deactivated at the pore mouth due to the metal and carbon depositions. The atomic absorption results agreed well regarding the textural properties of spent catalysts. Thus, incorporation of TiO₂ with γ-Al₂O₃ alters the nature of active metal interaction with support, which may facilitate the dispersion of active phases on the support surface. Therefore, the TiO₂ counterpart plays a promoting role to HDS activity due to the favorable morphology of MoS₂ phases and metal support interaction.     

Catalytic activities of Co(Ni)Mo/TiO2–Al2O3 catalysts in gasoil and thiophene HDS and pyridine HDN: effect of the TiO2–Al2O3 composition

The effect of the TiO₂–Al₂O₃ mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO₂ into the support, and particularly over rich- and pure-TiO₂-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO₂. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO₂ content and large differences are observed between the catalysts supported on pure Al₂O₃ and pure TiO₂. In contrast, in the case of the thiophene test, the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al₂O₃- and pure TiO₂-based catalysts is relatively small and dependent on the H₂ pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H₂ partial pressure on the thiophene HDS, and on the effect of H₂S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking.     

Hydrodesulfurization of thiophene, dibenzothiophene and gas oil on various Co---Mo/TiO2-Al2O3 catalysts

Evaluation of Co---Mo catalysts prepared on various TiO₂-Al₂O₃ supports has been made for thiophene under atmospheric pressure, dibenzothiophene under high pressure and gasoil in a classical pilot plant. Comparison of activities indicates DBT as more representative of a real feedstock and the Co---Mo/TiO₂ (50%)-Al₂O₃ (50%) catalyst appears more active than the Co---Mo/Al₂O₃ sample toward HDS, HDN and hydrodearomatization.     

Synthesis of boron modified CoMo/Al2O3 catalyst under different heating methods and its gasoline hydrodesulfurization performance

Catalytic hydrodesulfurization (HDS) technique is widely used for clean gasoline production. However, traditional HDS catalyst (CoMo/γ-Al₂O₃) exhibits high hydrogenation performance of olefins (HYDO), resulting in the loss of gasoline octane number. To achieve high HDS/HYDO ratio, the key issue is to reduce the interaction between active metals and the support, therefore, in this research, the modified CoMo/γ-Al₂O₃ catalysts with various boron amounts were investigated under traditional or microwave heating. The effects of preparing methods as well as boron amounts on the active phase, acidic properties and HDS catalytic activities were examined. Results show that the modification, especially under microwave treatment, can significantly weaken the interaction between the active component and the support by enlarging the surface area and pore diameter, and reducing the acidity of the support. As a result, the stacking numbers of MoS₂ slabs were obviously improved by the modification and microwave treatment, contributing to higher edge/rim ratio, and resulting in higher HDS performance and selectivity to olefin.