加氢催化剂器外预硫化技术研究

近年来,随着加氢催化剂器外预硫化技术的发展,硫化剂及硫化剂负载工艺条件的研究不断深入。本研究采用一步浸渍法,重点考察了硫化剂加入量、浸渍温度、浸渍时间对加氢催化剂浸渍效果的影响,优化出与器内硫化催化剂活性至少相当的器外预硫化技术的工艺条件。     

器外预硫化加氢催化剂的研究

不同的硫化剂与催化剂混合制备器外预硫化加氢催化剂,以考察催化剂的集中放热现象和集中耗氢现象。结果表明:200℃左右氮气氛围的条件下催化剂中的活性组分与硫化剂结合生成有机氧硫化物。适当比例混合的硫化剂与催化剂制成的器外预硫化催化剂,能有效的缓解集中放热和集中耗氢现象;有效的避免了床层飞温和氢气压力骤降问题。并且制成的器外预硫化催化剂拥有很高的持硫率和活性。     

器外预硫化型加氢催化剂的制备与性能研究

以Ni和Mo为活性组分,Al2O3为载体,制备了氧化型Ni-Mo/Al2O3催化剂O-1,在此基础上,以自制的水溶性复合硫化物为硫化剂,制备了器外预硫化型Ni-Mo/Al2O3催化剂S-1,通过BET、XRD和HRTEM等手段对2种催化剂的物化性质做了表征,并对比考察了催化剂对劣质石脑油加氢脱硫脱氮的性能。结果表明：器外预硫化型催化剂对劣质石脑油加氢脱硫脱氮的性能与氧化型催化剂接近,其加氢石脑油产品的硫氮含量均低于0.5 μg/g,这说明采用水溶性复合硫化物为硫化剂可以对氧化型催化剂进行有效地器外预硫化。     

器外预硫化耐硫变换催化剂的研制

探讨了器外预硫化耐硫变换催化剂的制备方法,研究了不同硫化剂以及硫化剂的加入方式、浸渍方法、硫化温度和时间对催化剂活性的影响,同时考察了该催化剂的储存性能。结果表明,以本实验采用的单质硫、有机多硫化物A和助剂K2溶于溶剂D1作为硫化剂,并在120℃时以共浸法浸渍4h制备的器外预硫化耐硫变换催化剂,在密闭条件下储存性能较为稳定,活性优于传统的固定床硫化的催化剂。     

器外预硫化加氢催化剂放热研究

将氧化态NiMo/Al2O3加氢催化剂器外预硫化,然后使用TA-MS、HPDSC、XRD进行表征,以考察催化剂在惰性气体下的放热行为及组分相应的变化.结果表明,硫化剂与催化剂中的活性组分在惰性气体氛围加热的条件下结合成有机金属氧硫化物,适当提高加热温度能显著提高器外预硫化催化剂的活性和持硫率.但温度过高,有机金属氧硫化物分解,催化剂的活性降低.有机金属氧硫化物的生成是器外预硫化效果的关键,本实验制备的器外预硫化催化剂具有良好的活性.     

加氢催化剂膨胀床器外预硫化工艺研究

采用膨胀床对加氢催化剂进行了器外预硫化研究。研究了预硫化工艺条件对加氢催化剂硫化度α的影响。结果表明,α随着硫化温度的增加而增加,但是,烯烃加氢活性在370 ℃时出现最大值。吡啶-TPD表征结果证明,硫化温度高,催化剂的酸性强,而酸性影响催化剂加氢活性。对膨胀床和器内CS₂硫化两种方法预硫化的催化剂进行烯烃加氢活性对比,发现膨胀床器外预硫化催化剂α值高、加氢活性好。器外预硫化的适宜工艺条件:硫化时间10 t₀,硫化温度370 ℃,床层膨胀率12％。硫化和还原同时进行的催化剂活性高。     

加氢催化剂的器外预硫化技术开发

分别用含硫有机物和元素硫对加氢催化剂进行器外预硫化技术的研究.实验室评价表明,二种器外预硫化催化剂都达到器内预硫化的活性,用含硫有机物作预硫化剂制得的器外预硫化催化剂进行了工业化试验,开工过程反应平稳未出现飞温,催化剂活性达到了器内预硫化的活性水平.     

器外预硫化催化剂加氢脱酸性能研究

为探索器内硫化与器外预硫化催化剂的催化活性,采用等体积浸渍法制备同一批次镍-钨氧化态催化剂,分别采用器内硫化与器外预硫化得到3种不同的催化剂,考察3种新鲜催化剂的物化性质、催化活性和使用后催化剂的物化性质。结果表明：随着催化剂上硫化物负载量增加,预硫化催化剂的表观密度增加,比表面积、孔容、平均孔径均降低,同时预硫化催化剂在各个孔径范围内的分布均降低;3种催化剂中高负载硫的器外预硫化催化剂上W ⁴⁺态金属和NiWS活性相原子分数最高,器内硫化催化剂次之,低负载硫的器外预硫化催化剂最低;在反应压力为3.0 MPa、空速为1.0 h ^-1、氢油体积比为400∶1条件下,以绥中常二线、减三线馏分油为原料在不同反应温度下评价催化剂的活性,高负载硫的器外预硫化催化剂的脱酸、脱硫、脱氮活性最高,器内硫化催化剂次之,低负载硫的器外预硫化催化剂的催化活性最差。     

加氢催化剂预硫化技术现状

介绍了器内预硫化和器外预硫化两种加氢催化剂预硫化技术,阐述了催化剂预硫化反应原理,并对硫化剂进行了比选,讨论了干法硫化和湿法硫化两种器内预硫化技术的特点。干法硫化技术主要适用于分子筛含量较高的加氢催化剂,而湿法硫化技术主要适用于加氢精制类催化剂。通过对比器内预硫化与器外预硫化技术的优缺点,并对国内外器外预硫化技术研究现状进行了综述,认为器外预硫化技术具有开工时间短、环境污染小等优点,必将逐渐替代现有的器内预硫化技术成为加氢催化剂预硫化的主要技术,将是加氢催化剂预硫化技术未来研究发展的方向。     

焦炉煤气制液化天然气加氢催化剂的硫化与应用

介绍了在焦炉煤气制液化天然气中，针对焦炉煤气精脱硫的两级加氢反应、两级精脱硫工艺，着重介绍了加氢催化剂的硫化及脱硫工艺原理、硫化剂的选择及硫化详细过程和工艺操作要点。     

钼/活性炭渣油加氢催化剂的硫化

钼/活性炭催化剂是一种新型渣油加氢催化剂,其硫化效果直接决定着催化剂的活性和稳定性。实验考察了硫化条件对钼/活性炭催化剂（Mo/AC）硫化度的影响,运用X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电镜（TEM）等手段对硫化态催化剂进行了表征。结果表明,以二硫化碳为硫化剂,正十六烷为硫化介质,在硫化温度350 ℃,硫化时间3 h,氢气初压6 MPa条件下催化剂硫化度为85%,活性相MoS2堆垛结构为4～6层,晶片长度为6～10 nm,分布比较均匀,具有良好的加氢活性。     

Activity and sulfidation behavior of the CoMo/Al2O3 hydrotreating catalyst: The effect of drying conditions

The influence of drying condition of the CoMo/Al₂O₃ catalyst prepared using citric acid as a chelating agent on the sulfidation behavior and on the catalytic activity to hydrodesulfurization of straight-run gas oil (SRGO) was investigated. The catalysts dried at 110, 220, 300 and 400 °C were studied using Raman, IRS and DTG techniques. The sulfidation behavior with straight-run gas oil spiked with dimethyldisulfide (DMDS) was investigated using gas chromatography (GC) with a thermal conductivity detector and GC with an atomic-emission detector for analysis of gas and the liquid phases, respectively. It was shown that the sulfidation behavior of the catalysts prepared using the chelating agents depends on the drying condition: the lower drying temperature, the later DMDS conversion and oxide precursor sulfidation starts. A higher activity in SRGO desulfurization was obtained with catalysts dried at 110 and 220 °C. This phenomenon was accounted for by the stabilization effect of chelating agent that retards precursor sulfiding but provides favorably the formation of active CoMoS phase and achieving the highest activity.     

Effect of sulfidation process on catalytic performance over unsupported Ni-Mo-W hydrotreating catalysts

Oxidic unsupported Ni-Mo-W catalysts were chosen to elucidate the effect of sulfidation conditions on the catalytic performance. The catalysts were sulfided in situ by using dimethyl sulfide as sulfiding agent. The relationships between the time needed for sulfidation and the sulfiding conditions were studied by GC-analysis method. Straight-run gas oil with high sulfur and nitrogen content was used to evaluate the hydrotreating performance. The oxidic catalyst precursors and sulfided catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). With increasing sulfiding liquid hourly space velocity (LHSV) of the sulfiding agent, the reaction time necessary for the sulfidation decreased, while the activity of the catalyst increased significantly. The higher catalytic activity might be due to the MoS₂/WS₂ slabs with shorter length and higher stacking number, which might contribute to the catalyst with more active sites. Sulfiding at 330 °C took the longest sulfidation time, while the catalytic activity was also the highest after sulfiding at this temperature. Furthermore, within a certain range, the sulfidation pressure had no evident effect on the catalytic behavior or activity. The purpose of this work was to provide a basis for actual production and a reference for further research.     

焦炉气加氢催化剂及净化工艺的开发

介绍了适合于焦炉气加氢催化剂及净化工艺的研究实验结果,实验表明,JT-1及JT-8型加氢催化剂均可适用于含高浓度CO和CO2气氛下原料气的加氢净化,且净化度高,副反应小,并满足以焦炉气为原料的甲醇厂的原料净化要求,可将原料气中硫化物脱除至总硫体积分数<0.1×10-6。     

Study of accelerated deactivation of hydrotreating catalysts by vanadium impregnation method

The main causes of catalysts deactivation for hydrotreating are coking and metals deposition. In this present work, accelerated deactivation of hydrotreating catalysts was studied. In this respect, vanadium which is deposited with nickel during hydrotreating reaction was impregnated into the fresh hydrotreating catalyst. Different percentage of vanadium was impregnated and their hydrodemetalization (HDM) and hydrodesulfurization (HDS) activities were studied in bench-scale reactor of heavy crude oil. Accelerated deactivations for both HDM and HDS were observed on vanadium impregnated catalysts. The rate of HDS deactivation was faster than that of HDM reaction. The rapid deactivation of HDS may be due to the coverage of active sites by impregnated vanadium atom. The deactivation is slower when the V loading is low; but above 10 wt% loading a rapid deactivation is observed. A comparison of deactivation is made in between normal deactivation and the deactivation by vanadium impregnation. It was found that deactivation by vanadium impregnation is lower than that of normal deactivation. It suggests that at initial stage the formation of coke causes deactivation of the catalyst whereas at later stage when metals sulfides deposition is quite high, these sulfides take part in deactivation.     

焦炉煤气加氢脱硫催化剂的试验及应用

焦炉煤气生产甲醇的技术关键之一是其深度净化技术,有机硫的加氢净化精度是转化催化剂和甲醇催化剂长周期稳定运行的关键。介绍了焦炉煤气加氢净化催化剂的组成、使用条件及批试验结果,以及研制的JT-8和JT-1型焦炉煤气两级加氢催化剂的工业应用结果,可使出口总硫小于0.1×10-6,达到工艺设计要求,具有较好的社会效益和经济效益。     

有机硫加氢(HDS)催化剂的预硫化

预硫化是HDS、HDN过程中决定催化剂活性的最重要环节。在分析催化剂硫化反应原理、硫化条件、硫化与还原的关系等基础上进一步指出了在工业过程中预硫化的一些原则。     

Highly active sulfided CoMo catalyst on nano-structured TiO2

High surface area (>300 m² g⁻¹) nano-structured TiO₂ oxides (ns-T) were used as CoMo hydrodesulfurization catalyst support. Cylindrical extrudates were impregnated by incipient wetness with Mo (2.8 Mo at. nm⁻²) and Co (atomic ratio Co/(Co + Mo) = 0.3). Characterization of impregnated precursors was carried out by N₂ physisorption, XRD and atomic absorption and laser-Raman spectroscopies. Sulfided catalysts (400 °C, H₂S/H₂) were studied by X-ray photoelectronic spectroscopy. As indicated by XRD and after various preparation steps (extrusion, Mo and Co impregnation and sulfiding) the nano-structured material was well preserved. XPS analyses showed that Co and Mo dispersion over the ns-T support was much higher than that on alumina. Very high surface S concentration suggested that even ns-T was partially sulfided during catalyst activation. Dibenzothiophene hydrodesulfurization activity (5.73 MPa, 320 °C, n-hexadecane as solvent) of CoMo/ns-T was two-fold to that of an alumina-supported commercial CoMo catalyst. The improvement was even more remarkable in intrinsic pseudo kinetic constant basis. No important differences in selectivity over the catalysts supported on either Al₂O₃ or ns-T were observed, where direct desulfurization to biphenyl was favored. Both Mo dispersion and sulfidability were enhanced on the ns-T support where Mo⁴⁺ fraction was notably increased (100%) as to that found on CoMo/Al₂O₃.     

Deactivation control through accelerated precoking for the CoMo/γAl<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts in thiophene hydrodesulfurization

Information on the degree of deactivation is very important for predicting catalyst life, from which the catalyst design could be further improved. The CoMo/Al₂O₃ catalysts, used for the hydrodesulfurization of light oil, are known to have a commercial operation time of around two years. Our goal was to establish the accelerated precoking conditions for obtaining a desired degree of deactivation for CoMo/Al₂O₃ catalysts. The effect of coking temperature on the catalytic activity for thiophene hydrodesulfurization was investigated for three coke precursors. Precoking with heavier precursors resulted in higher coke content and higher aromaticity as expected, i.e., in order of anthracene>naphthalene>cyclohexene. It is suggested that the established conditions of precoking for the commercial catalysts could provide a quantitive reference for evaluating the lifetime of any commercial catalysts.