乙二醇对NiMoP/Al2O3上二苯并噻吩加氢脱硫反应的影响

在NiMoP浸渍液中添加不同含量乙二醇,制备了一系列NiMoP/Al₂O₃催化剂,以二苯并噻吩为模型化合物,考察有机添加剂乙二醇对NiMoP/Al2O3催化剂加氢脱硫性能的影响。结果表明,乙二醇的加入显著提高催化剂的加氢脱硫性能,乙二醇中的羟基与Ni物质的量比为5∶1时,催化剂的加氢脱硫活性最高。乙二醇明显改善NiMoP/Al₂O₃催化剂的加氢性能。     

柠檬酸促进NiMoP催化剂上二苯并噻吩脱硫反应

车用燃油中的含硫化合物是大气主要污染物SOx的主要来源,降低燃油中该类化合物含量是减少汽车尾气SOx排放量的重要保障。燃油加氢脱硫技术是满足这一环保要求的最重要手段,技术的关键是研制高效加氢脱硫催化剂。通过在NiMoP浸渍液中添加不同含量的柠檬酸,制备一系列NiMoP/Al₂O₃催化剂,以二苯并噻吩为模型化合物,考察催化剂在制备过程中添加柠檬酸对NiMoP/Al₂O₃催化剂加氢脱硫性能的影响。结果表明,柠檬酸的加入能够提高催化剂的加氢脱硫性能,明显改善NiMoP/Al₂O₃催化剂的加氢性能。     

二苯并噻吩在Ni-Mo-W/γ-Al2O3上加氢脱硫机理的研究

研究了二苯并噻吩(DBT)在Ni-Mo-W/γ/Al2O3上的加氢脱硫(HDS)反应产物分布、可能的反应网络以及温度对产物分布的影响,揭示了HDS反应的可能机理.研究发现,DBT在Ni-Mo-W/γ-Al2O3上的HDS反应主要通过直接氢解路径和加氢路径进行,且后者的速率是前者的两倍.考察了芳烃(萘)、硫化物(硫化氢)和氮化物(喹啉)三种物质对DBT在Ni-Mo-W/γ-Al2O3催化剂上HDS反应的影响,结果表明,芳烃对反应有较弱的抑制作用,并且对两个路径的抑制作用相当.氮化物喹啉对反应有较强的抑制作用,其主要是通过竞争吸附作用抑制加氢路径.硫化物H2S对反应也有一定的抑制作用,其抑制直接氢解脱硫路径,但对加氢路径有一定的促进作用.     

NiW/Al2O3催化剂上二苯并噻吩的加氢脱硫宏观动力学

以二苯并噻吩(DBT)为含硫模型化合物,在实验室中压滴流床反应装置中研究了工业NiW/Al2O3催化剂RN-10上的加氢脱硫反应的动力学规律,详细考察了工艺条件:氢分压2.4～4.5 MPa、氢油比150～700(v/v)、液时空速(WHSV)15～60 h-1、反应温度300～380C对DBT转化率的影响.实验结果表明:提高反应温度可大大提高DBT的转化率,但反应温度达到330℃后,再提高反应温度,对DBT转化率的提升有限;在较高氢分压的条件下,DBT的转化率受氢分压的影响很小;当氢油比较小时,随着氢油比的提高,DBT转化率逐渐增加,但当氢油体积比大到一定程度(500)时,继续增大氢油比对脱硫率几乎没有影响.采用修正了的2级反应动力学模型对实验数据进行拟合,求得了二苯并噻吩加氢脱硫反应的表观活化能为75.95 kJ·mol-1.经检验,模型计算结果与实验结果能较好地吻合.     

二苯并噻吩的加氢脱硫反应研究综述

加氢脱硫是一种比较成熟的生产工艺,已在原油精制中普遍使用了多年.随着原油质量变差和更严格的环境法规的应用(例如,需要降低燃料中的硫含量),人们对该工艺不断更新.在实现燃料低硫水平方面,特别重要的是一类特殊化合物如:二苯并噻吩、4-甲基二苯并噻吩和4,6-二甲基二苯并噻吩所造成的受阻问题.在使用现有催化剂加氢精制时,二苯...     

MoO3/TiO2催化剂的二苯并噻吩加氢脱硫性能

以介孔氧化钛晶须成型材料为载体,通过浸渍法制备不同MoO3负载量的MoO3/TiO2加氢脱硫催化剂. XRD分析表明,介孔氧化钛晶须成型载体为纯锐钛矿相,MoO3负载量为7.2%(w)的催化剂未出现MoO3的衍射峰;BET分析显示,负载7.2%(w) MoO3后,氧化钛晶须成型载体的比表面积和孔容能保持原来的80%以上. 活性评价结果表明,未经预硫化的MoO3/TiO2催化剂直接应用于二苯并噻吩(DBT)加氢脱硫反应时,在温度280~300℃、氢分压2.0 MPa、体积空速4 h-1、H2/油体积比600的条件下,DBT转化率达100%. 将模型溶液中硫含量由400′10-6 g/g降至10′10-6 g/g以下,催化剂表现出较高的活性,且在一定条件下运行1000 h未出现失活迹象.     

TiO2载体特性对二苯并噻吩加氢脱硫性能的影响

以自制的大比表面介孔二氧化钛晶须作为加氢脱硫催化剂的载体,采用一步浸渍法制备了MoO₃-NiO/TiO₂催化剂,并用 X 射线衍射、N₂ 吸附-脱附、SEM、拉曼衍射等技术对载体和催化剂进行了表征,考察了TiO₂晶须材料作为二苯并噻吩(DBT)上加氢脱硫(HDS)催化剂载体的性能及优越性,并详细考察了不同TiO₂载体的晶型与比表面积对催化剂加氢脱硫反应活性的影响。结果表明,TiO₂介孔晶须具有较为活泼的锐钛矿相和晶须形貌,同时提供了大的比表面积和特殊的孔道结构,在温度280℃、氢分压2.0 MPa、氢/油体积比400、体积空速4 h^-1的温和条件下,DBT转化率即可接近100%。比表面积相近时,催化剂的脱硫效果依次为锐钛矿相>混晶>金红石相;同为锐钛矿相TiO₂载体,催化剂的脱硫效果随着比表面的增大而增加。     

CoMo/Al2O3-TiO2催化剂上加氢深度脱硫反应及其宏观动力学

采用气液固三相滴流床反应器,在反应温度(493~558) K,氢压(1.5~3.0) MPa和氢油体积比为200~800条件下,研究了苯并噻吩和二苯并噻吩模型化合物在钴钼基催化剂上加氢脱硫反应及其宏观动力学。根据幂函数型动力学方程,以全局通用算法结合马夸特算法对动力学参数进行估值,建立了与实验数据相吻合的柴油中含硫模型化合物的深度加氢脱硫反应动力学模型。其中,苯并噻吩的一级方程活化能为3.985×104 J·mol^-1,二苯并噻吩的二级方程的活化能为3.130×104 J·mol^-1。残差检验和统计学考察表明,模型计算结果和实验数据吻合良好。     

乙二醇对NiMoP/Al2O3催化剂上喹啉加氢脱氮反应的影响

燃料油中的含氮化合物是空气中NOx的主要来源,为了降低NOx排放,满足日益严格的排放标准,需要降低燃料油中含氮化合物含量,开发研制高效的加氢精制催化剂是达到这一目标的有效手段。通过在NiMoP浸渍液中添加不同含量乙二醇,制备一系列NiMoP/Al₂O₃催化剂,以喹啉为模型化合物,对催化剂进行加氢脱氮活性评价,分析表征各类脱氮产物。结果表明,乙二醇的加入能够大幅提高喹啉脱氮率,尤其是喹啉全加氢产物中C-N键的直接断键能力得到较大提高。     

Ni-Mo/TiO_2催化剂上二苯并噻吩加氢脱硫性能

采用浸渍法,以TiO_2成型载体制备Ni-Mo/TiO_2催化剂,考察MoO_3负载量对二苯并噻吩加氢脱硫性能的影响,采用XRD和BET等对催化剂进行表征。结果表明,当MoO_3负载质量分数大于10%时,已超过TiO_2载体的单层负载量,MoO_3晶相开始聚集长大,堵塞部分孔道,造成催化剂的比表面积和孔容显著下降。MoO_3负载质量分数10%时,二苯并噻吩转化率最高,继续提高MoO_3的负载质量分数,催化剂活性反而下降。对Ni-Mo/TiO_2催化剂进行30天的稳定性试验,催化剂没有失活。     

Effect of supercritical deposition synthesis on dibenzothiophene hydrodesulfurization over NiMo/Al2O3 nanocatalyst

The synthesis of two NiMo/Al₂O₃ catalysts by the supercritical carbon dioxide/methanol deposition (NiMo‐SCF) and the conventional method of wet coimpregnation (NiMo‐IMP) were conducted. The results of the physical and chemical characterization techniques (adsorption–desorption of nitrogen, oxygen chemisorption, XRD, TPR, TEM, and EDAX) for the NiMo‐SCF and NiMo‐IMP demonstrated high and uniform dispersed deposition of Ni and Mo on the Al₂O₃ support for the newly developed catalyst. The hydrodesulfurization (HDS) of fuel model compound, dibenzothiophene, was used in the evaluation of the NiMo‐SCF catalyst vs. the commercial catalyst (NiMo‐COM). Higher conversion for the NiMo‐SCF catalyst was obtained. The kinetic analysis of the reaction data was carried out to calculate the reaction rate constant of the synthesized and commercial catalysts in the temperature rang of 543–603 K. Analysis of the experimental data using Arrhenius' law resulted in the calculation of frequency factor and activation energy of the HDS for the two catalysts. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Kinetics of hydrodesulfurization of dibenzothiophene over NiO-MoO3/γ-Al2O3 catalyst

The kinetics of the hydrodesulfurization(HDS) of dibenzothiophene (DBT) has been studied over a NiO-MoO₃/γ-Al₂O₃ catalyst in the temperature range of 473-673 K for partial pressures of DBT from 20 x 10⁵Pa to 70 x 10⁵Pa. A form of the Langmuir-Hinshelwood type rate equation was used to describe the kinetics of the reaction. The reaction was carried out at low conversion level to obtain initial reaction rate data. From this study the rate equation giving the best fit to the data was , which suggests that DBT and hydrogen adsorb on the same type of active sites and that hydrogen adsorbs dissociatively.     

Oxidative desulfurization of dibenzothiophene over Fe promoted Co–Mo/Al_2O_3 and Ni–Mo/Al_2O_3 catalysts using hydrogen peroxide and formic acid as oxidants

This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al_2O_3 catalysts in the oxidative desulfurization(ODS) of dibenzothiophene(DBT) using H_2O_2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60 °C and 150 min reaction time over Fe–Ni–Mo/Al_2O_3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al_2O_3 catalysts following the activity order: Fe–Ni–Mo/Al_2O_3 NFe–Co–Mo/Al_2O_3 NNi–Mo/Al_2O_3 NCo–Mo/Al_2O_3, while H_2O_2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy(SEM), X-ray diffraction(XRD), energy dispersive X-ray(EDX)analysis, Atomic Absorption Spectroscopy(AAS) and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.     

Propylene metathesis over Re2O7/Al2O3-B2O3 catalysts

A series of alumina aluminum borate (AAB) with various Al/B molar ratios were prepared by the coprecipitation method. The supported rhenium oxide catalysts with various contents of Re₂O₇ were also prepared by the impregnation method with perrhenic acid. The catalytic activity and stability of Re₂O₇/AAB catalysts for the reaction of propylene metathesis were tested in a fixed-bed microreactor. It was found that Re₂O₇/AAB is more active, stable and regenerable than Re₂O₇/Al₂O₃ for propylene metathesis. The optimum Al/B molar ratio was found to be in the range of 4–10.     

Benzene hydroisomerization over Pt/MOR/Al2O3 catalysts

Benzene hydroisomerization is among the promising processes converting benzene into methylcyclopentane (MCP), which is an environmentally friendlier, octane boosting component of motor fuels. Benzene hydroisomerization into MCP over the Pt/MOR/Al₂O₃ (MOR = mordenite) catalytic system is reported here. The dependence of the yield of the target product on the acidic properties of the support and platinum precursor ([Pt(NH₃)₄]Cl₂ or H₂PtCl₆) have been investigated in order to optimize the catalyst composition. The acidic properties of the surface have been altered by introducing 30–95 wt % alumina into the support. Catalytic activity has been measured in the hydroisomerization of cyclohexane and a benzene (20 wt %) + n-heptane (80 wt %) mixture in a flow reactor at 250–350°C, 1.5 MPa, H₂: CH = 3: 1, a cyclohexane LHSV of 6 h^?1, a mixed feedstock LHSV of 2 h^?1, a catalyst bed volume of 2 cm³, and catalyst pellet sizes of 0.25–0.75 mm. The most efficient catalyst for cyclohexane and n-heptane isomerization and benzene hydroisomerization is the platinum-containing catalyst (0.3 wt % Pt) whose support consists of 30 wt % MOR and 70 wt % Al2O3. The highest yield of the target products of isomerization in the presence of this catalyst is attained in the temperature range from 280 to 310°C, which is thermodynamically favorable for MCP formation from benzene. This indicates that this catalyst is promising for the hydroisomerization of benzene-containing gasoline fractions. Use of H₂PtCl₆, a readily available chemical, as the platinum precursor is favorable for commercialization of the catalyst and ensures price attractiveness in its industrial-scale manufacturing.