类型硫在催化裂化过程中的转化机理分析及脱硫方法探讨

主要对原料油中噻吩、苯并噻吩、硫醚等类型硫在催化裂化过程中的转化机理和路径去向进行了综述和分析,并与催化汽油中类型硫的标定结果进行了对比;讨论了催化操作条件、催化剂类型及原料油组成对类型硫的裂化脱硫过程的影响,对于两种主要脱硫技术吸附脱硫和加氢精制进行了探讨。噻吩在催化剂B酸中心易形成β碳正离子并进一步转化为不同的中间产物,再经过氢转移反应和裂化反应开环裂化脱硫生成H 2S进入气相,或生成烷基噻吩等硫化物主要进入汽油馏分段,苯并噻吩和二苯并噻吩比噻吩更难开环裂化,其脱硫产物主要进入柴油馏分段。较低的反应温度、较高的剂油比、较长的反应时间、晶胞参数高、酸密度大的催化剂及较多的供氢剂有利于脱除类型硫。     

FCC汽油硫化物在ZSM-5催化剂上的加氢脱硫路径

 采用气相色谱-原子发射光谱(GC-AED)方法,考察了催化裂化(FCC)汽油中的硫化物和相应模型硫化物在ZSM-5催化剂上的催化转化性能.结果表明, FCC汽油硫化物总转化率为86.3%, 其中,硫醚和四氢噻吩的转化率都达到100%, 硫醇、噻吩、烷基噻吩和苯并噻吩的转化率分别为96.6%、78.8%、85.8%和81.4%. 3-甲基噻吩在ZSM-5催化剂上的转化产物中含有噻吩、2-甲基噻吩、2,5-二甲基噻吩、2,4-二甲基噻吩和2,3-二甲基噻吩.烷基噻吩和苯并噻吩硫化物在ZSM-5催化剂上脱硫反应网络中, 一方面含有直接加氢脱硫反应, 另一方面含有包括歧化、异构化和裂解等反应的间接加氢脱硫反应.     

分散性催化剂作用下噻吩类化合物的临氢转化规律

以有机钼为前驱体制备了分散性纳米RDC-Mo催化剂,采用微型反应釜进行了噻吩类模型化合物噻吩、苯并噻吩和二苯并噻吩(DBT)热转化及RDC-Mo催化临氢热转化反应,对比了热转化及催化临氢过程噻吩类模型化合物热转化反应效果。采用X射线衍射(XRD)及高分辨率的透射电镜(HRTEM)对所制备的分散型催化剂进行了分析表征。采用模拟计算方法深入研究了分散型催化剂催化临氢热转化显著提高噻吩类化合物转化率以及不同结构噻吩类反应差异的内因。结果表明：制备的分散型催化剂RDC-Mo具有高度分散纳米尺寸特征,其晶粒尺寸为3.63 nm。相比于热转化,高分散纳米催化剂RDC-Mo作用的催化临氢过程显著强化了噻吩类化合物的转化,使其转化率大幅度提高。高分散度纳米催化剂显著强化了噻吩类化合物与催化剂活性中心、H₂的可接近性;H₂经纳米催化剂活化形成的氢自由基强化噻吩类化合物中与S相连的芳环碳定向加氢,促使C—S键断裂能垒大幅下降,在较低温发生断裂;该反应路径正是造成分散型催化剂临氢体系显著提高噻吩类化合物裂化转化率的内在原因。受定向加氢的概率、在活性中心MoS₂吸附难易以及定向加氢后C—S键键长变化3方面的影响,不同结构噻吩类化合物转化率由大到小顺序为苯并噻吩、噻吩、二苯并噻吩。     

噻吩类硫化物在催化裂化过程中转化规律的研究

采用固定流化床实验装置,以噻吩、2-丁基噻吩和苯并噻吩为模型化合物,研究了不同结构的噻吩类硫化物在催化裂化条件下的反应特性和产物硫分布规律。结果表明：噻吩和苯并噻吩的转化率均较低（小于20%）,产物主要分布在焦炭和液体中,很难发生裂化脱硫反应;2-丁基噻吩具有较高的反应活性,主要发生脱烷基、侧链裂化和裂化脱硫反应,气体硫的选择性达到28%左右。对于Y型分子筛催化剂,噻吩类硫化物的产物收率和硫分布选择性均与转化率呈很好的线性关系。     

催化裂化柴油加氢处理综合利用技术方案

在分析催化裂化柴油(LCO)的烃类组成及杂原子分布的基础上,针对LCO的不同馏分段,提出了不同的加工技术路线。结果表明：LCO中苯胺类氮化物和吲哚类氮化物主要分布在馏程低于290℃的轻、中馏分段,咔唑类氮化物主要集中在馏程高于320℃的重馏分段;LCO中几乎没有噻吩类硫化物,苯并噻吩类硫化物存在于馏程高于290℃的馏分中,且重馏分中的硫化物几乎均为二苯并噻吩类。全馏分LCO需要在较高苛刻度下加氢精制才能实现十六烷值提升;而LCO中馏分段(240～320℃)在较温和条件下加氢饱和,产品十六烷值提高13.9,可用作国Ⅵ车用柴油调合组分;对于LCO轻馏分段(<240℃),可进行催化裂化,生产高辛烷值汽油调合组分。     

Conversion of nickel and vanadium porphyrins under catalytic cracking conditions

The conversion of nickel and vanadium porphyrins under conditions of catalytic cracking has been studied. Samples of porphyrins and their mechanical mixtures with a cracking catalyst have been investigated by thermogravimetric analysis. As a result of the cracking of porphyrins, a significant amount of gaseous and liquid products are formed. The liquid products are mainly represented by polycyclic compounds. A possible mechanism of nickel and vanadium porphyrin conversions has been suggested.     

Catalytic cracking of alternative raw materials and their mixtures with petroleum fractions over microspherical zeolite-containing catalysts

Features of catalytic cracking of mixtures of a hydrotreated vacuum distillate and oxygenated compounds derived in biofuel production (acetone, glycerol, and methanol) over a microspherical zeolite-containing catalyst have been studied. It has been found that these oxygenated compounds undergo complete conversion under catalytic cracking conditions. The dependence of the process parameters on the reaction temperature and the concentration of oxygenated additives has been examined. The possible chemistry and mechanism of conversion of the oxygenated compounds under catalytic cracking have been discussed.     

汽油馏分中硫含量及硫形态分布方法的研究

采用气相色谱和硫化学发光检测器（GC—SCD），建立了汽油馏分中各种硫化物类型分布的分析方法。考察了色谱条件对汽油馏分中各种硫化物分离的影响，定性了汽油馏分中的107个硫化物，测定出当硫化物中的硫含量在0．2—200ng／ul时，其峰面积与质量浓度呈较好的线性关系，相关系数达0．999，响应与硫化物的类型无关。汽油中几种主要硫化物（噻吩、正丁硫醇、2-甲基噻吩、3-甲基噻吩、2，4-二甲基噻吩）浓度测定值重现性的相对标准偏差（RSD）均小于5．0％。当信噪比（S／N）为3时，测得2一甲基噻吩的检测限为0．1ng／ul。本研究所建立的方法可用于分析不同装置的汽油馏分的硫化物形态分布规律。     

异丙苯在酸性催化剂上的主要化学反应路径

 采用小型固定流化床装置(ACE-Model R), 研究了反应温度在450～600℃范围内, 异丙苯在酸性催化剂上的主要化学反应路径。结果表明, 异丙苯在酸性催化剂上的主要化学反应有脱烷基反应、烷基侧链裂化反应、烷基转移反应和氢转移反应等, 其中脱烷基反应是最主要的化学反应, 其选择性为67%～88%;烷基侧链裂化反应选择性为1%～2%;烷基转移反应选择性为1%～10%; 氢转移反应选择性为1%～3%。提高反应温度既有利于脱烷基反应又有利于烷基侧链裂化反应, 烷基侧链裂化反应选择性的增加有利于C₁～C₂等小分子烃类和短侧链芳烃的生成, 但高温不利于烷基转移反应和氢转移反应.     

Al/BMMs双介孔分子筛催化剂的制备及其在异丙苯催化裂化中的应用

通过后铝化合成方法制备了Al/BMMs双模型介孔分子筛催化剂;采用XRD、BET、FT-IR、TG等分析手段对其结构和性能进行了表征,并且考察了不同硅/铝摩尔比的催化剂在异丙苯催化裂化中的催化性能。结果表明,反应后Al/BMMs催化剂仍然保持了双介孔结构;同时随着Al含量的增加,异丙苯的转化率增加,当n(Si)/n(Al)=20时,转化率达到最大(约54%)。     

超临界状态下正十二烷/异辛烷双元模型燃料的催化裂解反应

在超临界状态下,以HZSM-5分子筛为催化剂,在固定床反应器中进行了正十二烷与异辛烷质量比为1∶1的正十二烷/异辛烷双元模型燃料催化裂解反应的研究,考察了转化率、气体产物收率、主要气体产物选择性及积碳量与裂解温度和压力的关系。实验结果表明,在超临界状态下,双元模型燃料的转化率和气体产物收率随裂解温度的升高而增加,裂解温度为400～450℃时,气体产物的主要组分为丙烷、异丁烷和正丁烷,与纯正十二烷裂解的气体产物分布类似;裂解温度为450～500℃时,甲烷、乙烷和氢气的选择性明显提高,气体产物分布与纯异辛烷裂解的气体产物分布相近。在0.1～7.0MPa的范围内,随裂解压力的增大,在双元模型燃料中正十二烷转化率和气体产物收率下降。积碳量随裂解温度的升高呈现先降低后增加的趋势,450℃时积碳量最少。     

反应温度和剂油比对催化裂化反应的影响

选取各种不同孔径的分子筛催化剂如AIMCM-41、纳米双介孔分子筛(NBMAS)和微孔分子筛HZSM-5,以异丙苯和1,3,5-三异丙苯为模型反应物,采用脉冲法考察反应温度和剂油比对催化裂化反应的影响。实验结果表明,不同反应物的催化裂化反应采用不同的催化剂、反应温度和剂油比对裂解转化率和裂解产物的分布有不同的影响。异丙苯裂化反应中,在转化率增加的同时,小分子烯烃的选择性增加,其副产物(对-二异丙苯和间-二异丙苯)的选择性降低;在1,3,5-三异丙苯的裂解反应中,随着裂解程度的加深,小分子烯烃的选择性增加,中间产物(异丙苯和二异丙苯)的选择性降低。     

催化裂化过程中苯并噻吩的转化规律

在固定流化床装置上,采用USY-Cat和V-USY-Cat催化剂,考察了苯并噻吩与四氢萘以不同比例混合进料在催化剂作用下的转化路径和硫分布。结果表明,苯并噻吩在催化裂化过程中主要发生氢转移-裂化、缩合、烷基转移和歧化反应。纯苯并噻吩很难开环裂化脱硫,其气体硫、液体硫和焦炭硫的摩尔选择性分别为0.45%、49.71%和49.84%。四氢萘的加入改变了苯并噻吩反应路径的选择性,使气体硫的摩尔选择性略有增加,焦炭硫的摩尔选择性下降到3.18%。催化剂的酸性质对产物硫分布也有影响,酸密度越高,越有利于气体硫的生成;V的加入提高了USY-Cat催化剂的L酸/B酸比,使焦炭硫的选择性上升。     

Oxidative cracking of crude oil by hydrogen peroxide in the presence of iron oxide nanoparticles

The interaction of hydrogen peroxide aqueous solutions with crude oil and high-boiling refined products, such as fuel oil and vacuum gas oil, in the presence of an oxidative cracking catalyst in the form of iron oxide nanosized particles is studied. This study is aimed at modeling processes occurring in the case of using hydrogen peroxide solutions in the catalytic cracking of crude oil. It is found that, in the presence of iron particles, the reaction of hydrogen peroxide decomposition causes the cracking of petroleum hydrocarbons. This process may be accompanied by reduction in the viscosity and density of crude oil and refined products. The reaction of catalytic cracking performed under these conditions leads to a marked increase in the fraction of light hydrocarbons in the composition of crude oil and high-boiling refined products.     

重油催化裂解制取丙烯的分子反应化学

从分子水平研究了重油催化裂解反应中原料性质的影响、丙烯生成反应化学和丙烯再转化反应化学,创新了重油催化裂解反应理论和知识。在重油催化裂解制丙烯反应中,原料氢含量和饱和烃含量是影响丙烯产率的重要指标,而原料烃分子结构与大小对丙烯产率的影响也很大;丙烯的生成来自重质原料一次裂解和中间产物馏分二次裂解反应的共同贡献;烷烃分子经五配位正碳离子引发链反应是导致干气选择性高而丙烯选择性低的主要原因;催化裂解产物中丙烯存在再转化反应。同时提出了催化裂解增产丙烯并抑制干气和焦炭生成的新技术,并在工业装置上得到了验证;与原技术相比,在相同原料油和操作条件下,其丙烯产率提高了90.29%,而焦炭产率降低了17.53%,干气与丙烯质量产率比降低了34.88%。     

沥青质裂解反应选择性分析

在703 K 下,考察了1种正戊烷不溶的沥青质的热裂解、临氢热裂解和 NiMo/γ-Al₂O₃存在时的临氢催化裂解反应。结果表明,在相同的反应物转化率水平下,3种裂解反应按液体产物选择性从大到小的排列顺序为临氢催化裂解、临氢热裂解、热裂解反应,而按焦炭的选择性的排列顺序则相反。在热裂解反应中,沥青质中大量的硫被转化生成高硫焦炭;在临氢热裂解反应中,氢气分子对高硫焦炭的生成只起到有限的抑制作用;在临氢催化裂解反应中,催化剂充分激活氢气分子,使其有效地对沥青质及中间产物发生“加氢”（氢化）作用,显著地抑制了焦炭的生成,提高了液体产物的稳定性、选择性和品质（低相对分子质量和低硫含量）。     

Catalytic conversion of cellulose into hydrocarbon fuel components

The results of catalytic processing of cellulose to hydrocarbon fuel component are presented. Nanoscale Mo,Fe(III) catalytic systems have been formed from organic solutions of mono- and bimetallic complex compounds on the surface of the substrate. Tetralin, an analogue of naphthenoaromatic compounds of crude oil and its refining products, has been used as a hydrogen donor. The effect of the precursor nature and catalyst activation method on the parameter of the process has been investigated. It has been shown that the cellulose conversion reaches 97–98% under optimal conditions, yielding up to 90% of liquid hydrocarbons with the exhaustive deoxygenation. It has been found that the most efficient method of preliminary activation of both active components and cellulose is ultrasonic treatment leading to an increase of the rate of cellulose conversion into hydrocarbons.     

Destructive Conversion of Gas Oil in the Presence of a Nickel-Based Nanosized Catalyst

The decomposition of nickel 2-ethylhexanoate by heating in a vacuum gas oil (VGO) medium at 355–365°С has been found to yield nickel and nickel sulfide nanoparticles. The size of the particles is 20–120 nm. The catalytic cracking of VGO in the presence of these nickel-containing particles provides a 70.15% yield of the distillate with a boiling point up to 220°C. The structural-group composition of the products of VGO cracking in the presence of nickel-based nanoscale catalysts has been studied using gas chromatography–mass spectrometry. The group composition of samples containing cracked products has been analyzed to cover eleven classes of organic compounds. The structural composition of the test samples has been considered with respect to eight groups of compounds, of which three include two to three classes of compounds. In the catalytic cracking of VGO, the concentration of alkanes increases by 3.11% and that of alkenes and alkylbenzenes decreases by 1.31 and 2.59%, respectively, as compared to their content in the products of VGO distillation without a catalyst.     

Efficient desulfurization of gasoline fuel using ionic liquid extraction as a complementary process to adsorptive desulfurization

The extractive desulfurization of a model gasoline containing several alky]thiols and aromatic thiophenic compounds was investigated using two imidazolium-based ionic liquids(ILs).1-butyl-3-methylimidazolium tetrachloroaluminate,and l-oetyl-3-methylimidazolium tetrafluoroborate.as extractants.A fractional factorial design of experiments was employed to evaluate the effects and possible interactions of several process variables.Analysis of variance tests indicated that the number of extraction steps and the IL/gasoline volume ratio were of statistically highly significant,but none of the interactions were significant.The results showed that the desulfurizalion efficiency of the model gasoline by the ILs could reach 95.2%under the optimal conditions.The optimized conditions were applied to study the extraction of thiophenic compounds in model gasoline and several real gasoline samples:the following order was observed in their separation:benzothiophene > thiophene > 3-methylthiophene > 2-melhylthiophene.with 96.1%removal efficiency for benzothiophene.The IL extraction was successfully applied as a complementary process to the adsorptive desulfurization with activated Raney nickel and acetonitrile solvent.The results indicated that the adsorptive process combined with IL extraction could provide high efficiency and selectivity,which can be regarded as a promising energy efficient desulfurization strategy for production of low-sulfur gasoline.     

GC-FID/MS技术应用于苯并噻吩催化裂化转化规律的研究

首次利用相对质量响应因子建立了GC-FID/MS技术分析裂化液体中硫化物的方法,并将其应用于苯并噻吩催化裂化转化规律的研究。结果表明,该方法的准确度较高,苯并噻吩催化裂化反应后的硫平衡均高达95%以上。在催化裂化条件下,纯苯并噻吩很难开环裂化脱硫,四氢萘的加入可明显促进苯并噻吩的转化,提高气体硫的摩尔选择性,并降低裂化汽油馏分段的硫含量。