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。     

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。     

供氢组分对氢转移反应的影响

在催化裂化汽油中掺入供氢组分可强化氢转移反应，从而降低汽油的烯烃和硫含量，并改善产品分布。本研究考察了不同供氢组分及其掺入率、反应温度、催化剂的酸性对氢转移反应的影响。结果表明，四氢萘为合适的供氢组分，四氢萘通过降低反应活化能来强化氢转移反应；提高反应温度有利于提高四氢萘的供氢能力，但温度高于450℃后，四氢萘裂化倾向加大；催化剂的酸性对供氢组分的选择性供氢有影响，合适的酸量和酸密度有助于促进供氢组分参加的氢转移反应。     

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。     

四氢萘和十氢萘的催化裂化反应途径及特征产物

在小型固定流化床催化裂化试验装置上,考察了十氢萘和四氢萘在酸性催化剂上的裂化反应途径及特征产物。结果表明,初始阶段质子化裂化是四氢萘裂化的主要引发反应,H⁺攻击C-C键形成五配位正碳离子是十氢萘裂化的主要引发反应;随着反应深度的进行,氢转移反应成为四氢萘的主要反应,而十氢萘裂化生成的烷基环烷正碳离子的β断裂成为十氢萘的主要反应。四氢萘在酸性催化剂上的反应产物中萘、H₂和苯的摩尔分数最高,是其反应特征产物;十氢萘在酸性催化剂上的反应产物中异丁烷和汽油异构烷烃组分的摩尔分数最高,是其反应特征产物,为多环环烷烃或氢化芳烃的高效利用提供理论依据。     

负氢离子释放剂对2-甲基-2-丁烯氢转移反应的影响

负氢离子转移反应是氢转移反应的基元反应,促进负氢离子转移反应可以强化选择性氢转移反应。在反应温度510 ℃、剂/油质量比5、质量空速12 h^-1、N₂气氛条件下,分别考察了四氢萘和十氢萘作为负氢离子释放剂对2-甲基-2-丁烯氢转移反应的影响。结果表明：四氢萘和十氢萘均能有效地促进2-甲基-2-丁烯发生选择性氢转移反应,产物中C₅烯烃产率由52.95%最低分别降至37.83%和17.03%,异戊烷产率由17.80%最高分别增加至42.98%和54.58%,焦炭产率由5.28%最低分别降至3.11%和2.85%;且十氢萘比四氢萘具有更好的供氢能力,相同含量的十氢萘对于产物中烯烃产率的降低幅度、异构烷烃产率和选择性的增加幅度的影响均比四氢萘更大,对焦炭产率的抑制作用更强。在含烯烃汽油中分别加入质量分数10%四氢萘和十氢萘后,烯烃产率由11.20%分别降低至5.48%和4.01%;同时能够很好地抑制焦炭的生成,尤其加入十氢萘后焦炭产率由5.30%降到2.82%。     

四氢萘催化裂化研究进展

加氢处理油中含有一定量的环烷基单环芳烃,研究四氢萘催化裂化有利于加强对更多环数环烷基单环芳烃催化裂化的认识。综述了四氢萘催化裂化过程的反应机理,认为四氢萘主要遵循单分子裂化机理;从反应活化能、扩散、吸附等动力学角度对四氢萘裂解行为进行了解释;催化剂适宜的孔径和BrØnsted酸强度有利于四氢萘开环;随着反应温度升高、剂/油质量比增大、质量空速减小,四氢萘反应活性增强,同时氢转移反应愈发明显。适宜的催化剂孔径和Brnsted酸强度、反应温度、剂/油质量比以及质量空速有利于四氢萘裂化生成低碳烯烃。     

二异丙基萘在分子筛催化剂上的侧链断裂反应

在小型固定流化床(FFB)装置上,考察了以Y和ZSM-5分子筛作为催化剂,温度、剂/油质量比对二异丙基萘裂化侧链断裂反应的影响。结果表明,二异丙基萘在分子筛催化剂上极易发生侧链断裂反应,生成萘、C1~C4烷基萘、四氢萘、烷基四氢萘和丙烯等低碳烯烃;较少量的二异丙基萘通过脱氢缩合生成菲、芘等三环以上多环芳烃甚至焦炭。由于扩散和吸附性能的影响,二异丙基萘侧链断裂反应与催化剂的孔径有关,并与催化剂B酸量密切相关。在B酸量较少、吸附性能适宜的ZSM-5催化剂上其侧链断裂反应选择性比Y催化剂的高。当反应温度在425~525℃、剂/油质量比在3~8范围,随着反应温度升高,或者剂/油质量比增加,脱氢缩合反应增强,而烷基侧链断裂反应选择性降低。     

四氢萘在分子筛催化剂上环烷环开环反应的研究

在小型固定流化床(FFB)装置中考察了Y与ZSM-5分子筛催化剂以及温度、剂油比对四氢萘裂化环烷环开环的影响。结果表明,四氢萘在分子筛催化剂上通过环烷环开环反应生成丙烷、丙烯、丁烷、丁烯、甲基戊烷和环戊烷、环己烷等非芳烃,苯、C1～C4烷基取代苯等单环芳烃;并通过脱氢缩合反应生成萘、甲基萘等双环芳烃,菲、芘等三环以上芳烃甚至焦炭等;其中环烷环开环与脱氢缩合反应的相对比例在两种分子筛上分别为1.22、0.95。由于扩散和吸附性能的影响,其裂化开环反应的选择性在Y分子筛催化剂比ZSM-5分子筛催化剂上高;温度在450～550℃、剂油比在3～9范围,反应温度升高或者剂油比增加,双分子氢转移以及脱氢缩合反应增强,从而导致环烷环开环产物选择性降低。     

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.     

The effect of H<Subscript>2</Subscript>S on the selectivity of light alkenes in the FE-Mn-catalyzed Fischer-Tropsch synthesis

Iron-manganese oxides are prepared using a co-precipitation procedure and studied for the conversion of synthesis gas to light olefins. In particular, the effect of a range of preparation variables is investigated in details. In this investigation, sulfur absorption and effect of sulfur poisoning on Fe-Mn catalysts have been studied. In the Fischer-Tropsch synthesis process, the poisoning of the catalyst is one of the important parameters causing a decrease in the catalyst activity, declaring the sulfur compounds as virulent poisons in this process. In the present investigation, poisoning of Fe-Mn catalysts were performed in a gas circulation system and H₂S was injected into a circulation loop. The prepared catalysts were exposed to a mixture of H₂S and N₂ at about 450°C in the stainless-steel micro reactor via co-precipitation method. H₂S was produced by addition of H₂SO₄ to Na₂S × H₂O and this gas was mixed with an inert carrier gas (N₂). Comparing the activity and selectivity of fresh and poisoned catalysts, indicates that the selectivity and CO conversion are affected by high-level sulfur adsorbed on the catalysts. The results show that the CO conversion and selectivity with respect to methane production and coke formation were decreased, but the selectivity of light alkenes such as propylene was increased over poisoned catalysts. Characterization of both precursors and calcined catalysts by powder X-ray diffraction, BET specific surface area and thermal analysis methods such as TGA and DSC showed that the poisoning of Fe-Mn catalysts influenced the catalyst structure.     

Sulfur Reduction in FCC Gasoline with a Commercial Additive: A Microactivity Study

Abstract

The use of advanced FCC catalysts and additives to reduce sulfur in gasoline remains the preferred option to refiners because of its economic and operation incentives. The performance of a commercial sulfur-reducing additive blended with a fresh RE-USY catalyst was assessed in a microactivity (MAT) unit using Arabian Light vacuum gas oil (VGO). The additive was evaluated at different concentrations (0–15 wt%) in terms of sulfur reduction capability and its effect on product yield structure, mainly gasoline. At 5 wt% additive, the results showed a 14 wt% reduction in total gasoline sulfur with minor effect on catalytic activity and product selectivity. Minimal reduction capability was observed towards benzothiophene (BT), which is difficult to crack and remove under cracking conditions. Upon increasing additive concentration to 10 wt%, total sulfur was reduced to 21 wt% compared to 27 wt% reduction at 15 wt% additive. At this additive concentration, aromatic sulfur compounds mainly C4-thiophenes and a portion of BT were cracked to tetrahydrothiophene, or thiophene, which were subsequently cracked to H₂S and light gases.     

复合SiO2-WO3催化剂的制备、表征及氧化脱除苯并噻吩性能

 采用溶胶-凝胶法制备了SiO₂-WO₃催化剂,并采用XRD、FT-IR、BET、TG-DTA等方法对催化剂进行表征。以苯并噻吩(BT)为模型化合物,H₂O₂为氧化剂,考察了催化剂的活性元素、制备方法、n(W)/n(Si)和焙烧温度对其催化氧化脱硫活性的影响。结果表明,W的引入降低了SiO₂的比表面积,SiO₂-WO₃催化剂中W的主物相为WO₃。在以W为活性组元,且n(W)/n(Si)为0.1时,500℃焙烧得到的SiO₂-0.1WO₃催化剂具有最好的催化脱硫活性。在模拟油20 mL、催化剂SiO₂-0.1WO₃用量0.04 g、n(H₂O₂)/n(S)为15.9、乙腈/模拟油体积比0.3、65℃反应60 min的条件下,苯并噻吩模拟油脱硫率可达99.3%。     

Oxidative Desulfurization of Fuel Catalyzed by Amphiphilic Peroxomolybdate

Abstract

The oxidation of sulfur-containing compounds (benzothiophene [BT], dibenzothiophene [DBT], and 4,6-dimethyldibenzothiophene [4,6-DMDBT]) was studied in an emulsion system composed of model oil, hydrogen peroxide, and an amphiphilic catalyst [C₇H₇C₁₂H₂₅(CH₃)₂N]₂Mo₂O₃(O₂)₄. The most suitable conditions were suggested: n (DBT): n (catalyst): n (H₂O₂) = 1:0.1:10, at 60°C for 2 hr. Under optimized experimental conditions, the removal of DBT, BT, and 4,6-DMDBT could reach 98.0, 94.0, and 62.7%, respectively. The oxidation product sulfones could be readily separated by extraction. The catalyst could be recycled five times without a significant decrease in catalytic activity.     

An optimization of process parameters for deep desulfurization of model fuel by ZSM-5/ZnO photocatalyst using response surface method

One of the major factors that causes air pollution are sulfur oxides) SO_x) that exiting from vehicles exhaust by combustion of fossil fuel. Although hydrodesulfurization method has always been the option in oil refineries to reduce sulfur contents, but it is almost impossible to meet stringent new environmental regulation by this method. The Achilles heel of the conventional method is weakness in removing aromatic sulfur recalcitrant compounds. In the present research, photocatalytic oxidative desulfurization (PhOD) based on the ZSM-5/ZnO catalyst is developed. n-Decane as the model fuel and benzothiophene (BT) and dibenzothiophene (DBT) as the sulfur compounds are used. Then by the response surface method the optimum conditions were developed. The result indicates that catalyst with 6%wt Zn/ZnO, 45 min reaction time, UV power of 32 watts and catalyst to fuel ratio of 2 gr/L is able to remove BT and DBT with efficiency of 86.1% and 74.0%, respectively.     

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）。     

FCC汽油选择性加氢硫转移催化剂的研究

 制备了以γ-Al₂O₃为载体的Ni基选择性加氢硫转移催化剂Mo-Ni/γ-Al₂O₃,并用于催化裂化汽油的加氢硫转移反应。对比了预硫化型和氧化型Mo-Ni/γ-Al₂O₃催化剂的活性和选择性,并考察了无氧焙烧温度、活性组分负载量对预硫化型Mo-Ni/γ-Al₂O₃催化剂加氢硫转移催化性能的影响。采用模型化合物研究了硫醇在Mo-Ni/γ-Al₂O₃催化下的反应,考察了烯烃和硫醇对硫转移反应的影响。结果表明,无氧焙烧温度400℃下制备得到的w(NiO)=8.2%、w(MoS₂)=5.6%的预硫化型Mo-Ni/γ-Al₂O₃催化剂具有相对较高的加氢硫转移反应催化活性和选择性;硫醇与烯烃的反应在催化剂表面的加氢活性位上进行,硫醇先加氢脱硫,生成吸附态H₂S,吸附态H₂S再与吸附的烯烃反应生成大分子硫醇或硫醚,达到硫转移的目的。     

Upgrading Heavy Oil Using Syngas as the Hydrogen Source with Dispersed Catalysts

Abstract

Upgrading heavy oil using syngas (CO + H₂) as an alternative hydrogen source with a dispersed catalyst was investigated. Finely dispersed catalysts for upgrading were prepared by means of microemulsion, and their performance was investigated in a batch-type autoclave. This process was compared to the traditional pure hydrogen hydro-upgrading process. Feedstock conversion, light-oil yield, coke yield, product distribution, sulfur, nitrogen and viscosity were investigated comprehensively to optimize the process. The addition of finely dispersed catalysts could improve the distribution and performance of cracking products, and inhibit the cracking gas and coke formation. This work shows that residue-syngas coprocessing is promising for heavy oil upgrading.