Straight-run Light Research Articles

Catalytic pyrolysis of straight-run light oil to light olefins: Role of molecular structure and catalytic materials

The development of straight-run light oil catalytic pyrolysis to light olefins process is an important approach of achieving the transformation and upgrading of the current oil refining industry. However, the industrialization of the catalytic pyrolysis process for straight-run light oil has been slow. Herein, we investigated the decomposition of complex straight-run light oil into different structural units and further examined their effects on light olefins production. The results indicated that the yields of light olefins cracked over MFI zeolite were about 45 % and 30 % for alkane structure and cycloalkane ring structure, respectively. Further analysis showed that the olefin structure could theoretically be cracked to 100 % light olefins, but in fact, 40 % of the light olefins were lost due to the transfer of 10 % hydrogen. Subsequently, the effects of zeolite topology and acid properties on the cracking of different structural units were further analyzed. It was found that zeolites with MTT and MFI topologies contributed to the catalytic pyrolysis of chain and cycloalkane ring structures, respectively, because appropriate pore size helped diffusion of hydrocarbon molecules and inhibited side reactions such as hydrogen transfer. Compared with MFI zeolite, the light olefins yield produced by chain structure cracking over MTT zeolite increased by 5.83 %-10.54 %. In addition, it was discovered that zeolites with total and strong acids in the range of 0.2–0.4 mmol/g and 0.1–0.2 mmol/g, respectively, were beneficial for the cracking of light alkanes in straight-run light oils to light olefins. This work provides useful insights into the fundamental understanding and development of straight-run light oil catalytic pyrolysis to light olefins process.

Reaction mechanism study of catalytic conversion of light straight-run naphtha to light olefins over micro-spherical HZSM-5 zeolite catalyst

Catalytic conversion of naphtha has attracted attention as an alternative method to the conventional thermal cracking to produce light olefins in an environment-friendly and energy-efficient way. In this work, a reaction mechanism study of light straight run naphtha cracking over micro-spherical catalyst containing HZSM-5 was systematically investigated using single hydrocarbon feeds, and the straight run naphtha itself. The identified reaction pathways from the single feeds along with the naphtha experimental data have been utilized to investigate reaction pathways of the naphtha conversion reactions. The experimental tests were carried out in the temperature ranges of 450–650 ℃ and space-times of 0.3–1.5 min using a fixed bed micro-reactor in isothermal and isobaric conditions. The product distribution for the naphtha feed shows that light paraffins and light olefins are the primary products, which are products of monomolecular protolytic cracking of the paraffin components of the naphtha feed. The olefin interconversion reactions illustrated that oligomerization and cracking by β-scission dominate the secondary reactions of naphtha catalytic cracking conversions. The experiments conducted on cyclohexane, cyclohexene and n-hexane single feeds revealed that BTX formation proceeds through the formation of C6-C8 naphthenes, and C6-C8 cyclo-olefinic intermediates. Low temperatures and space times promote the selectivity to propylene while the selectivity of ethylene increases with temperature. The degree of thermal cracking (DTC) illustrated that thermal cracking is considerable only for temperatures of higher than 550 ℃.

Synthesis of two-dimensional TiO2@multi-walled carbon nanotube nanocomposites as smart nanocatalyst for ultra-deep oxidative desulfurization of liquid fuel: Optimization via response surface methodology

The novel heterogeneous catalysts of 2D-TiO2@MWCNT nanocomposites are designed and synthesized via grafting TiO2 nanoparticles onto functionalized multi-walled carbon nanotubes and used for oxidative desulfurization of dibenzothiophene and real straight run light gas oil. The 2D-TiO2@MWCNT nanocomposite catalysts are completely characterized by FT-IR, Raman spectroscopy, XRD, TEM, NH3-TPD, ICP, and N2 adsorption–desorption isotherms. At first, the effect of various loading Ti on the MWCNT for ODS efficiency was investigated. The results revealed that 2D-0.6TiO2@MWCNT had the highest sulfur removal for the model, and SRLGO fuel compared to the other catalyst. Then, the optimal design of experiments using Box–Behnken experimental design was used to evaluate the effects of individual process variables such as temperature, O/S molar ratio, time, catalyst dosage, and their optimum values were found to be 69 °C, 46 min−1, O/S molar ratio: 9, and 0.03 g cat (25 ml DBT model fuel with 500 ppm S or 25 ml SRLGO with 12500 ppm S, 25 ml of acetonitrile), to achieve a high removal sulfur efficiency for DBT model oil (100%) and SRLGO (97.5 %), respectively. Based on optimal conditions, the 2D-0.6TiO2@MWCNT catalyst possesses superior catalytic activity and excellent reusability. The desulfurization reaction could be recycled for at least nine cycles without considerable reduction of catalytic performance, showing the good stability of the nanocomposite catalysts. An empirical kinetic model was applied to explain the rate data. Also, 2D-0.6TiO2@MWCNT nanocomposite catalyst had the lowest activation energy (27.65 Kj.mol−1) with the highest turnover frequency (16.15 h−1, around 2–3 times of the best catalyst so far) in desulfurization reactions compared to any TiO2-based catalysts. Furthermore, the catalytic reaction mechanism is investigated.

Catalytic activity of synthesized 2D MoS2/graphene nanohybrids for the hydrodesulfurization of SRLGO: experimental and DFT study.

Hydrodesulfurization (HDS) of straight run light gas oil (SRLGO) using novel highly active two-dimensional (2D) MoS2/graphene (G) nanohybrid catalysts is a precursor technology for the production of clean heavy fuel. The aim of this research is the synthesis of 2D MoS2/G nanohybrid catalysts by use of exfoliation method from commercial bulky MoS2 and graphite using hydrothermal ball milling system, which is a low-cost, high-yield, and scalable method. These nanohybrid catalysts were characterized by XRD, Raman spectroscopy, XPS, SEM, TEM, STEM, ICP, BET surface, TPR, and TPD techniques. Also, catalytic activities of 2D MoS2/G nanohybrid catalysts were evaluated under different operating conditions such as temperature, pressure, LHSV, and H2/Feed (SRLGO) ratio in the HDS reaction. The conversion of the HDS of SRLGO with 14000 ppm sulfur showed a considerably higher activity of 2D MoS2/G nanohybrid catalyst (99.95% HDS efficiency) compared with the Co-Mo/γAl2O3 as a commercial catalyst (90% HDS efficiency) in the operation condition (340 °C, 40 bars, LHSV: 1 h-1and H2/oil: 600 NL L-1) which is economically valuable. Using density functional theory calculations, the detailed mechanism of the HDS process over MoS2/G catalyst was explored. It was found that sulfur coverage on the Mo edge of MoS2 plays an important role in the hydrogenation of sulfur components.

Simulation of pentane plant of Kermanshah oil refinery company

ABSTRACTPentane unit is one of the sub-units of Kermanshah oil refinery in which high purity pentane is produced through decomposing from Light Straight Run Gasoline (LSRG). The effects of the process variables, such as feed flow rate, feed entrance tray, feed temperature, and number of trays on the purity of n-pentane were investigated. It was found that the mean absolute percentage error for temperature, the pressure and composition of normal pentane were 0.944,1.492 and 1.28, respectively. Based on the results, using distillation, LSRG was decomposed into normal pentane of 97% using the two columns.

Pt-Zn/HZSM-5 as a highly selective catalyst for the Co-aromatization of methane and light straight run naphtha

Selectivity of catalysts has become increasingly important in the petrochemical industry in order to reduce waste, maximize efficiency, and reduce costs. Reported here is a catalyst in the form of Pt-Zn/HZSM-5 with low acidity to reduce over cracking and maximize selectivity of benzene, toluene, and xylene (BTX) during the aromatization of naphtha under methane environment. The Pt-Zn combination when coupled with HZSM-5 support over light straight run naphtha (LSR) and methane, is capable of BTX selectivity of 94.4% with no formation of detrimental polyaromatics and olefins. Such a performance is attributed to the appropriate distribution of acid sites (seen via NH3-TPD and pyridine DRIFT) with regards to strength and type because of loading Pt and Zn as well as Zn’s ability to reduce coke formation as seen via TGA-DSC (1 μg coke/(g cat·h) for Zn/HZSM-5 and 5.9 μg coke/(g cat·h) for HZSM-5). TEM imaging shows that a methane environment effectively suppresses metal particle agglomeration (1.4 nm average metal nanoparticle diameter) compared to nitrogen (2.1 nm average metal nanoparticle diameter) with XRD showing Pt’s ability to maintain catalyst crystallinity during moderate temperature and moderate pressure as well as reaction time of 1 h. It has been seen here that by employing Zn and Pt in tandem over HZSM-5, catalytic performance can be greatly increased (22.4% BTX yield) when compared to sole loading of Zn (13.4%) or Pt (13.1%), thus a positive synergetic effect is witnessed. Such a selective and coke resistant catalyst shows great promise for the future of LSR reformation to valuable products with methane as a very feasible co-reactant capable of contributing to positive liquid products.

Direct upstream integration of biogasoline production into current light straight run naphtha petrorefinery processes

There is an urgent need to address environmental problems caused by our transportation systems, which include the reduction of associated CO2 emissions. In the short term, renewable drop-in fuels are ideal, as they allow a direct integration into the existing infrastructure. However, preferably they would perform better than current alternatives (for example, bioethanol) and be synthesized in a more efficient way. Here we demonstrate the production of biogasoline with a direct upstream integration into processes in existing petrorefinery facilities that targets the 10% bio-based carbon in accordance with the current European Union directives (for 2020) for biofuels. To achieve this goal, we show the valorization of (hemi)cellulose pulp into light naphtha using a two-phase (H2O:organic) catalytic slurry process. A C5–C6 alkane stream, enriched with bio-derived carbon and compatible with further downstream petrorefinery operations for (bio)gasoline production, is automatically obtained by utilizing fossil light straight run naphtha as the organic phase. The ease of integration pleads for a joint petro/bio effort to gradually produce bio-enriched gasolines, wherein the chemical compounds of the bio-derived fraction are indistinguishable from those in current high-quality gasoline compositions.

Effect of Vanadium Introduction on the Activity of NiMo/Al2O3 Catalysts in the Hydrotreating of Diesel Fractions

The influence of the introduction of V2O5 into NiMo/Al2O3 catalysts on their activity in hydrodesulfurization (HDS) and hydrogenation reactions of the components of petroleum fractions has been studied. The activity of the synthesized catalysts has been determined in the straight-run diesel and light coker gas oil hydrotreating processes in a flow-through unit under hydrogen pressure. The most active catalyst for HDS and hydrogenation of polycyclic aromatic hydrocarbons has been synthesized using VMo12 heteropoly compounds: the activity increases by 6–10 and 11–13 wt % in HDS and PAH hydrogenation, respectively, at different temperatures. It has been shown that the activity of the regenerated catalyst further impregnated with the vanadium compound in HDS and PAH hydrogenation increases by 2–5 rel. %, as compared to the regenerated catalyst.

Co-Mo/Al2O3 and Ni-W/Al2O3 catalysts: Potential and prospects for use in hydrotreating of light cycle oil from catalytic cracking

Со-Мо/Al2O3 and Ni-W/Al2O3 catalysts were tested in hydrotreating of light cycle oil from catalytic cracking, of the straight-run gasoil, and of their mixture under typical hydrotreating conditions used in industry. The catalysts prepared using PMo12 and PW12 heteropoly acids exhibit high catalytic activity. The Со-Мо/Al2O3 catalyst is more active in hydrodesulfurization and hydrogenation of olefin and diene hydrocarbons, whereas the Ni-W/Al2O3 catalysts are more active in hydrogenation of mono- and polycyclic aromatic hydrocarbons. Comparison of the quality characteristics of the hydrogenizates obtained with the requirements of the technical regulations shows that the required levels of the sulfur content and cetane number of the hydrogenizates at practically accessible process parameters can be reached for mixtures of the straight-run gasoil and light cycle oil from catalytic cracking with high content of the latter component only when the process with the Со-Мо/Al2O3 system and Ni-W/Al2O3 catalysts is performed in two steps.

Material Balance And Reaction Kinetics Modeling For Penex Isomerization Process In Daura Refinery

Penex Deisohexanizer isomerization of light straight run naphtha is a significant process for petroleum refining and proved to be effective technology to produce gasoline components with a high octane number. Modeling of the chemical kinetic reactions is an important tool because it is a better tool for optimization of the experimental data into parameters used for industrial reactors. The present study deals on the isomerization process in Daura refinery. Material balance calculations were done mathematically on the unit for the kinetics prediction purpose. A kinetic mathematical model was derived for the prediction rate constants K 1 and K 2 and activation energy Ea at operating temperatures range 120-180°C. According to the model, the results show that with increasing of temperature leads to increased K 1 directly, where the K 2 values proportional inversely. The activation energy results show that Ea 1 (nC6) 1(C5) 1 (CH) , and for Ea 2 (iC5) 2 (2,2-DMB) 2 (2,3-DMB) 2 (MCP)..

Hydroupgrading of Mixtures of Straight-Run Diesel Fraction and Light Catcracking Gasoil Using a NiMo Sulfide Catalyst on a Zeolite-Containing Support

A NiMo sulfide system with an alumina support containing aluminosilica phosphate SAPO-31 (catalyst NiMo/Al 2 O 3 -SAP) was suggested for synthesis of high-quality diesel fuel from a mixture of straight-run diesel fraction and light catcracking gasoil (LCCG). Against the traditional NiMo/Al 2 O 3 or CoMo/Al 2 O 3 sulfide catalysts, this catalyst was demonstrated to provide production of higher quality diesel fuel through hydroupgrading of the feedstock containing 30 wt.% LCCG. The fact that the proportion of aliphatic hydrocarbons is higher in the products than in the feedstock indicates the activity of the NiMo/Al 2 O 3 -SAP catalyst to ring opening. Application of the suggested catalyst will allow the quality of diesel fuels to be improved during hydroupgrading of the LCCG-containing feedstock.

Hydrotreating of vacuum gasoil in mixture with delayed coking products on industrial NiMo/Al2O3 catalyst

To examine the influence exerted on the degree of hydrogenation and hydrogenolysis by the content of olefin (diolefin) and polycyclic aromatic hydrocarbons at different fractional compositions of distillate mixtures, joint hydrotreating of vacuum gasoil with benzine and light and heavy coking gasoils was performed. The study was carried out in a laboratory installation under a hydrogen pressure of 5.0 MPa, temperature of 375°C, volumetric flow rate of raw materials of 1 h−1, and H2/raw material ratio of 1000/1. The effect of the composition of raw materials and process conditions on the chemical composition and quality parameters of the resulting products was demonstrated. It was shown that a pronounced competition between olefin and polycyclic aromatic hydrocarbons in hydrogenation reactions is observed for mixtures of heavy vacuum gasoil and light coking gasoil, in contrast to mixtures of straight-run diesel fraction and light coking gasoil.

Enzymatic hydrolysis of chitosan in acetate buffer solution

To examine the influence exerted on the degree of hydrogenation and hydrogenolysis by the content of olefin (diolefin) and polycyclic aromatic hydrocarbons at different fractional compositions of distillate mixtures, joint hydropurification of vacuum gasoil with benzine and light and heavy coking gasoils was performed. The study was carried out in a laboratory installation under a hydrogen pressure of 5.0 MPa, temperature of 375°C, volumetric flow rate of raw materials of 1 h−1, and H2/raw material ratio of 1000/1. The effect of the composition of raw materials and process conditions on the chemical composition and quality parameters of the resulting products was demonstrated. It was shown that a pronounced competition between olefin and polycyclic aromatic hydrocarbons in hydrogenation reactions is observed for mixtures of heavy vacuum gasoil and light coking gasoil, in contrast to mixtures of straight-run diesel fraction and light coking gasoil.

Process for producing high octane gasoline having lower benzene content and distillation end point with its environmental effect of engine exhaust emissions

In this research, a process is discussed for upgrading reformate and power former in Iraq’s Al-Doura refinery, by reducing the amount of benzene in the gasoline product with simultaneous reduction in the gasoline’s ASTM distillation end point. The process consists of fractionation of the reformate and power former to recover that fraction (90–180°C) of hydrocarbons. This was directly used as gasoline without further conversion. The heavy bottom fraction (180°C—EBP) consisting of the aromatic and non-aromatic hydrocarbons was recovered and used as antiknock additives to gasoline. The other fraction with (IBP—90°C) was used as feedstock to producing benzene by solvent extraction. The reformate and power former fractions (90–180°C) are blended with light straight run naphtha at ratio (75: 25) to producing gasoline as well as Al Doura gasoline. It was found that the amount of benzene was reduced from 1.41 wt % in the original pool to 1.37 and 1.31 in the alternative products. Engine emissions were also reduced when using the alternative products compared with original pool product.

Ultradeep hydrodesulfurization of diesel fuels using highly efficient nanoalumina-supported catalysts: Impact of support, phosphorus, and/or boron on the structure and catalytic activity

In this paper, new nanocatalysts—CoMoP/nanoAl2O3, CoMoB/nanoAl2O3, CoMo/nanoAl2O3–B2O3, CoMoPB/nanoAl2O3, and CoMoP/microAl2O3—were prepared by a wet co-impregnation method on micro- and nanostructured alumina supports. The effects of physicochemical and chemical properties of the supports—new mesoporous nano-γ-Al2O3 [high surface area (403.05m2g−1), cylindrical pore size (104.59Å), large pore volume (1.69cm3g−1), surface defects, and acidic surface] and conventional micro-γ-Al2O3 [surface area (246.20m2g−1), pore volume (0.5cm3g−1), pore size (70.30Å), and neutral surface]—and of phosphorus (P) and boron (B) addition on the local structure and hydrodesulfurization (HDS) activity of CoMoS catalytic sites were studied in hydrodesulfurization reactions of straight-run light gas–oil (SRLGO). Porosity, morphological, and structural characterizations of the supports and nanocatalysts were done by informative techniques such as nitrogen physisorption, Mo and S X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy–energy dispersive X-ray (HRTEM–EDX), Mo- and Co-extended X-ray absorption fine structure (EXAFS), Co X-ray absorption near-edge structure (XANES), and diffuse reflectance spectroscopy–ultraviolet–visible (DRS–UV–vis). The characterization results showed that dispersion of Co and Mo to form the CoMoS II phase is improved on the nanoAl2O3 support. It was found that CoMoPB/nanoAl2O3 with suitable physicochemical properties—large pore size (101.26Å) and high surface area (247.97m2g−1)—was the highest active catalyst, which enabled it to decrease 13,500ppm (1.35wt%) sulfur of SRLGO feedstock to a sub-10ppm transparent diesel fuel. The HDS catalytic activity of the most refractive substituted dibenzothiophene (DBT) compounds in the feed followed the sequence 4,6-dimethyl-DBT<2,4-dimethyl-6-ethyl-DBT<4,6-diethyl-DBT<2,4,6,8-tetramethyl-DBT<4-methyl-DBT determined by comprehensive two-dimensional gas chromatography (GC×GC-SCD) analysis. It was confirmed that the HDS reaction and catalytic activity of the CoMoS sites is controlled particularly by pore size, surface area, acidity, and the surface properties of the support.

Mechanistic kinetics of catalytic oxidation of 1-butanethiol in light oil sweetening

In the present study the kinetics of liquid phase oxidation of light thiols using novel cobalt phthalocyanine sulphonamide catalyst developed indigenously was investigated in a semi batch reactor. 1-Butanethiol was chosen to represent thiols in lighter range of petroleum fractions like liquefied petroleum gas and light straight run naphtha. Rate data was collected under experimental conditions representing industrial conditions. Effects of process parameters like catalyst concentration and initial feed mercaptan concentration on reaction rates were investigated. A mechanism based rate expression was deduced to explain the observed behavior. Its parameters estimated using Line weaver plots and further fine tuned by using optimization technique. The effective rate law represented a first order kinetics which explained the observed experimental phenomenon reasonably well for commonly encountered industrial conditions.

Study on a new desulfurization method based on imitating ionic liquids for light diesel oil

A simulated light oil consisting of model sulfur compounds of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) and straight-run light diesel oil fractions as solvent was employed for desulfurization tests imitating silver-salt method for ionic liquids (ILs). Under the conditions of a nitrogen atmosphere, reaction temperature of 303 K, reaction time of 24 h, the effects of different alkylating agents and amount of agent on the sulfur removal were investigated in more details. The results showed that when ratio of bromoethane (CH3CH2Br) to sulfur is 80: 1 (mol/mol) and ratio of potassium tetrafluoroborate (KBF4) to sulfur 30: 1 (mol/mol), the desulfurization yield were 72.6%.

The Kinetics of Catalytic Oxidation of 1-Butanethiol in a Gas Liquid System

In the present study the kinetics of liquid phase oxidation of light thiols using reformulated cobalt phthalocyanine based catalyst has been investigated in a semi batch bubble column reactor. 1-Butanethiol is chosen to represent thiols in lighter range of petroleum fractions like liquefied petroleum gas and light straight run naphtha. The study has shown that rate of catalytic oxidation of 1-butanethiol is linear at lower concentrations and of nonlinear nature at higher concentrations. A mechanism based rate expression has been obtained to explain this behavior and its parameters are estimated. The derived rate law is similar to Michaelis-Menten rate equation.

Catalytic Co-Processing of delayed coker light naphtha with other refinery gasoline streams

Upgrading of delayed coker light naphtha is very difficult due to its high diolefin and silicon content. Mixtures of light straight run naphtha and delayed coker light naphtha fractions were hydrotreated in two stages over NiMo/Al 2 O and CoMo/Al 2 O catalysts (diolefin saturation followed by hydrodesulphurization ). The results showed that naphtha fractions free of diolefins, olefins, sulphur and silicon can be produced with the two stage hydrogenation. These are excellent feeds for naphtha isomerization. One-stage selective hydrodesulphurization tests were also conducted with blends of coker naphtha (up to 5 vol%) and fluid catalytic crackers gasoline over CoMo/Al 2 O . Diolefin-free products of < 10 mg/kg sulphur could be produced with a research octane number loss of max. 3.

Hydrodesulfurization of Diesel Oils by MoS2 Catalyst Prepared by in situ Decomposition of Ammonium Thiomolybdate

An unsupported MoS2 catalyst was prepared by in situ decomposition of ammonium thiomolybdate (ATM)in the presence of water. The catalyst was characterized by XRD, scanning electron microscopy (SEM) andspecific surface area measurements (BET, BJH). Its catalytic activity was evaluated for the hydrodesulfurization(HDS) of diesel oils (straight run gas oil, SRGO and light cycle oil, LCO). Selected refractory sulfur compounds:benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in oils wereinvestigated. The high catalytic activity resulted from the large surface area of the catalyst due to water addition.Reactivity order of the sulfur compounds were determined. The results showed that the reactivity order in SRGOwhich contains nitrogen content is different from that in LCO. This reveals that matrix effect of the oil has someinfluences on the reactivity of the sulfur compounds. Key Words: Ammonium thiomolybdate; Diesel oils; Hydrodesulfurization