Straight-run Naphtha Research Articles

Catalytic pyrolysis of straight-run naphtha to light olefins: Experiment and molecular-level kinetic modeling study

In this work, molecular-level kinetic modeling was developed for the fluid catalytic pyrolysis of straight-run naphtha based on the structural unit and bond-electron matrix framework. The kinetic parameters were tuned and optimized using systematic experimental data from a fluidized bed under different conditions, the predicted values of the fraction yield, naphtha composition, and gas product yield were in agreement with the experimental data. The model can obtain the typical reaction rate of naphtha with different carbon numbers and structure compositions at the molecular level under typical conditions. The model can also quantify and compare the effects of eliminating different side reactions on the light olefins production, and different optimized reaction types of naphtha feedstocks under two typical conditions were revealed, quantitative model calculations show a significant boost in light olefin yield of 15–33 percentage points without hydrogen transfer.

Separation of Aromatic Hydrocarbons from Straight-Run Naphtha by Bimetallic Halides

Separation of Aromatic Hydrocarbons from Straight-Run Naphtha by Bimetallic Halides

Alternative Options for Ebullated Bed Vacuum Residue Hydrocracker Naphtha Utilization

The vacuum residue hydrocracker naphtha (VRHN) is a chemically unstable product that during storage changes its colour and forms sediments after two weeks. It cannot be directly exported from the refinery without improving its chemical stability. In this research, the hydrotreatment of H-Oil naphtha with straight run naphtha in a commercial hydrotreater, its co-processing with fluid catalytic cracking (FCC) gasoline in a commercial Prime-G+ post-treater, and its co-processing with vacuum gas oil (VGO) in a commercial FCC unit were discussed. The hydrotreatment improves the chemical stability of H-Oil naphtha and reduces its sulphur content to 3 ppm. The Prime-G+ co-hydrotreating increases the H-Oil naphtha blending research octane number (RON) by 6 points and motor octane number (MON) by 9 points. The FCC co-cracking with VGO enhances the blending RON by 11.5 points and blending MON by 17.6 points. H-Oil naphtha conversion to gaseous products (C1–C4 hydrocarbons) in the commercial FCC unit was found to be 50%. The use of ZSM 5 containing catalyst additive during processing H-Oil naphtha showed to lead to FCC gasoline blending octane enhancement by 2 points. This enabled an increment of low octane number naphtha in the commodity premium near zero sulphur automotive gasoline by 2.4 vol.% and substantial improvement of refinery margin. The processing of H-Oil naphtha in the FCC unit leads also to energy saving as a result of an equivalent lift steam substitution in the FCC riser.

On the influence of low octane gasoline and biodiesel on diesel engine operating characteristics

Biodiesel is a promising alternative fuel, but it has drawbacks. This research aims to diminish the NOx dilemma for diesel and biodiesel by utilizing straight-run naphtha as an additive. It has a low carbon footprint of production from light distilled crude oil without any requirement for the thermal cracking process. The diesel was blended with naphtha at percentages of 5%, 10%, and 15% that abbreviated by N5, N10, and N15, respectively. The biodiesel/diesel blend was mixed with the same naphtha concentrations forming the blends B30N5, B30N10, and B30N15, respectively. Experiments were applied on a single-cylinder engine at 2,000 rpm and different loads. The findings revealed that N15 declined the brake specific fuel consumption (bsfc) at most loads relative to neat diesel. Contrarily, biodiesel blends reflected a spiking trend of bsfc at tested loads. Notably, the NOx emissions declined with N15 blend at high loads relative to neat diesel. The blends B30N15 and B30N10 reduced NOx at high loads compared to the diesel/biodiesel blend. The straight-run naphtha was found to be a promising additive because the balanced composition of the iso-paraffins and n-paraffins. Hence, it dominated the ignition tendency and reduced NOx emissions due to its cooling effect.

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 ℃.

Recent progress on catalyst technologies for high quality gasoline production

ABSTRACT The growing demand for clean and efficient fuels in the world reflects the rapid growth in automotive vehicles and more stringent environmental regulations. Hence, the refining industry must employ diverse strategies to obtain a gasoline pool made up of streams from different processes focused on improving the fuel quality and the octane ratings suitable for the current demanding automotive performance. The composition of gasoline varies mainly from each country’s policies, climate, environmental regulations, financial capacity, and local producer’s oil refining infrastructure. However, a generally accepted composition by source of the gasoline pool is: FCC naphtha and reformate, making up about 60%, light straight-run naphtha and alkylate gasoline, around 30%, isomerate, close to 5%, and variable proportions of butane, oxygenating agents, such as methyl-ter-butyl ether (MTBE), ter-amyl-methyl ether (TAME) and/or ethanol and additives for the remaining 5%. This review is focused on the recent research in the advancement and development of catalysts for the different processes used by the oil refining industry to improve the composition and properties of gasoline fuels. A detailed section on the Fischer-Tropsch process, where liquid hydrocarbons are potentially employed to further produce clean gasoline, is also discussed. A section devoted to research on biogasoline as a potential renewable fuel is also addressed. Finally, a discussion of the physicochemical properties of the gasoline blending components is also provided.

Hydrostabilization of Straight-Run Naphtha Pyrocondensate in the Presence of a Nickel–Chromium Catalyst

Hydrostabilization of Straight-Run Naphtha Pyrocondensate in the Presence of a Nickel–Chromium Catalyst

Oxidative Desulfurization of Straight-Run Naphtha Fraction Using Heterogeneous Catalysts with Two Types of Active Sites

Oxidative Desulfurization of Straight-Run Naphtha Fraction Using Heterogeneous Catalysts with Two Types of Active Sites

Artificial intelligence approach in crude distillation unit operation

This study incorporates the use of Artificial Intelligence in the monitoring of atmospheric distillation unit of large scale refining operation using Google AutoML tables, Jupyter, and Python software. The process involved training, evaluation, improvement, and deployment of the models based on the input data. The predicted yield (vol %) for the models were: Auto ML model: liquefied petroleum gas (LPG) - 1.41 , straight run gasoline (SRG)– 4.96, straight run naphtha (SRN) – 17.87, straight run kerosene (SRK) – 14.5, light diesel oil (LDO) – 26.47, heavy diesel oil (HDO) – 2.7, and atmospheric residue (AR) –30.03; Jupyter Model: LPG – (0.93), SRG – (4.69), SRN – (17.24), SRK – (14.39), LDO – (26.43), HDO – (2.7), and AR – (30.18); and Python Model:LPG – (1.66) , SRG – (7.58), SRN – (11.68), SRK – (14.92), LDO – (24.77), HDO – (4.59), and AR – (24.59). The coefficient of determination (R2) values of 0.99981, 0.99943, and 0.93078 and Standard Error values of 0.240918, 0.419291, 3.536064, were obtained for the 3 models, respectively. All the software gave good predictions of the actual yield, although the Google Auto ML Table gave the best prediction. The training of the model is fundamental to its performance and precision.

РАБОТА КОНДЕНСАЦИОННОГО ОБОРУДОВАНИЯ УСТАНОВОК ИЗОМЕРИЗАЦИИ ЛЕГКОЙ ПРЯМОГОННОЙ НАФТЫ

the analysis of the operation of the condensation equipment of the units for the pre liminary fractionation of raw materials for the isomerization of straight-run naphtha. Variants of ar rangement of condensing devices of rectification columns are considered, their efficiency is e

Experimental and modeling studies for intensification of mercaptans extraction from LSRN using a microfluidic system

We investigated the performance of a T-type microchannel for mercaptan extraction from light straight-run naphtha (LSRN) with sodium hydroxide solution. The aim of this work is to introduce the microfluidic system as a potential tool for mercaptan extraction from light petroleum products. Modeling the extraction process of mercaptan from LSRN has not been carried out previously. In this regard, mercaptan extraction was modeled by response surface methodology (RSM) and artificial neural network (ANN) to analyze the effect of operating parameters on the mercaptan extraction process. The independent variables are considered as temperature, sodium hydroxide concentration, and the volume ratio of sodium hydroxide to LSRN. Two models were compared based on error analysis of the predicted data. Root mean square error, mean relative error, and determination coefficient for the neural network were 0.5650, 0.4341, and 0.9862, respectively. The values of these parameters for the RSM model were 0.6854, 0.7648, and 0.9798. The results showed that the prediction accuracy for both models is appropriate, but the precision of the neural network model is slightly higher than that of the RSM model. The genetic algorithm (GA) technique determined the optimal values of the independent variables with the aim of maximizing the extraction percentage. The mercaptan extraction percentage value of 85.08% was achieved at 303.15 K, the sodium hydroxide concentration of 20 wt%, and the volume ratio of sodium hydroxide to LSRN of 0.128. Furthermore, results showed a higher mercaptan extraction percentage of the microfluidic system compared to a conventional extractor at the same process condition.

Принцип предфракционирования в схеме разделения бензиновой фракции

The requirements to motor fuels are tightened, in particular, restrictions on the content of hydrocarbons and benzene, with the adoption of new emission standards in the modern oil refining industry. At many Russian refineries problem of benzene content decreasing in reformate, which is the main component of gasolines, and, consequently, problem of benzene content decreasing in commercial gasoline, is solved by increasing the initial boiling point of the feedstock for catalytic reforming units to 100°C. At the same time, the main benzene-forming components have boiling points up to 85˚С. This approach is explained by the limitations of technological equipment and a significant increase in energy consumption when creating proper sharpness of rectification at CDU units, while it has a negative impact on the refinery economic efficiency. The article is devoted to approach to modernization of the typical straight-run naphtha distillation unit, configured to the maximum extraction of feedstock for catalytic reforming unit while meeting the requirements imposed on the content of benzene and benzene precursors in it. The proposed solutions can be implemented in the unit current configuration and do not require replacement of main process equipment. Changes in material balance and utility consumption of the unit after described modernization are presented.

Optimization of SRT-VI Pyrolysis Furnaces of High-Capacity Ethylene Plant

The development and solution of an optimization model of real-time control of pyrolysis of straight-run naphtha are considered. The model takes into account the constraints imposed by downstream units of a high-capacity production plant on the pyrolysis process, among which are the primary pyrolysis-gas fractionation unit, pyrolysis-gas compression unit, pyrolysis-gas separation unit, ethylene and propylene refrigeration cycles, reactors of hydrogenation of acetylenic compounds, and separation columns. Optimization is performed using a mathematical model comprising three parts: calculation of the physicochemical characteristics of straight-run naphtha from data of density measurements and Engler distillation, calculation of the kinetic parameters of the process, and determination of the yields of 14 main products of the pyrolysis. The errors of modeling the yields of various pyrolysis products are as follows (rel %): ethylene ±1.5, propylene ±2.8, butadiene ±3.3, and benzene ±3.1. In the optimization, “light” (density 0.706 kg/L) and “heavy” (0.72 kg/L) straight-run naphthas were studied. For both types of feedstock at a target ethylene yield of 10.45 t/(h furnace) under the target constraints, the profit was maximized and the standard naphtha consumption was minimized. The results were compared with the requirements for the pyrolysis according to the standard operating procedures, according to which the ethylene yield did not reach the target value for either type of feedstock and was 10.32 and 9.68 t/(h furnace), respectively. After optimization, the maximum profit was 1143 and 935 cu/(h furnace), respectively. The minimization of the standard consumption gave 1.79 t/t for light naphtha and 1.84 t/t for heavy naphtha. The constraints were met, and the target ethylene yield was reached. It was concluded that the pyrolysis of straight-run naphtha taken directly from a supplier’s pipe is inefficient and that the feedstock should be prepared in stirred intermediate tanks, with naphtha density measurements and Engler distillation performed according to the standard operating procedures, the data of which should then be used in the optimization.

Development of a reduced four-component (toluene/n-heptane/iso-octane/ethanol) gasoline surrogate model

The prospect of blending gasoline fuel with ethanol is being investigated as a potential way to improve the knock residence of the base gasoline. However, one of the drawbacks is a lack of proper understanding of the reason for the non-linear response of blending ethanol and gasoline. This non-linearity could be better understood by an improved knowledge of the interactions of these fuel components at a molecular level. This study proposed a highly reduced four-component (toluene/n-heptane/iso-octane/ethanol) gasoline surrogate model containing 59 species and 270 reactions. The model was reduced using the direct relation graph with expert knowledge (DRG-X) (Lu and Law, 20015; Lu et al., 2011) and isomer lumping method. The computational singular perturbation (CSP) analysis were performed to reduce the potential stiffness issues by accordingly adjusting the Arrhenius coefficients of the proper reactions. The model has been comprehensively validated against wide range of ignition delay times (IDT) and flame speed (FS) measurement data as well as compared against two representative literature models from Liu et al. (2013) and Wang et al. (2015). Overall, good agreements were observed between model predictions and experimental data across the entire research octane number (RON), equivalence ratio, pressure and temperature range. In addition, the model has also been coupled with the computational fluid dynamic (CFD) models to simulate the experimental data of constant volume reacting spray of a low-octane gasoline (Haltermann straight-run naphtha), and in-cylinder pressures and temperatures of a high-octane gasoline (Haltermann Gasoline) combustion in a heavy duty compression ignition engine. The coupled model can qualitatively predict the experimentally obtained data with an improved performance for PRF, TPRF, and TPRF-ethanol surrogates.

Use of Span 80 and Tween 80 for blending gasoline and alcohol in spark ignition engines

Span 80 and Tween 80 are biodegradable surfactants that can be added to blended fuels such as hydrated bioethanol–gasoline and methanol–gasoline. They increase the fuels’ water tolerance and reduce their corrosive properties, without altering their fuel characteristics. For this study, a mixture of surfactants Span 80 and Tween 80 was added to create an emulsion and the optimum hydrophilic:lipophilic balance (HLB) was determined. The effect of this additive mixture on spark ignition (SI) engines and the resulting gas emissions were also investigated.Four kinds of fuel mixtures were tested in this study. They were: 10% denatured (DN) ethanol mixed with 90% commercial unleaded gasoline 92 (E10); a blend of 63% commercial unleaded gasoline 92, 17% straight-run naphtha and 20% DN ethanol (E20); 75% commercial unleaded gasoline 80 and 25% DN ethanol (E25); and 9% methanol with 91% commercial unleaded gasoline 92 (M9).The four product blends were compliant with the international standards EN-228 and ASTM-D4814. They also produced good engine performance and reduced amounts of carbon monoxide (CO) and nitrogen oxide (NOx) emissions compared with standard fuels.

Conversion of Straight-Run Naphtha to C5−C6 Alkanes on Co(Ni)/HZSM–5/SO 4 2- —ZrO2 Composite Catalysts

The conversion of straight-run naphtha on composite catalytic systems containing HZSM-5 zeolite modified with 0.4 wt % Co or Ni and 15% SZ (10% SO 4 2- /ZrO2), performed at atmospheric pressure in the interval 140–200°C, was studied. At 140–200°C, the major products of straight-run naphtha conversion are branched C5−C6 alkanes. At T ≥ 180°C, the reaction products become enriched in gaseous alkanes. Analysis of the conversion products suggests that the process occurs via formation of a skeleton-isomerized intermediate, followed by its cleavage (disproportionation) at the β- or α-bond. The conversion is influenced by the conditions of the reaction and reduction of the composite catalytic system. On the Co-containing composite catalyst reduced at 380°C, the conversion of C8+ components of straight-run naphtha at 180°C, feed space velocity of 2.5 h−1, and H2/CH = 3 is 76.8%, and the content of C5−C6 alkanes consisting to 78% of isoparaffins reaches 61%.

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.

A new approach for gasoline upgrading: Coupling octane enhancement and desulfurization of heavy straight-run naphtha over Ni/HZSM-5 catalyst

The effect of incorporating nickel in HZSM-5 zeolite on its performance of desulfurization alongside octane enhancement processes of heavy straight-run naphtha was investigated for the first time. Experimental results indicated that the synergy between Brönsted and Lewis surface acid sites of Ni/HZSM-5 at a low SiO2/Al2O3 ratio and consequently of high acidity made a great impact on the coupling aromatization and desulfurization reactions of heavy naphtha as a proper feed. After using a SiO2/Al2O3 ratio of 60, the amount (wt%) of total sulfur decreased by 88%. In addition, the research octane number increased from 52 to 94 at the SiO2/Al2O3 ratio of 40.

Autoignition of straight-run naphtha: A promising fuel for advanced compression ignition engines

Naphtha, a low-octane distillate fuel, has been proposed as a promising low-cost fuel for advanced compression ignition engine technologies. Experimental and modelling studies have been conducted in this work to assess autoignition characteristics of naphtha for use in advanced engines. Ignition delay times of a certified straight-run naphtha fuel, supplied by Haltermann Solutions, were measured in a shock tube and a rapid comparison machine over wide ranges of experimental conditions (20 and 60 bar, 620–1223 K, ϕ = 0.5, 1 and 2). The Haltermann straight-run naphtha (HSRN) has research octane number (RON) of 60 and motor octane number (MON) of 58.3, with carbon range spanning C3–C9. Reactivity of HSRN was compared, via experiments and simulations, with three suitably formulated surrogates: a two-component PRF (n-heptane/iso-octane) surrogate, a three-component TPRF (toluene/n-heptane/iso-octane) surrogate, and a six-component surrogate. All surrogates reasonably captured the ignition delays of HSRN at high and intermediate temperatures. However, at low temperatures (T < 750 K), the six-component surrogate performed the best in emulating the reactivity of naphtha fuel. Temperature sensitivity and rate of production analyses revealed that the presence of cyclo-alkanes in naphtha inhibits the overall fuel reactivity. Zero-dimensional engine simulations showed that PRF is a good autoignition surrogate for naphtha at high engine loads, however, the six-component surrogate is needed to match the combustion phasing of naphtha at low engine loads.