Gasoline Molecules Research Articles

Transformation rule-based molecular evolution for automatic gasoline molecule design

Automatic molecular design on computers is an emerging technology for the determination of optimal fuel molecules. We developed a computer-aided molecular design framework through a transformation rule-based molecular evolution method. The reaction rule was used as the elementary step to change the molecular structure. A molecule can achieve structural variation continuously using a series of reaction rules. The finding of the optimal molecule can be seen as the evolution of structure in the chemical space, which was guided by using a global optimization algorithm to select the best reaction routine. We showed that the optimized molecule is independent of the input initial structure, proving the robustness of the method. We then applied the method to design gasoline molecules for motor and aviation gasoline. The designed molecules can not only serve as competitive candidate components for high-quality gasoline, but also accelerate the synthesis rate of new molecules in the laboratory.

A molecular-level coupling model of fluid catalytic cracking and hydrotreating processes to improve gasoline quality

A molecular-level Fluid Catalytic Cracking (FCC)-Gasoline Hydrotreating (GH) process coupling model was established to guide the optimization of the hydrocarbon compositions in gasoline based on the Structure Oriented Lumping (SOL) method. 96 FCC reaction rules and 24 GH reaction rules were formulated, and a reaction network containing about 120,000 reactions was constructed. In order to establish the FCC-GH process coupling model, the effective transfer of composition information between the two processes was realized through the molecular composition matrix of gasoline. The molecular composition matrix of gasoline was obtained according to the classification rules of the molecular composition matrix of FCC products. The conversion laws of hydrocarbon molecules in gasoline were investigated by tracking their generation paths and reaction paths. The influences of reaction conditions on the distribution of hydrocarbons in the product gasoline could be calculated quantitatively by the FCC-GH process coupling model at molecular level.

Quantum molecular modeling of oxazolidines as detergent-dispersant additives for gasoline: A valuable technological adviser

Patented detergent-dispersant (DD) additives based on oxazolidines [1] were quantum-mechanics modeled in order to get molecular-level insights into their functionality for removing and preventing formation of gum deposits in gasoline internal-combustion engines. The DDs are derived from polyalkenyl N-hydroxyalkyl succinimides whose polarities were modulated through a radical (R) substituent which can be either a phenol derivative (phenyl, 2-hydroxy-), pentyl or atomic hydrogen attached to the oxazolidine ring. We propose a mechanism for the performance of DDs consisting in the attraction of gum molecules by the DDs’ polar heads and their subsequent transference onto the DDs’ hydrophobic alkyl tails. Density-Functional-Theory (DFT) calculations of electrostatic properties and interaction energies support the above molecular mechanism, and furthermore make the prediction that the best performance is reached when R = atomic hydrogen, as it was found through experimental tests [1]. DFT also allowed to realize that gum agglomerates within gasoline because the attractive interaction among gum monomers is stronger than among gum and gasoline molecules due to the gum’s high polarity induced by the carbonyl and alkene functional groups. Likewise, these functional groups are responsible for gum to adhere firmly to oxidized metallic surfaces in contact with gasoline because they complete the octahedral coordination of the exposed superficial iron atoms, reaching at this manner the same strongest spin polarization that iron atoms have at the bulk crystalline oxidized metal. However, the oxazolidine-based DDs remove deposited gum since they adhere stronger to these surfaces than gum does because their polar heads have more bonding sites than gum, the DD having the radical hydrogen being easiest to be desorbed after gum removal avoiding so be burned by sticking to the metallic surface during gasoline combustion.

Calculation of reaction network and product properties of delayed coking process based on structural increments

The delayed coking reaction kinetic model based on the structure-oriented lumping method showed good accuracy in predicting the yield and composition of coking products at the molecular level. Based on the basic law that molecular structure determines molecular properties, the structural increment contribution method was constructed to expand the functions of established reaction kinetic model to predict the characteristic properties of coking gasoline and diesel products: distillation range, density, research octane number (RON) or cetane number (CN). The contributions of different structural increments of hydrocarbon molecules in gasoline to the RON and those in diesel to the CN could also be calculated by the model. The RONs of the hydrocarbon molecules decreased with the increase of R, and increased with the increase of br and me for the coking gasoline. The CNs of the paraffins molecules improved with the increase of R, but reduced with the increase of br and A6 for the coking diesel. The effects of all structural increments on the RON and CN could be quantitatively calculated through the established correlation formulas. The prediction of composition and properties of coking gasoline and diesel based on the model could guide the subsequent processing and process optimization of delayed coking plant.

A Mythic Labyrinth Inside Your Vehicle Prevents Gasoline Leakage

It is hard to believe that our vehicles can contaminate the environment even when they are not running. This is a consequence of evaporated gasoline leaking from a vehicle’s fuel tank into the atmosphere. To avoid this leakage, evaporated gasoline is vented to a canister packed with charcoal particles called activated carbon. There are deep, channel-like spaces inside activated carbon where gasoline molecules are adsorbed. Adsorption is a process in which molecules of gas or liquid stick to the surface of something solid. Through adsorption it is possible to remove various pollutants from air and water. To understand how adsorption by activated carbon works, picture activated carbon as a maze that traps the gasoline particles and does not let them escape. Finally, we describe current efforts to develop new adsorbing materials from the waste product of another industry, to improve upon the activated carbon currently used in vehicles.

An Assessment on Ethanol-Blended Gasoline/Diesel Fuels on Cancer Risk and Mortality.

Although cancer is traditionally considered a genetic disease, the epigenetic abnormalities, including DNA hypermethylation, histone deacetylation, and/or microRNA dysregulation, have been demonstrated as a hallmark of cancer. Compared with gene mutations, aberrant epigenetic changes occur more frequently, and cellular epigenome is more susceptible to change by environmental factors. Excess cancer risks are positively associated with exposure to occupational and environmental chemical carcinogens, including those from gasoline combustion exhausted in vehicles. Of note, previous studies proposed particulate matter index (PMI) as a measure for gasoline sooting tendency, and showed that, compared with the other molecules in gasoline, 1,2,4–Trimethylbenzene, 2–methylnaphthalene and toluene significantly contribute to PMI of the gasoline blends. Mechanistically, both epigenome and genome are important in carcinogenicity, and the genotoxicity of chemical agents has been thoroughly studied. However, less effort has been put into studying the epigenotoxicity. Moreover, as the blending of ethanol into gasoline substitutes for carcinogens, like benzene, toluene, xylene, butadiene, and polycyclic aromatic hydrocarbons, etc., a reduction of secondary aromatics has been achieved in the atmosphere. This may lead to diminished cancer initiation and progression through altered cellular epigenetic landscape. The present review summarizes the most important findings in the literature on the association between exposures to carcinogens from gasoline combustion, cancer epigenetics and the potential epigenetic impacts of biofuels.

Molecular level analysis on performance of diameter expanding reactor to improve gasoline quality in FCC process

A molecular level model for Fluid Catalytic Cracking (FCC) process was established based on the Structure-Oriented-Lumping (SOL) method to investigate the effects of the diameter expanding reactor on the product distribution. According to the molecular composition characteristics of feed oil, 24 structural increments were adopted to construct a molecular matrix containing 4539 molecules. Combined with the SOL reaction rules, a reaction network consisting of 118,272 reactions was established using MATLAB. The contents of 266 molecules in gasoline and 1189 molecules in diesel oil were calculated using the molecular level models of diameter expanding reactor and conventional reactor. The olefins content in gasoline, which is the summarization of 83 olefins molecules, increased as the reaction temperature went up. Compared with the conventional reactor, the ratio of isopentane to pentene in the diameter expanding reactor increased from 1.38 to 2.59 and the ratio of toluene to methylcyclohexane increased from 2.69 to 3.94. The model illustrated that the diameter expanding reactor could enhance the hydrogen transfer and isomerization reactions from the molecular level to reduce the olefins content and improve the iso-paraffins content in gasoline. The model could describe the molecular level product distribution from the reactor inlet to the outlet.

Systematic performance evaluation of gasoline molecules based on quantitative structure-property relationship models

The future production of clean gasoline requires the evaluation of molecular performance. In this paper, we established a systematic performance evaluation model for molecules in the gasoline range. Antiknock, cleanliness, power, stability, and evaporation performance were investigated and are related to the production of high-quality and clean gasoline. Corresponding quantitative structure–property relationship (QSPR) models were developed to predict the octane number, yield sooting index (YSI), combustion heat, unsaturated bond content, and Reid vapor pressure. The obtained models precisely predict these key properties using only the molecular structure as the input. Several applications were made to show the benefit of the molecular performance evaluation model, including the screening of optimal gasoline molecules, the molecular performance distribution of gasoline mixtures, and the effect of the gasoline molecular conversion pathway. The developed model is potentially a useful tool for the identification of optimal gasoline molecules and related process design.

Catalytic cracking of vacuum gasoil over -SVR, ITH, and MFI zeolites as FCC catalyst additives

The cracking behaviour of three medium-pore zeolites -SVR, ITH, and MFI, with varying Si/Al molar ratio, was evaluated using an equilibrium FCC catalyst (E-Cat) and a hydrotreated vacuum gasoil (VGO) in a microactivity test unit (MAT). The increase in the yield of light olefins (21–29wt% over E-Cat/additive vs. 16wt% over E-Cat) was accompanied by a drop in the yield of gasoline (26–39wt% over E-Cat/additive vs. 43wt% over E-Cat) due to the cracking of reactive species in gasoline fraction (mainly olefins and isoparaffins). With increasing Si/Al ratio in zeolites MFI-280 and –SVR-120, propylene yield passed through maxima reaching 13.5wt% and 12.8wt%, respectively, compared with 7.0wt% over E-Cat. Maximum propylene yield occurred partially due to gasoline over-cracking to light olefins (inverse relation with Si/Al ratio). The effect of MFI crystal size showed that large size crystals enhanced the yield of light olefins as compared to small size crystals due to secondary cracking of gasoline molecules. Results of kinetic study based on 4-lump model showed proportional relation between MFI Si/Al ratio and activation energy for the conversion of gasoline to gases. Activation energy increased from 14.2kcal/mol to 16.3kcal/mol as Si/Al ratio increased from 30 to 2000.

Electrokinetic treatment of polluted soil at pilot level coupled to an advanced oxidation process of its wastewater

Soil contaminated with hydrocarbons is a current problem of great importance. These contaminants may be toxic, can retain water and block gas exchange with the atmosphere, which produces a poor-quality soil unsuitable for ecological health. Electroremediation is among the treatments for the removal of such contaminants. In this research, a pilot-level electroremediation test was applied using a circular arrangement of electrodes with a Ti cathode at the middle of the cell surrounded by six IrO2–Ta2O5 | Ti anodes. The presence of an NaOH electrolyte helps to develop the electromigration and electro-osmosis of gasoline molecules (at 1126 mg kg−1) surrounded by Na+ ions. The hydrocarbons are directed towards the cathode and subsequently removed in an aqueous Na+ – hydrocarbon solution, and the –OH migrates to the anode. During electrokinetic treatment, the physicochemical characteristics of the soil close to either the cathode or anode and at the half-cell were evaluated during the three weeks of treatment. During that time, more than 80% of hydrocarbons were removed. Hydrocarbons removed by the electrokinetic treatment of gasoline-polluted soil were collected in a central wastewater compartment and subsequently treated with a Fenton-type advanced oxidation process. This achieved more than 70% mineralization of the hydrocarbons to CO2 and H2O within 1.5 h; its low toxicity status was verified using the Deltatox® kit test. With this approach, the residual water complied with the permissible limits of COD, pH, and electrical conductivity for being discharged into water bodies, according to Mexican norm NOM-001-SEMARNAT-1996.

Characterization of gasoline/ethanol blends by infrared and excess infrared spectroscopy

Fuels for automotive propulsion are frequently blends of conventional gasoline and ethanol. However, the effects of adding an alcohol to a petrochemical fuel are yet to be fully understood. We report Fourier-transform infrared spectroscopy (FTIR) of ethanol/gasoline mixtures with systematically varied composition. Frequency shifts and excess infrared absorbance are analyzed in order to investigate the mixture behavior at the molecular level. The spectroscopic data suggest that the hydrogen bonding between ethanol molecules is weakened upon gasoline addition, but the hydrogen bonds do not disappear. This can be explained by a formation of small ethanol clusters that interact via Van der Waals forces with the surrounding gasoline molecules. Furthermore, approaches for measuring the chemical composition of ethanol/gasoline blends by FTIR are discussed. For a simplistic approach based on the Beer–Lambert relation, an optimized set of parameters for quantitative measurements are determined. The best compromise between measurement sensitivity and accuracy is found for the CO stretching mode of the alcohol. For the traditional method of calibrating the ratio of integrated band intensities of the CH and OH stretching regions it is found that narrowing the spectral window of the CH stretch can significantly improve the measurement sensitivity.

Highly efficient adsorbents based on hierarchically macro/mesoporous carbon monoliths with strong hydrophobicity

Hierarchically porous carbon monoliths (HPCMs) with both ordered hexagonal mesoporosity and three-dimensionally connected macroporosity were synthesized via a simple and time-saving hydrothermal process followed by a nanocasting pathway. These monoliths have high macropore volumes and specific surface areas, strong hydrophobicity, low densities and regular shapes. Importantly, these HPCMs showed excellent performance in cleaning/recycling spilled oils or organic solvents with high adsorption capacity, rate, stability, and reusability, and in adsorbing bilirubin with high adsorption capacity, blood compatibility and durability in plasma as well. The adsorption of oil was based on the dispersion interaction between gasoline molecules and the carbon basal planes of HPCMs, while the isotherm of bilirubin adsorption on the optimized HPCMs and the corresponding kinetic data were found better fitted by Langmuir adsorption model and pseudo-second-order kinetic model, respectively.

Effects of Magnetic Field on Fuel Consumption and Exhaust Emissions in Two-Stroke Engine

The energy of permanent magnets was used in this research for the treatment of vehicle fuel (Iraqi gasoline), to reducing consumption, as well as reducing the emission of certain pollutants rates. The experiments in current research comprise the using of permanent magnets with different intensity (2000, 4000, 6000, 9000) Gauss, which installed on the fuel line of the two-stroke engine, and study its impact on gasoline consumption, as well as exhaust gases. For the purpose of comparing the results necessitated the search for experiments without the use of magnets. The overall performance and exhaust emission tests showed a good result, where the rate of reduction in gasoline consumption ranges between (9-14) %, and the higher the value of a reduction in the rate of 14% was obtained using field intensity 6000 Gauss as well as the intensity 9000 Gauss. It was found that the percentages of exhaust gas components (CO, HC) were decreased by 30%, 40% respectively, but CO2 percentage increased up to 10%. Absorption Spectrum of infrared and ultraviolet radiation showed a change in physical and chemical properties in the structure of gasoline molecules under the influence of the magnetic field. Surface tension of gasoline exposed to different intensities of magnetic field was measured and compared with these without magnetization.

Pervaporation separation of n-heptane/thiophene mixtures by polyethylene glycol membranes: Modeling and experimental

Gasoline desulfurization by membrane processes is a newly emerged technology, which has provided an efficient new approach for sulfur removal and gained increasing attention of the membrane and petrochemical field. A deep understanding of the solution/diffusion of gasoline molecules on/in the membrane can provide helpful information in improving or optimizing membrane performance. In this study, a desulfurization mechanism of polyethylene glycol (PEG) membranes has been investigated by the study of sorption and diffusion behavior of typical sulfur and hydrocarbon species through PEG membranes. A solution–diffusion model based on UNIFAC and free volume theory has been established. Pervaporation (PV) and sorption experiments were conducted to compare with the model calculation results and to analyze the mass transport behavior. The dynamic sorption curves for pure components and the sorption experiments for binary mixtures showed that thiophene, which had a higher solubility coefficient than n-heptane, was the preferential sorption component, which is key in the separation of thiophene/hydrocarbon mixtures. In all cases, the model calculation results fit well the experimental data. The UNIFAC model was a sound way to predict the solubility of solvents in membranes. The established model can predict the removal of thiophene species from hydrocarbon compounds by PEG membranes effectively.

Fast, high temperature and thermolabile GC—MS in supersonic molecular beams

This work describes and evaluates the coupling of a fast gas chromatograph (GC) based on a short column and high carrier gas flow rate to a supersonic molecular beam mass spectrometer (MS). A 50 cm long megabore column serves for fast GC separation and connects the injector to the supersonic nozzle source. Sampling is achieved with a conventional syringe based splitless sample injection. The injector contains no septum and is open to the atmosphere. The linear velocity of the carrier gas is controlled by a by-pass (make-up) gas flow introduced after the column and prior to the supersonic nozzle. The supersonic expansion serves as a jet separator and the skimmed supersonic molecular beam (SMB) is highly enriched with the heavier organic molecules. The supersonic molecular beam constituents are ionized either by electron impact (EI) or hyperthermal surface ionization (HSI) and mass analyzed. A 1 s fast GC—MS of four aromatic molecules in methanol is demonstrated and some fundamental aspects of fast GC—MS with time limit constraints are outlined. The flow control (programming) of the speed of analysis is shown and the analysis of thermolabile and relatively non-volatile molecules is demonstrated and discussed. The tail-free, fast GC—MS of several mixtures is shown and peak tailing of caffeine is compared with that of conventional GC—MS. The improvement of the peak shapes with the SMB—MS is analyzed with the respect to the elimination of thermal vacuum chamber background. The extrapolated minimum detected amount was about 400 ag of anthracence- d 10, with an elution time which was shorter than 2s. Repetitive injections could be performed within less than 10 s. The fast GC—MS in SMB seems to be ideal for fast target compound analysis even in real world, complex mixtures. The few seconds GC—MS separation and quantification of lead (as tetraethyllead) in gasoline, caffeine in coffee, and codeine in a drug is demonstrated. Controlled HSI selectivity is demonstrated in the range of 10 1 to 10 4 anthracene/decane which helped to simplify the selective analysis of aromatic molecules in gasoline. The contribution of SMB to the operation of the fast GC—MS is summarized and the compatibility with conventional GC having a megabore column is shown. Splitless injections of 100 μL sample solutions for trace level concentration detection is also presented (with a conventional GC).

Effect of feedstock variability on catalytic cracking yields

Nine compositionally distinct vacuum gas oil feedstocks have been studied to develop a rational basis for understanding the distribution of major products in fluid catalytic cracking (FCC) reactions. Key hydrocarbon and carbon types have been quantitated from mass spectrometric data. Product yields were determined, under standardized conditions, using an FCC microactivity test (MAT) system. Severity conditions were varied to obtain yield profiles encompassing that MAT conversion where the yield of C 5F + gasoline was at maximum. These optimum yield profiles were correlated with the feedstock properties which characterized and quantitated those precursors capable of producing gasoline molecules. The correlations were tested against two further vacuum gas oils. The conclusions are that realistic comparisons between feeds may be made at conversions where the yield of gasoline is at maximum.

The chemistry of catalytic cracking with molecular sieve catalysts

In the commercial catalytic cracking of high-boiling petroleum fractions, the crystalline molecular sieve type catalysts exhibit three outstanding differences in comparison to the noncrystalline silica-alumina catalysts. (1) They are more active. (2) The gasoline contains more paraffins and aromatics and fewer olefins. (3) A greater proportion of the petroleum can be cracked before cracking (“over-cracking”) of the gasoline begins. It is proposed that the primary cracking step is the same for both catalysts and the differences are ascribed to differences in secondary reactions of a hydrogen transfer nature. With the molecular sieve catalysts, the gasoil molecules are too large to enter the catalyst cavities, so cracking occurs on the external surface, but the gasoline molecules can enter the cavities and the secondary reactions occur there. With the large pores of the noncrystalline silica-alumina, there is no separation of sites for the primary and secondary reactions. The observed differences are rationalized using these concepts.