Normal Paraffins Research Articles

Preparation of High-Purity Normal Hexane from Reformate Raffinate by Adsorption and Distillation Processes

In this study, a combination process of adsorption and distillation was adopted to obtain high-purity normal hexane. In the adsorption separation process, 5A zeolite was used as the adsorbent and the Shanghai Gaoqiao Petrochemical Corporation reformate raffinate containing 24.24 wt% normal hexane was separated into adsorption raffinate oil rich in non-normal paraffins and desorption oil rich in normal paraffins. At pre-specified operation conditions, concentration of n-hexane in the desorption oil reached higher than 96%. The concentrations of 3-methyl pentane and methyl cyclopentane, which are the light- and heavy-key components in the distillation tower of normal hexane, were reduced to 0.15% and 0.07%, respectively. According to the simulation results obtained using the software Aspen Plus, when the distillation tower has 15 stages, the n-hexane concentration can reach 99.02% with a recovery rate of 72.89% at the reflux ratio of 7.5. The combination process involving both adsorption and distillation ha...

Life cycle analysis of gas to liquids (GTL) derived linear alkyl benzene

The production of normal paraffin from the Gas to Liquids (GTL) process is of relevance to the detergents industry. The environmental benefits of GTL derived Linear Alkyl Benzene (LAB) production relative to petroleum derived LAB production can be demonstrated by a rigorous comparison of the lifecycle impacts of both pathways. Using current industrial knowledge and consistent Life Cycle Assessment (LCA) methodological choices, we estimated life-cycle cradle-to-gate environmental impacts, including greenhouse gas (GHG) emissions, of LAB production from petroleum-derived crude oil and natural gas, respectively. In addition, we developed sensitivity cases to assess the robustness of the results due to the uncertainty or variability of key parameters in both pathways. Our base case results show that the lifecycle cradle-to-gate GHG emissions of GTL LAB production are 20% lower than conventional LAB production. Compared to conventional LAB production, lifecycle GHG emissions of GTL LAB are consistently lower, regardless of which allocation method is applied. Despite this, cradle-to-gate GHG emissions of GTL LAB are highly sensitive to assumptions associated with upstream natural gas venting and flaring emissions. Other environmental impacts for the GTL LAB pathway also appear to be favorable when compared to conventional LAB production. This can be rationalized by the GTL LAB route achieving (a) reductions in fired-duty emissions associated with the avoided prefractionation/Molex™ step and (b) avoided fired-duty emissions associated with the normal paraffin coproduct displacing kerosene-derived paraffin production. These results are broadly consistent with previous studies that demonstrate high-quality GTL coproducts affording a net GHG emissions avoidance when displacing conventional, crude oil derived analogs.

Sooting tendency of paraffin components of diesel and gasoline in diffusion flames

The influence of the chemical structure on the sooting characteristics of some paraffin class hydrocarbons which are found in gasoline and diesel fuel is studied experimentally. The experiment involves the combustion of the paraffin in a wick-fed burner. Differential mobility spectrometry is used to measure the particle size distribution (PSD) at different flame heights. The wick-fed laminar diffusion flame is sampled at the tip; the flame height is modified systematically from small heights to large heights. Normal, iso and cyclo paraffins PSDs evolve in a similar way with flame height. At very low flame heights the PSD is unimodal, but rapidly evolves into a multi-modal one. The total number of particles peaks at small heights, and then decreases as flame height increase until it approaches constant values for all considered fuels. The mean soot particle diameter increases with flame height until a height where a maximum is achieved and sustained. Among each type of fuel, a systematic decrease in the maximum mean soot particle diameter was observed as the number of carbon atoms in the molecule increased. At all flame heights, comparing fuels with the same carbon number, cyclic paraffins presented the largest mean soot particles sizes, followed by iso-paraffins and the smallest particles for normal paraffins.

[Molecular composition of saturated hydrocarbons in diesels by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry]

An analytical method for separation and identification of the saturated hydrocarbons in diesels at molecular level by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC x GC-TOF MS)was established. The saturated hydrocarbons were pre-separated from diesel samples by solid phase extraction before GC x GC-TOF MS analysis. More than 1,000 individual compounds (including paraffins, naphthenes and ole- fins) in coker diesel were tentatively identified based on NIST library search, mass spectrum resolution, boiling point distribution law and separation characteristics. Normal paraffins showed great regularity and could be identified easily through the relative position with pristane and phytane. The cyclic alkanes arranged above paraffins with the increasing number of rings. The normal alkyl cyclohexanes and cyclopentanes were well distinguished due to the difference of their polarity. Normal α-olefins which were often neglected in the past were also identified. With the support of the above-introduced identification, the distribution by structural type and carbon number were presented using peak area normalization. This analytical method was suc- cessfully used to investigate the molecular composition of saturated fractions in different diesel samples. All the results indicated that the molecular compositions of saturates in catalytic cracking diesel and coker diesel were significantly different because of the processing mechanism. This method provided technical support for the characterization of saturated hydrocar- bons in diesels and the investigation of processing mechanism.

Optimization of Flowsheet for Scrubbing of Ruthenium during the Reprocessing of Fast Reactor Spent Fuels

The solvent extraction method using tri-n-butyl phosphate diluted with heavy normal paraffin is being used as an extractant for the recovery of plutonium and uranium present in spent fuel discharged from a nuclear reactor. The purification of uranium and plutonium from the fission product ruthenium is considered very important in the fast reactor fuel reprocessing process due to its complex chemistry. Systematic studies have been carried out in batch as well as countercurrent solvent extraction for optimization of parameters to get maximum decontamination factor for ruthenium. In dual scrubbing condition using 3 M and 6 M nitric acid with 60–70% uranium loading in organic phase, a decontamination factor of >103 for Ru is obtained in mixer-settler run.

Evaluation of teratogenic effects of crocin and safranal, active ingredients of saffron, in mice

Saffron (Crocus sativus) is a widely used food additive for its color and taste. Crocin and safranal are two main components of this plant. Numerous studies are underway to introduce saffron and its active ingredients as pharmacological agents. Safety assessments of these compounds are important parts of this endeavor. In this study, the effects of crocin and safranal administrations during embryogenesis have been investigated in mice. A total of 75 BALB/c pregnant mice were divided into six experimental and control groups. Four experimental groups received intraperitoneal injection of crocin (200 mg/kg or 600 mg/kg) daily or safranal (0.075 ml/kg or 0.225 ml/kg) on gestational days (GDs) 6 to 15. Control groups received normal saline or paraffin as solvents of crocin and safranal. Dams were dissected on GD18 and embryos were collected. Routine maternal and fetal parameters were recorded. Macroscopic observation of external malformations was also performed. Fetuses were then selected for double skeletal staining with alizarin red and alcian blue. All experimental groups caused significant decrease in length and weight of fetuses when compared with the control groups and revealed malformations such as minor skeletal malformations, mandible and calvaria malformations, and growth retardation. Minor skeletal malformations were the most commonly observed abnormality, which were statistically significant when compared with the control groups (p < 0.05). The severities of malformations were comparable in the crocin- and safranal-treated groups. This study suggests that crocin or safranal can induce embryonic malformations when administered in pregnant mice. Due to the wide use of saffron, further elaborate studies to understand the malformation mechanisms of these ingredients are recommended.

Dearomatization of normal paraffin by adsorption process using synthesized NaX zeolite

Linear alkyl benzenes (LABs) are the main materials for detergent production. The presence of aromatic compounds in this material can decrease the quality of the final product and enhance the deactivation rate of catalysts. In this research we used zeolite NaX for de-aromatization of the recycled paraffin from the alkylation unit of an LAB production complex. The effect of different parameters on the removal efficiency of adsorbent was studied and optimized. To study the re-usability of the adsorbent, the breakthrough curves were obtained by using a fixed bed column filled with the adsorbent. The results indicated that the adsorbent capacity remained unchanged after three regeneration cycles. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. It was concluded that the Langmuir model agreed well with the experimental data. The calculated thermodynamic parameters of the adsorption showed that the adsorption process was spontaneous and exothermic. The reaction rate was estimated by the pseudo-second order kinetic model.

Effects of experimental conditions on the molecular composition of maltenes and asphaltenes derived from oilsands bitumen: Characterized by negative-ion ESI FT-ICR MS

A vacuum topped Canadian oilsands bitumen (VTB) was subjected to solvent precipitation and subsequently characterized by elemental analysis, gel permeation chromatograph (GPC), 1H-NMR spectroscopy and negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Effects of experimental conditions such as solvent types (n-C5, n-C6, and n-C7), solvent purity, and solvent washing time on asphaltenes yields, bulk composition, and molecular composition of detectable heteroatom compounds in ESI source were determined. Elemental nitrogen and sulfur were enriched in asphaltenes while elemental oxygen had comparable content in maltenes and asphaltenes. Molecular composition of asphaltenes varies with separation conditions. The N1 and O1 species identified by ESI FT-ICR MS were enriched in maltenes. The O2 species exhibited two different double bond equivalents (DBE) distributions and solubility in normal paraffin solvents, indicating two types of molecular structures. Multi oxygen atom containing compounds mainly detected in asphaltenes. Compound class distributions are similar for maltenes derived from n-C5, n-C6, and n-C7, as well as for asphaltenes. The cyclic paraffin impurities in normal paraffin solvents had a significant influence on asphaltenes yields and heteroatom molecular composition. A portion of neutral N1 species and acidic O2 species adsorbed on asphaltenes could be dissolved by increasing washing time. Cautions should be exercised when interpreting the properties and composition of asphaltenes obtained with different experimental conditions.

Rational Formulation of Alternative Fuels using QSPR Methods: Application to Jet Fuels

Alternative fuels are a promising solution for road transport but also for aircraft. In the aviation field, a huge amount of work has been done in the past years with the approval to use up to 50 % by volume of SPK (Synthetic Paraffinic Kerosene) in blends with conventional fossil Jet A-1. SPK are Fischer-Tropsch (FT) fuels but also Hydroprocessed Esters and Fatty Acids (HEFA). However, these alternative fuels can have different chemical properties depending on the process used for their production. These properties include normal to iso paraffin ratio, carbon chain length and level of branching. R&D studies of alternative fuels are based on the evaluation of products coming from identified production processes. However, it appears that a better way of studying them could be firstly to determine the best chemical composition regarding aviation problems and secondly to find the best process and finishing process in order to obtain such a product. The objective of this work is to design a tool that aims to guide the future formulation of alternative fuels for aviation through the prediction of targeted physical properties. Thus, it is proposed to apply a methodology that identifies relationships between the structure and properties of a molecule (QSPR for Quantitative Structure Property Relationship), with the aim of establishing predictive models. These models will be built for hydrocarbons (normal and iso paraffins, naphthenes, aromatics, etc.) and oxygenated compounds (esters and alcohols). For aviation, oxygenated compounds are not considered as a drop-in fuel. It could be seen as a disruptive solution in a long term view. There are concerns with oxygenates in aviation that are covered in this paper such as the flash point but others such as the energetic content, the water affinity that are not taken into account in this paper. The properties currently studied are flash point, cetane number, density and viscosity. The data sets will contain data from the literature, from experimental measurements and from molecular simulations for complex molecules. The interest of such models in the selection of molecules can be shown for example by the trade-off between cold flow properties and density of paraffinic compounds. If the carbon chain length is too high, the cold flow properties are compromised. One solution can be to increase branching or incorporate fuel base with good cold flow properties such as naphthenic or aromatic compounds. However, this leads to a decrease in density below the jet fuel specification. Again, using naphthenic of alkyl-aromatic compounds produced from biomass can help.

Investigation of Paenibacillus alvei ARN63 ability for biodemulsifier production: Medium optimization to break heavy crude oil emulsion

The demulsifying performance of Paenibacillus alvei ARN63 (P. alvei), as a biodemulsifier-producing bacterium, for breaking water-in-heavy crude oil emulsion has been investigated. The produced lipopeptide biodemulsifier showed the potential to be used in the petroleum industry as an environmentally friendly and non-toxic material. To optimize the biodemulsifier production, the impacts of parameters such as temperature, pH, carbon source and carbon concentration at a constant agitation speed of 180rpm and with ammonium sulfate as the sole nitrogen source (1.0g/l) were studied in detail. Several normal paraffin compounds, vegetable oils and motor oil revealed the ability to be used as the carbon source for synthesis of biodemulsifier. The best biodemulsifier production was obtained employing motor oil as the carbon source with a concentration of 42.5g/l at 37°C and pH 7.0 after 72h of incubation. Under these conditions, the surface tension of the medium reduced from 58mN/m to 24.7mN/m and the biodemulsifier yield reached a value of 2.1g/l. The demulsification ratio approached 77% and the produced biodemulsifier by P. alvei strain effectively broke water-in-heavy crude oil emulsion. According to biodemulsifier production and growth time course profiles, the biosynthesis was growth associated. Besides, the produced biodemulsifier had good stability during exposure to salinities up to 20%, temperatures up to 80°C and a wide pH range of 2–12.

축소 노멀 도데케인 화학반응 메커니즘 개발

Generally, a reduced chemical mechanism of n-heptane is used as chemical fuel of a 3-D diesel engine simulation because diesel fuel consists of hundreds of chemical components and various chemical classes so that it is very complex and large to use for the calculation. However, the importance of fuel in a 3-D simulation increases because detailed fuel characteristics are the key factor in the recent engine research such as homogeneous charged compression ignition engine. In this study, normal paraffin, iso paraffin and aromatics were selected to represent diesel characteristics and n-dodecane was used as a representative normal paraffin to describe the heavy molecular weight of diesel oil (C10~C20). Reduced kinetics of iso-octane and toluene which are representative species of iso paraffin and aromatics respectively were developed in the previous study. Some species were selected based on the sensitivity analysis and a mechanism was developed based on the general oxidation scheme. The ignition delay times, maximum pressure and temperature of the new reduced n-dodecane chemical mechanisms were well matched to the detailed mechanism data.

Characterization of wax using potential energy and nanocalculation

Most reservoir fluids contain heavy paraffinic compounds that may precipitate as a solid or solid like material called wax if the fluid is cooled down. Wax precipitation is a phenomenon of considerable importance in oil industry. An increase in aggregation results in enhanced oil viscosity. This however causes significant negative effects on production, transportation and processing of crude oil. So, structural characterization of wax is considered to be important topic. In this work, normal paraffin molecules C20, C21, C23, C24, C25, C27, and C29 have been considered as representatives of wax molecule. Intermolecular forces have been calculated using quantum mechanics and statistical analysis. Second virial coefficients have been obtained for these molecules by applying intermolecular potential energy. Finally SRK and PR equation of states parameters have been achieved to have molecular consideration of wax structure.

Mechanisms of the oxidation and combustion of normal paraffin hydrocarbons: Transition from C1–C10 to C11–C16

Mechanisms of the oxidation and combustion of normal paraffin hydrocarbons: Transition from C1–C10 to C11–C16

Normal Paraffin Production Process of Kerosene in Oil Refinery Company

Look of unit 100 separating needed cuts for continuing the process and producing LAB of Oil cuts C10 _ C13 which is required. These are separated by two distillation towers. In the first tower called (STRIPPER COLUMN T_101) that consist of so trays, lighter cuts of C10 that are called LIGHT END. Are separated and the product of the lower level of tis tower goes to the 2nd tower called. This one consist of 60 Trays. In the bottom of tower products that are heavier than C13 and called heavy end are separated, and the products of the tower, as main products of unit 100 go to the unit 200 for hydrotreating. The purpose of using two tower is that in lower temperatures lighter materials get separated and in higher temperatures higher materials get separated.

Dearomatization of Normal Paraffin by Synthesized Nax Zeolite

Aromatic compounds produced in linear alkyl benzene (LAB) production process decrease the yield and quality of the product and enhance the deactivation rate of the catalysts. Therefore, the de-aromatization of different streams in LAB production complex is inevitable. In this research, the recycled paraffin from alkylation to dehydrogenation unit was de-aromatized by synthesized NaX zeolite. The effect of different parameters such as temperature, amount of the adsorbent, contact time and initial aromatic concentration was studied and optimized. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. It was concluded that the Langmuir model agreed very well with the experimental data. The calculated thermodynamic parameters of the adsorption showed that the adsorption process was spontaneous and exothermic. The reaction rate was estimated by the pseudo-second order kinetic model. To examine the re-generation ability of the adsorbent a fixed bed column was designed and the breakthrough curves were prepared for three successive regeneration cycles. The results indicated that the adsorbent capacity remained unchanged after three regeneration cycles.

Optimization of a divided wall column for the separation of C4-C6 normal paraffin mixture using Box-Behnken design

In the present study, simulation of a divided wall column (DWC) was carried out to study the product quality and energy efficiency as a function of reflux rate, liquid spilt and vapour split for the separation of C4-C6 normal paraffin ternary mixture. Rigorous simulation of the DWC was carried out using Multifrac model of ASPEN Plus software. Box-Behnken design (BBD) was used for the optimization of parameters and to evaluate the effects and interaction of the process parameters such as reflux rate (r), liquid split (l) and vapour split (v). It was found that the number of simulation runs reduced significantly for the optimization of DWC by BBD. Optimization by BBD under response surface methodology (RSM) vividly underscores interactions between variables and their effects. The predictions agree well with the results of the rigorous simulation.

Optimal Operation of Simulated Moving Bed Technology on Utilization of Naphtha Resource

Simulated moving bed (SMB) technology has attracted more and more attention in recent decades. The simulated moving bed (SMB) technology on optimal utilization of naphtha resource was studied in this paper. A simulated moving bed equipped with 16 columns was used to separate normal paraffins from naphtha. The effects of temperature (T), switching time (ts), extract oil flow rate (LAD), feed flow rate (LF), and desorbent flow rate (LD) on the separation performance were investigated, and the desorbent recycle process was simulated by Aspen Plus. The results showed that the optimal conditions for simulated moving bed were operation temperature (T) of 170°C, switching time (ts) of 900 s, extract oil flow rate (LAD) of 10 mL/min, feed flow rate (LF) of 5 mL/min, and desorbent flow rate (LD) of 20 mL/min. Through the SMB and the desorbent recycle system, the purity of the de-solvent extract oil (DEO) reached 98% and the purity of the de-solvent raffinate oil (DRO) reached 92%, which were the high-quality feed for the ethylene cracking process and the catalytic reforming process, respectively.

Comparison of normal phase operation and phase reversal studies in a pulsed sieve plate extraction column

The hydrodynamic characteristics of a pulsed sieve plate extraction column (PSPEC) was studied experimentally using two different liquid phase systems, namely water/kerosene and 30%TBP (tributyl phosphate) in NPH (normal paraffin hydrocarbon)/0.3M HNO3. The aqueous phase as the dispersed phase and the organic phase as the continuous phase (phase reversal) and vice versa (normal phase operation) studies in a pulsed sieve plate extraction column 0.076m in diameter and 1m height are presented in this paper. The hydrodynamic properties like drop size and holdup are characterized as a function of various operating parameters namely pulse velocity, dispersed phase and continuous phase velocity and duty cycle of pulsing. Flooding in the column was also investigated for the changes involving flow ratio of continuous phase to that of the dispersed phase for both insufficient and excessive pulsing. It has been observed that phase reversal mode of operation is not efficient as compared to normal phase operation for the PSPEC.

Comparative studies on the determination of di-n-butyl phosphate in degraded solvent of PUREX process by ion chromatography and gas chromatography methods

This paper describes comparative studies on the determination of di-n-butyl phosphate (DBP) by ion chromatography (IC) and gas chromatography (GC) techniques in spent solvent of PUREX process used for the reprocessing of spent nuclear fuels. The ion chromatography method involves the separation of DBP from 30% TBP–NPH (tri-n-butylphosphate diluted in normal paraffin hydrocarbon) containing heavy metal ion like uranium and nitric acid by extraction of DBP into alkaline medium. DBP was subsequently eluted by ion-exchange separation in ion chromatography column and followed by suppressed conductivity detection. DBP is quantified to a lower limit of about 1 ppm with 3% RSD. However, in order to determine DBP by gas chromatography technique DBP is first quantitatively converted into its volatile and stable derivatives by using diazomethane prior to analysis by GC. Results obtained with ion chromatographic technique are compared with those of obtained by standard gas chromatographic technique. It was observed that IC technique involves minimum steps and is much faster than GC analysis. The effect of mobile phase flow rate on the detector response, retention time, and column pressure are also investigated.

Experimental and modeling study on the pyrolysis and oxidation of n-decane and n-dodecane

High pressure n-decane and n-dodecane shock tube experiments were conducted to assist in the development of a Jet A surrogate kinetic model. Jet A is a kerosene based jet fuel composed of hundreds of hydrocarbons consisting of paraffins, olefins, aromatics and naphthenes. In the formulation of the surrogate mixture, n-decane or n-dodecane represent the normal paraffin class of hydrocarbons present in aviation fuels like Jet A. The experimental work on both n-alkanes was performed in a heated high pressure single pulse shock tube. The mole fractions of the stable species were determined using gas chromatography and mass spectroscopy. Experimental data on both n-decane and n-dodecane oxidation and pyrolysis were obtained for temperatures from 867 to 1739K, pressures from 19 to 74atm, reaction times from 1.15 to 3.47ms, and equivalence ratios from 0.46 to 2.05, and ∞. Both n-decane and n-dodecane oxidation showed that the fuel decays through thermally driven oxygen free decomposition at the conditions studied. This observation prompted an experimental and modeling study of n-decane and n-dodecane pyrolysis using a recently submitted revised n-decane/iso-octane/toluene surrogate model. The surrogate model was extended to n-dodecane in order to facilitate the study of the species and the 1-olefin species quantified during the pyrolysis of n-dodecane and n-decane were revised with additional reactions and reaction rate constants modified with rate constants taken from literature. When compared against a recently published generalized n-alkane model and the original and revised surrogate models, the revised (based on our experimental work) and extended surrogate model showed improvements in predicting 1-olefin species profiles from pyrolytic and oxidative n-decane and n-dodecane experiments. The revised and extended model when compared to the published generalized n-alkane and surrogate models also showed improvements in predicting species profiles from flow reactor n-decane oxidation experiments, but similarly predicted n-decane and n-dodecane ignition delay times.