Structure Of Hydrocarbons Research Articles

Lectin pathway proteins and association with complement activation and disease activity in patients with Systemic Lupus Erythematosus

Isomerization, ionization and fragmentation of molecular compounds in the interstellar medium can be triggered by stellar radiation and cosmic rays. In the present contribution, we examine the propensity for isomerization and the relative stability of aromatic rings in the pyrene and coronene molecules at various degrees of dehydrogenation by means of molecular modeling. Using the AIREBO reactive force field and advanced Monte Carlo techniques such as the Wang–Landau method based on suitable order parameters, entire free-energy profiles describing the isomerization pathways and equilibrium properties were calculated as a function of temperature or total energy. We generally find that hydrogenation significantly stabilizes the fully polycyclic aromatic hydrocarbon (PAH) structure, even though local dehydrogenation next to an aromatic ring favors ring opening. The formation of pentagonal rings, a typical defect motif in the polycyclic carbon skeleton, is predicted to be actually competitive with the loss of a hydrogen atom. Our investigation emphasizes the likely presence of defects in astrophysical PAHs, whose spectral features remain to be better characterized and understood.

Change of Hydrocarbon Structure Type in Lube Hydroprocessing and Correlation Model for Viscosity Index

Viscosity index (VI) is one of the most important properties that determine the quality grade of lube base oil and it strongly depends on the molecular structure of the hydrocarbon constitute. To produce group III base oil, which is the most valuable base oil type, through lube hydroprocessing, the VI of the final product should be over 120. However, rigorous studies and analyses on the compositional change in lube hydroprocessing and a practical correlation model for VI with respect to the chemical compositions are still lacking. In this study, pilot tests for lube hydroprocessing, which is composed of hydrotreating/cracking followed by hydroisomerization, are implemented with three different types of feedstocks (paraffinic, intermediate, and naphthenic vacuum gas oils) and under different reaction conditions (catalyst and temperature). The fractional changes of the hydrocarbon components by the lube hydroprocessing reactions are quantitatively confirmed using a gas chromatography with mass selective det...

Dehydrogenation effects on the stability of aromatic units in polycyclic aromatic hydrocarbons in the interstellar medium: A computational study at finite temperature

Isomerization, ionization and fragmentation of molecular compounds in the interstellar medium can be triggered by stellar radiation and cosmic rays. In the present contribution, we examine the propensity for isomerization and the relative stability of aromatic rings in the pyrene and coronene molecules at various degrees of dehydrogenation by means of molecular modeling. Using the AIREBO reactive force field and advanced Monte Carlo techniques such as the Wang–Landau method based on suitable order parameters, entire free-energy profiles describing the isomerization pathways and equilibrium properties were calculated as a function of temperature or total energy. We generally find that hydrogenation significantly stabilizes the fully polycyclic aromatic hydrocarbon (PAH) structure, even though local dehydrogenation next to an aromatic ring favors ring opening. The formation of pentagonal rings, a typical defect motif in the polycyclic carbon skeleton, is predicted to be actually competitive with the loss of a hydrogen atom. Our investigation emphasizes the likely presence of defects in astrophysical PAHs, whose spectral features remain to be better characterized and understood.

Epoxidation and oxidative dihydroxylation of C10–C13 unsaturated bridged hydrocarbons involving hydrogen peroxide and modified forms of heteromolybdic compounds

Induced oxidation of C10–C13 tricyclic bridged olefins synthesized from C5–C8 cyclodiene hydrocarbons using hydrogen peroxide has been studied. It has been shown that phosphomolybdic heteropoly compounds supported on a finely divided carbon material and additionally modified with HBr and CoCO3 or Gd2O3 exhibit high activity in this reaction. Depending on the conditions of the experiments, the main reaction products are the corresponding oxiranes and diols that retain the structure of the reactant hydrocarbons.

A Comprehensive Review of Effect of Biodiesel Additives on Properties, Performance, and Emission

Objectives:- To presents the literature review on effect of biodiesel additives on properties, performance and on emission. Method:-In the current paper reviews are taken from previous years paper which necessitates the need of addition of additives in the blends of biodiesel and studied the its effect on properties, performance and emissions. Emissions from the diesel powered vehicles mostly damaged the earth’s environment and also increased the overall earth’s temperature. This attracts the need of alternative fuels in the field of transportation sector. Past inventions and research showed that Biodiesel can be used as an alternative fuel for the diesel engine. Biodiesel have good combustion characteristics because of their long chain hydrocarbon structure. However biodiesel possesses few disadvantages such as lower heating value, higher flow ability, much high density and not able to flow at low temperature. Higher rate of fuel consumption is identified and higher level of NOx emissions when biodiesel used in an engine as an alternative fuels. Findings:-Different additives such as antioxidants, improvers for cetane number, cold flow properties improver, etc were investigated by the many researcher and scientists and added in the different feedstock of biodiesel or blends of biodiesel with diesel in different proportions. Directly or indirectly fuel additives can improve the reduction in the emissions, improve the fuel economy, and reduce the dependency of the one’s nation on other. Performances of biodiesel vehicles were drastically improved because of additioninthe blends of biodiesel with diesel fuel in specific percentages to meet the international emission standards. Addition of additives in the biodiesel or in the blends of biodiesel basically changes the high temperature and low temperature flow properties of blends of biodiesel. Current paper finds and compares properties of different additives and its effect on blends of biodiesel properties, performance and on emissions from diesel engines. Improvement:-This paper presents the literature review on effect of biodiesel additives on properties, performance and on emission.

Water-Ice Analogues of Polycyclic Aromatic Hydrocarbons: Water Nanoclusters on Cu(111).

Water has an incredible ability to form a rich variety of structures, with 16 bulk ice phases identified, for example, as well as numerous distinct structures for water at interfaces or under confinement. Many of these structures are built from hexagonal motifs of water molecules, and indeed, for water on metal surfaces, individual hexamers of just six water molecules have been observed. Here, we report the results of low-temperature scanning tunneling microscopy experiments and density functional theory calculations which reveal a host of new structures for water–ice nanoclusters when adsorbed on an atomically flat Cu surface. The H-bonding networks within the nanoclusters resemble the resonance structures of polycyclic aromatic hydrocarbons, and water–ice analogues of inene, naphthalene, phenalene, anthracene, phenanthrene, and triphenylene have been observed. The specific structures identified and the H-bonding patterns within them reveal new insight about water on metals that allows us to refine the so-called “2D ice rules”, which have so far proved useful in understanding water–ice structures at solid surfaces.

Intermolecular mechanistic treatment of recalcitrant environmental pollutants: Azo, benzene, naphthalene and vinyl sulfone

Abstract A new class of coagulant, from natural resource namely laterite soil has demonstrated efficiency in degrading a wide range of industrial organic pollutants into simple hydrocarbon structures or less toxic compounds. The composition study revealed the relative Si/Al/Fe: 0.57/0.33/0.10 ratios in laterite soil and surface morphology of laterite soil were investigated to analyze the fundamental degradation that drive the decolorization of Reactive Black 5 (RB 5). The interfacial and colloid aspects of laterite soil colloidosomes and dye particles were distinguished with the corresponding mechanism of coagulation–flocculation process. RB5 structure was destabilized by activation of laterite soil colloidosomes through charge neutralization and subsequent siloxane polymerization through enhancement of siloxanes monomers. This research also evaluated the rate laws and reaction mechanism for each of the main chemical network strands of RB 5. The result implied that all the chemical network strands followed the pseudo first order of reactions. Research approach has utilized Fourier Transform Infrared Spectroscopy, Gas Chromatography Mass Spectrometry and Ultraviolet–visible Spectrophotometry (FTIR, GCMS and UV–vis) to study the degradation intermediates structure, chemical derivatives and final products after coagulation–flocculation process.

Porous membrane modifier as a new trend for deoiling process

Porous membranes are prepared through micro phase separation of immiscible polymers consisting of hydrophobic polymer (polystyrene) and hydrophilic polymer (poly(2-vinylpyridine)). The greatest difficulties during petrolatum deoiling are related to the filtration stage for obtaining microcrystalline wax. The present study deals with the addition of porous membrane as modifier for the crystal structure of solid hydrocarbons, which will be the cornerstone in rearrangement and reformulation of new hard crystals in deoiling process. XRD and SEM photographs were used to evaluate the crystallinity and crystal sizes of the separated hard waxes.

Chemical modification of nanocellulose with canola oil fatty acid methyl ester

Cellulose nanocrystals (CNCs), produced from dissolving wood pulp, were chemically functionalized by transesterification with canola oil fatty acid methyl ester (CME). CME performs as both the reaction reagent and solvent. Transesterified CNC (CNCFE) was characterized for their chemical structure, morphology, crystalline structure, thermal stability, and hydrophobicity. Analysis by Fourier transform infrared (FTIR) and FT-Raman spectroscopies showed that the long chain hydrocarbon structure was successfully grafted onto CNC surfaces. After transesterification the crystal size and crystallinity of nanocrystals were not changed as determined by Raman spectroscopy and wide angle X-ray diffraction (XRD). CNCFE showed higher thermal stability and smaller particle size than unmodified CNCs. Water contact angle measurement indicated the CNCFE surface has significantly higher hydrophobicity than unmodified CNCs. The transesterified CNCs could be potentially used as hydrophobic coatings and reinforcing agents to hydrophobic polymer for nanocomposites.

Thermally induced interactions between adamantan-2-one and some pharmaceutical excipients

Adamantan-2-one is an adamantane derivative used as a precursor in the synthesis of different pharmacologically active substances, i.e., memantine hydrochloride which was investigated in one of our previous published papers, both as pure compound and in binary mixtures. The aim of our study is to determine the influence of the oxo group regarding the thermal stability of the hydrocarbon structure and also to evaluate possible interactions of the functional groups with various compounds used as excipients. For this purpose, we evaluated the thermal behavior of adamantan-2-one and its compatibility with some excipients used in drug formulations. The pure compounds and the binary mixtures of adamantan-2-one with different excipients were investigated by TG/DTG/HF thermal methods in dynamic air flow, at a heating rate of 10 °C min−1 until 550 °C and by FTIR spectroscopy.

Isolation and Characterization of Cyclic C33 Botryococcenes and a Trimethylsqualene Isomer from Botryococcus braunii Race B.

Three cyclic C33 botryococcenes and one new trimethylsqualene isomer were isolated from the B race, Showa (Berkeley) strain of Botryococcus braunii, which is known to produce large amounts of isoprenoid hydrocarbons ranging in carbon number from 30 to 34. Their purity was determined by GC-MS, and structures were characterized by 1D and 2D NMR. One of these molecules, cyclic C33-1 botryococcene (5), has an unusual connection of a methylenecyclohexane ring to the molecule backbone not seen before in botryococcenes. This report further adds to our knowledge of the wide range of isoprenoid hydrocarbon structures produced by B.braunii.

Pyrolysis of Iron–Vitamin B9 As a Potential Nonprecious Metal Electrocatalyst for Oxygen Reduction Reaction

This study presents the performance of a carbon-black-supported pyrolyzed vitamin B9 (folic acid)-treated cathode catalyst (py-Fe-FA/C) in the oxygen reduction reaction (ORR) and proton exchange membrane fuel cell (PEMFC). Electrochemical ORR measurements revealed that using py-Fe-FA/C resulted in excellent ORR activity through the direct four-electron reduction pathway. The H2–O2 PEMFC with py-Fe-FA/C in the cathodic side produces a maximum power density of 330 mW cm–2 with the 80 °C operation temperature and the 1 atm back pressure. X-ray photoelectron spectroscopy and in situ X-ray adsorption spectroscopy proved that the enhanced ORR activity was caused by the network structure of polyaromatic hydrocarbons, quaternary-type (graphitic) nitrogen, and the coordination structure of the py-Fe-FA/C, as confirmed by the ORR mechanism study using detailed XPS and in situ X-ray adsorption spectroscopy. Particularly, in situ X-ray adsorption spectroscopy elucidated the ORR mechanism of the py-Fe-FA/C.

Analysis of Petroleum and Coal Tar Pitches as Large Pah

Coal tar and petroleum pitches present quite different features, particularly in terms of structure, size and aliphatic substitution degree of the large polycyclic aromatic hydrocarbons (PAH) components. As such they are an important source of a wide range of different carbon materials mainly deriving from their thermal transformations. However, the difficulty in the controlled and modulated production of tailored carbon materials arises from the scarce compositional and structural knowledge of the parent pitches as well as that of intermediates and final products derived from their thermal treatment. The present work reports about a detailed mapping of the characteristics of solid petroleum and coal tar pitch samples kindly provided by RUTGERS Basic Aromatics GmbH (Castrop-Rauxel, Germany). Chemical and spectroscopic techniques have been employed in order to put in evidence similarities and differences in terms of volatility, molecular weight distribution and chemical structure. In particular, conventional and advanced tools including chromatography, elemental analysis, thermogravimetry, mass spectrometry, UV-Visible absorption and fluorescence were applied the altogether from one side to offset the limits and on the other side to exploit the advantages of each technique.

Layer-by-Layer Assembled Film of Asphaltenes/Polyacrylamide and Its Stability of Water-in-Oil Emulsions: A Combined Experimental and Simulation Study

Emulsions with interface-active components at the water/oil (w/o) interface are of fundamental and practical interest in many fields. Here we investigate the interfacial films of asphaltenes and asphaltenes/polyacrylamide (PAM) at the w/o interface of water-in-crude oil emulsions. With the combination of the dissipative particle dynamics simulation and experimental observation, the molecular interactions of asphaltenes and asphaltenes/PAM at the w/o interface are extensively analyzed. We show that the rigid mechanical film of asphaltenes originates from a rigid structure of polycyclic aromatic hydrocarbons (PAHs) and the π–π bonding interactions between the PAHs of asphaltenes, and at a higher concentration of asphaltenes, the nanoaggregates of asphaltenes, acting as a space fortress at the w/o interface, make the drop–drop coalescence more difficult. In addition, a layer-by-layer assembled architecture film of asphaltenes/polyacrylamide formed at the w/o interface is identified, and we observe that the i...

Comprehensive three-dimensional gas chromatography mass spectrometry separation of diesel

Diesel, a complex hydrocarbon mixture, was examined using comprehensive two-dimensional gas chromatography (GC×GC) and a field ionization mass spectrometer (FIMS), which preferentially yields molecular ions, providing an extra dimension for component separation. Molecular ions collected at low mass resolution can be assigned an NM-class (Nominal Mass-class) value that does not completely express hydrogen deficiency. In contrast to formulae and Z-class assignments that are possible from ultrahigh mass resolution, NM-class assignments are not unambiguous; however, the separation provided by GC×GC can result in coelution of components that differ in NM-class. Hence, compounds that are unresolved by GC×GC separation can be resolved by FIMS provided they differ in mass. This technique allows for easy, automated data processing, evaluation of coelution on quantitative analysis (e.g., using FID) and the identification of additional chemical species and structures. The development of GC×GC×MS creates new opportunities to improve the ability to determine hydrocarbon composition and structure in complex petroleum and refined petroleum products.

The production of fuel oil and combustible gas by catalytic pyrolysis of waste tire using waste heat of blast-furnace slag

In this study, a novel “waste energy recycling” strategy is presented, i.e., the sensible heat of blast-furnace (BF) slag is utilized for the production of fuel oil and combustible gas from the pyrolysis of waste tire. The effects of various operating parameters including the slag temperature, the mass ratio of BF slag to tire (B/T) and feedstock size on yields and characteristics of pyrolysis products were systematically studied. The results showed that the presence of BF slag greatly improved the production of derived-oil and increased the contents of H2 and CO in pyrolysis gases. This can be explained by the catalytic activity of BF slag and the CaO-MgO complex in BF slag can prevent the formation of stable chemical structures in hydrocarbons, speed up the degradation of hydrocarbons, weaken CC and CH bonds and make them dissociate more easily, and thereby decrease the activation energy of degradation reactions. Increasing BF slag temperature and B/T ratio, and decreasing feedstock (including both BF slag and tire powder) size favored the heat and mass transfer during pyrolysis process and therefore afforded more liquid and gaseous products. In addition, it was observed that the presence of BF slag decreased viscosity, density, H and O content and increased C content, C/H ratio and calorific value of derived-oil relative to pyrolysis oil derived from solely tire powder, thereby resulting in upgradation of oil quality.

Characterisation of paraffinic compositions in crude oils

The deposition and gelation of paraffin wax are among the significant risks in flow assurance during crude oil transportation. These risks are highly influenced by the structure of hydrocarbons in the produced composition from the well. In the present paper, four crude oil samples acquired from different Malaysian fields were experimentally analysed through gas chromatography/mass spectrometry, differential scanning calorimetry, and thermal gravimetric analyses. The crudes were investigated, with focus on the carbon number distribution, wax appearance temperature, and wax content. The results demonstrate that the crude oil samples with high molecular percentage of carbon distribution within a range of C20 to C40 comprehend high wax content. Measurement results of the four investigated crude samples revealed that the wax content is relatively high compared to other crudes produced in East Asian fields. Also, the four samples possess low wax appearance temperature characteristics, and all four crudes might behave as non-Newtonian at temperature around 38°C. The results provide useful information to manage the risk of wax formation in the transportation pipeline and the flow assurance of the crude. [Received: August 30, 2015; Accepted: July, 24, 2016].

Characterisation of paraffinic compositions in crude oils

The deposition and gelation of paraffin wax are among the significant risks in flow assurance during crude oil transportation. These risks are highly influenced by the structure of hydrocarbons in the produced composition from the well. In the present paper, four crude oil samples acquired from different Malaysian fields were experimentally analysed through gas chromatography/mass spectrometry, differential scanning calorimetry, and thermal gravimetric analyses. The crudes were investigated, with focus on the carbon number distribution, wax appearance temperature, and wax content. The results demonstrate that the crude oil samples with high molecular percentage of carbon distribution within a range of C20 to C40 comprehend high wax content. Measurement results of the four investigated crude samples revealed that the wax content is relatively high compared to other crudes produced in East Asian fields. Also, the four samples possess low wax appearance temperature characteristics, and all four crudes might behave as non-Newtonian at temperature around 38°C. The results provide useful information to manage the risk of wax formation in the transportation pipeline and the flow assurance of the crude. [Received: August 30, 2015; Accepted: July, 24, 2016].

Synthetic modulation of micro- and mesopores in polycyanurate networks for adsorptions of gases and organic hydrocarbons

Synthetic modulation of pores sizes in polycyanurates from 1.17 to 17.3 nm was achieved by varying geometrical shape, size and number of functional groups of monomers. The relationships between porous structure and adsorptions of gases and organic hydrocarbons were studied.

GC/FT-IR Analysis of Novel 4,6,9-Triene and 2,4,6,9-Tetraene Occurring in a Female Pheromone Gland of <i>Arctia plantaginis</i> (Erebidae: Arctiinae)

Fifteen subspecies of the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae: Arctiinae), have been recorded in the Northern Hemisphere. An analysis of crude pheromone extracts by GC equipped with an electroantennographic (EAG) detector showed four EAG-active components (Comps. I–IV) that were commonly involved in the pheromone glands of two subspecies inhabiting Japan and Finland. Comp. I is a major component (>75%) and the others are minor components (3% - 15%). Their mass spectra, measured by GC/MS, revealed the chemical structures of C21 unsaturated hydrocarbons as follows: 3,6,9-triene for Comp. I, 4,6,9-triene for Comp. II, 1,3,6,9-tetraene for Comp. III, and 2,4,6,9-tetraene for Comp. IV. Comps. I and III are known Type II pheromone compounds, and their retention times coincide with those of the authentic standards with all Z configurations. As a next step, the extract was analyzed by GC/FT-IR to determine the configuration of Comps. II and IV. Their IR spectra showed two characteristic C-H bending absorptions around 990 and 945 cm-1 due to the conjugated dienyl moieties; thus, Z and E configurations were assigned to the double bonds at the 2- and 4-positions, respectively. Their Z double bonds at the 6- and 9-positions are indicated by no absorptions around 970 cm-1, due to the isolated double bonds with E configurations. Finally, the structures of Comps. II and IV were confirmed by synthesis using a double Wittig reaction. The synthetic (4E,6Z,9Z)-4,6,9-triene and (2Z,4E,6Z,9Z)-2,4,6,9-tetraene showed strong EAG activity, and their chemical data coincided well with those of the natural Comps. II and IV, indicating the correctness of the structure determination by GC/FT-IR analysis and its usefulness for Type II pheromone compounds.