Straight-chain Hydrocarbons Research Articles

Rate Constants for the Reaction of OH Radicals with Hydrocarbons in a Smog Chamber at Low Atmospheric Temperatures

The photochemical reaction of OH radicals with the 17 hydrocarbons n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, cyclooctane, 2,2-dimethylbutane, 2,2-dimethylpentane, 2,2-dimethylhexane, 2,2,4-trimethylpentane, 2,2,3,3-tetramethylbutane, benzene, toluene, ethylbenzene, p-xylene, and o-xylene was investigated at 288 and 248 K in a temperature controlled smog chamber. The rate constants were determined from relative rate calculations with toluene and n-pentane as reference compounds, respectively. The results from this work at 288 K show good agreement with previous literature data for the straight-chain hydrocarbons, as well as for cyclooctane, 2,2-dimethylbutane, 2,2,4-trimethylpentane, 2,2,3,3-tetramethylbutane, benzene, and toluene, indicating a convenient method to study the reaction of OH radicals with many hydrocarbons simultaneously. The data at 248 K (k in units of 10−12 cm3 s−1) for 2,2-dimethylpentane (2.97 ± 0.08), 2,2-dimethylhexane (4.30 ± 0.12), 2,2,4-trimethylpentane (3.20 ± 0.11), and ethylbenzene (7.51 ± 0.53) extend the available data range of experiments. Results from this work are useful to evaluate the atmospheric lifetime of the hydrocarbons and are essential for modeling the photochemical reactions of hydrocarbons in the real troposphere.

Aqueous-Phase Synthesis of Hydrocarbons from Furfural Reactions with Low-Molecular-Weight Biomass Oxygenates

Catalytic pyrolysis of lignocellulosic biomass generates water-soluble low-molecular-weight oxygenates such as acetic acid, acetone, furfural, butanone, guaiacol, phenol, etc. These compounds are usually not suitable for conventional hydrocarbon fuel applications. A new heterogeneous catalyst has been developed that simultaneously catalyzes alkylation, hydrodeoxygenation, and hydrogenation of these small oxygenate molecules in aqueous media to produce C6 to C14 hydrocarbons in a one-pot synthesis. In these syntheses, acetic acid, propionic acid, furfural, butanone, pentanone, heptanone, and 2,6-dimethyl-4-heptanone reacted to produce straight- and branched-chain alkanes. The aldehydes reacted with furan to form straight-chain liquid hydrocarbons, while the ketones reacted with 2-methylfuran to produce branched-chain liquid hydrocarbons. All the reactions occurred in aqueous media at 350 °C. The gaseous products included low-molecular-weight hydrocarbons such as methane, propane, butane, and pentane.

Continuous Hydrothermal Decarboxylation of Fatty Acids and Their Derivatives into Liquid Hydrocarbons Using Mo/Al2O3 Catalyst.

In this study, we report a single-step continuous production of straight-chain liquid hydrocarbons from oleic acid and other fatty acid derivatives of interest including castor oil, frying oil, and palm oil using Mo, MgO, and Ni on Al2O3 as catalysts in subcritical water. Straight-chain hydrocarbons were obtained via decarboxylation and hydrogenation reactions with no added hydrogen. Mo/Al2O3 catalyst was found to exhibit a higher degree of decarboxylation (92%) and liquid yield (71%) compared to the other two examined catalysts (MgO/Al2O3, Ni/Al2O3) at the maximized conditions of 375 °C, 4 h of space time, and a volume ratio of 5:1 of water to oleic acid. The obtained liquid product has a similar density (0.85 kg/m3 at 15.6 °C) and high heating value (44.7 MJ/kg) as commercial fuels including kerosene (0.78–0.82 kg/m3 and 46.2 MJ/kg), jet fuel (0.78–0.84 kg/m3 and 43.5 MJ/kg), and diesel fuel (0.80–0.96 kg/m3 and 44.8 MJ/kg). The reaction conditions including temperature, volume ratio of water-to-feed, and space time were maximized for the Mo/Al2O3 catalyst. Characterization of the spent catalysts showed that a significant amount of amorphous carbon deposited on the catalyst could be removed by simple carbon burning in air with the catalyst recycled and reused.

Continuous catalytic pyrolysis of oily sludge using U-shape reactor for producing saturates-enriched light oil

Continuous catalytic pyrolysis of oily sludge was carried out in a special U-shape reactor for producing saturates-enriched light oil. The sludge underwent thermal pyrolysis first and then catalytic pyrolysis. During the thermal pyrolysis, chain hydrocarbons were first cracked and further polymerized into aromatics. The effect of temperatures (400–800 °C) on the products was investigated and the maximum liquid yield (67.7%) was obtained at 500 °C. High temperature promoted polymerization, thus the distribution of aromatics in the liquid product was increased and was more concentrated in polyaromatics at 800 °C. In the catalytic upgrading stage, dolomite was used as catalyst and aromatics were adsorbed on it, either aggregated or decomposed. As a result, a light oil product with 57.0% saturates was obtained at the residence time of 8.9 s due to the conversion of aromatics and heavy hydrocarbons into light aliphatic hydrocarbons such as straight chain hydrocarbons. Compared with the oil phase in the raw sludge sample, the content of saturates was increased by 45.0% and that of the asphaltenes was reduced by 88.5%. Meanwhile, the inherent moisture in the oily sludge could participate in the steam reforming reaction, promoting the decomposition of aromatics and leading to an increase in the H2 generation. Moreover, the release of H2S was reduced from 0.132 to 0.005 mol per kg sludge and the sulfur content of the oil product was also decreased in the presence of dolomite. The deactivation of dolomite can be attributed to the carbonization of CaO and deposition of polyaromatic coke on the catalyst surface.

NMR of orientationally ordered short-chain hydrocarbons

ABSTRACTThe proton NMR spectra of the straight-chain hydrocarbons from methane to -hexane orientationally ordered in nematic liquid-crystal solvents are reviewed. The theory behind reorientation-vibration coupling (that explains the anisotropic splittings observed in the spectrum of methane) is discussed. This coupling is also important for ethane where the torsional motion about the C–C bond becomes an issue. The ratios of propane to ethane dipolar couplings are found to be independent of liquid crystal and of temperature: this demonstrates that the hydrocarbons are ‘magic solutes’, i.e. their orientational order results from a single anisotropic interaction that involves short-range size-and-shape effects. The longer chains -butane, -pentane and -hexane (which give extremely complicated NMR spectra) exist in several symmetry-unrelated conformers. The spectra are analysed with the aid of evolution strategies. The dipolar couplings obtained are used in a model-free analysis (that is based on the constant ratio between ethane and propane dipolar couplings) to explore important information about the intermolecular potential. For example, the orientational order of longer conformers is favoured by the nematic phase.

Identification of Floral Volatiles and Pollinator Responses in Kiwifruit Cultivars, Actinidia chinensis var. chinensis.

Volatiles emitted from unpollinated in situ flowers were collected from two male cultivars, 'M33', 'M91', and one female cultivar 'Zesy002' (Gold3) of kiwifruit (Actinidia chinensis var. chinensis). The samples were found to contain 48 compounds across the three cultivars with terpenes and straight chain alkenes dominating the headspace. Electrophysiological responses of honey bees (Apis mellifera) and bumble bees (Bombus terrestris) to the headspace of the kiwifruit flowers were recorded. Honey bees consistently responded to 11 floral volatiles from Gold3 pistillate flowers while bumble bees consistently responded to only five compounds from the pistillate flowers. Nonanal, 2-phenylethanol, 4-oxoisophorone and (3E,6E)-α-farnesene from pistillate flowers elicited responses from both bee species. Overall, honey bees were more sensitive to the straight chain hydrocarbons of the kiwifruit flowers than the bumble bees, which represented one of the main differences between the responses of the two bee species. The floral volatiles from staminate flowers of the male cultivars 'M33' and 'M91' varied greatly from those of the pistillate flowers of the female cultivar Gold3, with most of the bee active compounds significantly different from those in the Gold3 flower headspace. The total floral emissions of 'M33' flowers were significantly less than those of the Gold3 flowers, while the total floral emissions of the 'M91' flowers were significantly greater than those of the Gold3 flowers.

Decomposition of Gasoline Hydrocarbons by Natural Microorganisms in Japanese Soils

Characterizing the mechanisms by which natural microorganisms in soil decompose gasoline hydrocarbons is of fundamental importance for a better understanding of natural attenuation and/or for predicting contaminant transport and fate in soils. To examine whether and how gasoline hydrocarbons can be decomposed under general environmental conditions, the decomposition of 10 major components generally contained in commercially available gasoline was analyzed in three arbitrarily selected Japanese soil samples. Gasoline hydrocarbons, especially aromatic hydrocarbons, are easily adsorbed by the tested Japanese soils, with straight chain hydrocarbons decomposing faster than branched hydrocarbons. Saturated monocyclic hydrocarbons were less easily decomposed than unsaturated monocyclic hydrocarbons. Enhancement of microbial decomposition of gasoline hydrocarbons requires a continuous supply of oxygen together with nutrients for the microorganisms.

1-Eicosane, A Hydrocarbon from Curvularia lunata an endophytic fungi isolated from bark tissue of Ficus religiosa

The aim of the present study was to confirm the presence of bioactive secondary metabolite, 1-Eicosane from the endophtic fungi Curvularia lunataisolated from the bark of the tree Ficus religiosa. Curvularia lunataproduced1-Eicosane, an unsaturated hydrocarbon in the crude extract after three weeks of incubation in Potato Dextrose media using ethyl acetate as the organic solvent. The compound was separated by column chromatography and further analysis of the compound was done by Thin Layer Chromatography (TLC), Ultra Violet (UV), Fourier Transform- Raman (FT-R) analysis, Nuclear Magnetic Resonance (NMR) and Gas-Chromatography - Mass spectroscopy (GC-MASS).The mass spectrum of the compound showed the highest peakand the compound was identified as the straight chain hydrocarbon, 1-Eicosane, with the molecular formula CH3CH2(18)CH3. The structure is further confirmed by comparison of the spectrum obtained with the mass spectrum of Eicosane from the GC-MS database WILEY and NIST respectively. Thus, the the endophytic fungi Curvularia Lunata serves as an alternative source for 1- Eicosane production which is used as a fuel in automobile industry.

Carboxylic Acids with Certain Molecular Structures Strengthen the Cell Membrane against Osmotic Pressure in Sheep Erythrocytes In Vitro

In sheep red blood cells (RBCs), considering osmotic fragility (OF) as an indicator, the reaction of monocarboxylic and dicarboxylic acids on membrane resistance to osmotic pressure were evaluated. Sheep RBCs were exposed to carboxylic acids at 0-100 mM in a buffer solution for 1 h and the 50% hemolysis was then determined by soaking in 0.1-0.8% NaCl solution. Although formic acid declined and n-caprylic acid increased OF, most of the monocarboxylic acids with straight hydrocarbon chains did not change OF in sheep RBCs. Whereas, all the tested dicarboxylic acids with straight hydrocarbon chains decreased OF with the degree of the decrease in OF dependent on the compound. Some monocarboxylic acids with branched or cyclic (including a benzene ring) hydrocarbon chains decreased OF with the degree of the decrease dependent on the number of carbons and form of branching in the hydrocarbon chain. Dicarboxylic acids with a cyclohexane ring or benzene ring decreased or tended to decrease OF with the degree of the decrease dependent on the position of the two carboxylic groups. There is no clear correlation between the effect of monocarboxylic or dicarboxylic acids on OF, and their partition coefficients. Thus the partition coefficient is not a suitable parameter for explaining the effect of both groups of carboxylic acid on the cell membrane as evaluated by the change in OF in sheep RBCs. It is speculated that the space composed of the acyl-chains of the phospholipids, into which hydrophobic hydrocarbons can enter to form a more rigid structure through their subsequent interaction, is an important factor related to the OF-decreasing effect of carboxylic acids.

Adsorption and separation of n/iso-pentane on zeolites: A GCMC study

Separation of branched chain hydrocarbons and straight chain hydrocarbons is very important in the isomerization process. Grand canonical ensemble Monte Carlo simulations were used to investigate the adsorption and separation of iso-pentane and n-pentane in four types of zeolites: MWW, BOG, MFI, and LTA. The computation of the pure components indicates that the adsorption capacity is affected by physical properties of zeolite, like pore size and structures, and isosteric heat. In BOG, MFI and LTA, the amount of adsorption of n-pentane is higher than iso-pentane, while the phenomenon is contrary in MWW. For a given zeolite, a stronger adsorption heat corresponds to a higher loading. In the binary mixture simulations, the separation capacity of n-and iso-pentane increases with the elevated pressure and the increasing iso-pentane composition. The adsorption mechanism and competition process have been examined. Preferential adsorption contributions prevail at low pressure, however, the size effect becomes important with the increasing pressure, and the relatively smaller n-pentane gradually competes successfully in binary adsorption. Among these zeolites, MFI has the best separation performance due to its high shape selectivity. This work helps to better understand the adsorption and separation performance of n- and iso-pentane in different zeolites and explain the relationship between zeolite structures and adsorption performance.

Nickel sulfide, nickel phosphide and nickel carbide catalysts for bio-hydrotreated fuel production

A series of nickel catalysts i.e. nickel sulfide (NiS), nickel phosphide (NiP) and nickel carbide (NiC) was investigated for hydrotreating of spent coffee oil to produce bio-hydrotreated fuel (BHF). Catalytic tests were carried out at 375–425°C and 20–40bar of initial H2 pressure (before heating) with reaction time of 0–3h. The activity of the catalysts are in the order of NiC>NiP>NiS; however NiC tended to promote cracking reaction resulting in high gasoline and gaseous yields. On the other hand, although NiS gives the lowest oil conversion, it is favorable to diesel yield with lowest methanation and cracking activity. Compared with decarboxylation (DCO2) and hydrodeoxygenation (HDO), decarbonylation (DCO) was the major route for deoxygenation of coffee oil for all the catalysts. The ratio of (DCO+DCO2) to HDO (as represented by Cn-1/Cn) decreased in the order NiS>NiC>NiP. Ketones as intermediate products (ca. 3wt%) were detected in case of NiP. They could be generated via rearrangement of alcohol and keto-enol tautomerism. Significant amount of aromatics (4wt%) with some isomerization products (0.9wt%) can also be observed in NiS catalyzed liquid products while trace amount of these compounds were detected for NiP and NiC catalysts. Physiochemical analysis of the diesel fraction exhibited satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL. Since main products are straight chain hydrocarbons, high cetane index (>110) could be achieved.

Deoxygenation of waste cooking to renewable diesel over walnut shell-derived nanorode activated carbon supported CaO-La2O3 catalyst

Waste cooking oil (WCO) is a potential non-edible feedstock that is sustainable for production of automotive green diesel. The present study focused on synthesis of WCO-derived green diesel through catalytic deoxygenation (DO) process using bimetallic acid-base CaO-La2O3/AC nanosized catalyst under zero hydrogen environment. Results indicated that the prepared nano-catalyst rendered high deoxygenation reactivity with 72% yield of straight chain hydrocarbons (C8-C20). The CaO-La2O3/AC catalysed reaction pathway favour in decarboxylation/decarbonylation route instead of cracking effect, which consistently formed major n-C15 fractions at approximately >80%. In addition, CaO-La2O3/AC showed high catalytic stability and reusability up to 6 cycles with >73% of yield and selectivity to n-C15 of >82%. The catalyst showed an excellent coke inhibitor with less than 2wt% of coke under TGA analysis.

Enabling the synthesis of medium chain alkanes and 1-alkenes in yeast

Microbial synthesis of medium chain aliphatic hydrocarbons, attractive drop-in molecules to gasoline and jet fuels, is a promising way to reduce our reliance on petroleum-based fuels. In this study, we enabled the synthesis of straight chain hydrocarbons (C7–C13) by yeast Saccharomyces cerevisiae through engineering fatty acid synthases to control the chain length of fatty acids and introducing heterologous pathways for alkane or 1-alkene synthesis. We carried out enzyme engineering/screening of the fatty aldehyde deformylating oxygenase (ADO), and compartmentalization of the alkane biosynthesis pathway into peroxisomes to improve alkane production. The two-step synthesis of alkanes was found to be inefficient due to the formation of alcohols derived from aldehyde intermediates. Alternatively, the drain of aldehyde intermediates could be circumvented by introducing a one-step decarboxylation of fatty acids to 1-alkenes, which could be synthesized at a level of 3mg/L, 25-fold higher than that of alkanes produced via aldehydes.

Identification of in situ flower volatiles from kiwifruit (Actinidia chinensis var. deliciosa) cultivars and their male pollenisers in a New Zealand orchard

In situ flower volatiles from six kiwifruit cultivars (Actinidia chinensis var. deliciosa); ‘Hayward’, ‘Chieftain’, ‘M56’, ‘Zes007’ (Green11), ‘M36’, and ‘M43’ were collected by dynamic headspace sampling. Forty-five compounds were detected in the headspace of the flowers, with straight chain hydrocarbons and terpenes accounting for >98% of the volatiles emitted quantitatively across the six cultivars. Of these hydrocarbons, (3Z,6Z,9Z)-heptadecatriene is reported for the first time from a floral source while (8Z)-hexadecene and (9Z)-nonadecene are reported for the first time from kiwifruit flowers. All three hydrocarbons were verified by synthesis. Quantitative comparison of the six honey bee perceived compounds from the headspace of the cultivars showed that the males ‘M36’ and ‘M43’ closely matched the female cultivar Green11 that they are used to pollinate. Males ‘M56’ and ‘Chieftain’ were not as closely matched to the female cultivar ‘Hayward’ that they are used to pollinate. The male ‘M56’ in particular differed significantly from the female ‘Hayward’ in four of the six honey bee perceived compounds.

Effects of potassium hydroxide on the catalytic pyrolysis of oily sludge for high-quality oil product

Oily sludge has received increasing attention for its hazardousness as well as its high potential as an energy resource. Previous studies have developed many methods for oil recovery from oily sludge. In this paper, the effect of KOH on improving the quality of oil product from different oily sludge through pyrolysis was studied. Gel permeation chromatography (GPC), rheometer and gas chromatography–mass spectrometry (GC–MS) were applied to characterize the pyrolysis oil products. The product yields along with possible reaction mechanisms and kinetic characteristics were discussed. It was found that the oil yield decreased while the gaseous yield and solid residues increased with the addition of KOH. The GPC results showed that hydrocarbon species in the pyrolysis oil were more pure and the average molecular weight could be reduced by 53% for the used sample when KOH was added, which could be possibly explained by the cracking reaction of heavy oil into light species. The viscosity of the oil product also showed a significant reduction while the heating value increased in the case of adding KOH. Additionally, SARA fractions were extracted from oil to obtain the asphaltenes content and to identify the detailed components of saturated compounds. Results showed that the concentration of asphaltenes was declined by half and more saturate hydrocarbons (such as C14H30 to C17H36) were produced when KOH ratio reached up to 10%. It revealed that quality of oil product was improved in terms of smaller average molecular weight, lower viscosity, higher heating value, less asphaltenes and more straight chain hydrocarbons.

Comparative behavior of piloted turbulent premixed jet flames of C1[sbnd]C8 hydrocarbons

An exploratory study was performed on highly turbulent piloted premixed jet flames of straight chain (paraffin and olefin), branched, cyclo, and aromatic C1C8 hydrocarbons. The goal was to investigate fuel effects on global and local flame observables under flow conditions corresponding to the transition from the thin to the broken reaction zone regimes. The experiments were performed at atmospheric pressure, reactant temperature of 298K, jet Reynolds numbers of 12,500 and 25,000, and various equivalence ratios and fuels in order to assess the attendant effects on the flame characteristics. The effects of heat losses from the flame were considered also in order to sensitize kinetic effects. Measurements were performed using particle image velocimetry and spontaneous luminosity imaging. The averaged and fluctuating velocity components as well the average flame height were determined to scale in general with the laminar flame speed. The exception to this scaling was the height of methane flames that exhibit notable differences compared to large molecular weight fuels. Subtle differences were identified even among the large hydrocarbon flames and became evident from measurements of the instantaneous luminosity field. Finally, high-speed luminosity imaging revealed that there are apparent fuel effects on the local structure of the flame as evident by the distribution and size of luminous pockets. These results suggest that the fuel effects should be also the focus of further investigations by the community.

Dicarboxylato ligands in osmium carbonyl sawhorse clusters: Chelating vs. bridging

Seven new complexes comprising of diosmium(I) tetracarbonyl sawhorse units bound to dicarboxylate anions (DCAs) have been synthesized using microwave heating. Succinic, adipic, pimelic, suberic, tetradecanedioic, and terephthalic acids react with Os3(CO)12 at temperatures ranging from 180 to 205 °C for 12–20 min to produce the osmium sawhorse complexes, which are subsequently reacted with phosphine ligands to replace the labile axial CO ligands. X-ray crystallographic analysis was used to determine the molecular structures of these complexes. Two complexes, those with suberato and tetradecanedioato ligands, are dinuclear species containing Os2 sawhorse molecules with chelating DCAs that form intramolecular loops. The succinato, adipato and pimelato complexes are tetranuclear species consisting of two Os2 sawhorse moieties linked together by two bridging DCAs. Thus the straight-chain hydrocarbon backbone of the DCAs must contain at least six carbon atoms in order for these ligands to prefer to chelate a single Os2 unit instead of forming bridges between multiple Os2 units. The terephthalato complex is a triangular hexanuclear species consisting of a trimer of dimers with three bridging dicarboxylato anions.

Cuticular hydrocarbons in queens, workers and drones of the Indian honeybee Apis cerana indica (Fab.)

AbstractCuticular hydrocarbons (CHCs) have evolved as a communication cues and they play a significant role in the life of social insect. Although the primary function is to prevent desiccation, CHCs are also used in recognition of individuals and insect gregariousness. In this paper we examined the CHCs composition of queens, workers and drones of Apis cerana indica. CHCs analysis by Gas Chromatography – Mass Spectrometry revealed 45 different molecules. In drones, 21–37 carbon chain length hydrocarbons comprising of a complex mixture of alkanes, alkenes, mono-, di-, tri-methyl alkanes and alkadienes were detected. Alkanes of drones resemble those found in workers except pentacosane and triacontane which was not detected in the latter. Workers showed pentacosane, heptacosane, 11-Methyl-heptacosane, 13-Methyl-heptacosane, nonacosane, nonacosene, 13-Methyl-nonacosane and 15-Methyl-nonacosane as major CHCs. Workers had an equal number of straight alkanes and alkenes but differing in their proportions and also containing fewer branched hydrocarbons with chain lengths ranging from 21–37 carbons. Further, workers had significantly higher concentration of nonacosene, pentatriacontene, heptatriacontene as compared to drones. In queens much simpler and straight chain hydrocarbons with carbon chain ranging from 21–37 were detected. Several branched hydrocarbons as compared to drones and workers were absent. Queens had a higher concentration of alkanes than workers and drones.

Optimization study of SiO2-Al2O3 supported bifunctional acid–base NiO-CaO for renewable fuel production using response surface methodology

Optimization study on NiO-CaO5/SiO2-Al2O3 catalysed deoxygenation of triolein towards paraffin yield was investigated. Response surface methodology-central composite design (RSM-CCD) was used to design the experiments with three operating parameters: catalyst loading (1–9wt.%), reaction temperature (270–390°C) and reaction time (30–150min). The present study indicated that maximum yield of straight chain hydrocarbons (73.3%) was achieved under deoxygenation condition of 7wt.% of catalyst, 340°C within 60min, which the interaction effect between reaction temperature-catalyst amount greatly influenced the straight chain hydrocarbons yield. In addition, the generated RSM model was statistically significant and adequate to predict the results with minimum error of <4%. The NiO-CaO5/SiO2-Al2O3 catalysed deoxygenation of triolein was mainly occured in decarboxylation/decarbonylation(deCOx) pathways of decomposed oleic acid, which lead to the majority of straight chain hydrocarbons at carbon ranged of C17. Furthermore, the NiO-CaO5/SiO2-Al2O3 catalyst showed high reusability with maintained the straight chain hydrocarbons yield (>65%) for 4 consecutive reaction cycles.

Dealkylation of Aromatics in Subcritical and Supercritical Water: Involvement of Carbonium Mechanism

Under hydrothermal environments covering the subcritical and supercritical regions of water, the involvement of the carbonium mechanism in the dealkylation of aromatics and its resulting influence on the pyrolysis of heavy oil were surveyed. α-Olefin groups, as either a part of straight chain hydrocarbons or the terminal of alkyl substitutes of aromatics, are protonated spontaneously by hydronium ions into carboniums, followed by β-scission with similar reaction kinetic characteristics. The probability of the protonation of α-olefins under hydrothermal environments depends on the ionic product of water, so the occurrence of the β-scission in the carbonium mechanism is related to the thermodynamic state of water. With the aid of the carbonium mechanism at increasing water density, a recovered conversion rate and an increasing ratio of propene to ethylene in the product occur during the pyrolysis of a model α-olefin of dodecene under hydrothermal environments. Also, the dealkylation involved in the pyrolysi...