Smaller Carbon Numbers Research Articles

Deactivation of an Fe-based catalyst in the dehydrogenation of light alkanes under H2S co-feeding: A case study

Deactivation of an Fe-based catalyst in the dehydrogenation of light alkanes under H2S co-feeding: A case study

Experimental study of the steam distillation mechanism during the steam injection process for heavy oil recovery

Abstract Steam distillation can effectively enhance heavy oil recovery during steam injection process in heavy oil reservoirs. However, the mechanism of steam distillation is complex, and the changes in oil properties during distillation remain unclear. In this study, three comparative steam distillation experiments were designed and conducted, including distillation processes employing saturated steam, steam superheated by 10 °C, and steam superheated by 40 °C. Heavy oil samples were derived from the Jin-1 Block in a typical heavy oilfield, in China. The density, viscosity, SARA fractions, and carbon number distribution of the residual oil were compared to those obtained before conducting steam distillation experiments. The steam distillation rates obtained with steam superheated by 40 °C, steam superheated by 10 °C, and saturated steam were 11.158%, 10.903% and 10.423%, respectively. The results indicate that the steam distillation rate of heavy oil increases significantly with increasing degree of superheating. During the steam distillation process, the density and viscosity of residual oil increase, the contents of saturated hydrocarbons and resin decrease, and the contents of aromatic hydrocarbons and asphaltenes increase. In addition, analysis of the distilled components indicates that lightweight components with smaller carbon numbers are removed firstly by steam distillation, followed by heavier components with larger carbon numbers. Moreover, all hydrocarbons with carbon numbers less than C22 are removed from heavy oil in the distillation process, while the maximum carbon number of the distilled components was C34. This study is favorable for understanding the changes in the properties of residual oil after distillation during the steam injection process for heavy oil recovery.

Detailed chemical kinetics for thermal decomposition of low molecular weight‐methyl esters generated by using biodiesel fuel

Low molecular weight‐methyl ester (LMW‐ME), which was reported in our previous study [1], was generated by the use of biodiesel fuel (BDF) with a diesel power generator. In this article, the detailed chemical kinetics for the thermal decomposition of LMW‐MEs was investigated at atmospheric pressure and a temperature range of 773 to 973 K. Six standards of LMW‐MEs were used for thermal decomposition in a continuous flow reactor. The kinetic data, such as reaction orders, activation energies, and rate constants, were then calculated. The reaction orders and activation energies of the thermal decomposition reactions of C4, C5, C6, C7, C8, and C9 were 1.13, 0.96, 1.17, 0.80, 0.99, 0.84, and 312.04, 117.37, 87.29, 62.94, 74.80, 75.79 kJ mol−1, respectively. The decomposition of LMW‐MEs with higher carbon numbers was faster than those with smaller carbon numbers, except for C8. The C4 methyl ester was stable and abundant in the product of the decomposition as well as in the exhausted gas from the engine combustion using BDF. This kinetic data will be applied to modeling study on BDF decomposition and engine technologies to mitigate toxic emissions from BDF combustion. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1190–1197, 2016

Kinetic study on thermal decomposition of toluene in a micro fluidized bed reactor

Abstract This study concerned the pyrolysis behavior of toluene as the tar model compound. Pyrolysis experiments were carried out in a micro fluidized bed reactor (MFBR) under an isothermal condition. Pyrolysis kinetics for the gas components, including hydrogen, methane, ethylene and propane were calculated based on the model-free and model-fitting methods. Results showed that methane and ethylene were the major gas components at lower temperatures (650–800 °C) while propane and ethylene were the main composition of pyrolysis gas mixture at higher temperatures (800–850 °C). For the range of conversion fraction (20–80%), the apparent activation energy of propane (16.34 kJ/mol) was lower than that of ethylene (17.59 kJ/mol), then accompanied with methane (23.27 kJ/mol) and hydrogen (69.55 kJ/mol). The most probable reaction mechanism for the generation of hydrogen was three-dimensional diffusion while the evolution profiles of methane could be described by the mechanism of nucleation and growth. Chemical reaction was the most probable reaction mechanism for ethylene and propane. Results from the present study indicated that MFBR can enable a quicker reaction within the reactor than other traditional approaches. The generation of propane is easier to proceed compared to other hydrocarbons with smaller carbon numbers during pyrolysis of toluene. A comparison of kinetic models and experimental results suggested that the developed models closely predicted the thermal cracking behavior of toluene.

Molecular-level characterization of crude oil compounds combining reversed-phase high-performance liquid chromatography with off-line high-resolution mass spectrometry

A reversed-phase separation technique was developed in a previous study (Loegel et al., 2012) and successfully applied to the de-asphalted fraction of crude oil. However, to the best of our knowledge, the molecular-level characterization of oil fractions obtained by reversed-phase high-performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (MS) has not yet been reported. A detailed characterization of the oil fractions prepared by reversed-phase HPLC was performed in this study. HPLC fractionation was carried out on conventional crude oil and an oil shale pyrolysate. The analyses of the fractions showed that the carbon number of alkyl chains and the double bond equivalent (DBE) value were the major factors determining elution order. The compounds with larger DBE (presumably more condensed aromatic structures) and smaller carbon number (presumably compounds with short side chains) were eluted earlier but those compounds with lower DBE values (presumably less aromatic structures) and higher carbon number (presumably compounds with longer alkyl chains) eluted later in the chromatograms. This separation behavior is in good agreement with that expected from the principles of reversed-phase separation. The data presented in this study show that reversed-phase chromatography is effective in separating crude oil compounds and can be combined with ultrahigh-resolution MS data to better understand natural oils and oil shale pyrolysates.

Direct production of aviation fuels from microalgae lipids in water

Abstract In this contribution, we confirmed that aviation fuels could be synthesized directly from microalgae lipids in water over a Pt/C catalyst without additional hydrogen. After decarboxylation at 330 and 370 °C for 120 min, the oxygen content in the microalgae lipids was significantly reduced and the heating value of produced aviation fuels was greatly increased. The reaction mechanism of direct decarboxylation of microalgae lipids to aviation fuels was further investigated using each of the representative compounds in microalgae lipids, such as methyl laurate, methyl eicosanoate, methyl stearate, ethyl stearate, and tristearin as the starting material in separate reactions under the same conditions. Those reaction conditions, solvent, water loading, catalyst loading and reactant loading, were optimized. It was concluded that among the tested solvents, water was the most favorable for the selective decarboxylation of methyl stearate, that the catalytic decarboxylation rate of fatty acid esters with larger carbon numbers in water was faster than those with smaller carbon numbers, and that the Pt/C catalyst retained its activity through its third use. These results provide new insights for the direct decarboxylation of microalgae lipids to aviation fuels.

Detailed characterization of polar compounds of residual oil in contaminated soil revealed by Fourier transform ion cyclotron resonance mass spectrometry

Effects of remediation technologies on polar compounds of crude oil in contaminated soils have not been well understood when compared to hydrocarbons. In this study, ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize the changes in NSO polar compounds of crude oil and residual oil after long-term natural attenuation, biostimulation and subsequent ozonation following biostimulation of contaminated soils. N1 and O1 species, which were abundant in the crude oil, were selectively biodegraded, and species with higher double bond equivalent values and smaller carbon numbers appeared to be more resistant to microbial alteration. O2-O6 species were enriched by biodegradation and contained a large number of compounds with a high degree of unsaturation. Ozone could react with a variety of polar compounds in residual oil after biodegradation and showed high reactivity with polar species containing aromatic or multi-aliphatic rings, including the residual N1 and O1 species, naphthenic acids and unsaturated O3-O6 compounds. Fatty acids and O3-O8 species dominated by saturated alkyl compounds were resistant to ozonation or the primarily incomplete ozonation products. Principal component analysis of identified peaks in the FT-ICR MS spectra provided a comprehensive overview of the complex samples at the molecular level and the results were consistent with the detailed analysis. Taken together, these results showed the high complexity of polar compounds in residual oils after biodegradation or ozonation in contaminated soil and would contribute to a better understanding of bioremediation and ozonation processes.

Removal of Emulsified PHCs from Brackish Water by Coagulation

Chemical coagulation is a well-known method for removing colloidal particles that cause turbidity in water. In this study coagulation was used to remove emulsified petroleum hydrocarbons (PHCs) found in fuel oils from brackish water. Comparison of the total ion chromatograms of PHCs before and after coagulation clearly showed that PHCs with carbon numbers between 11 and 35 (naphthalene to pentatriacotane) with long chain alkanes were removed completely from the brackish water by coagulation followed by settling. Smaller carbon number (C7–C9) benzene derivatives were partially removed. For the PHCs with smaller carbon numbers, the removal efficiency increased with increasing carbon number.

Identification and chemical properties of antitumor active monoglycerides from fungal mycelia. Studies on antiviral and antitumor antibiotics. X.

Substances with antitumor activity isolated from Sepedonium ampullosporum, Cercospora oryzae and Coriolus unicolor were chemically and spectrometrically studied. They were identified as the mixtures of 1-monoglycerides, having octadecenoic and octadecadienoic acids with or without hexadecanoic acid as the main components. They contain other fatty acids with larger and smaller carbon numbers as the minor components. Fatty acid composition of the monoglycerides depends upon the origin of the glycerides.