Hexane

About: Hexane is a research topic. Over the lifetime, 3759 publications have been published within this topic receiving 57996 citations. The topic is also known as: CH3-[CH2]4-CH3 & hexyl hydride.

Crystallization of β-sitosterol using a water-immiscible solvent hexane

Abstract: Cooling crystallization of β-sitosterol that is a kind of phytosterol was carried out, where a water-immiscible solvent hexane containing a ppm level of water was used as a solvent. The initial ratio of water and β-sitosterol concentration adopted in this work was 330/10, 1315/10 and 645/20 ppm/(g/L), which corresponded to 0.51, 2.0, and 0.50 in water/β-sitosterol mole ratio, respectively. When the initial ratio of water and β-sitosterol concentration was 1315/10 ppm/(g/L), thin plate-like crystals were precipitated and were identified as the monohydrate crystals of β-sitosterol. On the other hand, when the initial ratio of water and β-sitosterol concentration was 645/20 ppm/(g/L), needle-like crystals of hemihydrate were precipitated. This result meant that the ppm level of water plays an important role for the pseudo-polymorphism. Since the crystal structure of β-sitosterol hemihydrate had never been reported, we determined it by a single crystal XRD analysis.

Evolution of strong acidity and high-alkane-cracking activity in ammonium-treated USY zeolites

Abstract: USY zeolites prepared by steam treatment of NH4-Y zeolites were treated with ammonium nitrate solutions. Treatment with ammonium nitrate solutions resulted in a significant enhancement of the octane-cracking activity of the USY zeolites. We found by infrared spectroscopy/mass spectrometry-temperature programmed desorption (IRMS-TPD) of NH3 that the prepared USY zeolites have acidity strong enough to catalyze alkane cracking. The acid strength (ΔH) values of the enhanced Bronsted OH on the USY are found to be ca. 150 kJ mol−1. A linear correlation between ΔH and the activation energy in alkane cracking was obtained when Y-type zeolites were used for the reaction. The heats of adsorption of octane and hexane were almost constant over various types of FAU zeolites. This means that the higher the strength of the acid site, the smaller the intrinsic activation energy of the alkane cracking. This study clearly indicated that treatment with NH4+ was the key to creating very strong acidity in USY zeolites. Furthermore, the origin of the high catalytic activity of the ammonium-treated USY zeolites was attributed to the evolution of strong acidity rather than changes in the adsorption energies of the alkanes, based on the measurements of acid strength, heat of alkane adsorption, and activation energy.

A novel process for the aqueous extraction of oil from Camellia oleifera seed and its antioxidant activity

Abstract: Aqueous extraction is a promising green alternative to hexane extraction. This study used a salt effect-aided aqueous extraction process (AEP-SE) for extracting Camellia oleifera seed oil (COSO) to improve oil extractability and avoid emulsification in the aqueous system. The highest oil extractability rate of 88.8% was obtained under 1.48 mol L –1 sodium carbonate, a solution-to-flour ratio of 3.85, and 3.23h of extraction time with the quality of the aqueous system-extracted oil being similar to those of a commercial sample of COSO and hexane-extracted oil in terms of color, iodine value and saponifcation value, although its moisture content was higher. Furthermore, the free fatty acid content of the aqueous system-extracted oil was lower than that of the solvent-extracted oil. The values of the inibihitory concentration at 50% of oil obtained by AEP-SE and organic solvent extraction as measured by DPPH scavenging activity essay, were 2.27 mg/mL and 3.31 mg/mL. AEP-SE is therefore a promising environmentally friendly method for the large-scale preparation of COSO.

Comparative Study of Oil-Dilution Capability of Dimethyl Ether and Hexane as Steam Additives for Steam-Assisted Gravity Drainage

Abstract: Dimethyl ether (DME) was investigated as a potential additive to steam to improve steam-assisted gravity drainage (SAGD) in a previous simulation study. The main objective of this research is to compare DME with n-hexane in terms of the capability of viscosity reduction for Athabasca bitumen. In addition, new experimental data are presented for bubblepoint pressures, densities, and viscosities of Athabasca bitumen and its mixtures with DME and n-hexane. Results show that DME results in slightly higher viscosity than n-hexane when they are mixed with the same Athabasca bitumen at a given pressure, temperature, and molar concentration. For example, the equimolar mixture of DME with Athabasca bitumen is 79 cp, and that of n-hexane with the same bitumen is 49 cp at 328 K and 60 bar. However, the two solvents are equivalent as diluent at temperatures higher than 380 K. For example, the difference is approximately 1 cp at 382 K and 35 bar between the equimolar mixture of Athabasca bitumen with DME and that with n-hexane. The viscosity data measured for bitumen/n-hexane mixtures and bitumen/DME mixtures in this research were correlated with three different viscosity models: a modified Arrhenius model, the power-law model, and the Walther (1931) model. The viscosity data were well-correlated with the modified Arrhenius model, but not with the original Arrhenius (log-linear mixing) rule. The modified Arrhenius model can be used directly with a commercial simulator. Liquid/liquid separation for solvent/bitumen mixtures, which occurred for n-butane/Athabasca bitumen in Gao et al. (2017), was not observed for any of the DME/bitumen and n-hexane/bitumen mixtures in this research. The highest solvent concentration in this study was 80 mol% DME for the DME/bitumen system and 92 mol% n-hexane for the n-hexane/bitumen system.