Topic
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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, different types of commercial nonporous polymeric membranes were screened for their ability to separate FFA, MG, DG, and TG from a lipase hydrolysate of high-oleic sunflower oil after diluting it with organic solvents (ethanol and hexane).
Abstract: Different types of commercial nonporous (reverse osmosis and gas separation) polymeric membranes were screened for their abilities to separate FFA, MG, DG, and TG from a lipase hydrolysate of high-oleic sunflower oil after diluting it with organic solvents (ethanol and hexane). Cellulose acetate (CA) (NIR-1698) membrane gave the largest difference in rejection between FFA and glycerides and high flux in oil/ethanol mixtures. In the hexane system, the values of permeate flux and rejection were generally lower than those in the ethanol system. The silicone-polyimide composite membrane (NTGS-2100) gave the highest flux and rejections of solutes (70.2% for FFA, 94.4% for TG) in oil/hexane mixtures. In the ethanol system with the CA membrane, TG had the highest rejection (98%) followed by DG (90%) and MG and FFA (50–70%) when the oil concentration was varied from 6.3 to 45.8%. A discontinuous diafiltration process (16 batches) using the CA membrane with ethanol changed the composition of the oil from 31∶28∶9∶32 TG/DG/MG/FFA to 65∶30∶1∶4. The results of this study showed that oil constituents can be separated in suitable solvents using appropriate nonporous membranes.
39 citations
TL;DR: In this paper, the effects of supercritical fluid (SCF) solvents (pentane or hexane) on product distributions from Fischer−Tropsch synthesis (FTS) over an alumina-supported cobalt catalyst in a fixed-bed-reactor was studied.
Abstract: This study is designed to examine the effects of supercritical fluid (SCF) solvents (pentane or hexane) on product distributions from Fischer−Tropsch synthesis (FTS) over an alumina-supported cobalt catalyst in a fixed-bed-reactor. The influence of reaction conditions (such as temperature, pressure, syngas feed ratio, contact time, and space velocity) on the FTS hydrocarbon product distributions in the supercritical solvents was studied. Changing the density-dependent bulk thermophysical properties of the supercritical pentane medium, by tuning either temperature (210−250 °C) or pressure (45−65 bar), resulted in notable effects on the (C6+) hydrocarbon product distributions and selectivity. One particular set of experiments was designed to directly compare hexane and pentane solvent effects at constant density (ca., ρ = 0.3 g/cm3) and temperature (240 °C) where significantly higher pressure was required in pentane to achieve this density. Interestingly, both pentane and hexane supercritical FTS performed ...
39 citations
39 citations
TL;DR: In this paper, the results in terms of free fatty acids contents were compared with those obtained when n-hexane was used as the solvent, and no significant differences between the oils extracted by both methods were found.
Abstract: Pumpkin, Cucurbita ficifolia, seed oil was extracted with supercritical carbon dioxide (SC-CO2) in the temperature range of 308–318 K and in the pressure range of 18–20 MPa. In addition, the influence of the superficial velocity within a tubular extractor was studied. The oil content determined by a Soxhlet apparatus was 43.5%. Physical and chemical characteristics of the oil were obtained. The results in terms of free fatty acids contents were compared with those obtained when n-hexane was used as the solvent, and no significant differences between the oils extracted by both methods were found. The main fatty acid was ω6-linoleic acid (about 60%), followed by palmitic acid (about 15%) and oleic acid (about 14%). Oxidative stability was studied by using the induction time determined by the Rancimat method. The oil obtained by supercritical fluid extraction (SFE) was less protected against oxidation (4.2 h for SFE-extracted oil and 8.3 h for the pumpkin seed oil extracted with n-hexane). The oil extracted by SC-CO2 was clearer than that extracted by n-hexane, showing some refining. The acidity index was 5.5 for the n-hexane extracted oil. For the oils extracted by SC-CO2, two analyses were made: for the oils obtained at 15 min of extraction time, for which the acidity indices varied from about 15 to 20, and for the remaining oils (extracted until 150 min), for which the acidity indices varied from about 2 to 2.6. The central composite nonfactorial design was used to optimise the extraction conditions, using the Statistica, version 5, software (Statsoft). The best results, in terms of oil recovered by SC-CO2, were found at 19 MPa, 308 K and a superficial velocity of 6.0×10−4 ms−1.
39 citations
TL;DR: In this paper, the authors showed that HZSM-5 zeolites with different SiO2/Al2O3ratio, when prepared in the absence of water vapor, contain acidic centers equal in activity and selectivity.
39 citations