Lipase-catalyzed synthesis of biodiesel from acid oil in fixed bed reactor

Acid oil, which is a by-product in vegetable oil refining, mainly contains free fatty acids (FFAs) and acylglycerols and is a feedstock for production of biodiesel fuel now. The transesterification of acid oil and methanol to biodiesel was catalyzed by immobilized Candida lipase in fixed bed reactors. The reactant solution was a mixture of acid oil, water, methanol and solvent (hexane) and the main product was biodiesel composed of fatty acid methyl ester (FAME) of which the main component was methyl oleate. The effects of lipase content, solvent content, water content temperature and flow velocity of the reactant on the reaction were analyzed. The experimental results indicate that a maximum FAME content of 90.18% can be obtained in the end product under optimum conditions. Most of the chemical and physical properties of the biodiesel were superior to the standards for 0(#) diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D6751).

Production and characterization of biodiesel from tung oil

The feasibility of biodiesel production from tung oil was investigated. The esterification reaction of the free fatty acids of tung oil was performed using Amberlyst-15. Optimal molar ratio of methanol to oil was determined to be 7.5:1, and Amberlyst-15 was 20.8wt% of oil by response surface methodology. Under these reaction conditions, the acid value of tung oil was reduced to 0.72mg KOH/g. In the range of the molar equivalents of methanol to oil under 5, the esterification was strongly affected by the amount of methanol but not the catalyst. When the molar ratio of methanol to oil was 4.1:1 and Amberlyst-15 was 29.8wt% of the oil, the acid value decreased to 0.85mg KOH/g. After the transesterification reaction of pretreated tung oil, the purity of tung biodiesel was 90.2wt%. The high viscosity of crude tung oil decreased to 9.8mm(2)/s at 40 degrees C. Because of the presence of eleostearic acid, which is a main component of tung oil, the oxidation stability as determined by the Rancimat method was very low, 0.5h, but the cold filter plugging point, -11 degrees C, was good. The distillation process did not improve the fatty acid methyl ester content and the viscosity.

Conversion of Soybean oil to Biodiesel Fuel with Immobilized Candida Lipase on Textile Cloth

The characteristic of biodiesel fuel production from transesterification of soybean oil is studied. The reactant solution is the mixture of soybean oil, methanol, and solvent. A new lipase immobilization method, textile cloth immobilization, was developed in this study. Immobilized Candida lipase sp. 99-125 was applied as the enzyme catalyst. The effect of flow rate of reaction liquid, solvents, reaction time, and water content on the biodiesel yield is investigated. Products analysis shows that the main components in biodiesel are methyl sterate, methyl hexadecanoate, methyl oleate, methyl linoleate, and methyl linolenate. The test results indicate that the maximum yield of biodiesel of 92% was obtained at the conditions of hexane being the solvent, water content being 20 wt%, and reaction time being 24 h.

Study on the technology of thermal cracking of paraffin to alpha olefins

Alpha olefins are mainly produced from paraffin cracking in China, but their quality is not good because of bad quality of cracking feed and outdated technology. The technology of paraffin once-through cracking, paraffin recycle cracking of removing the heavy fraction after wax vaporizing and that of removing the heavy fraction before wax vaporizing were investigated in this paper. It was found that the technology of paraffin recycle cracking of removing the heavy fraction before wax vaporizing is new and better under the same operating conditions. Using hard paraffin (mp 54-56 degrees C) as feed, the high-quality alpha olefins products (C-5-C-21) containing more than 97 wt% of olefins and more than 88 wt% of alpha olefins are produced under optimum process conditions, which are a steam to paraffin ratio of 15 wt%, process temperature of 600 degrees C, low hydrocarbon partial pressure and residence time of 2 s. In addition, with the technology of the second injecting steam in ethylene cracking used in paraffin cracking, producing coke in paraffin cracking furnace has been markedly reduced.

Upgrading bio-oil over different solid catalysts

Solid acid 40SiO(2)/TiO2-SO42- and solid base 30K(2)CO(3)/Al2O3-NaOH were prepared and compared with catalytic esterification activity according to the model reaction. Upgrading bio-oil by solid acid and solid base catalysts in the conditioned experiment was investigated, in which dynamic viscosities of bio-oil was lowered markedly, although 8 months of aging did not show much viscosity to improve its fluidity and enhance its stability positively. Even the dehydration by 3A molecular sieve still kept the fluidity well. The density of upgraded bio-oil was reduced from 1.24 to 0.96 kg/m(3), and the gross calorific value increased by 50.7 and 51.8%, respectively. The acidity of upgraded bio-oil was alleviated by the solid base catalyst but intensified by the solid acid catalyst for its strong acidification. The results of gas chromatography-mass spectrometry analysis showed that the ester reaction in the bio-oil was promoted by both solid acid and solid base catalysts and that the solid acid catalyst converted volatile and nonvolatile organic acids into esters and raised their amount by 20-fold. Besides the catalytic esterification, the solid acid catalyst carried out the carbonyl addition of alcohol to acetals. Some components of bio-oil undertook the isomerization over the solid base catalyst.

Formation and Properties of a Novel Heavy-Metal Chalcogenide Glass Doped with a High Dysprosium Concentration

A novel heavy-metal chalcogenide glass doped with a high dysprosium ion (Dy(3+)) concentration was prepared by the well-established melt-quenching technique from high-purity elements. The results show that when Cadmium (Cd) is introduced into chalcogenide glass, the concentration of Dy(3+) ions doped in GeGaCdS glasses is markedly increased, the thermodynamic performance improves, and the difference between T(g) and T(x) is >120 degrees C. The Vickers microhardness is also modified greatly, about 245 kgf/mm(2). The optical spectra indicate that all absorption and emission bands of Dy(3+) are clearly observed and red-shifted with increasing Dy(3+) concentration.

CHANNELING ALIGNMENT FOR EPITAXIAL LIGHT-MASS FILM ON HEAVY-MASS SUBSTRATE

A simple procedure for obtaining a background-free backscattering spectrum of a light-mass film on a heavy-mass substrate by a normal incidence/grazing exit geometry has been described. Using this method such films can be aligned rapidly and accurately, and the impurity or defect information on the films can be obtained without need for realignment. Example is given from MeV Li-3+ analysis of a deposited film of Si on a single crystal substrate of yttria-stabilized, cubic zirconia.

POLARIZATION OF HOT PHOTOLUMINESCENCE IN QUANTUM-WELLS AND HEAVY-LIGHT HOLE MIXING

Hot electrons excited from the valence band by linearly polarized laser light are characterized by certain angular distributions in momenta. Owing to such angular distributions in momenta, the photoluminescence from the hot electrons shows a certain degree of polarization. A theoretical treatment of this effect observed in the photoluminescence in quantum wells is given, showing that the effect depends strongly on heavy and light hole mixing. The very large disparity between the experimentally observed and theoretically expected values of the degree of polarization in the hot-electron photoluminescence suggests the presence of random quasielastic scattering. The effects of such additional scattering and the presence of a perpendicular magnetic field are incorporated into the theory. it is shown that the measurements of the degree of polarization observed in the hot electron photoluminescence, with and without an applied perpendicular magnetic field can serve to determine the time constants for both LO-phonon inelastic and random quasielastic scattering. As an example, these time constants are determined for the experiments reported in the literature.

Effects of heavy and light hole mixing in quantum well physics