Reduced Pressure Distillation Research Articles

Improved Method for Determining the Atmospheric Distillation Curve of Biodiesel Fuels from Reduced Pressure

Vacuum distillation is widely accepted as a useful technique for obtaining the distillation curves of fuels that boil beyond their decomposition temperatures at atmospheric pressure. After their measurement, the obtained curves must be converted to atmospheric-equivalent-temperature curves following the standard method proposed in ASTM D1160. However, this method was originally developed for petroleum-derived hydrocarbons, but not for oxygenated fuels. A specific method to convert reduced-pressure distillation curves of biodiesel fuels to their atmospheric distillation curves is proposed, based on their projection toward a focal point specifically selected for the methyl esters usually composing biodiesel fuels. This projection was made using a generalized Antoine-type equation with Antoine coefficients estimated from a two-parameter correlation as a function of the number of carbon atoms of the original fatty acid and the number of double bonds. The method (named here the Calingaert-like method) is based on the observation that saturation Antonie-type curved lines for pure hydrocarbons converge to a focal point when plotted in the form of log p versus 1/T and was found to be more accurate than ASTM D1160 method. Another tested method (named here the Cox-like method), based on the convergence of straight lines to a different focal point, was shown to provide intermediate results. Therefore, the Calingaert-like method is proposed as an improved alternative to the ASTM D1160 method for the distillation of biodiesel fuels at reduced pressure.

Improving the quality of fast pyrolysis bio-oil by reduced pressure distillation

Abstract In the present study, reduced pressure distillation was performed to obtain distilled bio-oil from fast pyrolysis bio-oil. The experiments were completed at temperature 80 °C with a residual pressure of 15 mmHg. The distilled bio-oil yields of 61 wt% from reduced pressure distillation of fast pyrolysis bio-oil were obtained. The oxygen contents of the distilled bio-oil is 9.2 wt% and the distilled bio-oil has lower content of oxygen than the fast pyrolysis bio-oil. For this reason, compared with the fast pyrolysis bio-oil, the distilled bio-oil has higher heating value, lower corrosivity and better stability. The heating value of distilled bio-oil is 34.2 MJ/kg, which is about 2 times of that of fast pyrolysis bio-oil. It is found that the distilled bio-oil stored at 60 °C results in a weight loss of about 0.3% for mild steel and the distilled bio-oil’s viscosity hardly increases during storage. These properties of distilled bio-oil make it more suitable for fuel oil use or as a source of chemicals than fast pyrolysis bio-oil.

Research on the Extraction of Plant Volatile Oils

Microwave-assisted extraction will probably be the main technique in the near future for industrial essential oil production. Two kinds of new methods for essential oil extracting were used in this paper: microwave-assisted extraction (MAE) and supercritical carbon dioxide extraction (SC-CO2). The steam extraction system was designed by ourselves, according to Chinese Pharmacopoeia. The device has a double advantage of the fast with microwave assisted extraction and of high purification with the Chinese Pharmacopoeia. The optimum extraction conditions for SC-CO2 were obtained by parallel and uniform design experiments, and searched for the method of purifying product by reduced pressure distillation. The compare of the volatile oils from Lavender from the two extractions was made via gas chromatography. The optimum conditions of Lavender essential oil extracted by supercritical CO2 extraction process: extraction pressure 22MPa, extraction temperature 45°C, extraction time of 1h, and the factors influence on the extraction rate is: extraction pressure> extraction temperature> extraction time. The yield of the product extracted under the optimal conditions was 4.80%. The results from GC analysis show that: the amount of the component of lavender essential oil is 84 obtained by microwave combination of steam distillation with more than of 0.05% before the retention time of 40minutes, compared with supercritical received only 65. The microwave-assisted extraction combined steam distillation is a good process for sample pretreatment with convenient operation and high effective ingredient, and is more suitable for analysis. The supercritical carbon dioxide extraction is a good method with high yield, high relative content and large treat amount for industrial production.

Electrochemical synthesis and characterization of tantalum alkoxides

Tantalum(V) propoxide (Ta(OPr n) 5), isopropoxide (Ta(OPr i) 5) and butoxide(Ta(OBu n) 5) were synthesized by electrochemical reactions of corresponding alcohol at sacrificial tantalum anode in the presence of tetraethylammonium chloride as a conductive additive. The pure products were isolated by reduced pressure distillation under 5 kPa. The crystal of Ta(OPr i) 5 was obtained by recrystallization from hexane at −10 °C. These samples were characterized by Fourier transform infrared spectra (FT-IR), Raman spectra, nuclear magnetic resonance spectra (NMR), TG/DTA and ICP-MS. The results show that direct electrochemical synthesis of metal alkoxides has a high current efficiency and electrolysis yield. These alkoxides have a high purity of 99.97% and can be directly used as the precursor of Ta 2O 5 films.

Bridging the Gap between Ionic Liquids and Molten Salts: Group 1 Metal Salts of the Bistriflamide Anion in the Gas Phase

Fourier transform ion cyclotron resonance mass spectrometry experiments showed that liquid Group 1 metal salts of the bistriflamide anion undergoing reduced-pressure distillation exhibit a remarkable behavior that is in transition between that of the vapor-liquid equilibrium characteristics of aprotic ionic liquids and that of the Group 1 metal halides: the unperturbed vapors resemble those of aprotic ionic liquids, in the sense that they are essentially composed of discrete ion pairs. However, the formation of large aggregates through a succession of ion-molecule reactions is closer to what might be expected for Group 1 metal halides. Similar experiments were also carried out with bis{(trifluoromethyl)sulfonyl}amine to investigate the effect of H(+), which despite being the smallest Group 1 cation, is generally regarded as a nonmetal species. In this case, instead of the complex ion-molecule reaction pattern found for the vapors of Group 1 metal salts, an equilibrium similar to those observed for aprotic ionic liquids was observed.

Dehydration of caprolactam–water mixtures through cross-linked PVA composite pervaporation membranes

ɛ-Caprolactam (CPL) is the monomer of nylon-6 used extensively in the manufacture of high quality nylon-6 fibers and resins. Since CPL is a very heat-sensitive substance and water is the most important impurity in the final CPL purification, reduced pressure distillation through triple-effect evaporation sets is widely adopted by chemical industry. But high energy consumption, high wastage and condensate pollution have restricted the wide-scale production of CPL and the commercial profit of the manufactures. To improve or develop a new CPL dehydration process, pervaporation separation of CPL–water mixtures was investigated using composite membranes consisting of a selective poly(vinyl alcohol) (PVA) membrane as top layer and a porous polyacrylonitrile (PAN) substrate. The selective layer was formed by PVA matrix followed by the cross-linking reaction of PVA with glutaraldehyde. The membranes were characterized by SEM, FTIR and TGA. Due to the formation of more compact cross-linked structure, cross-linked PVA composite membranes exhibited enhanced thermal stability. Through evaluating the pervaporation performance, we introduced a pervaporation transport equation to normalized permeation fluxes in terms of water permeance, CPL permeance and selectivity. The evaluated results have revealed that the separation performances of PVA composite membranes are strongly related to its hydrophilic/hydrophobic nature as well as the operating parameters, such as feed concentration and operating temperature. Experimental data showed that the PVA composite membranes had superior pervaporation separation performances for dehydration of caprolactam–water mixtures, which provided a new way for CPL dehydration.

A General Base Condensation of Diynes to a Spirocyclopropenyl System.

When a cold (200 K) THF solution of 1,6-heptadiyne is exposed to potassium tert-butoxide, in the presence of 18-crown-6, a green, EPR active solution is spontaneously formed. The intensity of the EPR signal can be augmented by exposure to alkali metal. Analysis of the EPR splitting pattern indicates that the signal originates from the anion radical of 7,14-di-trans-1,5- [14]annuldiyne. Allowing the green-colored solution to warm to ambient temperatures causes an immediate color change (to deep purple) and loss of the EPR activity. Reduced pressure distillation of the solution affords a colorless THF solution containing (spiro[2.6]nona-2,6,8-triene), which is only the second spirocyclopropene compound reported. The base condensation of the diyne is of a general nature as the same spirocyclopropenyl system is obtained from 1,6-heptadiyne, 1,7-octadiyne, and 1,8-nonadiyne. Laser irradiation (337 nm) of tungsten hexacarbonyl in the presence of the spirocyclopropenyl compound yields the stable organometallic: eta2-olefin pentacarbonyl complex.

The Nature of Ionic Liquids in the Gas Phase

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) experiments showed that when aprotic ionic liquids vaporize under pressure and temperature conditions similar to those of a reduced-pressure distillation, the gas phase is composed of discrete anion-cation pairs. The evolution of the mass spectrometric signals recorded during fractional distillations of binary ionic liquid mixtures allowed us to monitor the changes of the gas-phase composition and the relative volatility of the components. In addition, we have studied a protic ionic liquid, and demonstrated that it exists as separated neutral molecules in the gas phase.

Separation of caprolactam–water system by pervaporation through crosslinked PVA membranes

ɛ-Caprolactam (CPL) is usually crystallized from CPL–water mixtures by reduced pressure distillation through triple-effect evaporation sets. But high energy consumption and low heat transfer coefficient limit economic profit of this process. To improve or substitute the CPL aqueous solution dehydration process, pervaporation separation of caprolactam–water system was investigated using PVA crosslinked membranes. An in-depth study of sorption, swelling, pervaporation performances of caprolactam–water mixtures and crosslinked membrane had been conducted. The experimental data demonstrated that the PVA crosslinked with glutaraldehyde showed excellent dehydration performances. The novel separation technique is feasible for application to the dehydration of CPL–water mixtures.

Crystal structure of 2(R)-(5-fluorouracil-1-yI)acetyl-2-phenylglycin dimethylformamide solvate, C14H12FN3O5 • C3H7NO

C17H19FN4O6, monoclinic, P121/c1 (no. 14), a = 5.2042(5) A, b = 21.778(2) A, c = 16.932(2) A, = 101.165(2)°, V = 1882.7 A, Z = 4, Rgt(F) = 0.068, wRref(F) = 0.198, T = 298 K. Source of material The starting material 5-fluoro-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-1-acetic acid was prepared from 5-fluorouracil and bromoacetic acid following the method of the literature [1]. The key intermediate methyl 2(R)-(5-fluorouracil-1-aceto)amino-2phenyl acetatewas synthesized from5-fluorouracil-1-acetic acid, dicyclohexyl carbodiimide (dcc), and 1-hydroxybenzotriazole (btOH). A solution (25 ml) of dcc (0.024 mol) in dimethylformamide (dmf) was dropped in a dmf solution (75 ml) of 5-fluorouracil-1-acetic acid (0.02 mol) and btOH (0.02 mol) at 273 K. After 5 h reaction at room temperature, methyl 2(R)-amino-2phenyl acetate (0.02mol) and triethylamine (0.02mol)were added to the abovemixture.After 4 h stirring, awhite solidmethyl 2(R)(5-fluorouracil-1-aceto)amino-2-phenyl acetate was obtained after filtration, reduced pressure distillation of dmf, and column chromatography separation. The title compound was obtained by hydrolysis with 1 M sodium hydroxide solution. The purified product was dissolved in 95 % ethanol and single crystals were separated after 10 d.Mass, IR, HNMR and CNMR are available in the CIF. Discussion 5-Fluorouracil (5FU) is an antimetabolite with good antitumor activity but has side effects [1-3].Much attention has been paid to the derivatives of 5FU and their anticancer activities [4-6]. In an extension of this research, we report the crystal structure of a peptide derivative of 5FU, 2(R)-(5-fluorouracil-1-yl)acetyl-2-phenylglycin. The atoms (C1, C2, C3, C4, N1 and N2) in the heterocyclic ring and the atoms (C9 – C14) of the benzene ring are essentially planarwith r.m.s. deviations of 0.0104A and 0.0100A, respectively. The dihedral angle between the two rings is 53.8(2)A.Moreover, the N3—C6 bond distance (1.327(5) A) is shorter than a typical C—N bond length (1.443(4) A) [7] indicating the electron delocalization of the atoms O3, C6 and N3. In the crystal structure, 2(R)-(5-fluorouracil-1-yl)acetyl-2-phenylglycin and N,N-dimethylformamide solventmolecules are linked by intermolecular O4–H4···O6, N3–H3···O2 (i: x,–y+ 2,z– 2) and N2–H2···O5 (ii: x,–y+ 2,z– 2) hydrogen bonds to produce a zigzag chain along [001] direction (figure, bottom). Z. Kristallogr. NCS 221 (2006) 39-40 39 © by OldenbourgWissenschaftsverlag,Munchen Crystal: colorless block, size 0.14 × 0.15 × 0.26 mm Wavelength: Mo K radiation (0.71073 A) : 1.13 cm−1 Diffractometer, scan mode: Bruker APEX SMART CCD, / 2 max: 50.02° N(hkl)measured, N(hkl)unique: 9665, 3321 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 2514 N(param)refined: 255 Programs: SHELXS-97 [8], SHELXL-97 [9], SHELXTL [10] Table 1. Data collection and handling.

Synthesis and characterization of Sm(DPM) 3 used as precursor for MOCVD

High pure Sm(DPM) 3 (DPM=2,2,6,6-tetramethyl-3,5-heptanedionato) powder was successfully synthesized from Sm(NO 3) 3 and HDPM in ethanol/aqueous solution followed by reduced pressure distillation and recrystallization from toluene. This metal β-diketonate complex used as precursor for metal-organic chemical vapor deposition (MOCVD) of Sm 2O 3 film has been characterized by elemental analyses, 1H-NMR spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA analysis), infrared spectroscopy and mass spectroscopic analysis. The thermal decomposition behavior of the complex is sensitive to the ambient gases and Sm(DPM) 3 is sufficiently stable after it being exposed to air for 30 days. The chemical bonds in the complex are decomposed in the sequence of C–O>SmO>C–C(CH 3) 3>C–C and C–H at elevated temperatures. At 400°C this complex thoroughly converts into Sm 2O 3 and Sm 2(CO 3) 3 in air. The decomposition mechanism may be somewhat different at different operation conditions.

Properties characterization of Ce(DPM) 4 served as precursor for MOCVD

High purity Ce(DPM) 4 (DPM=2,2,6,6-tetramethyl-3,5-heptanedionato) powder was successfully synthesized from Ce(NO) 3 and HDPM followed by reduced pressure distillation and recrystallization from toluene. This metal β-diketonate complex used as precursor for metal–organic chemical vapor deposition (MOCVD) of CeO 2 film has been characterized by elemental analyses, X-ray diffraction (XRD), thermogravimetry–differential thermal analysis (TG–DTA) analysis, 1 H -NMR spectroscopy, and infrared spectroscopy. The structure of this complex is monocline and the sublimation temperature is 145°C. This product was sufficiently stable after it was exposed to air for 30 days, as only a few impurities such as Ce 2(CO 3) 3·8H 2O, Ce(OH) 3, and H 2O can be identified. Ce(DPM) 4 decomposes during evaporation, the chemical bonds dissociate in the sequence of CC(CH 3) 3>CH>CO and CC by heating. At 280°C this complex thoroughly decomposes to CeO 2.

The influence of alkane class-types on crude oil wax crystallization and inhibitors efficiency

The effect of paraffin class-types on the wax crystallization tendency in oils and the activity of paraffin inhibitors was studied for waxy crude oils. Oils enrichment with isolated paraffin fractions allowed the assessment of the influence of their molecular weight on the cloud point and the behavior of crystal modifiers. An insensitive crude oil without response to wax inhibitors was separated into its (normal/cyclo+branched) paraffin fractions. Reduced pressure distillation, n-heptane asphaltenes precipitation from the residue, high performance liquid chromatography (HPLC) of maltenes, and molecular sieves inclusion of the saturates were the separation techniques used for the isolation of the (cyclo+branched) paraffin fraction. (Cyclo+branched) paraffins, also known as (naphthene+iso) alkane isomers, were added to the selected crude, in order to investigate their effect on the cloud point. These fractions have no significant impact in the inhibitors effect for concentrations lower than 40 wt%, but they increase the crude oil cloud point when their amount was greater than 50 wt%. This increment in the cloud point was believed to arise as a consequence of the higher average molecular weight introduced by these components. The effect of cyclic and branched alkanes on the activity of a commercial crystal modifier was studied and observed to be a complex one. At low-medium concentrations, the effect was antagonistic and believed to be controlled by the average molecular mass of the added fractions. High concentrations of cyclo+branched alkanes (>50 wt%) enhanced the activity of the crystal modifier. This result was believed to be caused by an structural effect, i.e., loose packing of crystals from the steric effect of naphthenic and branched structures.

Peroxide-initiated vinylsilane grafting: Structural studies on a hydrocarbon substrate

The peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto dodecane has been examined as a model for grafting onto polyethylene. At 160°C, 2% v/v VTMS and 0.08% v/v initiator, the monomer was grafted onto dodecane with a 59% conversion and an average of 2.37 VTMS grafts per dodecane. These values were obtained by separation of the grafted material through reduced pressure distillation then characterization with FTIR and NMR spectroscopy, mass spectrometry, and gel permeation chromatography. NMR studies strongly indicate that the multiple grafts consist predominantly of multiple single grafts rather than homopolymer grafts. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3517–3525, 1997

Peroxide‐initiated vinylsilane grafting: Structural studies on a hydrocarbon substrate

The peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto dodecane has been examined as a model for grafting onto polyethylene. At 160°C, 2% v/v VTMS and 0.08% v/v initiator, the monomer was grafted onto dodecane with a 59% conversion and an average of 2.37 VTMS grafts per dodecane. These values were obtained by separation of the grafted material through reduced pressure distillation then characterization with FTIR and NMR spectroscopy, mass spectrometry, and gel permeation chromatography. NMR studies strongly indicate that the multiple grafts consist predominantly of multiple single grafts rather than homopolymer grafts. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3517–3525, 1997

Simulation of hydrodynamic behaviour and mass transfer efficiency of reduced pressure distillation

AbstractA random packing hydrodynamic simulator is designed specially to carry out experiments under reduced pressures with a counter‐current flow air/water system. The simulator results (air/water system) compared to those obtained in a real packed distillation column (benzylchloride/ ethylbenzene system) show a good agreement between hydrodynamic parameters like pressure drop, flooding flow rate, and total liquid hold‐up. Empirical relationships derived from the simulator experimental results are proposed allowing the calculation of the pressure drop in a packed distillation column, operating in the pressure range between 10 kPa and atmospheric pressure. The influence of reduced pressure on the HETP in the distillation column and interfacial area in the simulator was also investigated.

Prediction of flavour intensity of blackcurrant (Ribes nigrum L.) drinks from compositional data on fruit concentrates by partial least squares regression

SummaryConcentration of fruit juice by reduced pressure distillation causes substantial loss of volatile components, and produces new less‐volatile flavour compounds which affect the flavour of drinks prepared from the resulting concentrate. Free‐choice profiling indicated that blackcurrant drinks could be classified into three groups, depending mainly on the extent of processing. the flavour intensity of a series of drinks prepared from blackcurrant concentrate was measured by sensory analysis using magnitude estimation, and 214 volatile components of the concentrates were quantified by capillary gas chromatography. Partial least squares regression was successful in modelling the perceived flavour intensity of the drinks from gas chromatographic data on concentrate composition.

High resolution g.l.c. specifications for plant spray oils

AbstractHigh resolution g.l.c. chromatograms of a series of reference plant‐spraying oils were used for the development of proposed g.l.c standards for spraying oils in Australia. The mean size and size‐range of molecules in the oils have been specified in relation to carbon number positions for reference n‐paraffins. Problems with reproducibility and precision with reduced pressure distillation (10 mm Hg) of plant‐spraying oils have been demonstrated and discussed.

Determination of Ammoniacal Nitirogen in the Presence of Urea

Abstract There is no approved AOAC procedure for determining ammoniacal nitrogen in the presence of urea, which is required for the quality control of urea-ammonium phosphate-based fertilizers. A comparative study has been made of various methods available for this estimation. We found that the automated spectrophotometric method, the ion selective electrode method, and the reduced pressure distillation method all furnish results of comparable precision and accuracy. The MgO distillation method, even though not recommended for the above type of sample, still yields results of satisfactory accuracy when certain precautions are taken.

Determination of Ammoniacal Nitrogen in the Presence of Urea with an Ammonia Electrode

Abstract A recently introduced commercial electrode is shown to be suitable for the determination of ammoniacal nitrogen in the presence of urea. The results compare favorably with those of the reduced pressure distillation method. Standard deviations for the electrode method and the reduced pressure distillation method for ammoniacal nitrogen in urea ammonium phosphate are 0.12 and 0.09%, respectively.