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1.
Methanol has recently attracted significant interest in the energetic field. Current technology for the conversion of methane
to methanol is based on energy intensive endothermic steam reforming followed by catalytic conversion into methanol. The one-step
method performed at very low temperatures (35°C) is methane oxidation to methanol via bacteria. The aim of this work was to
examine the role of copper in the one-step methane oxidation to methanol by utilizing whole cells of Methylosinus trichosporium OB3b bacteria. From the results obtained it was found that copper concentration in the medium influences the rate of bacterial
biomass growth or methanol production during the process of methane oxidation to methanol. The presented results indicate
that the process of methane oxidation to methanol by Methylosinus trichosporium OB3b bacteria is most efficient when the mineral medium contains 1.0 × 10−6 mol dm−3 of copper. Under these conditions, a satisfactory growth of biomass was also achieved.
Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May
2008. 相似文献
2.
Yingxin Zhang Jiaying Xin Linlin Chen Chungu Xia 《Applied biochemistry and biotechnology》2009,157(3):431-441
Methanotrophs have promising applications in the epoxidation of some alkenes and some chlorinated hydrocarbons and in the
production of a biopolymer, poly-β-hydroxybutyrate (poly-3-hydroxybutyrate; PHB). In contrast with methane monooxygenase (MMO)
activity and ability of PHB synthesis of four kinds of methanotrophic bacteria Methylosinus trichosporium OB3b, M. trichosporium IMV3011, Methylococcus capsulatus HD6T, Methylomonas sp. GYJ3, and the mixture of the four kinds of strains, M. trichosporium OB3b is the highest of the four in the activity of propene epoxidation (10.72 nmol/min mg dry weight of cell [dwc]), the
activity of naphthalene oxidation (22.7 mmol/mg dwc), and ability in synthesis of PHB(11% PHB content in per gram dry weight
of cell in 84 h). It could be feasible to improve the MMO activity by mixing four kinds of methanotrophs. The MMO activity
dramatically decreased when the cellular PHB accumulated in the second stage. The reason for this may be the dilution of the
MMO system in the cells with increasing PHB contents. It has been found that the PHB contents at the level of 1–5% are beneficial
to the cells for maintenance of MMO epoxidation activity when enough PHB have been accumulated. Moreover, it was also found
that high particulate methane monooxygenase activity may contribute to the synthesis of PHB in the cell, which could be used
to improve the yield of PHB in methanotrophs. 相似文献
3.
Eng William Palumbo Anthony V. Sriharan Shobha Strandberg G. W. 《Applied biochemistry and biotechnology》1991,(1):887-899
The effect of methanol on trichloroethylene (TCE) degradation by mixed and pure methylotrophic cultures was examined in batch
culture experiments. Methanol was found to relieve growth inhibition ofMethylosinus trichosporium (OB3b) at high (14 mg/L) TCE concentrations. Degradation of TCE was determined by both radiolabeling and gas chromatography
techniques. When cultures were grown on methanol over 10 to 14 d with 0.3 mg/L TCE, OB3b degraded 16.89 ±0.82% (mean± SD)
of the TCE, and a mixed culture (DT type II) degraded 4.55±0.11%. Mixed culture (JS type I) degraded 4.34±0.06% of the TCE.
When grown on methane with 0.3 mg/L TCE, 32.93±2.01% of the TCE was degraded by OB3b, whereas the JS culture degraded 24.3
±1.38% of the TCE, and the DT culture degraded 34.3 ±2.97% of the TCE. The addition of methanol to cultures grown on methane
reduced TCE degradation to 16.21 ±1.17% for OB3b and to 5.08±0.56% for JS. Although methanol reduces the toxicity of TCE to
the cultures, biodegradation of TCE cannot be sustained in methanol-grown cultures. Since high TCE concentrations appear to
inhibit methane uptake and growth, we suggest the primary toxicity of TCE is directed towards the methane monooxygenase. 相似文献
4.
Masayuki Takeguchi Takako Furuto Daisuke Sugimori Ichiro Okura 《Applied biochemistry and biotechnology》1997,68(3):143-152
Methylosinus trichosporium OB3b is a methanotrophic bacterium containing methane mono-oxygenase, catalyzing hydroxylation of methane to methanol. When
methane is oxidized, the product is subsequently oxidized by methanol dehydrogenase contained in the same bacterium. To prevent
further oxidation of methanol, the cell suspension was treated by cyclopropanol, an irreversible inhibitor for methanol dehydrogenase,
leading to extracellular methanol accumulation. However, the reaction was terminated at approx 3 h with a final methanol concentration
below 2.96 mmol/g dry cell. The methanol production efficiency (the ratio of the produced methanol per methane consumption)
was 2.90%. By selecting the culture conditions and the reaction conditions, the reaction continued for 100 h, resulting in
a methanol concentration of 152 mmol/g dry cell. This level was 51 times higher than that of the conventional reaction, and
the methanol production efficiency was 61%. 相似文献
5.
Ji-Sun Han Chang-Min Ahn Biswanath Mahanty Chang-Gyun Kim 《Applied biochemistry and biotechnology》2013,171(6):1487-1499
Using a methanotrophic consortium (that includes Methylosinus sporium NCIMB 11126, Methylosinus trichosporium OB3b, and Methylococcus capsulatus Bath) isolated from a landfill site, the potential for partial oxidation of methane into methanol through selective inhibition of methanol dehydrogenase (MDH) over soluble methane monooxygenase (sMMO) with some selected MDH inhibitors at varied concentration range, was evaluated in batch serum bottle and bioreactor experiments. Our result suggests that MDH activity could effectively be inhibited either at 40 mM of phosphate, 100 mM of NaCl, 40 mM of NH4Cl or 50 μM of EDTA with conversion ratios (moles of CH3OH produced per mole CH4 consumed) of 58, 80, 80, and 43 %, respectively. The difference between extent of inhibition in MDH activity and sMMO activity was significantly correlated (n?=?6, p?<?0.05) with resultant methane to methanol conversion ratio. In bioreactor study with 100 mM of NaCl, a maximum specific methanol production rate of 9 μmol/mg h was detected. A further insight with qPCR analysis of MDH and sMMO coding genes revealed that the gene copy number continued to increase along with biomass during reactor operation irrespective of presence or absence of inhibitor, and differential inhibition among two enzymes was rather the key for methanol production. 相似文献
6.
Kinetic studies for hydroxylation of a series of alkanes (methane, ethane and propane) with intact cells and cell-free extracts
ofMethylosinus trichosporium OB3b were carried out.K
m values for alkane hydroxylation with cell-free extracts were lower than those with intact cells, suggesting that cytoplasm
plays an important role in the solubility of alkanes to increase their concentration. 相似文献
7.
《Journal of Molecular Catalysis #》1991,64(3):373-380
Alcohol formation was studied by the hydroxylation of alkanes with Methylosinus trichosporium (OB3b). When M. trichosporium was treated with cyclopropane, accumulation of primary alcohol (methanol, ethanol, 1-propanol, 1-butanol) was observed from the respective lower alkane (methane, ethane, propane, n-butane). It was found that cyclopropane was a selective inhibitor for the alcohol dehydrogenase contained in the same bacterium, and that alcohol oxidation with this enzyme was inhibited. The inhibition mechanism is also discussed. 相似文献
8.
Sean W. Ewart Thomas W. Karjala Mehmet Demirors 《Journal of polymer science. Part A, Polymer chemistry》2017,55(5):861-866
The use of post‐metallocene bis‐phenylphenoxy catalysts to polymerize ethylene under high ethylene pressures (>25,000 psi) results in some remarkable catalytic properties. The high ethylene pressure produces molar ethylene concentrations in the reactor as much as 40 times higher than in typical low pressure ethylene polymerizations. This high ethylene concentration results in high catalyst efficiency at high temperatures and low reactor residence time, between 180 °C and 240 °C the catalyst efficiency surprisingly increases with increasing temperature, allowing for use of these catalysts at temperatures much higher than can be utilized in the low pressure processes. It has further been demonstrated that under these conditions increasing hydrogen levels up to 0.5 mol% does not significantly affect the polymer molecular weight; however, polymer molecular weight control can be realized with varying reactor temperature. The polymer produced is shown to be high density polyethylene made from a single site catalyst and not free radical initiated low density polymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 861–866 相似文献
9.
El-Shobaky G. A. Radwan N. R. E. Radwan F. M. 《Journal of Thermal Analysis and Calorimetry》2002,68(1):275-287
The results obtained showed that the addition of small amounts of LiNO3 to the reacting mixed solids, consisting of equimolar proportion of Fe2O3 and basic MgCO3 much enhanced the thermal decomposition of magnesium carbonate. The addition of 12 mol% LiNO3 (6 mol% Li2O) decreased the decomposition temperature of MgCO3 from 525.5 to362°C. MgO underwent solid–solid interaction with Fe2O3 at temperatures starting from800°C yielding MgFe2O4. The amount of ferrite produced increased by increasing the precalcination temperature of the mixed solids. However, the
completion of this reaction required prolonged heating at elevated temperature above 1100°C. Doping with Li2O much enhanced the solid–solid interaction between the mixed oxides leading to the formation of MgFe2O4 phase at temperatures starting from 700°C. The addition of 6 mol% Li2O to the mixed solids followed by precalcination at 1050°C for 4 h resulted in complete conversion of the reacting oxides
into magnesium ferrite. The heat treatment of pure and doped solids at 900–1050°C effected the disappearance of most of IR
transmission bands of the free oxides with subsequent appearance of new bands characteristic for MgFe2O4 structure. The promotion effect of Li2O towards the ferrite formation was attributed to an effective increase in the mobility
of the various reacting cations. The activation energy of formation (ΔE) of magnesium ferrite was determined for pure and variously doped solids and the values obtained were 203, 126, 95 and 61
kJ mol−1 for pure mixed solids and those treated with 1.5, 3.0 and 6.0 mol% Li2O, respectively.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
The effects of pressure on the compressibility and crystallization of poly(ethylene terephthalate) (PET) have been investigated. The Instron capillary rheometer was adapted as a high-pressure dilatometer to perform experiments up to 40,000 psi. Compressibilities of solid and molten PET were measured. The increases in compressibility with increase in temperature for the solid state are discussed in terms of free-volume theory. Results obtained for the melt are explained by invoking the second law of thermodynamics and the effect of pressure on the Gibbs free energy. The effects of temperature and compression rate on the pressure of crystallization (Pc) were also studied. As the crystallization temperature was increased from 240 to 286°C, Pc increased by about 16,000 psi. As the compression rate was raised from 1%/min to 8%/min, Pc increased 10,000 psi. At some undetermined compression rate above 8%/min it seemed impossible to induce crystallization in the melt, even with pressures up to 40,000 psi. Analysis of data on the kinetics of crystallization of PET melt under high pressures revealed low Avrami exponents, for which no unequivocal explanation is offered. It is possible, however, that crystallization at high pressure promotes the formation of a morphology made up of a certain percentage of “extended chains.” The alteration in the attendant spatial geometry involved in the crystallization might explain the lower Avrami exponents found. In another set of experiments, crystallization temperatures (Tc) were measured by slowly cooling PET melt under high pressures. As the pressure was raised from 3000 to 15,000 psi, Tc increased from about 246 to 282.5°C. These results are consistent with thermodynamic theory. 相似文献
11.
Phosphorus-containing carbons have been obtained by carbonization of porous copolymer of 4,4′-bis(maleimidodiphenyl)methane (50 mol%) and divinylbenzene (50 mol%) in presence of phosphoric acid at temperatures 400–1000 °C. Porous structure was analyzed by nitrogen adsorption isotherms while surface chemistry was investigated by potentiometric titration method. It has been shown that carbons obtained at 500–1000 °C are micro-mesoporous with pore sizes of 1–1.1, 2–3 and 5.4 nm. The most developed porosity was achieved at 600 °C reaching BET surface area 890 m2/g and total pore volume 0.45 cm3/g. Carbons obtained by carbonization of polyimide precursor in presence of phosphoric acid showed acidic character with 30–40 % of phosphate surface groups. Maximum total amount of acidic surface groups was achieved at 800 °C reaching 3.2 mmol/g. Assignment of strongly acidic surface groups to phosphates was corroborated by pK value, phosphorus content and thermal gravimetric analysis. 相似文献
12.
G. M. Bower J. H. Freeman E. J. Traynor L. W. Frost H. A. Burgman C. R. Ruffing 《Journal of polymer science. Part A, Polymer chemistry》1968,6(4):877-887
Linear polyimides prepared from m-phenylene diamine (MPD) and 3,4,3′,4′-benzophenonetetracarboxylic dianhydride (BTDA) were modified so as to be thermosetting. This was done by replacing a portion of the MPD with either 2,4-diaminoacetanilide or p-(2,4-diaminophenoxy) acetanilide and 3,5-diaminobenzoic acid; it is thought that during final processing of the laminates the carboxyl group and the acetamido group react, forming amide crosslinks. Alternatively, excess anhydride was incorporated into the polymer to react with some of the attached acetamido groups; these would give imide crosslinks. A series of resins and glass-reinforced laminates incorporating these resins was prepared. The laminates were aged and tested at 315°C. Flexural strength at 315°C. versus hours aged at 315°C. is presented. Flexural strength after 100 hr. at 315°C. for two of the better laminates from modified polymers was about 48,000 psi, compared to 24,000 psi for the straight linear polymer. The flexural strength of the modified polymers decreased more rapidly, however, and after 1000 hr. of aging at 315°C. the flexural strength of the best laminates, including the linear polymer, was 12,000 psi. 相似文献
13.
M. S. Sinsky R. G. Bass J. W. Connell P. M. Hergenrother 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2279-2295
Novel poly(enamine-ketones) were prepared with inherent viscosities as high as 1.99 dL/g using the Michael-type addition of various diamines to 1,1′-(1,3 or 1,4-phenylene)bis(3-phenyl-2-propyn-1-one) in m-cresol at 60–130°C. Tough, clear, amber films with tensile strengths of 12, 400 psi and tensile moduli of 397, 000 psi were cast from solutions of the polymers in chloroform. The polymers exhibited Tgs as high as 235°C and weight losses of 14% after aging at 232°C in circulating air for 60 h. The synthesis and characterization of several poly(enamine-ketones) are discussed. 相似文献
14.
J. L. Lundberg E. J. Mooney C. E. Rogers 《Journal of Polymer Science.Polymer Physics》1969,7(5):947-962
Diffusion coefficients and solubilities of methane in polyisobutylene have been measured at four temperatures between 102 and 188°C. in the pressure range 23–341 atm. Diffusion coefficients extrapolated to atmospheric pressure range from 1.72 × 10?6 cm.2/sec. at 102°C. to 1.5 × 10?5 cm.2/sec. at 188°C. corresponding to an activation energy for diffusion of 8.7 ± 0.4 kcal./mole. Solubilities are small, about one molecule of methane for every forty carbon atoms in the polyisobutylene at 300 atm. partial pressure of methane. Solubilities vary little with temperature, but show an apparent minimum between 127 and 188°C. With improved methods of data analysis, diffusion coefficients and solubilities have been recalculated from previously reported studies on nitrogen in branched polyethylene and methane in branched polyethylene, linear polyethylene, and polystyrene. Recalculated diffusion coefficients are essentially the same as those reported previously, but the recalculated solubilities are decreased from 2 to 30%. The solubilities of all five systems show strong deviations from Henry's law, i.e., increases in partial pressure of methane and nitrogen with respect to solubility exceed linearity. The partial pressure (or fugacity)—solubility data may be interpreted in terms of a sorption model in which sorbed molecules are accommodated in widely dispersed, unoccupied volumes or sites in the polymer. An almost equivalent, solution model in which the first sorbed molecules to enter the polymer are accommodated to a large extent in existing volumes in the polymer, with successively sorbed molecules swelling the polymer to a greater extent (i.e., partial molal volume of sorbed molecules, V 1, increasing with concentration) can also account for these data. 相似文献
15.
V. Dvořák V. Danielik O. Matal Marta Chrenková M. Boca 《Journal of Thermal Analysis and Calorimetry》2008,91(2):541-544
The phase diagram of the binary system NaF-SnF2 was determined by using the thermal analysis method. In addition to the crystallisation
fields of pure components the formation of three other crystallisation fields was observed and these were attributed to the
compounds: NaF·2SnF2, NaF·SnF2 and 2NaF·SnF2. The coordinates of the four eutectic points are: e
1: 70 mol% NaF, 30 mol% SnF2 and 255°C e
2: 58 mol% NaF, 42 mol% SnF2 and 238°C e
3: 44 mol% NaF, 56 mol% SnF2 and 246°C e
4: 18 mol% NaF, 82 mol% SnF2 and 191°C
The model independent on the real structure of the melt was applied for the calculation of phase diagram comprising the calculation
of excess molar Gibbs energy of mixing. The probable inaccuracy in the calculated phase diagram is σ=2.0°C. XRD analysis of
solidified mixtures was performed in order to confirm the formation of expected compounds. 相似文献
16.
The phase diagrams of the binary system KF-AlF3 as well as the ternary system NaF-KF-AlF3 in the range up to 50 mol% AlF3, were measured using the thermal analysis method. In the system KF-AlF3 the coordinates of the eutectic points are: E
1: 8.0 mol% AlF3, 821.2°C, and E
2: 45.5 mol% AlF3, 565.0°C. In the investigated concentration range of the ternary system 2 eutectic points have been found with the calculated
coordinates: E
1: 36.3 mol% NaF, 62.7 mol% KF, 1.0 mol% AlF3; t=711.2°C; and E
2: 51.9 mol% NaF, 27.4 mol% KF, 20.7 mol% AlF3; t=734.5°C. Other eutectic points lie most probably beyond the investigated part of the system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
R. G. Bass E. Cooper P. M. Hergenrother J. W. Connell 《Journal of polymer science. Part A, Polymer chemistry》1987,25(9):2395-2407
Novel poly(enonsulfides) were prepared with inherent viscosities as high as 1.35 dL/g by nucleophilic addition of various aromatic dithiols to 1,1′-(1,3- or 1,4-phenylene)bis(3-phenyl-2-propyn-1-one) in m-cresol at 25–40°C. A tough clear yellow film with a tensile strength of 11,300 psi and a tensile modulus of 466,000 psi at 25°C was cast from a chloroform solution of the polymer prepared from 1,3-dithiobenzene and 1,1′-(1,4-phenylene)bis(3-phenyl-2-propyn-1-one). The poly(enonsulfides) exhibited Tg's as high as 180°C and weight losses of approximately 10% at 331°C in air. The synthesis and characterization of several poly(enonsulfides) are discussed. 相似文献
18.
Hua Ma Zhanliang Tao Feng Gao Jun Chen Huatang Yuan 《Frontiers of Chemistry in China》2006,1(3):260-263
The structure, morphology and hydrogen-storage capacity of MS2 (M = Mo, Ti) nanotubes prepared by different experimental methods were studied. It was found that the MoS2 nanotubes treated by KOH displayed the gaseous storage capacity of 1.2 wt% hydrogen (under the hydrogen pressure of 3 MPa
and 25°C) and the electrochemical discharge capacity of 262 mAh/g (at the discharge current density of 50 mA/g and 25°C) that
corresponds to about 1.0 wt % hydrogen. In comparison, TiS2 nanotubes can store 2.5 wt% hydrogen under the hydrogen pressure of 4 MPa and 25°C. The results show that MS2 compound nanotubes are promising materials for hydrogen storage.
__________
Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2005, 38(4) (in Chinese) 相似文献
19.
Guy Rabilloud Bernard Sillion 《Journal of polymer science. Part A, Polymer chemistry》1978,16(9):2093-2111
Three new monomers with phenylglyoxyloyl groups fixed on the 4,4′-, 4,6′-, and 4,4″-positions of m-terphenyl were synthesized by different pathways. They were used to prepare a series of polyphenylquinoxalines by solution polycondensation with 3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenyl ether. These polymers exhibited excellent oxidative and thermal stability as shown by thermogravimetric analysis and isothermal aging in circulating air between 300 and 450°C. Clear yellow films, cast from m-cresol solution, were used to measure their softening temperature by thermomechanical analysis (TMA). Numerical data thus obtained, indicated a thermoplastic behavior in the temperature range 300 ± 15°C. Crosslinking of the linear polymers by isothermal heat exposure under argon between 300 and 500°C was investigated by means of TMA. Molded materials were fabricated under constant pressure (996 psi) at 500–525°C with an Instron testing machine. These polymers were also used for preliminary evaluation as matrices for 181-E glass reinforced composites. Flexural values obtained after isothermal aging in air up to 400°C indicated a potential use varying from 150 hr at 350°C to 24 hr at 400°C. 相似文献
20.
Minoru Nagata Tsuyoshi Kiyotsukuri Taizou Hasegawa Naoto Tsutsumi Wataru Sakai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):965-973
Abstract Network copolyesters were made from adipic acid and ethylene glycol with 10–40 mol% trimesic acid (Y). Prepolymers prepared by melt polycondensation were cast from dimethylformamide solution and postpolymerized at 260°C for various times to form a network. The degree of reaction (D R), estimated from the infrared absorbance of hydroxyl and methylene groups, increased with increasing postpolymerization time and leveled out at about 90% after 4–6 hours. Heat distortion temperatures (T h) measured by thermomechanical analysis increased greatly from ?83 to 48°C upon the incorporation of Y. Wide-angle x-ray diffraction patterns showed that the copolymer films are amorphous. Density, tensile strength, and Young's modulus decreased for the copolymers with 10–30 mol% Y, whereas they increased drastically for the copolymer with 40 mol% Y. The enzymatic degradation was estimated by the weight loss of the copolymer films in buffer solutions with a lipase at 37°C. The weight loss decreased remarkably with increasing Y and showed no weight loss for the copolymer with 40 mol% Y. On the other hand, the weight loss by alkali hydrolysis increased for the copolymers with 10 and 20 mol% Y, implying a difference in the degradation mechanism between enzymatic degradation and alkali hydrolysis. 相似文献