共查询到20条相似文献,搜索用时 17 毫秒
1.
Yu. V. Belokopytov Yu. I. Pyatnitskii T. A. Tatarinova A. V. Strashnenko 《Theoretical and Experimental Chemistry》1985,21(1):100-103
A general outline is given of a kinetic model of oxidation of a hydrocarbon under the conditions of coexistence on the catalyst surface of sections of different oxidation levels. An analytical dependence has been obtained of the selectivity of the process and conversion on the composition of the reaction mixture. A qualitative agreement has been established between the theoretical and experimental dependences of selectivity and conversion on the ratio of the benzene and oxygen concentrations in the reaction mixture.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 105–108, January–February, 1985. 相似文献
2.
3.
Yu. G. Gol'tsov Z. V. Smelaya L. A. Matkovskaya V. V. Tsyrina V. G. Il'in 《Theoretical and Experimental Chemistry》1999,35(2):109-113
It has been established that supramolecular structures of lecithin can act as templates in the synthesis of mesoporous aluminosilicates. Mesoporous substances, with pore dimensions up to 100 Å and biporous materials can be obtained when various combinations of lecithin with cetyltrimethylammonium bromide or octadecylamine are used as template agents in the aluminosilicate system. 相似文献
4.
5.
6.
G. D. Zakumbaeva L. A. Beketaeva A. Sh. Kuanyshev 《Reaction Kinetics and Catalysis Letters》1980,14(3):341-345
The effect of an organic reaction medium on the Pt-black surface formation has been studied. It has been shown that under the action of the reaction medium an irreversible change of the catalyst surface occurs.
Pt-. , .相似文献
7.
The Pictet-Spengler reaction with N-protected α-amino aldehydes was found to be very sensitive to reaction conditions. The outcome of the reaction can be controlled mainly by choice of solvent. Tetrahydro-β-carbolines were obtained in apolar solvents, while in polar media octahydro-bipyrroloindoles were the main compounds. Temperature, amount of acid and reaction time also influenced the final results of the PS reaction. Depending on conditions, products with opposite configuration of stereogenic centre, descended from amino aldehydes, were formed as byproducts. 相似文献
8.
O. V. Udalova E. V. Khaula Yu. N. Rufov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(9):1511-1514
Three methods for the introduction of singlet oxygen into the reaction mixture were tested, including thermal generation of singlet oxygen on the catalyst itself, the introduction of singlet oxygen from an external source, and photogeneration of singlet oxygen on the catalyst. Zeolites with admixtures of Mo, Bi, V, and Ni and SiO2 with deposited Mo, V, and Bi were used. Common to all reactions was an increase in the yield of deep oxidation products in the presence of singlet oxygen. A sharp increase in the yield of mild oxidation products was observed in the oxidation of propylene on a Bi/SiO2 catalyst. The generation of singlet oxygen under irradiation at 240–260 nm was found to cause deep oxidation only. Mild oxidation products could only form under the action of total mercury lamp light. 相似文献
9.
10.
In this paper, a new predictive model is proposed for prediction of gas hydrate formation conditions in the presence of single and mixed electrolytes and solutions containing both electrolyte and a polar inhibitor such as monoethylene glycol (MEG), diethylene glycol (DEG) and triethylene glycol (TEG). The proposed model is based on the γ–φ approach, which uses modified Patel–Teja equation of state (VPT EOS) for characterizing the vapor phase, the solid solution theory by van der Waals and Platteeuw for modeling the hydrate phase, the non-electrolyte NRTL-NRF local composition model and Pitzer–Debye–Huckel equation as short-range and long-range contributions to calculate water activity in single electrolyte solutions. Also, the Margules equation was used to determine the activity of water in solutions containing polar inhibitor (glycols). The model predictions are in acceptable agreement with experimental data. For single electrolyte solutions, the model predictions are similar to available models, while for mixtures of electrolytes and mixtures of electrolytes and inhibitors, the proposed model gives significantly better predictions. In addition, the absolute average deviation of hydrate formation pressures (AADP) for 144 experimental data in solutions containing single electrolyte is 5.86% and for 190 experimental data in mixed electrolytes solutions is 5.23%. Furthermore, the proposed model has an AADP of 14.13%, 5.82% and 5.28% in solutions containing (Electrolyte + MEG), (Electrolyte + DEG) and (Electrolyte + TEG), respectively. 相似文献
11.
Landoulsi J Genet MJ Richard C El Kirat K Rouxhet PG Pulvin S 《Journal of colloid and interface science》2008,320(2):508-519
The ennoblement of the free corrosion potential (E(corr)) of AISI 316L stainless steel which did not occur in synthetic fresh water (SFW), was observed after introduction of glucose oxidase (Gox) and glucose, or of hydrogen peroxide (H(2)O(2)). The composition of the surface was monitored using AFM and XPS, a detailed XPS analysis being based on the discrimination between oxygen of organic and inorganic nature proposed in a previous study. In H(2)O(2) medium, the main changes regarding the inorganic phase were the increase of the oxygen concentration in the passive film, the increase of the molar concentration ratio of oxidized species Fe(ox)/Cr(ox) and the growth of nanoparticles, presumably made of ferric oxide/hydroxide. In Gox medium, no significant changes were observed in both oxygen concentration and Fe(ox)/Cr(ox) ratio, but the density of colloidal particles decreased, indicating a dissolution of Fe oxide/hydroxide under the influence of gluconate. In contrast with H(2)O(2), in SFW and Gox the amount of organic compounds increased due to the accumulation of polysaccharides and proteins. The influence of glucose oxidase on the ennoblement of stainless steel is not due to indirect effects of H(2)O(2) through the change of surface composition. The E(corr) ennoblement seems to be directly due to the presence of H(2)O(2) and to the electrochemical behavior of H(2)O(2) and related oxygen species. This consideration is important for understanding and controlling microbial influenced corrosion. 相似文献
12.
Applied Biochemistry and Biotechnology - 相似文献
13.
An abnormal dependence of overall hydrogenation rate on the composition of a cyclopentadiene-isoprene mixture for the case of pseudo-zero reaction order has been interpreted in terms of a model accounting for the inhomogeneity of active sites.
, , .相似文献
14.
Nakano K Doi K Tamura K Katsumi Y Tazaki M 《Chemical communications (Cambridge, England)》2003,(13):1544-1545
Glucose oxidase (GOx) has been attached covalently to form uniform enzyme monolayers on self-assembled monolayers (SAMs) from 11-aminoundecanethiol (AUDT) by taking advantage of chemical oxidation of GOx carbohydrate residues followed by coupling the resulting 'aldehydic' enzyme with the terminal amino group in the SAM as characterized by AFM imaging, IR, QCM, and electrochemical measurements. 相似文献
15.
The redox potentials of the reaction mixtures in the course of pentaerythritol synthesis and of transformations of formaldehyde and glucose in a NaOH solution without catalyst and in the presence of copper prepared by reduction of CuO were measured. 相似文献
16.
17.
The paper presents the results of investigations into the technological possibilities of controlling the transgalactosylation
process of lactose in permeate after whey ultrafiltration in order to improve the efficiency of galactooligosaccharides or
lactulose synthesis. The synthesis efficiency was influenced by the selection of a β-galactosidase preparation, substrate
concentration and, in the synthesis of lactulose, also by the ratio of lactose and fructose added to the reaction mixture.
The obtained synthesis efficiency of GOS and, most of all, of lactulose (65 g L−1), may be found satisfactory. The study also resulted in a proposed GOS or lactulose concentrates (concentrated or dried)
production technology using permeate after ultrafiltration of milk or whey as lactose sources.
Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May
2008. 相似文献
18.
19.
Ayala P Grüneis A Kramberger C Rümmeli MH Solórzano IG Freire FL Pichler T 《The Journal of chemical physics》2007,127(18):184709
Single and multiwalled nitrogen-doped carbon nanotubes were grown by chemical vapor deposition varying the feedstock composition between pure acetonitrile and ethanol/acetonitrile mixtures. The advantage of using CN sources that develop close vapor pressure values has been used in order to elucidate the effects of the reaction atmosphere in the synthesis of N-doped nanotubes. Our findings show that the morphology of the nanotube material depends strongly on the composition of the reaction atmosphere. When carrying out the experiments in an atmosphere solely determined by the vapor pressure of the feedstock components, improved homogeneity is achieved with pure CN sources or low concentration of the foreign solute. Under these conditions the temperature has strong influence in the diameter distribution. 相似文献
20.
E. V. Krupko G. Ya. Grodzyuk Yu. B. Khalavka G. M. Okrepka L. P. Shcherbak 《Theoretical and Experimental Chemistry》2011,47(2):101-107
A study was carried out on the dependence of the optical properties such as the maxima in the absorption and luminescence spectra, Stokes shift, and quantum yield on the composition of the three-component Cd2+—L-Cys—S2− reaction system under synthesis conditions at 298 ± 2 K and pH 7. Equations describing the dependence of the position of the maximum in the luminescence and absorption spectra of solutions on their composition were obtained by mathematical planning using the Scheffe simplex-lattice design and treatment of the data. The region of compositions for unstable colloidal solutions was determined. 相似文献