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1.
Studies of the effect of zinc chloride and aluminium additives on the activity of a Pd/Al2O3 catalyst (5 wt.%Pd) in the isomerization of heptene-1, allylbenzene,p-allylphenol and 4-allyl-2-methoxyphenol (eugenol) indicate that the rate and selectivity of isomerization depend on the sequence of addition of salts and reagent to the catalytic system. The simultaneous addition of ZnCl2 or AlCl3 with olefin, produces a 2–3 fold increase in the isomer yield compared to ethanol.
Pd/Al2O3- (5 .% Pd) -1, , -, 4--2- (). , . ZnCl2 AlCl3 2–3 .
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2.
The oxidation of methane on supported chromia was studied at temperatures varying between 423 and 743 K and CH4/O2 ratios between 1 and 9 in a differential reactor. The main reaction products observed were carbon monoxide and formaldehyde. The rates of reaction obey a power law expression.
, 423 743 CH4/O2 1 9, . . .
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3.
Reducibility of NiO/Al2O3 and CuO–NiO/Al2O3 catalysts has been studied by the TPR method within the temperature range 293–873 K. The results suggest that the copper content essentially does not influence the reducibility of NiO/Al2O3.
NiO/Al2O3 CuO–NiO/Al2O3 TPR 293–873 . , NiO/Al2O3.
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4.
New highly active catalysts for metathesis of olefins were obtained through the interaction of bis(acetylacetonato)dioxymolybdenum(VI) with surface OH groups of -Al2O3 and subsequent reduction in H2 or CO.
()(VI) OH -Al2O3 H2 CO .
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5.
Electrolytic supporting of metallic sodium on the surface of TiO2 and Pt/TiO2 films is shown to change significantly the Fermi level of the semiconductor substrate already at small concentrations of sodium. The steady-state catalytic activity changes only at high concentrations of supported sodium, varying the chemical composition of the active phase. The contact process does not play any significant role in the catalytic process.
, TiO2 Pt/TiO2 . , . .
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6.
The acidic properties of a series of TiO2–SiO2 catalysts with different Ti/Si mole ratios have been studied. In order to determine the amount of acid centers and the acid strength distribution, the Benesi method of discontinuous titration has been used. Thermogravimetric measurements were also carried out.
TiO2–SiO2 Ti/Si. , - . .
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7.
Transformation of cis- and trans-2-butene at 40°C was investigated over a MoO3/A2O3 catalyst reduced with hydrogen and subjected to different pretreatments. Isomerization is accelerated by hydrogen preadsorbed either at low or high temperatures. The cometathesis of 2-butenes with the 1-butene intermediate, however, is enhanced only by hydrogen preadsorbed at low and suppressed by hydrogen adsorbed at high temperatures.
- -2- 40°C MoO3/Al2O3, . , , . 2- 1- , ; , .
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8.
Dispersity of palladium for a series of Pd/SiO2 catalysts has been determined by TEM and H2–O2 chemisorption. The mean crystallite dimensions obtained by these methods have been compared. Assuming O/Pds to be 0.6 for Pd crystallites larger than 9 nm, good agreement has been observed between the results of the two experimental methods.
Pd/SiO2 H2–O2. , . O/Pds0.6, Pd 9 , .
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9.
The species resulting in CO, CO+H2 or CO+D2O adsorption on supported Ni catalysts were followed by IR spectroscopy and their role in methane synthesis mechanism is discussed.
- , CO, CO+H2 CO+D2O . .
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10.
Comparison of adsorptive properties of Rh–Al2O3 catalysts in relation to H2, O2 and CO as adsorbates points to different surface interactions between the adsorbates and metallic surface of the catalysts. The differences may result from the changing composition of bimetal surface in relation to the catalyst composition and/or from the changing stoichiometry of surface interactions of the adsorbates.
H2, O2 CO Rh–Ag/Al2O3 . , , () .
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11.
Hydrogenation of CO2 was investigated on iron-copper supported catalysts. Hydrocarbons, except methane, were formed through the CO intermediate, which is formed first in the water gas-shift reaction.
CO2 - . CO, , , .
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12.
New active and selective catalysts were prepared by adding different quantities of Te to CdMoO4. These were already selective at low Te levels, but the one with a Cd/Te/Mo ratio of 1/1/1 was specific for butadiene. The catalytic behavior of the Cd–Te–Mo–O system has been correlated mainly with the CdTeMoO6 phase in the region rich in Te and with the CdMoO4 phase with Te as dopant in the region poor in Te.
Te CdMoO4. Te, CdTeMo=111 . Cd–Te–Mo–O CdTeMoO6 Te, CdMoO4 Te , Te.
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13.
According to kinetic studies on the reduction of commercial Co–Mo/Al2O3 and model catalysts in H2 at 523–773 K, the kinetic curves for the reduction process have been determined. The reduction rate is shown to be higher for the commercial catalyst. Activation energies Eact for the reduction of several forms of Mo and Co in Co–Mo/Al2O3 catalysts are presented.
H2 523–773 . , : Mo Co .
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14.
In (E+Rh)/Al2O3 catalysts (E=Sn, Pb, Mo and W) the catalytic properties of rhodium in benzene hydrogenation, propane hydrogenolysis and n-hexane conversion change drastically. For modified rhodium the decrease in the hydrogenolysis rate of C–C bonds in paraffins leads to an increased yield of the products of non-destructive conversion of n-hexane.
(E+Rh)/Al2O3 (E:Sn, Pb, Mo, W) , , -. C–C -.
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15.
Following hydrogen treatments at high temperature a decrease in hydrogen chemisorption at room temperature is observed in almost all group VIII elements supported on SiO2 or Al2O3. The effect is attributed to self inhibition by strongly chemisorbed hydrogen on the metals.
VIII , SiO2 Al2O3. .
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16.
Kinetics of OsO4 catalyzed oxidation of chalcones by Ce4+ has been studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in [oxidant] is zero while the order with respect to [substrate] and [catalyst] are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while [H+] had practically no effect on the rate The rates of various substituted chalcones (with substituents in the phenyl. ring attached to the moiety) are in the orderp-CH3>m-CH3>H>p-Cl>m-Cl>m-NO2>p-NO2. A mechanism in which formation of a cyclic ester between chalcone and OsO4 in a fast step followed by its decomposition in a rate-determining step is envisaged.
Ce4+, OsO4, - 313–338 . —, —. , [H+] . ( , : -CH3>-CH3>H>-Cl>-NO2>-NO2. , OsO4 , , .
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17.
Under reforming conditions, the rate of n-heptane conversion on a large Pt/Al2O3 catalyst grain, in contrast to that in the kinetic region, depends on the hydrogen to hydrocarbon mole ratio. The rate equation for the reaction on a large grain agrees well with the experimental results obtained by a gradientless method under pressure.
- , , : . , .
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18.
Studies of SO2 oxidation on a molten component of vanadium catalysts in non-steadystate conditions indicates that the kinetics agree fairly well with an oxidation-reduction mechanism. In the low temperature range (<790 K) tetravalent vanadium can be partially crystallized.
. , - . ( 790 ) .
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19.
The kinetics and mechanism of redox reactions of U3+ ions with 2-chloro and 2-bromopropanoic acids were studied. The influence of pH led to the determination of the rate constants corresponding to two parallel steps. The influence of binary mixtures on the reaction rate was followed. The kinetic results for halogen-substituted carboxylic acids forming an isokinetic series have been compared.
U+3 2-- 2- . pH . . , .
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20.
Kinetic data show that in the presence of K2WO4/Al2O3, methanethiol is largely produced by the reaction of H2S with metanol and partly with dimethyl ether. Dimethyl sulfide is formed during the interaction of methanethiol with methanol, of H2S with dimethyl ether and as a result of methanethiol disproportionation. Methane and carbon oxides are the decomposition products of methanethiol and dimethyl sulfide and of methanol and dimethyl ether, respectively.
, K2WO4/Al2O3 H2S — . , H2S . , — .
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