Chemiluminescent method to measure generation rates of active centers in reaction of hydrogen peroxide with hemin and pyridinehemichrome

A chemiluminescent method was used to measure generation rates of active intermediates in the interaction of hemin with hydrogen peroxide with and without pyridine at pH=8–9. The effect of various inhibitors in these two cases has been examined.

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pH=8+9. .

     

IR-spectroscopic studies of the interaction of pyridine bases with vanadium and molybdenum oxides supported on magnesia

As shown by IR-spectroscopic studies, pyridine bases interacting with V₂O₅ and MoO₃ supported on MgO form hydrogen bonds with surface hydroxyls and coordinate bonds with V and Mo ions. The interaction of 2,6-dimethylpyridine adsorbed on the surface with oxygen leads to the formation of 6-methylpyridine-2-carboxaldehyde, whose formyl group interacts with surface hydroxyls.

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, V₂O₅ MoO₃, MgO, V Mo. 2,6- 6--2-, OH-.

     

Influence of cobalt phthalocyanine: Deposited onto the particles of mixed Cd/CuxS suspensions on photocatalytic evolution of hydrogen from aqueous solutions of Na2S

Deposition of water-insoluble cobalt phthalocyanine CoPc onto the particles of mixed suspensions of CdS and Cu_xS can increase the rate of photoinduced evolution of H₂ from Na₂S and Na₂SO₃ solutions. At [Na₂S]=5×10^–2 M, the rate of photocatalytic reaction is almost doubled upon deposition of 6.4×10^–10 mol CoPc onto 4×10^–5 mol of CdS and of 2.9×10^–8 mol of CoPc onto 10^–5 mol of Cu_xS. At [Na₂S]=10^–1 M, which is close to the optimal concentration of Na₂S, the deposition of CoPc can provide only a 30% increase of the reaction rate.

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, CoPc CdS/Cu_xS H₂ Na₂S Na₂SO₃. Na₂S=5·10^–2 M 6.4·10^–10 CoPc 4·10^–5 CdS 2.9·10^–8 CoPc 10^–5 Cu_xS. Na₂S=10^–1 M, CoPc 30% .

     

Selective oxidation and ammoxidation of isobutene over mixed oxides of tin and antimony

The oxidation and ammoxidation of isobutene were studied over mixed oxides SnO₂/Sb₂O₄ as catalysts, in a pulse reactor between 598 and 698 K. From the point of view of methacrylonitrile production the catalysts of compositions SnSb=4–51 behaved most appropriately at the optimum reaction temperature of 673 K. Below this temperature the production of methacrolein was preferred, even in the presence of ammonia, whereas at higher temperatures total oxidation prevailed.

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SnO₂/Sb₂O₄, 598 698 . SnSb=4–51 , 673 . , , .

     

Effect of bond energies of a catalyst with reacting atoms on the selectivity of CO hydrogenation over metals

In hydrogenation over metals (M)_j carbon monoxide is adsorbed as a molecule. C–O bond rupture in partially hydrogenated complex, MCHOH, leads to MO and MCH₂ and then to hydrocarbons, while transformation of MCHOH into MCH₂OH gives alcohols and other oxygen-containing compounds. Selectivity towards hydrocarbons increases with increasing energy of M–O bonds.

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(M) . C–O MCHOH MO MCH₂ — ; MCHOH MCH₂OH . M–O.

     

Sintering of supported palladium

Sintering results of Pd supported on carbon black at 723–973 K, in water vapor, in H₂ and under high vacuum are reported. They are compared with sintering data of Pd on other supports. The observed sequences are: SiO₂C>sepioliteAl₂O₃>AlPO₄ and H₂O>high vacuum>H₂.

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Pd 723–973 , , H₂ . Pd . : SiO₂Al₂O₃>AlPO₄ H₂O> >H₂.

     

Hydrogenation of carbon monoxide catalysts prepared by pyrolysis of Co2(CO)8 on various oxide supports

Catalysts prepared by pyrolysis of Co₂(CO)₈ on oxide supports have been studied in the hydrogenation of CO. It is shown that MgO and -Al₂O₃-based catalysts are less active than those supported on SiO₂, TiO₂ and ZrO₂. The application of -Al₂O₃ as a support increases the relative yield of light hydrocarbons.

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, Co₂(CO)₈ , CO. , MgO -Al₂O₃ SiO₂, TiO₂ ZrO₂. -Al₂O₃ .