Magnetic field effects on the optical spectrum of FeCl2

The intensity of the ligand-field zero-phonon line of FeCl₂ at 4272 Å has been measured in magnetic fields up to 40 kOe at temperatures of 8 and 11°K. The intensity first rises and then falls with increasing field, as the crystal passes through a phase transition from an antiferromagnetic (metamagnetic) to a ferromagnetic state.     

The mechanism of SO2 oxidation by CH3O2 radicals. Rate coefficients for the reactions of CH3O2 with SO2 and NO

The reactions of CH₃O₂ with SO₂ and NO have been studied by steady state photolysis of azomethane in the presence of O₂SO₂→NO mixtures at 296 K and 1 atm total pressure. The quantum yield of NO oxidation by CH₃O₂ radicals is increased substantially when SO₂ is added to the system indicating an SO₂ induced chain oxidation of NO. The rate law gives k₁/k₂ = (2.5 ± 0.5) × 10^?3 for CH₃O₂ + SO₂ → CH₃O₂SO₂ (1), CH₃O₂ + NO → CH₃O + NO₂ (2). Combining this ratio with the absolute value of k₁ = 8.2 × 10^?15 cm³ s^?1 gives k₂ = 10^{?11.5 ± 02} cm³ s^?1.     

Bond function parameter transferability in SO2, SF2 and SO2F2

Ab initio MO studies of the use of gaussian bond functions in the molecules SO₂,SF₂ are presented. It is shown that optimization of bond function exponent and position parameters in the small molecules is a good approximation to the optimum parameter set for SO₂F₂,     

Ch-stretching gas phase overtone spectrum of symmetric neopentane-d4

The overtone spectrum of neopentane-d₄, C(CH₂D)₄, is examined and the local mode model is used to assign the prominent peaks. Proposed coupling routes for intramolecular vibrational relaxation of CH-stretching overtones are discussed. The dominant vibrational relaxation pathway is identified by comparisons of neopentane-d₄, neopentane and benzene overtone bandwidths.     

A shock tube study of vibrational relaxation in SO2, SO2Ar and SO2He

Vibrational relaxation times in SO₂, SO₃Ar (11%, 20% and 54% SO₂) and SO₂He (9.5% SO₂) were measured behind incident shock waves using the laser schlieren technique in the temperature ranges 550–1200 K, 700–2100 K and 700–1600 K respectively for the three systems. An analysis of the density gradient signals revealed a double exponential behaviour consistent with earlier studies. The fast relaxation rates were not quantitatively studied and the slow relaxation rates were found to fit the following equations:

where Pτ is the relaxation time in atm μs and T is in °K. The collision numbers corresponding to the slower rates were found to agree well with a recent theoretical calculation using SSH-Tanczos theory.     

Theoretical investigations on the SO2 + HO2 reaction and the SO2–HO2 radical complex

The mechanism of the SO₂ + HO₂ reaction was studied theoretically for the first time. Three product channels were revealed, namely, O₂ + HOSO, O₂ + HSO₂, and OH + SO₃. The O₂ + HOSO channel dominates the reaction under combustion conditions. A five-member-ring complex [SO₂–HO₂] exists at the entrance of the reaction. The structure and binding energy (D_e and D₀) of the SO₂–HO₂ complex have been calculated. In view of D₀ = 21.2 ± 2.0 kJ mol⁻¹, the SO₂–HO₂ complex should be stable at low temperature. The infrared spectra and frequency shifts were calculated for both SO₂–HO₂ and SO₂–DO₂, and compared with the available experimental data.     

Calculation of the rate of SO2 oxidation to SO3

Approximate equation to calculate the effectiveness factor of catalyst for SO₂ oxidation to SO₃ has been derived. Calculated data agree well with those predicted by a quasi-homogeneous model.

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Gas phase photoreaction of SO2 with n-pentane in the presence of NO

The spectrum of an intermediate, ascribed to nitrosopentane, has been detected in the photolysis of SO₂-pentane-NO mixtures. This may be explained by a radical photolysis mechanism involving an initial H-atom abstraction from the pentane molecule by SO₂.

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SO₂--NO , . , H .

     

Subsolidus phase relations in the systems CeO2RE2O3 (RE2O3 = C-type rare earth sesquioxide)

The systems CeO₂RE₂O₃ (RE₂O₃ = C-type rare earth sesquioxide) were studied to: (1) investigate the claims of several workers for the existence of a complete solid solution series between CeO₂ and RE₂O₃ and (2) to characterize the weak C-type X-ray diffraction peaks reported by others from samples in the single-phase fluorite solid solution region. It is shown that a complete solid solution series does not exist, and an explanation for the observations of others reporting such is tendered. It is also shown that the observation of C-type reflections in the supposed single-phase fluorite field can be attributed to the partial reduction of Ce⁴⁺ to Ce³⁺ at the firing temperature, resulting in the movement of the bulk composition into a two-phase field of the CeO₂RE₂O₃Ce₂O₃ phase diagram, rather than the formation of a domain structure due to ordering.     

Investigation of phase equilibria in the systems K2SO4Sc2(SO4)3, Rb2SO4Sc2(SO4)3 and Cs2SO4Sc2(SO4)3

Phase diagrams of the systems K₂SO₄Sc₂(SO₄)₃, Rb₂SO ₄Sc₂(SO₄)₃ and Cs₂SO₄ Sc₂(SO₄)₃ have been investigated by X-ray diffraction phase analysis and differential thermal analysis techniques. A salient feature of all the systems is the formation of M₃Sc(SO₄)₃, which melt incongruently, and MSc(SO₄)₂, which on heating decompose in the solid state.     

High-temperature reduction of SO2 by methane at various CH4/SO2 ratios

The character of the effect of initial reaction mixture and temperature on the selectivity of catalytic reduction of sulfur dioxide by methane in the presence of oxygen has been studied.

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Mass-spectrometric analysis of SO3 in SO2 oxidation over vanadium catalysts

The detailed composition of the reaction mixture and, in particular, SO₃ concentration, in SO₂ oxidation over vanadium catalysts, have been determined experimentally. Both oxidized and reduced catalysts were shown to absorb a considerable amount of SO₃, the desorption rate of SO₃ being lower than that of its adsorption.

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, , . , , SO₃, .

     

Ab initio studies on photochemical reactions of Al atoms with H2 molecules

Potential energy surfaces are computed for the five lowest electronic states of the Al + H₂ system in its symmetric nuclear arrangement. Mechanisms of photochemical reactions of Al atoms with H₂ molecules are proposed, based on the calculated potential energy surfaces. The insertion reaction of the ground-state Al atom into the H₂ molecule is difficult under normal conditions. However, photoexcited Al atoms are capable of reacting with H₂ molecules along different pathways. The results obtained are consistent with experimental findings. The potential energy profiles of the dissociation reaction, AlH₂ → AlH + H, are traced by employing the UMP2 energy gradient method. Photocexcited Al atoms react with H₂ molecules along the 2 ²A₁ state pathway, and the AlH₂(²Σ_g⁺) formed dissociates easily into AlH(¹Σ) and H(²S). The dissociation reaction of ground-state AlH₂ is difficult.     

Electron beam process for SO2 removal from flue gases with high SO2 content

Flue gases with high SO₂ concentration are emitted from different industrial processes, e.g. combustion of coal with high sulfur content, copper smelting and sintering plant. The application of the electron beam process for SO₂ removal from such flue gases was investigated. A parametric study was carried out to determine the removal efficiency as a function of temperature and humidity of irradiated gases, dose and ammonia stoichiometry. At the dose 11.5 kGy 95% SO₂ removal efficiency was obtained when the temperature and humidity of irradiated flue gases and ammonia stoichiometry were properly adjusted. The synergistic effect of high SO₂ concentration on NO_x removal was observed. The collected by-product was the mixture of (NH₄)₂ SO₄ and NH₄NO₃. The content of heavy metals in the by-product was many times lower than the values acceptable for commercial fertilizer.     

Vibrational relaxation in SO2

SSH—Tanczos calculations are carried out to estimate the energy transfer probabilities and the slow vibrational relaxation time in SO₂ in the temperature range 300–2000 K. The theoretical results suggest a series process below 1000 K, and a complex series/parallel process above that temperature for the vibrational relaxation in SO₂. The theoretical results are compared with the known experimental data.     

Zur Bestimmung von SO2 und SO3, in ihren Gemischen

Ohne Zusammenfassung     

Pd含量对SO42-/ZrO2-WO3固体超强酸催化剂其异构化性能的影响

制备了Pd-SO₄^2-/ZrO₂-WO₃型固体超强酸催化剂,并采用XRD、FT-IR、TPR、XPS、BET和TG-DTA等表征手段对催化剂进行了表征。以正戊烷异构化为探针反应,考察了Pd含量对催化剂异构化活性的影响。结果表明,Pd可以明显地降低催化剂的还原温度,提高催化剂中SO₄^2-的分解温度,从而提高了催化剂热稳定性。当Pd质量分数为0.05%时,Pd-SO₄^2-/ZrO₂-WO₃固体超强酸催化剂的催化活性最好。该催化剂在反应温度260℃、反应压力2.0 MPa、质量空速为1.0 h^-1、氢油比为4.0时,异戊烷收率和液收率为40.1%和93.9%。     

The phase diagram of the system La2(SO4)3Ag2SO4

The phase diagram of the system La₂(SO₄)₃Ag₂SO₄ was studied by DTA, XRD, SEM, and optical methods. One double salt is formed at 67 mole% La₂(SO₄)₃ and this melts incongruently at 876±6°C. A eutectic is formed at 8 mole% La₂(SO₄)₃ and at a temperature of 618±3°C. Suppression of decomposition was effected by the sealed tube method, but some reference is made to experiments conducted with a flowing atmosphere of SO₃, SO₂ and O₂.     

Magnetic field decoupling experiments in NO2

Magnetic field decoupling experiments in the optically excited states of NO₂ yield decoupling signals with a width of 10 to 40 mG. We attribute these signals to the non-rigidity of the excited molecule.