- Low-Temperature Transformation of Methane to Methanol on Pd1O4Single Sites Anchored on the Internal Surface of Microporous Silicate
-
Direct conversion of methane to chemical feedstocks such as methanol under mild conditions is a challenging but ideal solution for utilization of methane. Pd1O4single-sites anchored on the internal surface of micropores of a microporous silicate exhibit high selectivity and activity in transforming CH4to CH3OH at 50–95 °C in aqueous phase through partial oxidation of CH4with H2O2. The selectivity for methanol production remains at 86.4 %, while the activity for methanol production at 95 °C is about 2.78 molecules per Pd1O4site per second when 2.0 wt % CuO is used as a co-catalyst with the Pd1O4@ZSM-5. Thermodynamic calculations suggest that the reaction toward methanol production is highly favorable compared to formation of a byproduct, methyl peroxide.
- Huang, Weixin,Zhang, Shiran,Tang, Yu,Li, Yuting,Nguyen, Luan,Li, Yuanyuan,Shan, Junjun,Xiao, Dequan,Gagne, Raphael,Frenkel, Anatoly I.,Tao, Franklin Feng
-
supporting information
p. 13441 - 13445
(2016/10/21)
-
- Methylperoxyl Radicals: A Study of the γ-Radiolysis of Methane in Oxygenated Aqueous Solutions
-
A product study has been made of the γ-radiolysis of aqueous solution that also contained nitrous oxide and oxygen.Formaldehyde (G = 2.8), hydrogen peroxide (G = 2.1), methanol (G = 1.5), methylhydroperoxide (G = 0.8), formic acid (G = 0.3), and dimethylperoxide (G = 0.1) were found.In alkaline solutions (pH 8, 1E-3 M phosphate buffer), the formaldehyde yield rises to G = 3.2, while the formic acid yield falls to almost zero (G = 0.05).The initial precursor of the carbon-containing products is the methylperoxyl radical.The methylperoxyl radicals decay through a short-lived tetroxide along various pathways.The most prominent one leads to formaldehyde, methanol and oxygen.Methoxyl radicals (and oxygen) are also formed and, after rearrangement into hydroxymethyl radicals and their conversion into hydroxymethylperoxyl radicals, eventually yield formic acid and probably further formaldehyde.A route to formaldehyd and hydrogen peroxide is also envisaged.Methylhydroperoxide is formed in the reaction of methylperoxyl radicals with HO2*/O2*(-) radicals (from radiolytic H atoms and the unimolecular decay of the hydroxymethylperoxyl radical). - Key words: Autoxidation; Peroxyl Radicals; Oxyl Radicals; Radical Rearrangements; Radiation Chemistry
- Schuchmann, Heinz-Peter,Sonntag, Clemens von
-
p. 217 - 221
(2007/10/02)
-
- Oxidation of Sulfur Dioxide by Methylperoxy Radicals
-
This study was made to resolve the apparent discrepancy between the finite rate constants observed for the CH3O2 reaction with SO2 in high-intensity flash photolysis and near zero values observed recently by us and others for this reaction in NO-free, CH3O2-SO2 experiments at low intensity.
- Kan, Charles S.,Calvert, Jack G.,Shaw, John H.
-
p. 1126 - 1132
(2007/10/02)
-
- Temperature Dependence of the Self-Reaction of CH3O2 Radicals
-
The flash photolysis-ultraviolet absorption technique was used to measure the rate constants for the reaction CH3O2 + CH3O2 -> products (1) over the temperature range 248-417 K and the pressure range 60-700 torr of N2.Rate constants were measured by observing the second-order disappearance of CH3O2 radicals.The measured Arrhenius expression is k1 = (1.40 +/- 0.20) x 1E-13 expcm3 molecule-1 s-1, where the rate constant is defined by the expression -d/dt = 2k12.
- Sander, Stanley,Watson, Robert T.
-
p. 2960 - 2965
(2007/10/02)
-
- Fourier Transform Infrared Studies of the Self-Reaction of CH3O2 Radicals
-
Product studies were made with the FT IR method in the photooxidation of CH3N2CH3 and in the Cl-atom initiated oxidation of CH4 in O2-N2 mixtures at 700 torr and 297 K.The major products were CH2O, CH3OH, and CH3O2H in both systems.A weak, broad absorption band centered at 1030 cm-1 was assigned tentatively to CH3O2CH3.These results are consistent with the following primary and secondary reactions: (primary) 2CH3O2 ---> 2CH3O + O2 (1a); 2CH3O2 ---> CH3OH + CH2O + O2 (1b); 2CH3O2 ---> CH3O2CH3 + O2 (1c); (secondary) CH3O + O2 ---> CH2O + HO2 (5); CH3O2 + HO2 ---> CH3O2H + O2 (6).The relative rate costants for reactions 1a-c were determined to be k1a:k1b:k1c = 0.32 : 0.60 : 0. 08, respectively.
- Niki, H.,Maker, P. D.,Savage, C. M.,Breitenbach, L. P.
-
p. 877 - 881
(2007/10/02)
-
- Kinetics Studies of Reactions of the CH3O2 with NO, NO2, and CH3O2 at 298 K
-
The flash photolysis/ultraviolet absorption technique was used to measure the rate constants for the reactions CH3O2 + NO -> CH3O + NO2 (1), CH3O2 + NO2 + M -> CH3O2NO2 + M (2), and CH3O3 +CH3O2 -> products (3) at 298 K over the pressure range 50-700 torr.Values for k1 and k3 were determined to be (7.1+/-1.4)E-12 cm3 molecule-1 s-1 and (3.6+/-0.7)E-13 cm3 molecule-1 s-1, respectively, where k3 is defined by the relation -d/dt=2k32; k2 was found to vary strongly with pressure, indicating that the reaction occurs primarily by addition and is in the falloff region between second third-order kinetics.Experimentally determined parameters describing the shape of the falloff curve for k2 were in reasonable agreement with those obtained by using theoretical methods developed by Troe and co-workers.An upper limit of 7E-18 cm3 molecule-1 s-1 was determined for the rate constant for the reaction CH3O2 + CO -> products.
- Sander, S. P.,Watson, R. T.
-
p. 1664 - 1674
(2007/10/02)
-