THE MECHANISM OF OXIDATION BY HYDROGEN ATOMS IN AQUEOUS SOLUTION. I. MASS TRANSFER AND VELOCITY CONSTANTS

1961 ◽  
Vol 65 (6) ◽  
pp. 956-960 ◽  
Author(s):  
Gideon Czapski ◽  
Joshua Jortner ◽  
Gabriel Stein
Keyword(s):  
Aqueous Solution ◽  
Mass Transfer ◽  
Hydrogen Atoms ◽  
Mechanism Of Oxidation

Study of aerobic oxidation of phenyl PtII complexes (dpms)PtIIPh(L) (dpms = di(2-pyridyl)methanesulfonate; L = water, methanol, or aniline)

2009 ◽  
Vol 87 (1) ◽  
pp. 110-120 ◽  
Author(s):  
Julia R Khusnutdinova ◽  
Peter Y Zavalij ◽  
Andrei N Vedernikov
Keyword(s):  
Aqueous Solution ◽  
Aerobic Oxidation ◽  
Reductive Elimination ◽  
High Yield ◽  
Ambient Conditions ◽  
Activation Barriers ◽  
Methanol Solutions ◽  
Anionic Species ◽  
Mechanism Of Oxidation ◽  
Solution Mechanism

Oxidation of phenyl PtII complexes K[(dpms)PtIIPh2], 1, (dpms)PtIIPh(MeOH), 2, (dpms)PtIIPh(OH2), 3, and methyl PtII complex (dpms)PtIIMe(NH2Ph), 6, with O2 in aqueous or methanol solutions under ambient conditions leads to corresponding (dpms)PtIVR(X)OH complexes (R = X = Ph, 7; R = Ph, X = OH, 8; R = Ph, X = OMe, 9; R = Me, X = NHPh; 11; dpms = di(2-pyridyl)methanesulfonate). Complexes 7–9 could be isolated in high yield. Complex 11 as well as its phenyl analogue (dpms)PtIVPh(NHPh)OH, 10 can be prepared in high yield by oxidation of corresponding (dpms)PtIIR(NH2Ph) with H2O2 in methanol. Phenyl PtII complexes (dpms)PtIIPh(HX) derived from HX = aniline and DMSO, 4 and 5, respectively, are inert toward O2. The rate of oxidation of 1–5 with O2 decreases in the order 1 > 3 ~ 2 » 4, and 5 is unreactive. Methyl analogues are significantly more reactive compared with their phenyl counterparts. Proposed mechanism of oxidation with O2 includes formation of anionic species (dpms)PtIIR(X)– responsible for reaction with dioxygen. Attempts at C–O and C–N reductive elimination from phenyl PtIV complexes 7–10 do not lead to phenyl derivatives PhX at 80–100 °C, consistent with the results of the DFT estimates of corresponding activation barriers, ΔG0 exceeding 28 kcal/mol.Key words: platinum phenyl complexes, oxidation, dioxygen, aqueous solution, mechanism.

scholarly journals Designing a Mesoporous Zeolite Catalyst for Products Optimizing in n-Decane Hydrocraking

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 766 ◽  
Author(s):  
Li Tan ◽  
Xiaoyu Guo ◽  
Xinhua Gao ◽  
Noritatsu Tsubaki
Keyword(s):  
Mass Transfer ◽  
Active Sites ◽  
Zeolite Catalyst ◽  
Catalytic Performance ◽  
Hydrogen Spillover ◽  
Mesoporous Zeolite ◽  
Mesoporous Catalyst ◽  
Hydrogen Atoms ◽  
Effect Factors ◽  
And Diffusion

Mesoporous ZSM-5 zeolite is developed to enhance the catalytic performance in a hydrocracking reaction. The generated mesopores and mesoporous channels in the new catalyst supply more opportunities for reactant accessing the active sites according to the better mass transfer and diffusion. Meanwhile, the acidity of the mesoporous catalyst is also weakened because of the removal of Si and Al species from its MFI structure, which makes the products distribution drift to more valued chemicals such as olefins. In the modified mesoporous ZSM-5 zeolites via different metallic promoters, the olefins’ selectivity increases as the alkalinity of the catalyst increases. The reason for this is that the formed olefins will be further hydrogenated into corresponding alkanes immediately over the extremely acidic zeolite catalyst. Hence, the moderate alkalinity will limit this process, while at the same time the remaining olefins products will too. Furthermore, the Pd-based mesoporous ZSM-5 zeolite shows an excellent n-decane conversion and high propane selectivity due to the occurrence of hydrogen spillover via the Pd promoter. The phenomenon of hydrogen spillover supplies more chemisorbed sites of hydrogen atoms for hydrocracking and hydrogenating in this reaction. In short, this study explores the important effect factors in n-decane hydrocracking reaction activity and products distribution. It also shows a potential for the further industrial application of petroleum-derived fuel hydrocracking according to the optimized products distribution under metallic promoted mesoporous zeolite.

pK a of the hydrazinium ion and the reaction of hydrogen atoms with hydrazine in aqueous solution

1996 ◽  
Vol 92 (14) ◽  
pp. 2541 ◽  
Author(s):  
Stephen P. Mezyk ◽  
Miyoko Tateishi ◽  
Roy MacFarlane ◽  
David M. Bartels
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atoms
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