Heterogeneous-homogeneous reactions involving free radicals in processes of total catalytic oxidation

Homogeneous Oxidation Reactions of Propanediols at Low Temperatures

“…[15] Glycerol did not react with O 2 at the temperatures of this study (430-570 K), as also reported in previous studies. [16] Thus, the homogeneous pathways reported here appear to reflect a reactivity in radical-mediated pathways that appears to be unique to diols among C 3 oxygenates.…”

Thermal and Photoreactivity of TiO2at the Gas−Solid Interface with Aliphatic and Aromatic Aldehydes

“…Figure shows the series of EPR spectra obtained after adsorption of acetaldehyde onto rutile TiO 2 that was thermally reduced at 823 K in vacuo (Figure a). After exposure of the sample to 1 Torr of acetaldehyde at 100 K, there was an increase in the intensity of the signal at g = 2.0023 associated with medium-polarized electrons (Figure b), which is indicative of adsorbate contact with the TiO 2 surface. , The simultaneous decrease in intensity of the Ti 3+ resonance at g = 1.962 is caused by partial reoxidation of the TiO 2 by acetaldehyde. A minor peak at g = 1.922 is also observed and believed to arise from traces of a second bulk Ti 3+ center but will not be discussed further in this paper.…”

“…To detect radical formation at heterogeneous gas−solid interfaces, many techniques have been developed including matrix isolation from reactor gas streams and low temperature studies (4 K) of the interface. The former method has been successfully used to detect organic radicals (such as acyl and acyloxyl species) desorbing from catalyst surfaces, but suffers from the drawback that the EPR spectra of the matrix isolated species may contain little information regarding radical identity . Direct EPR detection of surface-bound radical ions on TiO 2 has been successful for simple inorganic species such as SO 2 and O 2 .…”

Heterogeneous–homogeneous interactions in catalytic microchannel reactors

“…Margolis and coworkers were among the first to establish their role in catalytic oxidation of hydrocarbons 1 and, since then, a large number of investigations have established the importance of coupled heterogeneoushomogeneous reactions in a wide variety of reactions systems, most notably in catalytic combustion, [2][3][4] partial oxidation of small alkanes, [5][6][7] and oxidative coupling of methane. 8,9 All of these reactions systems have very high reaction temperatures (T Ͼ 700°C) as a common characteristic.…”