Thermodynamics and kinetics of gas and gas–solid reactions

Kinetics of CO2 Capture by Hydroquinone Clathrates

“…Finally, our conclusions agree with those of Lee et al (2011), who also found that the initial rate of formation of the HQ clathrates with pure CO 2 increases with temperature. Consequently, in the conditions of this study, increasing pressure and temperature significantly enhanced the enclathration kinetics, as observed in typical gas–solid reactions. − An increase in pressure effectively concentrates CO 2 molecules in the gas phase (and at the gas-solid interface) and enhances the probability of contact between CO 2 and the HQ surface. A temperature increase involves both a decrease of the density of the gas phase and the intensification of the degree of motion (i.e., thermal agitation) of the CO 2 molecules.…”

Techniques of Preparation of Thin Films: Catalytic Combustion

“…The results are unexpected, since it was considered that rougher Pt surfaces from nanoparticles are more active in CO oxidation as their low-coordinated sites bind both oxygen and CO stronger than the highly coordinated sites of smoother surfaces [187]. Nevertheless, NAP-XPS indicated more carbon accumulation on the 50 cycles Pt nanoparticles surface during the oxidation reaction, mostly due to CO disproportionation according to the Boudouard reaction (CO* + CO* → CO 2 + C*) [188]. Taking into account that atomic carbon acts as poison on the low-coordinated active sites for oxygen activation until it is possible to be replaced by oxygen at higher temperature, this behavior explains the higher reaction onset temperature of the Pt nanoparticles despite their expectedly more active surface, whereas the smoother 250 cycles Pt film presents less C poisoning with a lower reaction onset temperature.…”

Kinetics of interstitial uptake during gaseous carbo-oxidizing of titanium foils

“…If no equilibrium is achieved between foil and gas, as in a streaming gas, pO 2 and a C are in principle unknown, but are interdependent, because the temperature is the only adjustable parameter and dissociation of CO provides equal amounts of C and O to the surface. A gas mixture consisting of CO and CO 2 could be applied (Boudouard reaction), which would allow a controlled, albeit still interdependent, variation of pO 2 and a C by adjusting the ratio of CO and CO 2 [23]. Preliminary experiments using a gas mixture of 1 vol% CO 2 and 99 vol% CO at 1000 • C led to extensive oxidation; for this reason CO/CO 2 gas mixtures were not applied in the present study.…”