Photochemical fixation of supercritical carbon dioxide: the production of a carboxylic acid from a polyaromatic hydrocarbon

Photochemical and acoustic interactions of biochar with CO2 and H2O: Applications in power generation and CO2 capture

“…Hydrogen content shown in Tables , suggest light alone induces 24% hydrogenation. Thus, the reductive photochemical CO 2 fixation mechanism proposed by Chateauneuf et al (Reaction R1 in Section ***I.A) could cause hydrogenation and a moderate (19%) increase in heating value. However, photo‐irradiation alone does not seem to induce exfoliation of GO and graphite clusters, chemisorption of CO 2 on biochar, or additional mineral leaching.…”

“…The notable increase in hydrogen content during the photochemical treatment suggests that the sample is hydrogenated during photochemical treatment, and Reaction R1 discussed in Section I.D may indeed have taken place during the photochemical treatment. In this process, TiO 2 in biochar, not an amine as used by Chateauneuf et al in Reaction R1, may have served as an electron donor, and water may have served as a hydrogen donor. The small changes in carbon and oxygen content and atomic C/O ratios during both treatments do not provide substantial indication of whether carbon is fixed on the biochar, or oxygen is removed from the biochar.…”

“…A carbon‐centered radical anion is the reaction intermediate induced by the lamp and the electron donor. Instead of using a liquid solvent, Chateauneuf et al used supercritical CO 2 in their reductive photocarboxylation experiments. The reaction equilibrium favors carboxylated product under high CO 2 pressure.…”

“…First, both biochar and coal‐derived chars contain stacks of graphite clusters that contain graphene and graphene oxide (GO) layers whose edge carbons are reactive and could serve as binding sites for CO 2 . Second, titanium dioxide in biochar is a known semiconductor; it could serve as the electron donor in photocatalytic reactions of aromatics and CO 2 such as those identified by Chateauneuf, et al Moreover, graphite is an electron conductor, which is likely to enhance the desired electron transfer. Third, using the phenol decomposition rate reported by Horn et al, the estimated decomposition of phenol at typical biochar preparation temperatures of 550°C, with a 10 min residence time, is about 4.2%.…”

Selective Free Radical Reactions using Supercritical Carbon Dioxide

“…For reaction of Mu with ET the product corresponds to Mu addition . There is no reaction between CO 2 and ethyl radical, which means CO 2 combined with simple alkenes could not be used as a feedstock in free radical chemistry . Figure displays the pressure dependence of rate constants for Mu + ET in CO 2 at T = 305 K. A general increase in the rate of addition is observed as pressure increases.…”