Investigation of the Interaction of Carbon Dioxide with Modified Functional Groups of Nanotubes

The article presents a theoretical study of the possibility of interaction of one of the most common substances in nature – carbon dioxide – with modified functional carboxyl and amine groups of carbon nanotubes and borocarbon nanotubes of the BC5 type. The article analyzes the results of the interaction and provides a comparative analysis of the efficiency of the sorption interaction of a nanosystem with a carbon dioxide molecule. The performed studies prove the implementation of a weak physical sorption interaction between a nanosystem consisting of a carbon nanotube, a boundary-modified amine group, and a carbon dioxide molecule. This allows us talking about a possible sensory interaction that will allow using such a complex to detect a micro amount of a substance-carbon dioxide. Based on this, it can be concluded that modified carbon nanotubes can be elements of sensors for determining the quality of indoor air, act as probes for cantilevers of atomic force microscopes and other devices. Recommendations are given for further use of the results as a basis for creating a highly sensitive new-generation sensor device for detecting micro-quantities of substances.

Experimental analysis of the CO2/CH4 Replacement Efficiency due to Sodium Chloride Presence in Natural Gas Hydrates Reservoirs

Nowadays natural gas hydrates represent a promising opportunity for counteracting several crucial issues of the 21th century. They are a valid answer to the continuously increasing energy demand, moved by the global population growth; moreover, considering their conformation and the possibility of using them for carbon dioxide permanently storage, gas hydrates may become a carbon neutral energy source, where for each methane molecule recovered, another carbon dioxide molecule is entrapped in solid form. Considering that the combustion of one methane molecule for energy production leads to the formation of one CO2 molecule, the hydrates exploitation can be considered a clean process in terms of impact on the climate change. This work shows how the presence of sodium chloride affects the CO2/CH4 replacement process into a gas hydrates reservoir. Replacement experimental results carried out in pure demineralised water were compared with the same values performed in a mixture of water and salt, having a concentration of 37 g/l. Some parameters of interest were discussed, such us methane hydrates formed before the replacement process, total amount of hydrates (composed by both species) reached at the end of the whole process, CO2 moles that formed hydrate, quantity of hydrate present before the replacement process which were actually involved in the CO2/CH4 exchange and carbon dioxide amount which led to the formation of new hydrates structures.

Kinetic study of carbon dioxide catalytic methanation over cobalt–nickel catalysts

Based on the data of the thermoprogrammed desorption and using mass-spectroscopic analysis of desorbed products and on the kinetic patterns of the methanation process for cobalt–nickel catalysts, we suggested a mechanism for the reaction which passes through forming intermediate formyl compounds: CHO*, HCOH*, and HCOOH*. Because of the high stability of the carbon dioxide molecule, the step of adding the first hydrogen atom is the limiting step. Such a mechanism is in good agreement with the proposed kinetic equations.

Cerium oxide as a catalyst for the ketonization of aldehydes: mechanistic insights and a convenient way to alkanes without the consumption of external hydrogen

The atom-efficient transformation of two aldehyde molecules into a linear alkane at the expense of one carbon dioxide molecule.

Strong-field-induced wave packet dynamics in carbon dioxide molecule

Temporal evolution of electronic and nuclear wave packets created in strong-field excitation of the carbon dioxide molecule is studied employing momentum-resolved ion spectroscopy and channel-selective Fourier analysis. Combining the data obtained with two different pump-probe set-ups, we observed signatures of vibrational dynamics in both, ionic and neutral states of the molecule. We consider far-off-resonance two-photon Raman scattering to be the most likely mechanism of vibrational excitation in the electronic ground state of the neutral CO2. Using the measured phase relation between the time-dependent yields of different fragmentation channels, which is consistent with the proposed mechanism, we suggest an intuitive picture of the underlying vibrational dynamics. For ionic states, we found signatures of both, electronic and vibrational excitations, which involve the ground and the first excited electronic states, depending on the particular final state of the fragmentation. While our results for ionic states are consistent with the recent observations by Erattupuzha et al. [J. Chem. Phys.144, 024306 (2016)], the neutral state contribution was not observed there, which we attribute to a larger bandwidth of the 8 fs pulses we used for this experiment. In a complementary measurement employing longer, 35 fs pulses in a 30 ps delay range, we study the influence of rotational excitation on our observables, and demonstrate how the coherent electronic wave packet created in the ground electronic state of the ion completely decays within 10 ps due to the coupling to rotational motion.