Due to their complex chemical structure, identification and characterization of asphaltenes remain a big challenge for researchers in the oil industry. In the current contribution, solution-state two-dimensional (2D) nuclear magnetic resonance (NMR) spectra of the asphaltenes, obtained from either heavy or light crude oil samples, provide information on the chemical structures of asphaltenes at the molecular level. Two-dimensional 1H–13C heteronuclear NMR measurements are particularly useful for differentiating among several structural environments whose signals overlap in the one-dimensional 13C spectra. Both, 2D 1H–13C heteronuclear and 1H–1H homonuclear NMR spectra indicate short- and long-range interactions between different functional groups of the asphaltene samples, revealing even “bay”- and “fjord”-type structures. Based on the NMR correlations between different protons and carbons with different chemical environments, we propose various chemical structures (polyaromatic cores with aliphatic chains, porphyrin derivatives, organic salts). Furthermore, through molecular dynamics simulations, we have obtained Hildebrand solubility parameters of different asphaltene solvents and of two experimental recovered asphaltene structures. Our calculated solubilities are consistent with previous experimental and simulation works.

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The coconut shell-based activated carbon (AC) surface was effectively anchored with amine moieties with acid treatment followed by tetraethylenepentamine (TEPA) anchoring. The activated carbon surface enhanced with basicity is likely to increase the sorbent properties towards CO 2 adsorption. The AC surface was modified by varying TEPA concentrations. After amine doping, significant loss in textural property indicates their occupation inside the pores and surfaces. Further, the samples were thermally activated to retrieve the textural properties. The physicochemical properties of modified carbon were characterized using BET, TPD, FT-IR, Raman spectroscopy and elemental composition. The amine-modified and thermally activated carbons were tested for CO 2 adsorption up to 25 bar at 25°C. The acid-base properties of N-doped carbons were evaluated using isopropanol as a model test reaction at atmospheric pressure. The IPA reaction products of acetone and propene were quantified for their acid-base nature and correlated to CO 2 adsorption capacities. The CO 2 adsorption capacity increases by tailoring synergistic properties between surface basicity and micropores. Hence, 20 % TEPA-derived nitrogen-enriched carbon reveals a higher yield of acetone 73 %, which in turn enhanced CO 2 adsorption capacity of 9.9 mmol/g, and it is found to be a suitable applicant for CO 2 capture.