CO2 capture systems based on saccharides and organic superbases?

Faraday Discussions Pub Date: 2015-06-29 DOI: 10.1039/C5FD00044K

Abstract

In this report, novel systems, based on highly abundant saccharides, D-mannose, D-glucose, β-cyclodextrin, alginic acid and mannitol, in combination with an organic superbase, tetramethylguanidine (TMG) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), are studied for carbon dioxide capture. With D-mannose and D-glucose, several ratios of equivalents of alcohol groups of saccharide?:?superbase were tested: 1, 0.625, 0.5 and 0.25. High wt% values of CO2 uptake were obtained with TMG-based systems. However, TMG itself can react directly with CO2, and, in the presence of D-mannose, competition between carbonate and carbamate based products was established. In order to circumvent this competition and obtain exclusively the carbonate-based product, DBU was used instead as an organic superbase. In the D-mannose series the highest result was obtained with a D-mannose?:?DBU ratio eq. = 0.625 (13.9% CO2 uptake, 3.3/5 alcohol groups converted into carbonates). A more effective stirring system, designed to overcome the high viscosity of the products, allowed the use of a D-glucose?:?DBU = 1?:?1 ratio with 11.5 wt% of CO2 uptake and 2.47/5 alcohol groups converted into carbonates. Additionally a DSC thermal study was performed in order to study the stability/reversibility of the CO2 loaded systems.

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