Mesoporous zeolite-chitosan composite for enhanced capture and catalytic activity in chemical fixation of CO2.

Carbon dioxide is one of the greenhouse gases whose increasing concentration in the atmosphere can cause severe problems to both human health and wildlife. A simple ecofriendly procedure was developed to prepare zeolite-chitosan (ZY-CS) composite using solvent exchange followed by calcination for adsorption and chemical fixation of CO2. The as synthesized ZY-CS composite along with zeolite and chitosan were characterized by attenuated total reflection infrared, X-ray diffraction, thermogravimetric, scanning electron microscopy, high-resolution transmission electron microscopy and nitrogen adsorption-desorption isotherms studies. The ZY-CS composite showed enhanced CO2 adsorption capacity compared with pure zeolite and chitosan. The composites also exhibited significant catalytic activity in the chemical fixation of CO2 into cyclic carbonates. This work is foreshadowing the prospect of ZY-CS composite in enhanced capture and catalytic activity in chemical fixation of CO2 for environmental applications.

Carbon dioxide adsorption and cycloaddition reaction of epoxides using chitosan-graphene oxide nanocomposite as a catalyst.

One of today's major challenges is to provide green materials for a cleaner environment. We have conducted studies on carbon dioxide (CO2) adsorption and conversion to valuable products by an ecofriendly approach based in chitosan/graphene oxide (CSGO) nanocomposite film. Rheological behavior indicates that the CSGO has a better solvation property than the pure chitosan. An adsorption capacity of 1.0152mmolCO2/g of CSGO nanocomposite at 4.6bar was observed. The catalytic behavior of the CSGO nanocomposite in the presence of tetra-n-butylammonium iodide (n-Bu4NI) as co-catalyst was evaluated for the cycloaddition of CO2 to epoxides, to give cyclic carbonates, in the absence of any solvent. These results strongly suggest that the CSGO nanocomposite may open new vistas towards the development of ecofriendly material for catalytic conversion and adsorption of CO2 on industrial scale.

Carbon dioxide capture and conversion by an environmentally friendly chitosan based meso-tetrakis(4-sulfonatophenyl) porphyrin.

We have demonstrated the facile, environmentally friendly and sustainable preparation of chitosan based meso-tetrakis(4-sulfonatophenyl)porphyrin (CS-TPPS) for adsorption and catalytic conversion of carbon-dioxide (CO2). The ionic complexation between chitosan (CS) and meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) is confirmed by ultraviolet-visible (UV-vis) and Fourier transform infrared spectroscopy (FTIR). Physical properties, such as crystallinity, thermal stability, surface morphology and porosity were analyzed by X-ray diffraction, thermal analysis, scanning electron microscopy and BET isotherm analysis. CS-TPPS shows adsorption capacity of 0.9mmol CO2/g compared to the adsorption capacity of 0.05mmol CO2/g of pure chitosan and an adsorption capacity of 0.2mmol CO2/g of pure TPPS. It also exhibits higher conversion of CO2 and propylene oxide into cyclic carbonate (66%), compared to pure chitosan (31%). The results are encouraging, and may open new perspectives for the use of biopolymers involving porphyrin based material in environmental and industrial applications.