Synthesis of Zeolite-Templated Carbonaceous Materials Doped With Nitrogen for Carbon Dioxide Adsorption

摘要

Carbonaceous materials using natural zeolite (clinoptilolite) as a hard template were synthesized, varying the urea/glucose weight ratio from 0.2 to 0.4 as nitrogen/carbon precursors and preparation temperature 700 degrees C and 900 degrees C. The obtained carbons were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, organic elemental analysis, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption to determine their structural, morphological, and textural properties. The materials synthesized at 700 degrees C and 0.4 urea/glucose weight ratio presented the highest surface area and nitrogen content values (169 m(2) g(-1) and 5.85% w/w, respectively). Selected samples were evaluated in the CO2 capture process utilizing adsorption using volumetric equipment and a fixed bed. Results showed that nitrogen, particularly pyridine type functional groups, favors the adsorption of CO2. The experimental data were adjusted to the Langmuir isotherm model, achieving maximum adsorption capacities of 0.436 and 0.322 mol CO2 kg(-1) and 0.128 and 0.056 mol N-2 kg(-1) for the materials NC-700-0.4 and NC-700-0.2, respectively. A fixed bed mass transfer mathematical model was proposed and fitted to the experimental results of pure and binary mixtures in the material. Finally, the adsorption results were compared with commercial activated carbon. The prepared N-doped activated carbons presented 4.8 times higher selectivity to CO2 due to the higher density of basic species on the material surface.