Síntese de zeólitas a partir de cinzas de carvão para captura de dióxido de carbono

Abstract

The coal fly ash (CFA) is one of the main waste generated during the burning of fossil fuel. The annual global production of CFA is about 800 million tons and is increasing more and more. While a portion is recycled and reused in the construction area, much is still destined to landfills. This study aims to synthesize zeolites in two different scales employing for both CFA arising Thermoelectric Complex Jorge Lacerda, SC, in order to use them in carbon dioxide adsorption (CO2). For synthesis of zeolite was used hydrothermal process in two steps. The first step consisted mainly in the extraction of Si and Al contained in the CFA. The second step was to add an external source of Al in alkaline solution to hit the molar ratio and formation of zeolite of interest. The parameters time, temperature, Si/Al ratio and the reaction medium bench scale has been optimized for the scaling (5 times) was performed. The zeolitic material obtained was characterized using SEM-FEG, XRD, BET and NMR indicates the presence of zeolites X (major phase) and A. Under the conditions used was obtained on a smaller scale a mass of 5.5 g of zeolites of interest while with large scale it was possible to obtain a value of 7 times greater. Tests for adsorption/desorption of CO2 in the zeolitic material was pelleted using bentonite and PVA. The material was efficient in capture and CO2 adsorption selectivity both with He mixture (inert gas), as in admixture with other gases (CH4 and CO). Obtained CO2 adsorption capacities of 0.47 and 0.92 mmol.g-1 with the individual standard in a mixture of He, and with synthetic standard (CO, CH4 and CO2, balance in N2 ), respectively. The adsorbent material produced showed good regeneration, and easily to desorb the adsorbed CO2 both with and without heating, for three cycles of adsorption/desorption tested. The results of this study indicated that the synthesized zeolitic product (X and A) from CFA, has potential use for the adsorption of CO2 at different conditions.