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Production of fly ash zeolites may be an attractive method for the utilization of solid wastes from the energy sector. Different methods of synthesis often yield a variety of zeolite types, thereby affecting the properties of the resulting materials. The attention paid to carbon dioxide emission reduction technologies fully justifies the study of the sorption behaviours of fly ash zeolites synthesized by different methods. This work investigates the sorption properties of fly ash zeolites synthesized with different methods using CO 2. Sorption capacity and adsorption isotherms were determined following the volumetric method and textural parameters were resolved according to the Dubinin-Astakhov (DA) method. The CO 2 sorption capacity was in the range 0.24-4.16 mmol/g. The relationships between structure and sorption behaviour were studied for each synthesis method. Some strong similarities between commercial zeolites and fly ash zeolites were found. The mechanism for sorption was proved to be physisorption which is fully reversible under selected conditions. The observed trends were used to identify the best sorbent. It is believed that increasing the amount of CO 2 caused by anthropogenic emission (recently observed to exceed the 400 ppm) is leading to global climate change. Currently, many political and ecological actions are aimed at limiting CO 2 emissions into the atmosphere. Difficulty avoiding emissions in many sectors fully justifies the efforts made to capture carbon dioxide. The most common method is based on the utilization of liquid amines for the removal of CO 2 from flue gases. However, this process has some drawbacks due to amine degradation leading to low CO 2 capture efficiency, high regeneration energy requirements and corrosive effects on separation equipment units 1. Therefore, exploration of differentiated materials for CO 2 capture is needed. One possibility is the use of technologies based on adsorption processes. Adsorbents need to be cost-effective (low cost raw material), have low heat capacity, fast kinetics, high CO 2 adsorption capacity and selectivity, and thermal, chemical and mechanical stability under extensive cycling 2. The most interesting adsorbents include activated carbons, zeolites and MOFs. MOFs are currently of great importance for CO 2 capture as they have high microporosity, unlimited chemical adjustability and surface functionality compared to conventional porous zeolites and activated carbon. Although these adsorbents work well in CCS technologies, they may not be sufficient in post-combustion processes due to very high temperatures. Additionally, MOFs are extremely expensive relative to zeolites and activated carbon; the price is estimated to be approximately $130-200/kg 3. Activated carbon is one of the most widely used solid adsorbents for the capture of CO 2. This is due to its microporous character, adequate pore size distribution, low cost and easy regeneration. However, activated carbon CO 2 /N 2 selectivity is relatively low. For the purpose of adjusting the p...

Synthesis of zeolites from fly ash is an ecologically justified process aimed at the transformation of energy sector waste – fly ash into microcrystalline zeolites of broad possible application field. In this study, the synthesis of zeolites from fly ash by using a modified two-step synthesis was presented. The aim of such a planned experiment was to use the waste solutions from previous synthesis, in such a way that minimalization of negative influence of post-synthesis wastes on environment was possible. Received materials were tested for its sulfur dioxide sorption capacity, indicating its future possible application to capture SO2 from exhaust gases.

Abstract. The aim of the experiment was modifying raw fly ash through the demagnetisation process and determining its influence on the efficiency of the synthesis of zeolite materials out of fly ash. A series of experiments have been performed on modified samples and, for the purpose of verification, on non-modified fly ash. No direct correlation has been confirmed in relation to synthesis efficiency as well as the type of obtained zeolite material. The research results indicate that the composition of fly ash determines the type of the zeolitic phases obtained. Based on the analysis of experimental data, it was found that the demagnetisation process allows to obtain additional zeolite phases, while there is no direct impact of the process used on the increase of synthesis reaction efficiency.

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