Izabela Majchrzak-Kucęba

Assessment of the sorption capacity and regeneration of carbon dioxide sorbents using thermogravimetric methods

Adsorption methods using solid sorbents are an alternative to the absorption technology in the processes of purification gases from carbon dioxide. There is a need to rapidly assess the suitability of sorbents for use it in PSA, TSA, or VPSA installations. Important parameters which determine the quality of the sorbent are the sorption capacity of sorbent, selectivity to CO2 and the possibility of regeneration. This paper presents the results of sorption/desorption of CO2 study on the impregnated porous materials using thermogravimetric methods. Thermogravimetry allows for rapid assessment of sorption capacity and regeneration of the sorbents. Specially selected temperature program allowed to determine the sorption capacity of sorbents depending on the concentration of CO2 in the gas mixture and temperature. Degree of sorbent purification was determined in desorption process.

Thermogravimetry applied to characterization of fly ash-based MCM-41 mesoporous materials

The thermogravimetry (TG) was used for characterization of the fly ash (FA)-based MCM-41 mesoporous materials. MCM-41 mesoporous materials were synthesized using silica extracts from different FA. The synthesis of MCM-41 from FA was carried out by the hydrothermal method using the supernatants of coal FA (in the form of sodium silicate) and cationic cetyltrimethylammonium bromide (CTAB) surfactants as the structure-directing agents. On the basis of the data obtained from the TG analysis, thermal behaviour of FA-based MCM-41 mesoporous materials was assessed. This study has established the range of temperatures corresponding to the desorption of water, decomposition of the surfactant and condensation of silanol, thereby making the overall quality assessment of FA-based MCM-41 mesoporous materials.

A simple thermogravimetric method for the evaluation of the degree of fly ash conversion into zeolite material

The thermogravimetry was used for the evaluation of degree of conversion of fly ash into zeolite material alongside the CEC and XRD methods being currently proposed for this purpose. The present work proposes the calculation of the thermogravimetric fly ash-to-zeolite conversion factor, CFTGA, based on the comparison of the mass loss of the commercial zeolite (standard) occurred during dehydration with that of the fly ash-derived zeolite. This mass loss is characteristic of a specific zeolite type, and the corresponding zeolite water content in the sample of zeolites indicates their degree of crystallinity and zeolite phase content. The use of the TGA method for the indirect determination of the fly ash-to-zeolite conversion factor would be preferable owing to its “speed” compared to other methods proposed for this purpose, as well as the capability to use a consistent procedure. Because of its short CFTGA determination procedure, the thermogravimetric method can be used for the control and determination of the quality of fly ash-derived zeolite in an industrial plant.

Regeneration performance of metal–organic frameworks

The increasing attractiveness of the adsorption methods of CO2 capturing from coal power plant flue gas, which can be observed in recent years, is linked directly with the appearance and development of new, efficient CO2 adsorbents. The success of an adsorbent depends on the development of the material that, under flue gas temperature conditions, will have high sorption capacity and selectivity for CO2. At the same time, the ease of regeneration and the usable lifetime of the adsorbent are of key importance. The paper presents the potential of metal–organic frameworks (MOFs) for VPSA method for flue gas CO2 capture. In this study, the thermogravimetric test has been used to screen two kind of MOFs [CuBTC, MIL-53(Al)] and identification of promising materials for CO2 capture. The examination of the sorption capacity, stability and regeneration performance of metal–organic frameworks was carried out using a Mettler TGA/SDTA 851e thermobalance and TG-Vacuum system. The studies of adsorption/desorption on the MOFs showed complete desorption of CO2, which confirmed the reversible nature of the process and the ability to use in multiple cycles in VPSA unit.