Recent Findings on Fly Ash-Derived Zeolites Synthesis and Utilization According to the Circular Economy Concept

The synthesis and utilization of zeolites derived from fly ash (FA) gained significant attention years ago due to their potential to address environmental challenges and promote sustainable practices subscribing to the circular economy concept. This paper highlights the recent findings regarding the synthesis and utilization of zeolites derived from FA. It begins with a discussion about the recent challenges regarding industrial waste management and statistics regarding its availability on the global market with a special insight into the situation in Poland. The characteristics of FA obtained from various fuels were presented and the main differences were highlighted. Then, different methods used for the synthesis of zeolites from FA were discussed in small and pilot scales taking into consideration the main challenges and problems. The analytical methods used in porous materials synthesis verification and properties determination were described. The sorption properties of FA-derived zeolites were presented and discussed. Finally, the paper emphasizes the potential applications of fly ash-derived zeolites in different fields. Their importance as sustainable alternatives to conventional materials in industry, construction, agriculture, power, medicine, and other industrial sectors was analyzed

Chloride corrosion in biomass-fired boilers – Fe-O-Cl system thermodynamic analysis

The most common and easiest alternative technologies for conventional fossil fuel combustion are biomass combustion and co-combustion. However, high-chlorine fuels (Clar>0,2%) like: biomass, waste and high chlorine coals generate the risk of intensified corrosion process and a limited steel mechanical strength is observed. The paper presents a thermodynamic analysis of chloride-induced corrosion in the Fe-O-Cl system. The ranges of the metallic, oxide and chloride phase stability are determined within the temperature range T = 750-1000 K. Based on the parametric equations the equilibrium concentration of gaseous phase determined by Deacon reaction are presented. The effect of H2O concentration in the gaseous phase on high-temperature corrosion process and gaseous NaCl influence on NaFeO2 formation in the passive oxide scale layer (FeO/Fe3O4/Fe2O3) are discussed as well. The results are correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis is compared with assumptions of “active oxidation” model. The results may be used for experimental research prediction and a corrosion prevention in the industry

Chloride corrosion in biomass-fired boilers – Fe-O-Cl system thermodynamic analysis

The most common and easiest alternative technologies for conventional fossil fuel combustion are biomass combustion and co-combustion. However, high-chlorine fuels (Clar>0,2%) like: biomass, waste and high chlorine coals generate the risk of intensified corrosion process and a limited steel mechanical strength is observed. The paper presents a thermodynamic analysis of chloride-induced corrosion in the Fe-O-Cl system. The ranges of the metallic, oxide and chloride phase stability are determined within the temperature range T = 750-1000 K. Based on the parametric equations the equilibrium concentration of gaseous phase determined by Deacon reaction are presented. The effect of H2O concentration in the gaseous phase on high-temperature corrosion process and gaseous NaCl influence on NaFeO2 formation in the passive oxide scale layer (FeO/Fe3O4/Fe2O3) are discussed as well. The results are correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis is compared with assumptions of “active oxidation” model. The results may be used for experimental research prediction and a corrosion prevention in the industry

Methanation of carbon dioxide by hydrogen reduction – a thermodynamic analysis

The paper presents a thermodynamic analysis of the methanation of carbon dioxide by hydrogen reduction. Equilibrium gas phase composition was determined by means of parametric equations. Calculations were performed for the temperature range T = 500 – 700 K and the initial composition xCO20∈(0−1)${\rm{x}}_{C{O_2}}^0 \in (0 - 1)$. A crucial parameter for catalytic processes, carbon precipitation range [C]=f(T,xCO20)${\rm{x}}_{C{O_2}}^0 \in (0 - 1)$ was presented as a function of temperature and an initial gas phase CO2-H2 composition. The CO2 conversion efficiency and the methane yield in the process was determined. Obtained results may be used for experimental research prediction and in industrial pragmatic

A thermodynamic analysis of chloride corrosion in biomass-fired boilers for Fe-O-Cl-S system

The paper presents a thermodynamic analysis of chlorideinduced corrosion in the Fe-O-Cl-S system. The influence of steam concentration in the gas phase on chloride-induced corrosion process was presented. Based on the parametric equations the equilibrium concentration of the gas phase was determined. The effect of alkali metals chlorides in gas phase (Na,K)Cl on formation of (Na,K)FeO2 in the passive oxide scale layer (FeO/Fe3O4/Fe2O3) was analysed. Condensation of (Na,K)Cl vapors, formation of low-melting eutectic mixtures in deposits and consequences of this process on corrosion process were examined. Additionally, the role of SO2 in chlorination and oxidation process of steel in melted ash deposits was discussed as well. The results were correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis was compared with assumptions of an “active oxidation” model. The results may be used for experimental research planning and a corrosion process prevention in the industry

Methanation of carbon dioxide by hydrogen reduction – a thermodynamic analysis

The paper presents a thermodynamic analysis of the methanation of carbon dioxide by hydrogen reduction. Equilibrium gas phase composition was determined by means of parametric equations. Calculations were performed for the temperature range T = 500 – 700 K and the initial composition ${\rm{x}}_{C{O_2}}^0 \in (0 - 1)$. A crucial parameter for catalytic processes, carbon precipitation range ${\rm{x}}_{C{O_2}}^0 \in (0 - 1)$ was presented as a function of temperature and an initial gas phase CO2-H2 composition. The CO2 conversion efficiency and the methane yield in the process was determined. Obtained results may be used for experimental research prediction and in industrial pragmatic

A thermodynamic analysis of chloride corrosion in biomass-fired boilers for Fe-O-Cl-S system

The paper presents a thermodynamic analysis of chlorideinduced corrosion in the Fe-O-Cl-S system. The influence of steam concentration in the gas phase on chloride-induced corrosion process was presented. Based on the parametric equations the equilibrium concentration of the gas phase was determined. The effect of alkali metals chlorides in gas phase (Na,K)Cl on formation of (Na,K)FeO2 in the passive oxide scale layer (FeO/Fe3O4/Fe2O3) was analysed. Condensation of (Na,K)Cl vapors, formation of low-melting eutectic mixtures in deposits and consequences of this process on corrosion process were examined. Additionally, the role of SO2 in chlorination and oxidation process of steel in melted ash deposits was discussed as well. The results were correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis was compared with assumptions of an “active oxidation” model. The results may be used for experimental research planning and a corrosion process prevention in the industry

Biomass Thermochemical Conversion via Pyrolysis with Integrated CO2 Capture

The presented work is focused on biomass thermochemical conversion with integrated CO2 capture. The main aim of this study was the in-depth investigation of the impact of pyrolysis temperature (500, 600 and 700 °C) and CaO sorbent addition on the chemical and physical properties of obtained char and syngas. Under the effect of the pyrolysis temperature, the properties of biomass chars were gradually changed, and this was confirmed by examination using thermal analysis, scanning electron microscopy, X-ray diffraction, and porosimetry methods. The chars were characterised by a noticeable carbon content (two times at 700 °C) resulting in a lower O/C ratio. The calculated combustion indexes indicated the better combustible properties of chars. In addition, structural morphology changes were observed. However, the increasing pyrolysis temperature resulted in changes of solid products; the differences of char properties were not significant in the range of 500 to 700 °C. Syngas was analysed using a gas chromatograph. The following main components were identified: CO, CO2, CH4, H2 and C2H4, C2H6, C3H6, C3H8. A significant impact of CaO on CO2 adsorption was found. The concentration of CO2 in syngas decreased with increased temperature, and the highest decrease occurred in the presence of CaO from above 60% to below 30% at 600 °C

Pyrolysis of Biomass Wastes into Carbon Materials

This study presents the results of the biomass pyrolysis process focusing on biochar production and its potential energetic (as solid fuel) and material (as adsorbent) applications. Three kinds of biomass waste were investigated: wheat straw, spent coffee grounds, and brewery grains. The pyrolysis process was carried out under nitrogen atmosphere at 400 and 500 °C (residence time of 20 min). A significant increase in the carbon content was observed in the biochars, e.g., from 45% to 73% (at 400 °C) and 77% (at 500 °C) for spent coffee grounds. In addition, the structure and morphology were investigated using scanning electron microscopy. Thermal properties were studied using a simultaneous thermal analysis under an oxidising atmosphere. The chemical activation was completed using KOH. The sorption properties of the obtained biochars were tested using chromium ion (Cr3+) adsorption from liquid solution. The specific surface area and average pore diameter of each sample were determined using the BET method. Finally, it was found that selected biochars can be applied as adsorbent or a fuel. In detail, brewery grains-activated carbon had the highest surface area, wheat straw-activated carbon adsorbed the highest amount of Cr3+, and wheat straw chars presented the best combustion properties