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Aluminium-stabilized calcium-based materials are currently an excellent solution for capturing CO 2 directly from industrial flue gas. However, there is still no report on the technology of low-cost and large-scale assembly of Ca 3 Al 2 O 6 and CaO. In this study, we innovatively put forward a silicon-assisted strategy to facilely synthesize high-purity Ca 3 Al 2 O 6 and evaluate its cyclic performance for stabilizing uptake CO 2 after assembly. With regard to the Si/Al ratio of 0.2, Ca 3 Al 2 O 6 was prepared selectively among 850–900 °C, with only 5.2% CaO residually. The introduction of silicon inhibited the formation of Ca 5 Al 6 O 14 by-products and the mechanism of silicon at the calcium-aluminum interface was also explained by systematic characterization. The Ca 3 Al 2 O 6 modified sorbent with simple assembly showed extremely high cycle stability improvement compared with the pure precipitated calcium carbonate derived CaO. These works provide technical guidance for the industrial scale-up of the rational design of Al-stabilized calcium-based adsorption materials. [ABSTRACT FROM AUTHOR]

Solid amine adsorption is considered to be the most promising technology for post-combustion CO 2 capture, but it still has drawbacks due to the high cost of supports and the easy occurrence of CO 2 -induced chemical deactivation. Herein, we propose a novel eco-friendly method for realizing efficient and stable solid amine adsorbents. A calcium silicate hydrate (CSH) support with a pore volume of 3.0 cm3 g−1 is synthesized from coal fly ash (CFA) with the pore-expanded assistance of azeotropic distillation, and then the PEI@CSH adsorbents are prepared by impregnation. The adsorption capacity of the prepared 60%PEI@CSH-0.1 adsorbent reaches 198 mg g−1 and exhibits an excellent cyclic stability, with an attenuation of only 1.9% after 10 cycles under ideal regeneration conditions. Even under realistic regeneration conditions, the CO 2 uptake remains at 103 mg g−1 after 10 cycles, which shows obvious advantages over that of commercial SiO 2 supports. By using FT-IR, solid-state NMR and DFT calculations, we found that the CSH support promotes the conversion of primary amines to secondary amines in PEI molecules, and thus effectively inhibits the inactivation induced by the formation of urea compounds. Therefore, the PEI@CSH adsorbents provide a low-cost and high-efficiency approach for both in-situ CFA utilization and CO 2 mitigation inside coal-fired power plants. [Display omitted] • PEI@CSH adsorbents showed excellent adsorption capacity and cyclic stability. • The surface chemical property of CSH led to the anti-urea PEI@CSH adsorbents. • Solid-phase NMR and DFT calculation were applied for clarifying anti-urea mechanism. • PEI@CSH adsorbents realized both in-situ CFA utilization and CO 2 mitigation. [ABSTRACT FROM AUTHOR]

[Display omitted] • An innovative manner was used in the co-pyrolysis for more CO 2 consumption. • CP CO2 evaluation was innovatively constructed and realized in the CO 2 -looping system. • More CO 2 entered into pyrolysis products by Ca-based additives for improving CP CO2. • CaO not only improved CP CO2 by 21.2% but also reduced the total HMs at 500 ℃. • Mechanism for CO 2 assisted Ca-based on CP CO2 with temperature was proposed. In this study, the CO 2 -looping system was firstly attempted to build for exploring the effect of calcium-based (Ca-based) additives on pyrolytic characteristics and products in co-pyrolysis of sewage sludge (SS) and biomass. Then, an innovation method for the consumption of CO 2 (CP CO2) evaluation was proposed and carried out in the CO 2 -looping system, in which it was evaluated based on the syngas volume and CO 2 proportion. The results revealed that the addition of CaO and Ca(OH) 2 could significantly improve CP CO2 by 21.2% in the co-pyrolysis of 500 ℃, while the CaCO 3 addition decreased the CP CO2 by 1.0%. Besides, the co-pyrolysis temperature more than 700 ℃ would play more significant role on the CP CO2 than the addition of Ca-based additives. Then the effect of Ca-based types on biochar characteristics was also identified accompanied by the bio-oil composition. Results showed that the CaO and Ca(OH) 2 additives not only increased biochar mass and pH, but also enhanced the dissolved organic carbon content and the variety of dissolved organic matter, and reduced the total HMs content. Meanwhile, it was 15 types of components that was identified in bio-oil by NIST mass spectral library, found that the intensity of heptadecanenitrile and estra-1,3,5(10)-trien-17 beta-ol was influenced by Ca-based additives. Moreover, the CaO and Ca(OH) 2 played important roles for improving the CP CO2 in the CO 2 -looping system, which was further verified by Fact Sage. Finally, the mechanism for the Ca-based additives on CP CO2 was proposed at different co-pyrolysis temperatures. These findings can widen paths for biochar application and development of CO 2 capture materials. [ABSTRACT FROM AUTHOR]