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Amine-functionalized material has gained attention as a promising solid sorbent for CO2 capture. To obtain a high concentration of CO2 for storage, the thermal regeneration temperature of supported amine sorbents should be higher than 135 °C under pure CO2. The thermal stability of solid amine sorbents will become a problem of significance. This study investigated the thermal stability of supported amine sorbents at 140 °C from the perspective of amine types and reactors, with a focus on how to improve the thermal stability of solid amine sorbents. Supported amine sorbents were prepared by impregnating polyethylenimine (PEI) and tetraethylenepentamine (TEPA) of different molecular weights on silica particles. The thermal stability of these amine-functionalized silica particles was investigated as a function of temperature and molecular weight in a thermogravimetric analyzer (TGA) and in a single-fluidized-bed reactor. An important finding was that the supported amine sorbents exhibited much higher thermal stabilities in a single-fluidized-bed reactor than in a TGA for long-term operation (100 h) at 140 °C, because the evaporation of the amines could be greatly inhibited in the fluidized-bed reactor because of the presence of amine vapor in the gas phase. Based on this finding, a simple and effective method of inhibiting amine evaporation was proposed and demonstrated. Furthermore, continuous CO2 capture was demonstrated using PEI-impregnated silica particles in a laboratory-scale dual-fluidized-bed reactor (DFBR). The CO2 capture efficiency was approximately 80% in the absorber during 2 h of operation, and the sorbent still maintained good stability and performance.

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Formaldehyde (HCHO) pollution is a scientific problem of general concern and has aroused wide attention. In this work, a fluorometric method for sensitive detection of formaldehyde was developed based on the oxidase-mimicking activity of MnO2 nanosheets in the presence of o-phenylenediamine (OPD). The MnO2 nanosheets were prepared by the bottom-up approach using manganese salt as the precursor, followed by the exfoliation with bovine serum albumin. The as-prepared MnO2 nanosheets displayed excellent oxidase-mimicking activity, and can be used as the nanoplatform for sensing in fluorometric analysis. OPD was used as a typical substrate because MnO2 nanosheets can catalyze the oxidation of OPD to generate yellow 2,3-diaminophenazine (DAP), which can emit bright yellow fluorescence at the wavelength of 560 nm. While in the presence of formaldehyde, the fluorescence was greatly quenched because formaldehyde can react with OPD to form Schiff bases that decreased the oxidation reaction of OPD to DAP. The main mechanism and the selectivity of the platform were studied. As a result, formaldehyde can be sensitively detected in a wide linear range of 0.8–100 μM with the detection limit as low as 6.2 × 10–8 M. The platform can be used for the detection of formaldehyde in air, beer, and various food samples with good performance. This work not only expands the application of MnO2 nanosheets in fluorescence sensing, but also provides a sensitive and selective method for the detection of formaldehyde in various samples via a new mechanism.

Novel high‐entropy carbide ceramics (HEC) containing rare earth metals, namely (Ti, Zr, Hf, Ta, La, Y)C, (Ti, Zr, Hf, Ta, Nb, La, Y)C, and (Ti, Zr, Hf, Ta, Nb, Mo, W, La)C were prepared with single‐phase structure by polymer precursor method. Controlled co‐hydrolysis and polycondensation of equiatomic metal‐containing monomers were conducted successively, followed by blending allyl‐functional novolac resin as carbon source, and the polymer precursors were obtained as clear viscous liquid solutions. The single‐phase formation possibility was theoretically analyzed from the aspects of size‐effect parameter δ of the designed compositions. All as‐obtained ceramics possessed single face‐centered‐cubic structure of metal carbides and high‐compositional uniformity from nanoscale to microscale. The (Ti, Zr, Hf, Ta, Nb, Mo, W, La)C ceramic powder pyrolyzed at 1800°C exhibited low‐oxygen impurity content of 1.2 wt%. Thus, multicomponent high‐entropy carbide nanoceramics with over five metal elements containing even rare earth element were firstly synthesized and characterized.

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