Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Highly active and stable CuxFey/AC-H catalysts with CuFe2O4 for NO reduction by CO in the presence of H2O and SO2 under regeneration gas
No full textFor industrial flue gas, the synergistic removal of NOx and CO pollutants is in high demand but still has not been realized due to the presence of O-2. We propose firstly that activated carbon regeneration gas provides suitable O-2-free conditions for NO reduction by CO, but high contents of 5% SO2 and 5% H2O affect the catalyst activity. Here, we report a bimetallic modified catalyst CuxFey/AC-H that exhibits high catalytic activity under the abovementioned conditions due to the high amount of CuFe2O4. By regulating the Cu/Fe ratio, the formation of CuFe2O4 active sites is promoted, which improves the redox properties, adsorption and activation capacity of NO, the ratio of high valence metal, and content of synergistic oxygen vacancies. Based on in situ DRIFTS and fixed-bed FTIR/MS combined platform, it was found that the side reaction of H2O with the intermediate of-NCO forms NH3 above 250 degrees C and with CO forms H-2 above 400 degrees C center dot NH3 and H-2 provide additional reaction pathways of Fast-SCR and H-2-SCR to significantly improve the reaction activity with 92.0% of NO conversion at 450 degrees C and 108,000 mL g(-1)h(-1) on Cu2Fe2/AC-H. According to DFT calculations, CuFe2O4 active sites provide the high binding energy of sulfation, and then Cu2Fe2/AC-H demonstrates excellent activity and long-term stability with 72.2% of NO conversion at high contents of SO2 and H2O for 48 h. And CuxFey/AC-H provides great potential prospects for the application of NO reduction by CO under activated carbon regeneration gas
Confined Space and Heterojunction Dual Modulation of ZnO/ZnS for Boosting Photocatalytic CO2 Reduction
No full textThe reduction of CO2 to chemical fuel driven by solar energy can not only meet the growing demand for renewable energy, but also balance the carbon cycle in nature. However, the current photocatalysts have low CO2 conversion due to their poor light capture ability, narrow light response range, and high recombination probability of photogenerated carriers. Herein, a heterogeneous photocatalyst of hollow structured ZnO/ZnS decorated with Pt nanoparticles is synthesized through the hydrothermal process and photodeposition method, showing excellent photocatalytic activity for CO2 reduction in long-time stability and approximate to 100% CO selectivity, which can mainly contribute to natural enhanced light-capture ability of the hollow confined space due to multiple reflection and scattering of light in the cavity, thus improving separation efficiency of photogenerated charge carriers due to the type II junction constructed between ZnO and ZnS and the additional reaction active sites after decorating Pt nanoparticles in the surface of the hollow structure
Recovery of rare earths, lithium, and fluorine from rare earth molten salt electrolytic slag by mineral phase reconstruction combined with vacuum distillation
No full textA novel green method for the recovery of rare earths (REs), fluorine (F), and lithium (Li) from rare earth molten salt electrolytic slag (REMSES) was proposed and demonstrated by mineral phase reconstruction combined with vacuum distillation. Kinetic analysis revealed that the roasting process was controlled by the chemical interface reaction. Under the optimized conditions (roasting temperature of 600 degrees C, LiOH center dot H2O dosage coefficient of 1.1 times, and roasting time of 4 h), NdF3 and NdOF in the slag were almost completely converted to LiF and Ca2Nd8(SiO(4))6O(2). The removal rate of F and recovery rate of LiF were 99.98 % and 98.96 %, respectively, at 1100 degrees C and 10 Pa for 1 h, indicating that F could be effectively removed by vacuum distillation. The F and Li were recovered as LiF with a purity of 99.8 wt%, which could then be recycled in the molten salt electrolysis process for the preparation of RE metals. The leaching rate of TREO from distillation residue was 99.27 % using hydrochloric acid. This process not only successfully achieved the green and efficient recovery of REs, Li, and F from REMSES, but also eliminated environmental pollution caused by the release of F
Snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres with enhanced triethylamine sensing properties
No full textHerein, the snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres, in which two-dimensional (2D) g-C3N4 nanolayers were loaded onto the surface of ZnFe2O4 hollow microspheres, were constructed by a simple solid phase reaction. The effect of the g-C3N4 concentration on the structure, morphology and gas-sensing performance of the g-C3N4/ZnFe2O4 composites had been explored. On the basis of gas sensitivity test results, the composites owned lower working temperature (160 degrees C) and better selectivity toward TEA in comparison with pure ZnFe2O4. Notably, the sensor based on the g-C3N4/ZnFe2O4-15 hollow microspheres (adding 15 ml of g-C3N4 aqueous solution) exhibited outstanding sensing properties, including superior response (18.3) toward 100 ppm TEA at optimum work temperature of 160 degrees C, speedy response-recovery time (33, 30 s) and outstanding stability. And the sensor maintained high response of 4.3 to low concentration TEA (5 ppm). The improved gas-sensing performance of the composites could be attributed to the porous ZnFe2O4 hollow microspheres loaded by 2D g-C3N4 nanolayers with large specific surface area and the heterostructure formed between them. Hence, a potential application of the g-C3N4/ZnFe2O4 microspheres might be achieved in detecting TEA at a low optimum work temperature