• CeO2 doping significantly improved low-temperature NH3-SCR activity on FeTiOx.• The crystallinity of FeTiOx was decreased dramatically after CeO2 doping.• Unique Ce-O-Fe structure in FeCe0.2TiOx accounted for its superior redox property.• Facile activation of NH3 to-NH2 on FeCe0.2TiOx promoted the DeNOx efficiency. FeTiOx has been recognized as an environmental-friendly and cost-effective catalyst for selective catalytic reduction (SCR) of NOx with NH3. Aimed at further improving the low-temperature DeNOx efficiency of FeTiOx catalyst, a simple strategy of CeO2 doping was proposed. The low-temperature (<250℃) NH3-SCR activity of FeTiOx catalyst could be dramatically enhanced by CeO2 doping, and the optimal composition of the catalyst was confirmed as FeCe0.2TiOx, which performed a NOx conversion of 90% at ca. 200℃. According to X-ray diffraction (XRD), Raman spectra and X-ray absorption fine structure spectroscopy (XAFS) analysis, FeCe0.2TiOx showed low crystallinity, with Fe and Ce species well mixed with each other. Based on the fitting results of extended X-ray absorption fine structure (EXAFS), a unique Ce-O-Fe structure was formed in FeCe0.2TiOx catalyst. The well improved specific surface area and the newly formed Ce-O-Fe structure dramatically contributed to the improvement of the redox property of FeCe0.2TiOx catalyst, which was well confirmed by H2-temperature-programmed reduction (H2-TPR) and in situ XAFS experiments. Such enhanced redox capability could benefit the activation of NO and NH3 at low temperatures for NOx removal. The detailed reaction mechanism study further suggested that the facile oxidative dehydrogenation of NH3 to highly reactive-NH2 played a key role in enhancing the low-temperature NH3-SCR performance of FeCe0.2TiOx catalyst. 相似文献
Incompatible polypropylene (PP) and polyethylene (PE) are difficult to separate in mixed recycling streams such as waste plastic packaging, which makes polyolefin mixtures unsuitable for high-quality products. In this work, based on the free radical branching reaction, a co-branching reaction of isotactic polypropylene (iPP) and high-density polyethylene (HDPE) blends was carried out in the presence of the peroxide, free radical regulator and multifunctional acrylate monomer, and a star-like long-chain branching (LCB) copolymer was obtained. The effect of in situ compatibilization on the structures and mechanical properties of iPP/HDPE was investigated, and the compatibilization mechanism was discussed. Results showed that the mechanical properties of the modified blends were largely improved, and efficient in-situ compatibilization of iPP and HDPE could be taken place in a wide process window. Moreover, the sizes of the dispersed phase in the modified blends were clearly decreased, and the interfacial thickness increased. Compared with the pure iPP/HDPE blend, the initial crystallization temperature of iPP in the modified iPP/HDPE blend was increased, and long branched chains of the LCB copolymers were physically entangled with the chemical identical homopolymers or even participated in the crystallization of iPP and HDPE. Thanks to the in situ compatibilization strategy, the compatibility of iPP/HDPE was significantly improved.
• Emerging titanium coagulation was high-efficient for algae-laden water treatment.• Polytitanium coagulation was capable for both algae and organic matter removal.• Surface water purification was improved by around 30% due to algae inclusion.• Algae functioned as flocculant aid to assist polytitanium coagulation.• Algae could enhance charge neutralization capability of polytitanium coagulant. Titanium-based coagulation has proved to be effective for algae-laden micro-polluted water purification processes. However, the influence of algae inclusion in surface water treatment by titanium coagulation is barely reported. This study reports the influence of both Microcystis aeruginosa and Microcystis wesenbergii in surface water during polytitanium coagulation. Jar tests were performed to evaluate coagulation performance using both algae-free (controlled) and algae-laden water samples, and floc properties were studied using a laser diffraction particle size analyzer for online monitoring. Results show that polytitanium coagulation can be highly effective in algae separation, removing up to 98% from surface water. Additionally, the presence of algae enhanced organic matter removal by up to 30% compared to controlled water containing only organic matter. Polytitanium coagulation achieved significant removal of fluorescent organic materials and organic matter with a wide range of molecular weight distribution (693–4945 Da) even in the presence of algae species in surface water. The presence of algae cells and/or algal organic matter is likely to function as an additional coagulant or flocculation aid, assisting polytitanium coagulation through adsorption and bridging effects. Although the dominant coagulation mechanisms with polytitanium coagulant were influenced by the coagulant dosage and initial solution pH, algae species in surface water could enhance the charge neutralization capability of the polytitanium coagulant. Algae-rich flocs were also more prone to breakage with strength factors approximately 10% lower than those of algae-free flocs. Loose structure of the flocs will require careful handling of the flocs during coagulation-sedimentation-filtration processes. 相似文献
• A V2O5/TiO2 granular catalyst for simultaneous removal of NO and chlorobenzene.• Catalyst synthesized by vanadyl acetylacetonate showed good activity and stability.• The kinetic model was established and the synergetic activity was predicted.• Both chlorobenzene oxidation and SCR of NO follow pseudo-first-order kinetics.• The work is of much value to design of multi-pollutants emission control system. The synergetic abatement of multi-pollutants is one of the development trends of flue gas pollution control technology, which is still in the initial stage and facing many challenges. We developed a V2O5/TiO2 granular catalyst and established the kinetic model for the simultaneous removal of NO and chlorobenzene (i.e., an important precursor of dioxins). The granular catalyst synthesized using vanadyl acetylacetonate precursor showed good synergistic catalytic performance and stability. Although the SCR reaction of NO and the oxidation reaction of chlorobenzene mutually inhibited, the reaction order of each reaction was not considerably affected, and the pseudo-first-order reaction kinetics was still followed. The performance prediction of this work is of much value to the understanding and reasonable design of a catalytic system for multi-pollutants (i.e., NO and dioxins) emission control. 相似文献