Shemin Zhu

Effect of fluorine additive on CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3

A series of CeO2(ZrO2)/TiO2 catalysts with fluorine additive were prepared by impregnation method and tested for selective catalytic reduction (SCR) of NO by NH3. These samples were characterized by XRD, N2-BET, Raman spectra, SEM, TEM, NH3-TPD, H2-TPR and XPS, respectively. Results showed that the optimal catalyst with the appropriate HF exhibited excellent performance for NH3-SCR and more than 96% NO conversion at 360°C under GHSV of 71,400h-1. It was found that the grain size of TiO2 increased and the specific surface area reduced with the modulation of HF, which was not good for the adsorption of gas molecule. However, the modulation of HF exposed the high energy (001) facets of TiO2 and increased the surface chemisorbed oxygen concentration, oxygen storage capacity and Ce3+ concentration of catalyst. In addition, the synergy of (101) and (001) facets was beneficial to the improvement of catalytic activity.

Supported Ni–La–Ox for catalytic decomposition of N2O I: component optimization and synergy

A series of Ni–La–Ox complex oxides with Ni/La integer molar ratios from 1 to 10 supported on pretreated cordierite ceramics were prepared by an impregnation method and tested for direct catalytic decomposition of N2O. The Ni–La–Ox complex oxides showed considerable synergy in N2O decomposition compared with pure nickel oxide, and the supported Ni–La–Ox complex oxides exhibited much better catalytic performance in reactions. The promotional effects of material structure and synergy of Ni- and La-based oxides on catalytic performance for N2O decomposition were systematically studied through characterization by XRD, N2-BET, H2-TPR, N2O-TPD and XPS. The results show that the NiO and LaNiO3 are major active solid-phases for catalytic decomposition of N2O; the synergetic action between NiO and LaNiO3 promotes oxygen mobility and desorption, and stabilizes the active site of NiII. Furthermore, a new reaction mechanism for N2O decomposition over the supported Ni–La–Ox catalysts is proposed.

Effect of praseodymium additive on CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3

A series of praseodymium added CeO2(ZrO2)/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction (XRD), N2-brumauer-emmett-teller (N2-BET), NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), PL spectra, Raman spectra, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), respectively. Influence of preparation method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2(ZrO2)/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the structure of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3+ species, which was favourable for higher catalytic activity.

Anaerobic co-metabolic biodegradation of tetrabromobisphenol A using a bioelectrochemical system

Tetrabromobisphenol A(TBBPA), a pollutant in industrial wastewaters, needs to be removed due to its high toxicity and persistence. The main biodegradation pathway for TBBPA has been studied, and bisphenol A(BPA), which is toxic to the environment, is recognized as the general terminal product. In this study, we explored a new approach for the anaerobic biodegradation of TBBPA in a bioelectrochemical system (BES) through co-metabolic degradation of TBBPA with glucose. The half-life of TBBPA was significantly reduced to 13.5h-1 at 25μg/l of TBBPA. With an increase in the concentration of TBBPA, the removal rates of TBBPA rose to more than eighty percent. Based on the analysis of the products, we found that the degradation products of TBBPA were 2,6-dibromo-4-(1-methyl-1-phenylethyl) phenol, (double-benzenes product) and 2,6-dibromo-4-(prop-1-en-2-yl) phenol (single-benzene product), rather than BPA. Simultaneously, we proposed two degradation pathways for TBBPA in a BES system. According to the microbial diversity analysis of the anode biofilm, we speculated that the microorganism responsible for the biodegradation of TBBPA was Azoarcus. Additionally, we briefly analyzed the effect of TBBPA on the performance of BES system to pave the way for the further analysis of the interaction between the TBBPA and the BES system.

Promotional effects of copper doping on Ti-Ce-Ox for selective catalytic reduction of NO by NH3 at low temperature

Abstract A series of copper-doped Ti-Ce-O x complex oxide catalysts were synthesized by sol-gel method and evaluated for selective catalytic reduction of NO by NH 3 at low temperature. The promotional effect of copper doping on their structure, acidity and catalytic activity were investigated by means of Brumauer-Emmett-Teller (BET), temperature-programmed reduction (H 2 -TPR), X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed desorption (NH 3 -TPD) and pyridine adsorption infrared spectrum (Py-IR) technologies. Results showed that the copper additives could improve the low temperature catalytic performance for selective catalytic reduction of Ti-Ce-O x catalyst and the NO conversion efficiency of Ti-Cu-Ce-O x catalyst reached above 90% at 150–250 °C (Ti/Cu=4). The introduction of copper could enhance the redox property of the Ti-Ce-O x complex oxide catalyst, refine the particle size caused by lattice distortion and oxygen vacancy defect and enhance the acid amount of the Lewis acid site. Moreover, Ti-Cu-Ce-O x complex oxide catalyst also had good anti-sulfur ability and anti-water influence, when injecting 300 ppm SO 2 and 10 vol.%H 2 O, the NO conversion efficiency of Ti-Cu-Ce-O x catalyst reached 80%.

Promotional effects of Er incorporation in CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3

A series CeO 2 (ZrO 2 )/TiO 2 catalysts were modified with Er using a sol-gel method. The catalytic activity of the obtained catalysts in the selective catalytic reduction(SCR) of NO with NH 3 was investigated to determine the appropriate Er dosage. The catalysts were characterized using X-ray diffraction, N 2 adsorption, NH 3 temperature-programmed desorption, H 2 temperature-programmed reduction, photoluminescence spectroscopy, electron paramagnetic resonance spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the optimum Er/Ce molar ratio was 0.10; this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220-395℃ and a gas hourly space velocity of 71 400 h -1 . Er incorporation increased the Ti 3+ concentrations, oxygen storage capacities, and oxygen vacancy concentrations of the catalysts, resulting in excellent catalytic performance. Er incorporation also decreased the acid strength and inhibited growth of TiO 2 and CeO 2 crystal particles, which increased the catalytic activity. The results show that high oxygen vacancy concentrations and oxygen storage capacities, large amounts of Ti 3+ , and low acid strengths give excellent SCR activity.

Promotional effect of phosphorylation on CeSn0.8W0.6Ox/TiAl0.2Si0.1Oy for NH3-SCR of NO from marine diesel exhaust

Abstract A series of phosphorylation and blank CeSn 0.8 W 0.6 O x /TiAl 0.2 Si 0.1 O y catalysts prepared by extrusion molding were tested for NH 3 -SCR of NO, and were characterized by techniques of X-ray diffraction (XRD), Brumauer-Emmett-Teller (N 2 -BET), environmental scanning electron microscope (ESEM), temperature programmed reduction (H 2 -TPR) and temperature programmed desorption (NH 3 -TPD). Effects of phosphorylation on catalytic activity and sulfur-resisting performance of the CeSn 0.8 W 0.6 O x /TiAl 0.2 Si 0.1 O y for NH 3 -SCR of NO were mainly studied. Results showed that the phosphorylation improved the catalytic activity and sulfur-resisting performance in an active temperature window of 300–440 °C, and the phosphorylation catalyst with 0.4 wt.% H 3 PO 4 exhibited the best catalytic performance and the strongest sulfur-resisting performance. Analysis showed that the phosphorylation increased specific surface area, enhanced the surface acidity and improved redox properties.

Calcination conditions and stability of supported Ni4La oxide for catalytic decomposition of N2O

A series of novel supported Ni4La oxide catalysts (S-Ni4La for short) with the same mass loading amount of 10%, using pretreated cordierite ceramics as carrier, was prepared by an impregnation method and tested for catalytic decomposition of N2O at low temperature. The effects of calcination temperature and atmosphere on the catalytic performance were mainly studied, and the stability of the S-Ni4La in reaction was evaluated. Meanwhile, the solid-phase structure, micro-structure morphology, redox properties, valence and content of ions were characterized by the techniques of XRD, SEM, H2-TPR, N2O-TPD and XPS, respectively. Moreover, the catalytic mechanism for N2O decomposition over the S-Ni4La was discussed. The results showed that the S-Ni4La calcined at 400 °C in a nitrogen atmosphere completely decomposed N2O at 375 °C, which successfully breaks the technical bottleneck that low-cost supported metal oxides were not able to completely decompose N2O at below 400 °C. La2O3 and LaNiO3 were not active phases for catalytic decomposition of N2O, while NiO was a major active phase in reaction. The reducing atmosphere decreased crystallization and refined the grain size, so as to increase the effective specific surface area, thereby improving the catalytic performance. Furthermore, the Lan+1NinO3n+1+σ formed possessed a perfect migration performance of oxygen species, particularly for the catalyst calcined in a nitrogen atmosphere, and consequently the S-Ni4La calcined in a nitrogen atmosphere revealed a much better catalytic performance.

Activity and sulfur resistance of CuO/SnO2/PdO catalysts supported on γ-Al2O3 for the catalytic combustion of benzene

In this paper, five types of catalysts, (i.e. SnO2/PdO/γ-Al2O3, CuO/PdO/γ-Al2O3, PdO/γ-Al2O3, CuO/SnO2/γ-Al2O3 and CuO/SnO2/PdO/γ-Al2O3) were prepared by multiple step impregnation for the catalytic combustion of benzene. The catalysts were characterized by XRD, BET, H2-TPR and IR to investigate the internal structural and textural changes. The results indicated that the addition of copper to Pd-containing catalyst could promote the catalytic activity, and the addition of tin was beneficial for promoting the sulfur resistance of catalysts but did not bring any benefit to activity. In addition, the CuO/SnO2/PdO catalyst exhibited better sulfur resistance and catalytic activity than the other prepared catalysts which was attributed to the addition of both copper and tin.

Highly efficient Zr doped-TiO2/glass fiber photocatalyst and its performance in formaldehyde removal under visible light

Zr-doped-TiO2 loaded glass fiber (ZT/GF) composite photocatalysts with different Zr/Ti ratios were prepared with a sol-gel process. Zr4+ can replace Ti4+ in the TiO2 lattice, which is conducive to forming the anatase phase and reducing the calcination temperature. The glass fiber carrier was responsible for better dispersion and loading of Zr-doped-TiO2 particles, improving the applicability of the Zr-doped-TiO2. The ZT/GF photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and Barrett-Joyner-Halenda (BJH). The performance of photocatalysts with different loading was evaluated in formaldehyde degradation under visible light at room temperature. ZT/GF0.2 exhibited the highest activity, with a formaldehyde removal rate as high as 95.14% being observed, which is better than that of the photocatalyst particles alone. The stability of the catalyst was also tested, and ZT/GF exhibited excellent catalytic performance with 94.38% removal efficiency, even after seven uses.