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Arandiyan H.,Tsinghua University | Li J.,Tsinghua University | Ma L.,Tsinghua University | Hashemnejad S.M.,Iran University of Science and Technology | And 7 more authors.
Journal of Industrial and Engineering Chemistry

The perovskite metal-oxides LaNi xFe 1-xO 3 (0≤x≤1) were synthesized by a sol-gel method and investigated for the DR, POM, and CRM into synthesis gas. The catalysts were characterized by using XRD, BET, CA, SEM, EDS, HR-TEM, EDX and TPR in order to investigate the influence of the preparation parameters and evaluation condition. LaNi 0.4Fe 0.6O 3 showed great stability, and fewer carbon deposits were detected on the spent catalyst after 1800min evaluation on TOS. The effect of GHSV on the catalytic performance was investigated. The results obtained showed the H 2/CO molar-ratio was around 0.9, 1.7, and 1.1 over different catalysts for DR, POM and CRM, respectively. © 2012 The Korean Society of Industrial and Engineering Chemistry. Source

Kang Y.,Chongqing University | Lu X.,Chongqing University | Wang Q.,Chongqing University | Gan L.,CPI Yuanda Environmental Protection Engineering Co. | And 5 more authors.
Energy Conversion and Management

In this paper, experiments and numerical calculations were conducted to investigate the effect of H2 addition on dimethyl ether (DME) jet diffusion flame behaviors, in terms of thermal and chemical structures, reaction zone size, flame entrainment, and NOx and CO emission indices. A wide range of H2 additions from pure DME to pure H2 were involved herein, while maintaining the volumetric flow rate of fuel mixture constant. The results indicate that when H2 mole fraction in the fuel mixture exceeded 60%, the blended fuel was converted to H2-dominated. Besides, the flames behaved rather distinctly at the DME- and H2-dominated regimes. With the increment in H2 addition, flame temperature, H2, H, O, and OH concentrations increased gradually, but concentrations of the intermediate hydrocarbons (such as CO, CH2O, CH2, and CH3) decreased on the contrary. Additionally, after the flame became H2-dominated, the species concentrations varied increasingly quickly with H2 addition. The reaction zone length and width decreased nearly linearly with H2 addition at the DME- and H2-dominated regimes. But the decreasing speed of reaction zone length became faster after the flame was converted to H2-dominated. At the DME-dominated regime, the dependence of flame entrainment coefficient (Ce) on H2 addition was rather small. While at the H2-dominated regime, Ce increased increasingly quickly with H2 addition. Moreover, with the increment in H2 addition, NOx emission index increased and CO emission index decreased gradually. In addition, at the DME-dominated regime, NOx emission index increased fairly slowly with H2 addition; while at the H2-dominated regime, it increased significantly. The optimal H2 addition to DME was 60 vol.% in the practical engineering. © 2014 Elsevier Ltd. All rights reserved. Source

Peng Y.,Tsinghua University | Peng Y.,Jilin University | Li J.,Tsinghua University | Chen L.,Tsinghua University | And 5 more authors.
Environmental Science and Technology

The alkali metal-induced deactivation of a novel CeO 2-WO 3 (CeW) catalyst used for selective catalytic reduction (SCR) was investigated. The CeW catalyst could resist greater amounts of alkali metals than V 2O 5-WO 3/TiO 2. At the same molar concentration, the K-poisoned catalyst exhibited a greater loss in activity compared with the Na-poisoned catalyst below 200 °C. A combination of experimental and theoretical methods, including NH 3-TPD, DRIFTS, H 2-TPR, and density functional theory (DFT) calculations, were used to elucidate the mechanism of the alkali metal deactivation of the CeW catalyst in SCR reaction. Experiments results indicated that decreases in the reduction activity and the quantity of Brønsted acid sites rather than the acid strength were responsible for the catalyst deactivation. The DFT calculations revealed that Na and K could easily adsorb on the CeW (110) surface and that the surface oxygen could migrate to cover the active tungsten, and then inhibit the SCR of NO x with ammonia. Hot water washing is a convenient and effective method to regenerate alkali metal-poisoned CeW catalysts, and the catalytic activity could be recovered 90% of the fresh catalyst. © 2012 American Chemical Society. Source

Liu C.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,CPI Yuanda Environmental Protection Engineering Co. | Li J.,Tsinghua University | And 5 more authors.
Environmental Science and Technology

A series of novel metal-oxide-supported CeO2 catalysts were prepared via the wet impregnation method, and their NH3-SCR activities were investigated. The Ce/TiO2-SiO2 catalyst with a Ti/Si mass ratio of 3/1 exhibited superior NH3-SCR activity and high N2 selectivity in the temperature range of 250-450 °C. The characterization results revealed that the activity enhancement was correlated with the properties of the support material. Cerium was highly dispersed on the TiO2-SiO2 binary metal oxide support, and the interaction of Ti and Si resulted in greater conversion of Ce4+ to Ce3+ on the surface of the catalyst compared to that on the single metal oxide supports. As a result of in the increased number of acid sites on Ce/TiO2-SiO2 that resulted from the addition of SiO 2, the NH3 adsorption capacity was significantly improved. All of these factors played significant roles in the high SCR activity. More importantly, Ce/TiO2-SiO2 exhibited strong resistance to SO2 and H2O poisoning. After the addition of SiO 2, the number of Lewis-acid sites was not decreased, but the number of Brønsted-acid sites on the TiO2-SiO2 carrier was increased. The introduction of SiO2 further weakened the alkalinity over the surface of the Ce/TiO2-SiO2 catalyst, which resulted in sulfate not easily accumulating on the surface of the Ce/TiO 2-SiO2 catalyst in comparison with Ce/TiO2. © 2012 American Chemical Society. Source

Liu Q.-C.,Chongqing University | Xi W.-C.,Chongqing University | Xi W.-C.,Chongqing Yuanda Catalyst Manufacturing Co. | Yang J.,Chongqing University | And 3 more authors.
Gongneng Cailiao/Journal of Functional Materials

The V2O5-WO3/cordierite-TiO2 honeycomb catalysts were prepared by solid-liquid mixing method, with cordierite modified. Surface morphology, thermal stability crystal structure, abrasion resistance and activity were studied by SEM, XRD, BET, abration equipment and simulated flue gas analyzer, respectively. The results indicated that the cordierite modified was introduced, V2O5-WO3/cordierite-TiO2 honeycomb catalyst was a large number of micro pores in its surface(which promote the reaction), good thermal stability. The phase of V2O5 and WO3 was amorphous or nanocrystalline state after it was calcined at 700°C. Abration ratio of V2O5-WO3/10% cordierite-TiO2 was law. Especially in the 250-460°C reaction, the denitration rate can be maintained above 80%. Source

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