Novel Preparation of Cu and Fe Zirconia Supported Catalysts for Selective Catalytic Reduction of NO with NH3

Copper and iron promoted ZrO2 catalysts were prepared by one-pot synthesis using urea. The studied catalysts were characterized by XRD, N2 physisorption, XPS, NH3-TPD, and tested in the selective catalytic reduction of NO with NH3 (NH3-SCR) in the absence and presence of water vapor under the experimental conditions representative of exhaust gases from stationary sources. The influence of SO2 on catalytic performance was also investigated. Among the studied catalysts, the Fe-Zr sample showed the most promising results in NH3-SCR, being active and highly selective to N2. The addition of SO2 markedly improved NO and NH3 conversions during NH3-SCR in the presence of H2O. The improvement in acidic surface properties is believed to be the cause

Tri-reforming as a process of CO

Methane tri-reforming process is a combination of three reactions: steam methane reforming (SRM), dry methane reforming (DRM), and partial oxidation of methane (POM). The first two reactions have endothermic character, while the POM is the exothermic reaction, which allows to obtain the energy necessary for the other two processes in situ. CH4 reacts with H2O, CO2, O2, and synthesis gas is produced with desired H2/CO ratios (1.5 – 2.0). The presence of H2O and O2 in the reaction environment can positively influence the stability of the used catalyst, by the inhibition of coke formation. In this paper two scenarios for methane tri-reforming implementation are discussed: (i) Tri-reforming as a effective way for chemical CO2 utilization, without the separation of carbon dioxide from flue gases from fossil fuel-fired power stations, and (ii) dry reforming of methane improved by the addition of water and oxygen, which may be applied as a chemical energy storage process. The literature on the subject of trireforming is shortly reviewed, including thermodynamics of the process, the possible conversions of methane and carbon dioxide, and proposed catalysts, both studied in tri-reforming, and in single processes (SRM, DRM and POM)

The influence of the modification of acidic montmorillonites with polyacrylamide and copper deposition on SCR-NH3 catalytic performance

The aim of this work was to study the influence of the modification of montmorillonites by carbonaceous and Al species as well as copper deposition. Commercial acid-treated montmorillonites, K5 and K30 (Sigma-Aldrich GmBH), were modified and used as catalysts in Selective Catalytic Reduction process of nitrogen oxides by ammonia. The characterisation was carried out by low-temperature nitrogen sorption, Fourier-transform-infrared spectroscopy and X-ray diffraction. Catalytic performance in SCR-NH3 of so-modified montmorillonites was compared under the following conditions: mass of catalyst: 200 g, flow 100 cm3/min, reaction mixture: 800 ppm NO, 800 ppm NH3, 3 % O2, and He. The modification with copper and polyacrylamide led to the increase in NO conversion. The studied catalysts showed low N2O formation

The influence of the modification of acidic montmorillonites with polyacrylamide and copper deposition on SCR-NH3 catalytic performance

The aim of this work was to study the influence of the modification of montmorillonites by carbonaceous and Al species as well as copper deposition. Commercial acid-treated montmorillonites, K5 and K30 (Sigma-Aldrich GmBH), were modified and used as catalysts in Selective Catalytic Reduction process of nitrogen oxides by ammonia. The characterisation was carried out by low-temperature nitrogen sorption, Fourier-transform-infrared spectroscopy and X-ray diffraction. Catalytic performance in SCR-NH3 of so-modified montmorillonites was compared under the following conditions: mass of catalyst: 200 g, flow 100 cm3/min, reaction mixture: 800 ppm NO, 800 ppm NH3, 3 % O2, and He. The modification with copper and polyacrylamide led to the increase in NO conversion. The studied catalysts showed low N2O formation

Facile modifications of HKUST-1 by V, Nb and Mn for low-temperature selective catalytic reduction of nitrogen oxides by NH 3

International audienceHKUST-1 catalysts were impregnated with vanadium, niobium and manganese species and tested in NH 3-SCR for NO removal. No reduction of NO by NH 3 was registered for the unmodified HKUST-1 and disappearance of NO was attributed to adsorption. After a pretreatment at 185°C, the best catalytic performance was found for HKUST-1-Mn with 100% and 80% conversion of NH 3 and NO, respectively at 185°C. For the first time, the H 2 O tolerance was examined on the modified HKUST-1 catalyst. The addition of water vapor resulted in decrease of NO and NH 3 conversions, which was immediately recovered when H 2 O feeding was stopped. The NO conversion dropped from 76% to 68% after 35 min of H 2 O addition

Novel Preparation of Cu and Fe Zirconia Supported Catalysts for Selective Catalytic Reduction of NO with NH3

International audienceCopper and iron promoted ZrO2 catalysts were prepared by one-pot synthesis using urea.The studied catalysts were characterized by XRD, N2 physisorption, XPS, NH3-TPD, and tested inthe selective catalytic reduction of NO with NH3 (NH3-SCR) in the absence and presence of watervapor under the experimental conditions representative of exhaust gases from stationary sources.The influence of SO2 on catalytic performance was also investigated. Among the studied catalysts,the Fe-Zr sample showed the most promising results in NH3-SCR, being active and highly selectiveto N2. The addition of SO2 markedly improved NO and NH3 conversions during NH3-SCR in thepresence of H2O. The improvement in acidic surface properties is believed to be the cause

Syngas production from dry methane reforming over yttrium-promoted nickel- KIT-6 catalysts

International audienceDry reforming of methane was studied over Ni,Y-promoted KIT-6 ordered mesoporous silicas, prepared by incipient impregnation (nickel content 12 wt%, yttrium content of 4 wt%, 8 wt% or 12 wt%). The catalysts were characterized by XRF, FT-IR, TGA/DSC-MS, N2-adsorption, TEM, HRTEM, XRD and TPR-H2. The promotion with 8 wt% Y (Y/Si = 0.05) resulted in the highest activity and H2/CO molar ratio closer to the stoichiometric value at temperatures from 600 to 750 °C. The characterization results of the yttrium promoted materials showed higher reducibility of the bulk NiO, bigger Ni crystallite size after reduction and DRM test, and better dispersion of nickel in the channels of the KIT-6 support. Additionally, larger Ni particles were observed on the external surface of the support, which may be related to catalytic selectivity towards carbon forming reactions. Upon dry methane reforming the segregated phases of Niº, Y2O3, and possibly Y2Si2O7 were registered. No presence of a Ni,Y alloy was observed

Perspectives in Adsorptive and Catalytic Mitigations of NOx Using Metal–Organic Frameworks

International audienceBecause of its high polluting effect, a growing research interest in NOx monitoring, removal, and control has been noticed in the last years. Motivated by the high degree of functional and structural tunability of metal–organic frameworks (MOFs), researchers explored potential MOF-based adsorbents, sensors, and catalysts for NOx mitigation/control. However, this area of research is still in its infancy. In addition, the physical–chemical properties of NOx make this task extremely challenging as some materials suffer relatively weak thermal and/or chemical stability. Nevertheless, some recent encouraging studies have demonstrated superior stability properties that enable MOFs to be considered as alternative benchmark materials for the capture and conversion of NOx. This review offers an overview on the recent progress made in this field and provides some interesting routes on the uses of MOFs for selective NOx adsorption, release, and/or catalytic conversion (via selective catalytic reduction or photocatalysis)

Ce- and Y-Modified Double-Layered Hydroxides as Catalysts for Dry Reforming of Methane: On the Effect of Yttrium Promotion

Ce- and Y-promoted double-layered hydroxides were synthesized and tested in dry reforming of methane (CH4/CO2 = 1/1). The characterization of the catalysts was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 sorption, temperature-programmed reduction in H2 (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), H2 chemisorption, thermogravimetric analysis coupled by mass spectrometry (TGA/MS), Raman, and high-resolution transmission electron microscopy (HRTEM). The promotion with cerium influences textural properties, improves the Ni dispersion, decreases the number of total basic sites, and increases the reduction temperature of nickel species. After promotion with yttrium, the increase in basicity is not directly correlated with the increasing Y loading on the contrary of Ni dispersion. Dry reforming of methane (DRM) was performed as a function of temperature and in isothermal conditions at 700 °C for 5 h. For catalytic tests, a slight increase of the activity is observed for both Y and Ce doped catalysts. This improvement can of course be explained by Ni dispersion, which was found higher for both Y and Ce promoted catalysts. During DRM, the H2/CO ratio was found below unity, which can be explained by side reactions occurrence. These side reactions are linked with the increase of CO2 conversion and led to carbon deposition. By HRTEM, only multi-walled and helical-shaped carbon nanotubes were identified on Y and Ce promoted catalysts. Finally, from Raman spectroscopy, it was found that on Y and Ce promoted catalysts, the formed C is less graphitic as compared to only Ce-based catalyst