Selective reduction of NO with CO and naphthalene in the presence of oxygen on a core-shell CeO 2 @ TiO 2 supported copper-potassium-based catalyst (original) (raw)
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Materials Chemistry and Physics, 2019
A set of Cu/Ce/TiO 2-SiO 2 and K/Cu/Ce/TiO 2-SiO 2 catalysts was used for the simultaneous use of CO and naphthalene as reducing agents for the reduction of NO in the presence of oxygen. Only 5% of TiO 2 greatly increase the activity of the catalysts. It was also found that the addition of potassium is able to tune down these oxidation reactions allowing the reduction of NO. The Cu/Ce/TiO 2-SiO 2 catalyst achieves the full conversion of naphthalene at 302 o C, 96% of CO conversion at the same temperature, and negligible conversion of NO. On the other hand, the K/Cu/Ce/TiO 2-SiO 2 catalyst reaches the full conversion of CO at 330 o C, 90% conversion of NO at 342 o C, and 70% conversion of naphthalene at the latter temperature.
Low-temperature selective catalytic reduction of NO with CO over Nix-MOF-5
Journal of Materials Science, 2022
The catalytic activity of a series of Cu-Ce catalysts supported on carbon nanotubes was studied for NO reduction by CO. The 20 wt.% Cu1:Ce3/CNT catalyst showed the highest NOx conversion of 96% at 220 °C in the presence of oxygen (O2/CO ≤ 0.6). The catalytic activity of the CNT-supported catalysts was significantly enhanced due to synergistic interactions between surface oxygen vacancies and Cu + species in the CNT-supported catalysts. Shifting of redox equilibrium to right (Cu 2+ + Ce 3+ ↔ Cu + + Ce 4+) resulted in creation of more reduced state Cu +. In the presence of excess oxygen (O2/CO ≥ 0.6), the catalyst can effectively catalyze the CO−O2 reaction and the NO + CO reaction did not occur. Compared with Cu1:Ce3/CNT catalyst, Cu1:Ce3 catalyst supported on activated carbon showed lower activity due to the lower Cu + /Cu 2+. A possible reaction mechanism was proposed, providing insight into the catalytic reactions between NO and CO.
Simultaneous removal of NO and SO2 from combustion fuel gases using supported copper oxide catalysts
Issue 2
Nitrogen oxide (NOx) and sulphur dioxide (SO2) emissions produced by the combustion of fuel in stationary sources, such as power stations, industrial heaters or cogeneration plants, cause significant environmental problems. Selective catalytic reduction (SCR) is a well established process for the control of NOx emissions mainly due to its efficiency, selectivity and economics. High removal efficiencies for both NOx and SO2 can be achieved with the use of copper oxide catalysts, as they act as sorbents for the latter - forming copper sulfate - and catalyze the reduction of the former - to N2, in the presence of NH3. An added advantage is that these catalysts are relatively easy to be regenerated under reducing conditions. This study examines the deactivation and regeneration procedures of copper oxide catalysts/sorbents that are supported on Al2O3, SiO2, CeO2-Al2O3, in the presence of SO2 and identifies the appropriate conditions for the simultaneous removal of NO and SO2. The result...
Selective Reduction of NO with CO Over Titania Supported Transition Metal Oxide Catalysts
Catalysis Letters, 2008
A series of transition metal oxides promoted titania catalysts (MO x /TiO 2 ; M = Cr, Mn, Fe, Ni, Cu) were prepared by wet impregnation method using dilute solutions of metal nitrate precursors. The catalytic activity of these materials was evaluated for the selective catalytic reduction (SCR) of NO with CO as reductant in the presence of excess oxygen (2 vol.%). Among various promoted oxides, the MnO x /TiO 2 system showed very promising catalytic activity for NO + CO reaction, giving higher than 90% NO conversion over a wide temperature window and at high space velocity (GHSV) of 50,000 h -1 . It is remarkable to note that the catalytic activity increased with oxygen, up to 4 vol.%, under these conditions leading primarily to nitrogen. Our TPR studies revealed the presence of mixed oxidation states of manganese on the catalyst surface. Characterization results indicated that the surface manganese oxide phase and the redox properties of the catalyst play an important role in final catalytic activity.
Kinetics and Catalysis, 2008
Steady State Isotopic Transient Kinetic Analysis (SSITKA) experiments using on-line Mass Spectrometry (MS) and in situ Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) have been performed to study essential mechanistic aspects of the Selective Catalytic Reduction of NO by H 2 under strongly oxidizing conditions (H 2 -SCR) in the 120-300 ° C range over a novel 0.1 wt % Pt/MgO-CeO 2 catalyst. The N-path of reaction from NO to the N 2 gas product was probed by following the 14 NO/H 2 /O 2 15 NO/H 2 /O 2 switch (SSITKA-MS and SSITKA-DRIFTS) at 1 bar total pressure. It was found that the N-pathway of reaction involves the formation of two active NO x species different in structure, one present on MgO and the other one on the CeO 2 support surface. Inactive adsorbed NO x species were also found on both the MgO-CeO 2 support and the Pt metal surfaces. The concentration (mol/g cat) of active NO x leading to N 2 was found to change only slightly with reaction temperature in the 120-300 ° C range. This leads to the conclusion that other intrinsic kinetic reasons are responsible for the volcano-type conversion of NO versus the reaction temperature profile observed.
Catalysis Communications, 2010
CeO 2 /TiO 2 catalysts were prepared by three methods, and their activities for SCR of NO with NH 3 were investigated in the presence of O 2. The experimental results indicate that the catalysts prepared by the single step sol-gel method have the best SCR activity and SO 2 resistance regardless of the concentration of NO or SO 2. High surface area and good redox ability are important to the catalytic activity, while the strong interaction between ceria and titania as well as high concentration of amorphous or highly dispersed nano-crystalline ceria should be the reason for the excellent performance of the catalyst prepared by the single step sol-gel method.
GlobalNEST International Journal
Nitrogen oxide (NOx) and sulphur dioxide (SO2) emissions produced by the combustion of fuel in stationary sources, such as power stations, industrial heaters or cogeneration plants, cause significant environmental problems. Selective catalytic reduction (SCR) is a well established process for the control of NOx emissions mainly due to its efficiency, selectivity and economics. High removal efficiencies for both NOx and SO2 can be achieved with the use of copper oxide catalysts, as they act as sorbents for the latter - forming copper sulfate - and catalyze the reduction of the former - to N2, in the presence of NH3. An added advantage is that these catalysts are relatively easy to be regenerated under reducing conditions. This study examines the deactivation and regeneration procedures of copper oxide catalysts/sorbents that are supported on Al2O3, SiO2, CeO2-Al2O3, in the presence of SO2 and identifies the appropriate conditions for the simultaneous removal of NO and SO2. The result...
The influence of CO2 on NO reduction into N2 over reduced ceria-based catalyst
Applied Catalysis B: Environmental, 2018
Oxygen defects in reduced ceria are the catalytic sites for the NO reduction into N 2 in the Toyota Di-Air DeNO x abatement technology. Traces of NO (several hundred ppm) have to compete with the excess amount of other oxidants, e.g., 5% CO 2 and 5% O 2 , in an exhaust gas of a lean burn (diesel) engine. The reactivities of CO 2 and NO over a reduced ceria and noble metal loaded reduced ceria have been investigated under ultra-high vacuum system in TAP and under atmosphere pressure in in-situ Raman and flow reactor setup. The results showed that CO 2 was a mild oxidant which was able to oxidise the oxygen defects, but hardly oxidised deposited carbon over both ceria and noble metal loaded ceria. NO was a stronger oxidant and more efficient in refilling the oxygen defects and able to convert the deposited carbon, which acted as buffer reductant to extend the NO reduction time interval. NO was selectively and completely converted into N 2. The presence of excess CO 2 hardly affected the NO reduction process into N 2 .