Effects of oxygen and hydrogen chloride on NO removal efficiency by Rh/Al2O3 and Rh–Na/Al2O3 catalysts

Chang, Fu‐Min; Chen, Jyh-Cherng; Wey, Ming‐Yen

doi:10.1016/j.apcata.2009.02.041

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…It was proven that the addition of Na, which might provide strongly basic sites, would result in suppressed deactivation from HCl poisoning for Rh active sites over the Rh/Al 2 O 3 catalyst. 34 The strengths and distribution of basic sites over CeMoO x and VMo/Ti catalysts were characterized by O 1s XPS spectra and CO 2 -TPD (see Figure 3). The binding energy of the O β band decreased monotonously (from 529.7 to 529.4) as the preparation pH value increased from 6 to 12.…”

Section: Discussionmentioning

confidence: 99%

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Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Chang

Zhang

et al. 2015

Environ. Sci. Technol.

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A series of CeMoOx catalysts with different surface Ce/Mo ratios was synthesized by a coprecipitation method via changing precipitation pH value. The surface basicity on selective catalytic reduction (SCR) catalysts (CeMoOx and VMo/Ti) was characterized and correlated to the durability and activity of catalyst for simultaneous elimination of NOx and Hg(0). The pH value in the preparation process affected the surface concentrations of Ce and Mo, the Brunauer-Emmett-Teller (BET) specific surface area, and the acid-base properties over the CeMoOx catalysts. The O 1s X-ray photoelectron spectroscopy (XPS) spectra and CO2-temperature programmed desorption (TPD) suggested that the surface basicity increased as the pH value increased. The existence of strong basic sites contributed to the deactivation effect of HCl over the VMo/Ti and CeMoOx catalysts prepared at pH = 12. For the CeMoOx catalysts prepared at pH = 9 and 6, the appearance of surface molybdena species replaced the surface -OH, and the existence of appropriate medium-strength basic sites contributed to their resistance to HCl poisoning in the SCR reaction. Moreover, these sites facilitated the adsorption and activation of HCl and enhanced Hg(0) oxidation. On the other hand, the inhibitory effect of NH3 on Hg(0) oxidation was correlated with the competitive adsorption of NH3 and Hg(0) on acidic surface sites. Therefore, acidic surface sites may play an important role in Hg(0) adsorption. The characterization and balance of basicity and acidity of an SCR catalyst is believed to be helpful in preventing deactivation by acid gas in the SCR reaction and simultaneous Hg(0) oxidation.

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Section: Discussionmentioning

confidence: 99%

“…Modification of the basic sites on surface of the catalyst can be an effective way for improving HCl tolerance. It was proven that the addition of Na, which might provide strongly basic sites, would result in suppressed deactivation from HCl poisoning for Rh active sites over the Rh/Al 2 O 3 catalyst …”

Section: Discussionmentioning

confidence: 99%

Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Chang

Zhang

et al. 2015

Environ. Sci. Technol.

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“…This phenomenon indicated that increased in the formation of nitrate species (NO 3 and NO 2 ) obtained from H reacted with NO 2 or OH reacted with NO. Na may react with NO 3 to form NaNO 3 [5,7]. Moreover, the performance of the Rh-Na/Al 2 O 3 catalyst at 300°C did not decrease even though the content of H 2 O increased to 3.6 vol%.…”

Section: Reaction Systemmentioning

confidence: 91%

“…Selective catalytic reduction (SCR) has been an attractive method for NO reduction because of its high control efficiency, low reaction temperature, and low energy/fuel requirement. Many studies have applied SCR for NO reduction and the feasible catalysts include transition metal catalysts (Cu, Fe, V, Co and Ni) supported by activated carbon [1,2], noble metal catalysts (Pd-Rh) supported on alumina [3] and some combined/modified metal catalysts (Pd-Na and Rh-Na) [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Improving the Activity of Rh/Al2O3 Catalyst for NO Reduction by Na Addition in the Presences of H2O and O2

2009

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The effect of Na addition on the performance of Rh/Al 2 O 3 catalyst for NO reduction with CO in the presence of H 2 O and O 2 was investigated. The reacted catalysts were analyzed by the FTIR technique to identify the products for further investigation on the possible catalytic reaction mechanisms and the reasons behind the H 2 O poisoning. Experimental results show that the removal efficiency of NO by Rh/Al 2 O 3 catalyst was 63% at 250°C but that decreased as the H 2 O content increased. Adding Na to modify the Rh/Al 2 O 3 catalyst significantly enhanced the conversion of NO to 99% at 250-300°C even as the H 2 O content was 1.6 vol%. The FTIR analyses results reveal that the abundant H 2 O in the flue gas can compete with NO to adsorb on the surfaces of Rh/Al 2 O 3 and Rh-Na/ Al 2 O 3 catalysts and further enhance the formation of NO 3 that reacts with H. The effects of H 2 O on Rh/Al 2 O 3 and Rh-Na/Al 2 O 3 catalysts can be eliminated by increasing the reaction temperature to higher than 300°C. Rh-Na/Al 2 O 3 is a feasible catalyst for NO reduction at such condition with relative high H 2 O and O 2 contents.

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Chemical poison and regeneration of SCR catalysts for NO x removal from stationary sources

Peng

Chang

et al. 2016

Front. Environ. Sci. Eng.

115

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Effects of oxygen and hydrogen chloride on NO removal efficiency by Rh/Al2O3 and Rh–Na/Al2O3 catalysts

Cited by 7 publications

References 22 publications

Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Improving the Activity of Rh/Al2O3 Catalyst for NO Reduction by Na Addition in the Presences of H2O and O2

Chemical poison and regeneration of SCR catalysts for NO x removal from stationary sources

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Effects of oxygen and hydrogen chloride on NO removal efficiency by Rh/Al2O3 and Rh–Na/Al2O3 catalysts

Cited by 7 publications

References 22 publications

Design Strategies for CeO2–MoO3 Catalysts for DeNOx and Hg0 Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Design Strategies for CeO2–MoO3 Catalysts for DeNOx and Hg0 Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Improving the Activity of Rh/Al2O3 Catalyst for NO Reduction by Na Addition in the Presences of H2O and O2

Chemical poison and regeneration of SCR catalysts for NO x removal from stationary sources

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Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties

Design Strategies for CeO₂–MoO₃ Catalysts for DeNO_x and Hg⁰ Oxidation in the Presence of HCl: The Significance of the Surface Acid–Base Properties