Comparison of titania nanotubes and titanium dioxide as supports of low-temperature selective catalytic reduction catalysts under sulfur dioxide poisoning

Lee, Tsung-Yu; Liou, Sihyu; Bai, Hsun-Ling

doi:10.1080/10962247.2016.1231144

Cited by 16 publications

(7 citation statements)

References 54 publications

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“…The TNTs were also used to tune the redox property and adsorption ability of Mn–Ce composite oxides, and thus high LT activity and N 2 selectivity could be achieved . TNTs supported Fe–Mn oxide catalysts exhibited better SO 2 tolerance than TiO 2 supported ones, however, the LT SO 2 -resistant mechanism for this catalyst was not illustrated …”

Section: Metal Oxide Catalystsmentioning

confidence: 99%

Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects

et al. 2019

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Selective catalytic reduction with NH 3 (NH 3 −SCR) is the most efficient technology to reduce the emission of nitrogen oxides (NO x ) from coal-fired industries, diesel engines, etc. Although V 2 O 5 −WO 3 (MoO 3 )/TiO 2 and CHA structured zeolite catalysts have been utilized in commercial applications, the increasing requirements for broad working temperature window, strong SO 2 /alkali/heavy metal-resistance, and high hydrothermal stability have stimulated the development of new-type NH 3 −SCR catalysts. This review summarizes the latest SCR reaction mechanisms and emerging poisonresistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VO x , MnO x , CeO 2 , and Fe 2 O 3 to CuO based catalysts; acidic compound catalysts containing vanadate, phosphate and sulfate catalysts; ion exchanged zeolite catalysts such as Fe, Cu, Mn, etc. exchanged zeolite catalysts; monolith catalysts including extruded, washcoated, and metal-mesh/foam-based monolith catalysts. The challenges and opportunities for each type of catalysts are proposed while the effective strategies are summarized for enhancing the acidity/redox circle and poison-resistance through modification, creating novel nanostructures, exposing specific crystalline planes, constructing protective/sacrificial sites, etc. Some suggestions are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and practical requirements to realize their commercial applications in the near future.

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Section: Metal Oxide Catalystsmentioning

confidence: 99%

Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects

et al. 2019

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“…Orthogonal experimental results suggested that the optimum preparation conditions for the biochar materials were biochar carbon material, nitric acid, an acid/mass ratio of 1.50 and a pyrolysis temperature of 800°C. It has been well documented over the past several years that MnOx based catalysts provide high low temperature SCR performance compared with other metal oxides (Liu et al, 2016;Lee et al, 2017;Liu et al, 2017). In this reported work, the optimum carbon biochar material was used as a carrier to support the active catalyst component (MnO x ).…”

Section: Low Temperature Scr Performance Of the Supported Biochar Catalystsmentioning

confidence: 99%

Agricultural Waste Derived Catalysts for Low Temperature SCR Process: Optimization of Preparation Process, Catalytic Activity and Characterization

Wang

et al. 2020

Aerosol Air Qual. Res.

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Carbon-based catalytic materials have received significant attention for low temperature flue gas denitrification (DeNO x ) process, due to their physicochemical properties and ease of modification. To improve the DeNO x efficiency, preparation of biochar catalyst supports was conducted that included the acid treatment of the agricultural wastes rice straw, corn cobs and lotus leaves. Taguchi experimental design (3 4 ) was employed to screen suitable carbon materials and optimize the preparation parameters of the biochar. All of the acid-modified and unmodified samples were evaluated to determine their performance and they were characterized by using SEM, BET and FT-IR analysis. The experimental and characterization results showed that acid modification of the biochars improved their DeNO x performance, which may have been due to the changes in the physical and chemical properties of the carbon material following the acid treatment. The optimum combination in the acid modification procedure was found to be the use of lotus leaf carbon treated with an acid/mass ratio of 1.50 and a pyrolysis temperature of 800°C. The biochar prepared using these optimum preparation parameters were then employed as a carrier to support an active catalyst component (MnO x ). The lotus leaf biochar supported 10 wt% manganese catalyst prepared using ultrasonic impregnation method exhibited nearly 90% NO x conversion at 250°C at a high space velocity of 45, 000 -1 , and it exhibited strong resistance to H 2 O. Additional studies showed that higher redox capacity and suitable surface acidity were two of the deciding factors in the improved low temperature SCR performance of the 10% Mn/LBC catalysts.

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“…However, when reaction temperature increased, the SCR reaction mechanism would transform from Langmuir−Hinshelwood mechanism to Eley-Rideal mechanism. In our previous work [32], it was found that the gradual decrease (stage II) of NO consumption in the SCR reaction was probably due to the fact that SO 2 competed with NO to react with NH 3 and form ammonium salts. However, the MnFe/TiO 2 catalyst still had good activity at stage III.…”

Section: Scr Reactions With Somentioning

confidence: 95%

“…To understand the products and byproducts of oxidation reactions, the NH 3 and NO oxidation reactions over the MnFe/TiO 2 catalyst were studied within the temperature range of 100-300 • C, which was the most active temperature region for MnFe/TiO 2 catalyst in SCR reaction [32]. In addition, the N-balance of NH 3…”

Section: Oxidation Reactions Of Nh 3 and No Without Somentioning

confidence: 99%

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

Lee

Bai

2019

Catalysts

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The byproducts of ammonia-selective catalytic reduction (NH3-SCR) process over MnFe/TiO2 catalysts under the conditions of both with and without SO2 poisoning were analyzed. In addition to the NH3-SCR reaction, the NH3 oxidation and the NO oxidation reactions were also evaluated at temperatures of 100–300 °C to clarify the reactions occurred during the SCR process. The results indicated that major byproducts for the NH3 oxidation and NO oxidation tests were N2O and NO2, respectively, and their concentrations increased as the reaction temperature increased. For the NH3-SCR test without the presence of SO2, it revealed that N2O was majorly from the NH3-SCR reaction instead of from NH3 oxidation reaction. The byproducts of N2O and NO2 for the NH3-SCR reaction also increased after increasing the reaction temperature, which caused the decreasing of N2-selectivity and NO consumption. For the NH3-SCR test with SO2 at 150 °C, there were two decay stages during SO2 poisoning. The first decay was due to a certain amount of NH3 preferably reacted with SO2 instead of with NO or O2. Then the catalysts were accumulated with metal sulfates and ammonium salts, which caused the second decay of NO conversion. The effluent N2O increased as poisoning time increased, which was majorly from oxidation of unreacted NH3. On the other hand, for the NH3-SCR test with SO2 at 300 °C, the NO conversion was not decreased after increasing the poisoning time, but the N2O byproduct concentration was high. However, the SO2 led to the formation of metal sulfates, which might inhibit NO oxidation reactions and cause the concentration of N2O gradually decreased as well as the N2-selectivity increased.

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Comparison of titania nanotubes and titanium dioxide as supports of low-temperature selective catalytic reduction catalysts under sulfur dioxide poisoning

Cited by 16 publications

References 54 publications

Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects

Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects

Agricultural Waste Derived Catalysts for Low Temperature SCR Process: Optimization of Preparation Process, Catalytic Activity and Characterization

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

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Comparison of titania nanotubes and titanium dioxide as supports of low-temperature selective catalytic reduction catalysts under sulfur dioxide poisoning

Cited by 16 publications

References 54 publications

Selective Catalytic Reduction of NOx with NH3 by Using Novel Catalysts: State of the Art and Future Prospects

Selective Catalytic Reduction of NOx with NH3 by Using Novel Catalysts: State of the Art and Future Prospects

Agricultural Waste Derived Catalysts for Low Temperature SCR Process: Optimization of Preparation Process, Catalytic Activity and Characterization

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

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Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects

Selective Catalytic Reduction of NO_x with NH₃ by Using Novel Catalysts: State of the Art and Future Prospects