The application of modified layered double hydroxides in selective catalytic reduction of nitrogen oxides by ammonia (NH<sub>3</sub>-SCR)

Szymaszek, Agnieszka; Motak, Monika; Samojeden, Bogdan

doi:10.2478/pjct-2020-0009

Cited by 6 publications

(6 citation statements)

References 47 publications

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“…The system is highly active in the SCR process, but the use of noble metals in nitric acid plants is operationally unfavorable due to the high cost of the catalysts and their low selectivity to N 2 [19][20][21]. Many innovative supports have been proposed in the scientific literature so far, such as acti-vated carbon [22,23], carbon nanotubes [24,25], layered double hydroxides [26,27], layered clays [28][29][30][31], and zeolites [32][33][34][35][36]. Among them, significant attention was paid to zeolites that are microporous aluminosilicate minerals, either naturally occurring or industrially produced on a large scale.…”

Section: Introductionmentioning

confidence: 99%

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

et al. 2021

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Natural zeolite of the heulandite-type framework was modified with iron and tested as a catalyst for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) in the temperature range of 150–450 °C. The catalyst was prepared at a laboratory scale in a powder form and then the series of experiments of its shaping into tablets was conducted. Physicochemical studies of the catalyst (N2 sorption at −196 °C, FT-IR, XRD, UV-vis) were performed to determine the textural and structural properties and identify the surface functional groups, the crystalline structure of the catalysts and the form and aggregation of the active phase. The activity tests over the shaped catalyst were performed industry-reflecting conditions, using tail gases from the pilot nitric acid plant. The influence of a temperature, catalyst load, and the amount of reducing agent (ammonia) on the NOx reduction process were investigated. The results of catalytic tests that were performed on model gas mixture showed that non-modified clinoptilolite exhibited around 58% conversion of NO at 450 °C. The temperature window of the shaped catalyst shifted to a higher temperature range in comparison to the powder sample. The catalytic performance of the shaped Fe-clinoptilolite in the industry-reflecting conditions was satisfactory, especially at 450 °C. Additionally, it was observed that the ratio of N2O concentration downstream and upstream of the catalytic bed was below 1, which indicated that the catalyst exhibited activity in both DeNOx and DeN2O process.

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Section: Introductionmentioning

confidence: 99%

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

et al. 2021

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“…As already mentioned, the main two reasons of deactivation of Cu-doped catalysts used for SCR is the formation of copper and ammonium sulphates [10,14]. The effect of the formation of those compounds can be explained by the difference of desorption temperature between ammonia (150-400 • C) and sulphur oxide (>400 • C).…”

Section: Catalytic Testsmentioning

confidence: 98%

“…Another harmful pollutant emitted to the atmosphere as the result of fuel burning is sulphur dioxide (SO 2 ) [2,10,11]. This gas has a detrimental effect on human health and quality of the environment.…”

Section: Introductionmentioning

confidence: 99%

“…Many catalysts including modified layered clays [6,17,18], hydrotalcites [10,19] or zeolitesupported metal oxides [20,21] exhibited high catalytic activity in the abatement of NO emission using the SCR method. The special attention of many researchers has been recently directed to the application of modified activated carbon (AC) as NH 3 -SCR catalysts [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

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SO2 Poisoning and Recovery of Copper-Based Activated Carbon Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

et al. 2020

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A series of materials based on activated carbon (AC) with copper deposited in various amounts were prepared using an incipient wetness impregnation method and tested as catalysts for selective catalytic reduction of nitrogen oxides with ammonia. The samples were poisoned with SO2 and regenerated in order to analyze their susceptibility to deactivation by the harmful component of exhaust gas. NO conversion over the fresh catalyst doped with 10 wt.% of Cu reached 81% of NO conversion at 140 °C and about 90% in the temperature range of 260–300 °C. The rate of poisoning with SO2 was dependent on Cu loading, but in general, it lowered NO conversion due to the formation of (NH4)2SO4 deposits that blocked the active sites of the catalysts. After regeneration, the catalytic activity of the materials was restored and NO conversion exceeded 70% for all of the samples.

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“…1 Presently, the selective catalytic reduction (SCR) denitrification system with the NH 3 as the reducing agent is widely applied worldwide in the boilers of the coal-fired power plants to reduce NO x emissions so that it meets the environmental protection requirements and protects human health. [2][3][4][5][6] However, part of NH 3 that fails to participate in the reaction will escape from the SCR system and enter the flue gas. 7 The escaped NH 3 will react with SO 3 , H 2 O, or H 2 SO 4 in the flue gas to generate ABS under a temperature range of about 190-390 C, in which the temperature range is exactly the working temperature range of the heat recovery devices of boilers such as air preheater, the amount of generated ABS directly affected by the concentration of SO 3 and NH 3 .…”

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Experimental investigation of the strength characteristics of low‐temperature fouling containing ammonium bisulfate in boilers

Tang

Zhang

Wang

et al. 2022

Asia-Pacific J Chem Eng

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Low-temperature fouling is a severe problem in the heat recovery devices of coal-fired boilers; it is mainly caused by the condensation of ammonium bisulfate (ABS, NH 4 HSO 4 ) and is usually challenging to remove with soot-blowing equipment. This study investigates the strength of low-temperature fouling containing ABS, which is an essential indicator in soot blowing. The ash sample containing ABS with three different mass ratios was heated in a drop tube furnace (DTF) at several selected temperature conditions for different times.The compressive strength of ash blocks after heating was measured, and the energy-dispersive X-ray spectrometry (EDX) and scanning electron microscope (SEM) were used to clarify the relationship between ABS content with fouling strength. The results show that the higher content of ABS means higher fouling strength. The fouling strength could decrease by heating the fouling under the flue gas temperature is 350 C or more, and a higher heating temperature could result in lower strength of the fouling. To reduce the strength and maximize the removal of fouling effectively, taking into account the economy, the recommended heating condition is to heat the fouling for 5-20 min at a minimum temperature of 350 C.

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The application of modified layered double hydroxides in selective catalytic reduction of nitrogen oxides by ammonia (NH₃-SCR)

Cited by 6 publications

References 47 publications

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

SO2 Poisoning and Recovery of Copper-Based Activated Carbon Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

Experimental investigation of the strength characteristics of low‐temperature fouling containing ammonium bisulfate in boilers

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The application of modified layered double hydroxides in selective catalytic reduction of nitrogen oxides by ammonia (NH3-SCR)

Cited by 6 publications

References 47 publications

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

SO2 Poisoning and Recovery of Copper-Based Activated Carbon Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

Experimental investigation of the strength characteristics of low‐temperature fouling containing ammonium bisulfate in boilers

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The application of modified layered double hydroxides in selective catalytic reduction of nitrogen oxides by ammonia (NH₃-SCR)