Laboratory Investigation of Selective Catalytic Reduction Catalysts: Deactivation by Potassium Compounds and Catalyst Regeneration

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• 作者：Yuanjing Zheng ; Anker Degn Jensen ; and Jan Erik Johnsson
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2004
• 出版时间：February 18, 2004
• 年：2004
• 卷：43
• 期：4
• 页码：941 - 947
• 全文大小：129K
• 年卷期：v.43,no.4(February 18, 2004)
• ISSN：1520-5045

文摘

The deactivation and regeneration of selective catalytic reduction (SCR) catalysts poisoned bypotassium by a wet-impregnation method was investigated experimentally. Potassium in theform of both chloride and sulfate is a strong poison for the catalyst. The results indicate thatpotassium titrates the active sites for NH₃ adsorption. Simply increasing the operatingtemperature or the vanadium content in the catalyst cannot compensate the loss of catalystactivity: Increasing the temperature hardly increases the conversion of NO for the stronglypoisoned catalysts, and catalysts with high vanadium content become active for oxidizing NH₃to NO, causing a net NO formation. Deactivated catalysts can be regenerated by differentmethods. Sulfation by gaseous SO₂ is efficient provided the poison is first removed by washing.When regenerating by 0.5 M H₂SO₄, the catalyst regains a higher activity than that of the freshcatalyst at temperatures higher than 300 C. Heat treatment of the catalyst at 400 C for 2 hafter poisoning to simulate actual operation has no influence on the regeneration by 0.5 M H₂SO₄.Deactivated catalysts without the heat treatment step regain higher activities than that of thefresh catalyst at all temperatures when regenerated by 1 M NH₄Cl. However, the heat treatmentstep has a negative effect on the regeneration by NH₄Cl.