Research Of Catalytic Performance And Anti-poison Characteristics Over CuSO₄-V₂O₅/TiO₂-SiO₂ In Catalytic Removal Of NO_x

The NH₃-SCR method is now widely used in De-NO_x industry. SCR catalysts often run at a high temperature of 350℃, so the SCR reactor needs to be installed between the economizer and air preheater, however, the high concentration fuel gas and dust in the area will erode and pollute the SCR catalysts. The economizer, air preheater and boiler are installed into a entirety in our country, so the widely used NH₃-SCR method is inapplicable in our country. If the SCR reactor is designed after ESP , the damage of SCR catalysts will be less, however, the temperature of fuel gas is 150²50℃, it's lower than 350℃, so the low-temperature SCR catalysts are researched by many scholars. Besides NH₃-SCR method, the CO is a promising De-NO_x method. In industrial fuel gas, more than 90% of NO_x is in the form of NO. NO is hard to be absorbed by the water and lye. If oxidizing NO to NO₂, and using lye absorbe NO₂, the most of NO_x will be removed with SO₂. TiO₂-SiO₂ (TS) support was prepared by the co-precipitation method and a novel CuSO₄-V₂O₅/TS catalyst was prepared by impregnation method in the research. The SCR and CO activity of CuSO₄-V₂O₅/TS catalyst were studied. For analysing the affect of CuSO₄, the SCR activityof CuSO₄-V₂O₅/TS catalyst and V₂O₅/TS catalyst were compared in this study.The effects of preparation conditions and operating conditions were investigated. The influences of H₂O, SO₂ were also discussed. The results showed that catalyst prepared optimally performed high NO conversion of 99.1% at the conditions of reaction temperature 220℃, NO input concentrations 1000×10?6 (φ), NH₃/NO molar ratio 1.1, space velocity 5000 h?1 and O2 concentrations 4%(φ). The catalyst activity was litttle affected both in separate anti-water and separate anti-sulfur experiments. When the catalyst was examined under sulfur and water simultaneously condition, its conversion rate was above 86% within 28h. When H₂O and SO₂ were off, the conversion rate from 86.4% rose to 90.1% within 10 h. Comparing with the V₂O₅/TS catalyst, CuSO₄-V₂O₅/TS catalyst showed superior performance of low temperature activity and anti-poisoning of H₂O and SO₂ by the addition of CuSO₄.The CO activity of CuSO₄-V₂O₅/TS catalyst was studied, and its preparation conditions, operating conditions ( included the reaction temperature, O2 concentration and space velocity) and anti-poison characteristics were investigated. The results showed that the CuSO₄(10%)-V₂O₅(7%)/TS catalyst calcinated at 350℃performed high oxidation efficiency of 99.1% at the conditions of reaction temperature 300℃, NO input concentrations 500×10?6 (φ), space velocity 5000 h?1 and O2 concentrations 8%(φ). When reaction temperature was 300℃, H₂O competitively adsorbed with NO, then, the oxidation efficiency of the catalyst decreased. The activity of the catalyst became back to the high oxidation efficiency of 57.1% after cutting off the H₂O; NO and SO₂ happened a lead chamber reaction and H2SO4 corroded the catalyst in the presence SO₂, so the catalyst was polluted seriously. The activity of the catalyst recovered less after cutting off SO₂; Because of the lead chamber reaction between NO and SO₂, being corroded by H2SO4 and competitive adsorption between NO and H₂O in the H₂O and SO₂, the activity of the catalyst was just 23.1%. The activity of the catalyst recovered to 30.8% by cutting off SO₂ and H₂O simultaneously. CuSO₄-V₂O₅/TS catalyst is expected to be applied in the removal of NO_x from flue gas without SO₂ and the CO process of removing NO_x from nitric acid tail gas.