NH3-SCR low-temperature flue gas denitration catalyst and application thereof

Abstract

The invention provides an NH3-SCR low-temperature flue gas denitration catalyst which comprises 20-50% of an SSZ-13 molecular sieve in terms of hydrogen form, 5-12% of copper in terms of CuO and 4-8% of manganese in terms of MnO. The preparation method comprises the following steps: adding an aqueous solution of nitrates of Cu and Mn into an ammonium type SSZ-13 molecular sieve, carrying out ion exchange, filtering, washing with water, drying, and roasting at 550-580 DEG C to obtain Cu-Mn / SSZ-13 molecular sieve roasting powder which contains 2-4% of CuO and 1-2% of MnO; uniformly mixing 30-60 parts of Cu-Mn / SSZ-13 molecular sieve roasted powder, 5-12 parts of basic cupric carbonate, 4-11 parts of manganese carbonate and 30-50 parts of washed kaolin, spraying 100-130 parts of aluminum phosphate sol-pseudo-boehmite composite glue solution, kneading, extruding into strips, drying, and roasting at 500-550 DEG C; soaking the roasted strip in an acetic acid aqueous solution, drying, and roasting for 2-4 hours at 300-330 DEG C under the conditions of isolating air and adding methanol to prepare the low-temperature flue gas denitration catalyst; under the conditions that the temperature is 150-180 DEG C and the NH3 is excessive by 10-50%, NOx below 2000 mg / m<3> can be treated to the concentration level smaller than or equal to 80 mg / m<3>. The catalytic performance is stable, the corrosion resistance to acid components such as NO and NO2 is high, and powder falling or pulverization is not prone to occurring.

Description

technical field [0001] The invention belongs to the technical field of NOx-containing gas treatment, in particular to a kind of NH 3 -SCR low temperature flue gas denitration catalyst and its application. Background technique [0002] In the production process of many catalysts, purifiers and adsorbents, metal nitrates are often used as raw ingredients. The metal nitrate is decomposed in the subsequent kiln roasting process of the catalyst, purifying agent and adsorbent, and generates highly dispersed metal oxide active components in the catalyst, purifying agent and adsorbent, and releases NO at the same time. 2 , NO and other nitrogen oxide gases generally referred to as NOx, when NO 2 Concentrations over 2000 mg / m 3 When the gas is brownish-yellow to reddish-brown color, it generally needs to be absorbed by lye solution, acid urea solution and / or treatment solution containing oxidant to eliminate its color, and it is possible to meet the emission requirements. GB 3157...

AI Technical Summary

Problems solved by technology

When the NOx-containing tail gas is circulated and absorbed by lye, acidic urea solution, and / or oxidant-containing treatment liquid, due to the small scale of the absorption treatment device, the process is often not perfect, and the existing disadvantages include: the investment is not low, the operating cost High, there are waste water and waste residue problems, chimney exhaust gas entrains the final circulating absorption liquid, and causes "falling snow" to pollute the surrounding environment and other problems

The advantages of this method include high catalyst activity and long life under the condition of 200-350°C, and it can handle the airflow with the volume content of NOx within 1%; the disadvantage is that the operating temperature is high, and NOx is not easy to deal with due to the obvious secondary generation. Such as 80mg / m 3 Below, it is difficult to meet the requirements of denitrification when directly processing the airflow with a temperature below 180°C, and there are problems such as high consumption of ammonia gas and the toxicity of vanadium in the catalyst.