Low-temperature flue gas denitrification catalyst for selective reduction of NO by CO and its application

Abstract

The invention provides a low-temperature flue gas denitrification catalyst using CO to selectively reduce NOx, comprising 20-50% of SSZ-13 molecular sieve in terms of hydrogen type, 5-12% of copper in terms of CuO, and 4-8% of manganese in terms of MnO ; Made through the following steps: ammonium-type SSZ‑13 molecular sieve, adding Cu and Mn nitrate aqueous solution for ion exchange, filtering, washing, drying, and roasting at 550‑580 ° C to obtain Cu‑Mn / SSZ‑13 molecular sieve roasting powder , containing CuO2‑4%, MnO1‑2%; Cu‑Mn / SSZ‑13 molecular sieve roasting powder 30‑60 parts, basic copper carbonate 5‑12 parts, manganese carbonate 4‑11 parts, washed kaolin 30‑50 parts, Mix evenly, sprinkle 100-130 parts of aluminum phosphate sol-pseudo-boehmite composite glue, knead, extrude, dry, and roast at 500-550°C; the roasted bars are soaked in aqueous acetic acid solution, and after drying, isolate the air and add methanol Under the condition of 300-330 ℃ roasting 2-4hr, the low-temperature flue gas denitrification catalyst is prepared; at 120-180 ℃, the concentration of CO is relatively low, and it reacts with NOx to form N 2 Under the condition of required excess of 10-200%, 3000mg / m 3 NOx treatment below ≤60 mg / m 3 , including 300‑500mg / m 3 NOx treatment to ≤40mg / m 3 .

Description

technical field [0001] The invention belongs to the technical field of NOx-containing gas treatment, and in particular relates to a low-temperature flue gas denitrification catalyst using CO to selectively reduce NOx and its application. Background technique [0002] In industrial production, there are many combustion and roasting processes with a small amount of tail gas, and the exhaust stream contains a relatively low concentration such as 300-3000mg / m 3 NOx and CO with a slightly higher concentration, the gas flow temperature is lower such as 100-160 °C, and there are generally fluctuations in temperature and gas flow. This kind of gas is treated by dry chemical denitrification agent, or wet chemical absorption denitrification treatment, which can reach 200 or 100mg / m 3 However, it is inconvenient to pass the selective catalytic reduction reaction (NH 3 -SCR) for denitrification. The dry chemical denitrification treatment has high cost of solid denitrification agent a...

AI Technical Summary

Problems solved by technology

In this study, due to the high concentration of CO, when the conversion rate is high, the catalyst particles and bed temperature will increase significantly, thereby improving the NO removal rate. If the volume concentration of CO is 0.15%, the catalyst particles and bed temperature When the temperature is at the corresponding value, the NO removal rate will drop significantly

On the other hand, when an alumina carrier calcined at a temperature below 850°C is used, because of its high activity, a nitration reaction will occur at a temperature below 180°C and oxygen-containing conditions, resulting in the gradual deactivation of the catalyst; 850°C The alumina carrier calcined at the above temperature is not suitable for the preparation of the catalyst due to its low specific surface

[0007] There is also the prior art of using noble metals as catalyst active components, which has high activity in the low-temperature reaction of CO selective reduction of NOx, but the cost is too high, and it is not easy to apply in ordinary occasions