Low-temperature sulfur-resistant denitration catalyst and preparing method thereof

Abstract

The invention discloses a low-temperature sulfur-resistant denitration catalyst and a preparing method of the low-temperature sulfur-resistant denitration catalyst. The low-temperature sulfur-resistant denitration catalyst is formed by mixing, by weight, 15%-100% of active sites and 0-85% of carbon-based carriers; the active sites are formed by mixing one or two of the first active sites and the second active sites; the first active sites are composed of Mn(0.1-0.8)Ce(0.2-0.9)Ox or Mn(0.1-0.8)Mg(0.2-0.9)Ox dispersed into a 3A molecular sieve, and the value of the x is determined according to the content and the oxidation valence state of metallic elements in the chemical formula; the second active sites are composed of Mn (0.1-0.8)Mg(0.2-0.9) or Mn (0.1-0.8)Ce (0.2-0.9)Ox with the surface coated with a TiO2 or SiO2 protecting layer. According to the method, one or more of the first active sites and the second active site are mixed with carbon-based carriers to obtain the low-temperature sulfur-resistant denitration catalyst. As surface dewatering is performed on the catalyst, water molecules contained in flue gas are attached in an open-framework structure of the catalyst to form capillary condensation very difficultly or form vitriol or sulphurous acid ammonium salt with NH3 and SO2 or SO3 to cause deactivation of the catalyst.

Description

【Technical field】 [0001] The invention relates to the field of treatment of fossil fuel combustion tail gas, in particular to a low-temperature sulfur-resistant denitrification catalyst and a preparation method thereof. 【Background technique】 [0002] It is well known that nitrogen oxides (NO x ) is a harmful gas, the main air pollutant, not only can cause acid rain, photochemical smog, greenhouse effect and the destruction of the ozone layer; it can also cause serious water quality and soil quality deterioration, urban haze weather (PM2.5) and other environmental pollution problem, which poses a great threat to human health. 90% SO in air pollutants 2 and 70% NO x From the combustion of coal, the energy structure dominated by coal has led to a high total amount of air pollutant emissions. Potential environmental problems continue to emerge. Air pollution in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei region and other urban agglomerations has gra...

AI Technical Summary

Problems solved by technology

90% SO in air pollutants 2 and 70% NO x From the combustion of coal, the energy structure dominated by coal has led to a high total amount of air pollutant emissions. Potential environmental problems continue to emerge. Air pollution in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei region and other urban agglomerations has gradually become obvious. regional characteristics, the type of acid rain has changed from sulfuric acid type to sulfuric acid and nitric acid compound type, and the pollution of nitrogen oxides has not been effectively controlled

(2) Molecular sieve catalysts selectively reduce NO at higher temperatures x Has high catalytic activity, and the active temperature range is relatively wide, but resistant to H 2 O and SO 2 Poor ability

(3) Carbon-based catalysts exhibit good SCR activity at low temperatures, but their ability to resist sulfur poisoning is not strong, especially unstable and flammable at temperatures above 250 °C, which hinders their use in SCR research. development in

However, the problem is that the medium temperature catalyst must be operated at a temperature higher than 350°C to avoid SO 2 Weaken the activity, which requires that the SCR catalyst system must be placed above the desulfurization and dust removal devices (such as figure 1 shown) to take advantage of the high temperature of the flue gas, otherwise an air preheating device is required

However, such an installation position will greatly reduce the allowable operating temperature of the SCR reactor (150-200°C).

Such a reaction temperature makes all currently used high-temperature SCR catalysts significantly reduce their activity and cannot complete the task of denitrification.

At the same time, at such low temperatures, the SO present in the flue gas 2 Will react with added ammonia to form ammonium sulfate or ammonium sulfite which deposits on the catalyst surface leading to its deactivation

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