A sulfur-loaded molecular sieve for mercury removal and its preparation method

Abstract

The invention belongs to the field of mercury removal of coal-fired flue gas, and specifically discloses a sulfur-loaded molecular sieve for mercury removal and a preparation method thereof. Accordingto the preparation method, a molecular sieve placed in a sulfur-containing gas is subjected to plasma treatment, the sulfur-containing gas is converted into highly-active sulfur atoms or free radicals under the function of plasma and loaded on the molecular sieve to form sulfur active sites on the surface of the molecular sieve, and therefore the preparation of the sulfur-loaded molecular sieve is completed. Thus, the number of the sulfur active sites on the surface of the molecular sieve is increased, the mercury removal performance of the molecular sieve is improved, the preparation processis simple, the consumed time is short, the cost is low, the problem of complicated operation in the high-temperature activation and immersion modification methods is solved, products generated afterthe mercury removal of the sulfur-loaded molecular sieve are relatively stable, and the secondary release of mercury is avoided.

Description

technical field [0001] The invention belongs to the field of mercury removal from coal-fired flue gas, and more specifically relates to a sulfur-loaded molecular sieve for mercury removal and a preparation method thereof. Background technique [0002] Coal accounts for more than 60% of my country's primary energy structure, and this pattern will not change in the short term. In the process of burning coal, some mercury will be emitted. Mercury is toxic and bioaccumulative, which is very harmful to the human body. Mercury in coal-fired flue gas mainly has three forms: oxidized mercury (Hg 2+ ), particulate mercury (Hg p ) and elemental mercury (Hg 0 ). most Hg 2+ and Hg p Can be removed by existing pollutant control devices, but Hg 0 It is insoluble in water and extremely volatile, so it is difficult to remove. [0003] Currently widely used to remove Hg 0 The current technology is activated carbon injection technology, although this technology can remove Hg in coal-...

AI Technical Summary

Problems solved by technology

most Hg 2+ and Hg p Can be removed by existing pollutant control devices, but Hg 0 Insoluble in water and extremely volatile, so it is difficult to remove

[0003] Currently widely used to remove Hg 0 The current technology is activated carbon injection technology, although this technology can remove Hg in coal-fired flue gas 0 , but this method is relatively high in C / Hg, which leads to an increase in the carbon content of fly ash, which is not conducive to the secondary resource utilization of fly ash, and is difficult to be widely used. Therefore, scholars have proposed various methods to increase the Hg in coal-fired flue gas. 0 The removal efficiency, such as:

[0004] Patent CN105854544A discloses a mercury removal and purification method for flue gas. In this method, a flue gas conditioner is used to load and modify the zeolite, and the modified zeolite is impregnated with halide salts, and then the sulfur-halogen compound and halogen steam through the adsorption container loaded with halide salt zeolite for 2-8 hours, and finally heated to remove volatile halogen to obtain flue gas mercury removal adsorbent; the preparation method needs to go through multiple steps such as modification, impregnation and steam activation. The operation process is complicated and time-consuming;

[0005] Patent CN104785204A discloses a liquid-state modified composite molecular sieve mercury remover and its preparation method. In this method, the molecular sieve is purified by solution impregnation and roasted at 120°C to 600°C to remove impurities, and finally the molecular sieve is impregnated into CuCl 2 Perform ion exchange in the solution to obtain a composite molecular sieve mercury removal agent; this method requires two dippings in the solution, which will result in a large consumption of chemical reagents;

[0006] Patent CN106914215A discloses a modified and impregnated sulfur molecular sieve mercury remover and its preparation method. In this method, walnut shells are carbonized at 900°C to 1000°C, and the carbonized walnut shells are activated by steam under carbon dioxide and an oxidizing agent. The activated walnut shell and sulfur are mixed and heated to prepare a modified impregnated sulfur molecular sieve mercury removal agent; this preparation process needs to be carried out at high temperature, and it needs to be activated by steam under carbon dioxide and an oxidant, and the preparation path is complicated and consumes a lot of energy;

[0007] Patent CN106040210B discloses a mercury removal method and device based on activated carbon on-line activation. In this method, activated carbon and high-activity gas are subjected to low-temperature plasma treatment, so that the high-activity gas is loaded on the surface of activated carbon in an atomic or ion state, and the mercury removal of activated carbon is improved. efficiency; however, this method reacts with elemental mercury to form mercury compounds (such as HgCl 2 ) will dissolve under acidic conditions, resulting in the secondary release of mercury, and the injection of activated carbon will affect the secondary utilization of fly ash

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