In-situ level nano selenium carbon based mercury removal adsorbent material and preparation method and application thereof

Abstract

The invention discloses an in-situ level nano selenium carbon based mercury removal adsorbent material and a preparation method and application thereof. Sulfur dioxide gas is introduced into a selenium-loaded carbon based adsorbent material to prepare the in-situ level nano selenium carbon based mercury removal adsorbent material through a gas phase in-situ reduction method. The preparation methodis simple, the preparation cost is low, and the prepared in-situ level nano selenium carbon based mercury removal adsorbent material has the advantages of being high in selenium crystal adhesion force, not easy to fall off, and good in dispersity. There are many mercury adsorption active sites and active centers, the mercury adsorption capacity is high, the material has long service life, and therequirements of the mercury related industry, natural-gas mercury removal, a non-ferrous metal smelting plant, a coal-fired power plant and the like for complex mercury-containing flue gas exhaust processing are met.

Description

technical field [0001] The invention relates to atmospheric mercury pollution control technology, in particular to a preparation method, material and application of an in-situ nanometer selenium carbon-based mercury removal adsorption material. Background technique [0002] Mercury (Hg) is one of the most toxic heavy metal elements in the natural environment. Mercury is very volatile at room temperature, and the generated mercury vapor exists in a single molecular state, and the saturation concentration of mercury in the air is relatively high. At 5-30°C, the partial pressure of mercury vapor is 0.04-0.37Pa, and the saturation concentration is 3.52-29.5mg / m 3 , the heat of vaporization of mercury is 271.7J / g. [0003] At present, industries involved in atmospheric mercury pollution include PVC industry, anthraquinone compound production industry, coal-fired power plants and their coal-fired boilers, petroleum refinery industry, chemical industry, steel and non-ferrous metal...

AI Technical Summary

Problems solved by technology

[0008] (1) Mercury removal from coal-fired power plant fly ash, North China Electric Power University pioneered online halogen modification adsorption mercury removal technology for coal-fired power plant fly ash described in the invention patent [CN106732331A] and developed related equipment, with a comprehensive mercury removal rate of 90%, but If the mercury content in the import is too high, its use effect is not stable, and there is no corresponding mercury discharge standard for the mercury discharge in the export, and the elements iodine and bromine used are rare non-metallic elements, the price is high and it is not easy to recycle (in a certain Under medium and high temperature conditions, bromine and iodine elements are easily oxidized to Br 2 , I 2 , HBr, HI and other toxic vapors are discharged into the atmosphere, causing secondary pollution, seriously damaging the ecological balance of the air and human health), and the overall cost is high

Invention patent [CN103495322A] describes "an integrated device and method for dust removal and mercury removal", although the method is good, it does not mention the problem of mercury emission compliance, and the process is relatively complicated, so it cannot be really used in industrial production

[0009] (2) Activated carbon demercuration, the adsorbent for flue gas demercuration and its preparation method described in the invention patent [CN101497029] uses low-cost sulfur and activated carbon to make sulfur-loaded activated carbon, but does not specify the mercury removal efficiency and The standard emission limit that can be achieved after mercury removal cannot really prove the adsorption effect of sulfur-loaded activity on mercury

The flue activated carbon injection method (ACI) described in the document "Activated Carbon Injection Technology for Controlling Mercury Emissions in Coal-fired Power Plants" by Zhou Qiang and others is the most mature and feasible technology for reducing mercury emissions in coal-fired power plants. It has been widely used in coal-fired power plants in the United States. The development of ACI technology in the United States has gone through laboratory tests, pilot tests, and field tests. At present, there are still problems such as high cost, large concentration range of acid gases in flue gas, and short residence time of adsorbents.

[0010] Plasma mercury removal, a flue gas dedusting and mercury removal device with a plasma reactor combined with a film-coated filter bag described in the invention patent [CN105709597A] and its treatment method, the oxidation rate of plasma to elemental mercury is only 70%, which cannot reach Up to 100% oxidation efficiency, back-loaded Mn-Ce / TiO 2 Catalyst polytetrafluoroethylene layer, its coating thickness is relatively thin (if the thickness is thicker, the space resistance will increase, the exhaust gas will be difficult to pass through the system normally, and the system will be paralyzed), mercury vapor can easily penetrate this catalyst layer, and it is difficult to ensure the remaining 30% of the elemental mercury is all catalyzed and adsorbed, and the total mercury removal efficiency is between 65% and 92%, and the mercury removal efficiency is not stable

The double-tower plasma-coupled sodium-based absorption flue gas deep purification device and method described in the patent [CN105056723A] does not mention the removal rate of mercury, and whether elemental mercury can meet the requirements of the national emission limit standard for mercury Not explained, unable to prove that it can be normally used in the industrial production process, this technology is not yet mature

[0011] (4) Amalgam-type mercury removal agent, a preparation method of a silver-based mercury removal agent described in the invention patent [CN104645927A], which does not explain the mercury removal effect that this type of mercury removal agent can achieve, and the mercury removal of mercury-containing gas The mercury content in the final tail gas is uncertain, and the mercury emission limit of the national standard that can be achieved is uncertain. This kind of mercury removal technology is immature

Honeywell produces UOP HgSIVTM molecular sieve renewable adsorbent, which can be used for the adsorption of mercury in natural gas, but this kind of adsorbent can only be used for mercury removal of natural gas in small quantities. It is suitable for non-ferrous metal smelting, coal-fired power plants, and mercury recovery industries. The ultra-large flue gas flow rate, the use cost of this kind of adsorbent is bound to be high

The cost of using amalgam-based adsorbents under large-scale flue gas conditions will be very high, and they are not really used under the conditions of ultra-large flue gas flow

[0012] (5) Selenium-loaded adsorbent, a nano-selenium-loaded activated carbon and its chemical preparation and application described in the invention patent [CN106582517A] mentioned that sodium selenite is dispersed in polyvinyl alcohol aqueous solution, and activated carbon is added, Reduction with ascorbic acid, drying to obtain activated carbon loaded with nano-selenium, the mercury removal efficiency is between 94% and 99%, but according to the content of [0007] in this patent, this type of selenium-loaded activated carbon is mainly used in new research and development Masks cannot be used in the treatment of large-scale mercury-containing flue gas and mercury-containing tail gas from other important mercury-related industries.

Invention patents [CN107051045A] and [CN106902776A] provide sponges loaded with nano-selenium and their chemical preparation and application, and the preparation method of mercury-removing wallpaper. In this method, the sponge is placed in a polydopamine solution, and sodium selenite is adsorbed. Reduction to obtain sponges loaded with nano-selenium. The production process is easy to generate waste water. The mercury-containing sponge after mercury-containing gas demercuration cannot be treated. The mercury emission limit that the gas can reach after demercury gas has not been defined, and the effect of industrial use is unknown.

[0014] ①Reduction is carried out in aqueous solution. The reducing agent ascorbic acid (VC) is a strong organic reducing agent. When PH≦4, its redox potential is 0.166V, while E Se +4 / Se 0 =0.74V, the nano-selenium particles generated under the high reduction potential are easy to agglomerate, and finally sponge-type selenium particles are formed on the activated carbon.

[0015] ②Elemental selenium is insoluble in water, affected by the weak wettability of water molecules to selenium particles, the reduced selenium is easily eluted by the aqueous solution, and the spherical selenium particles float in the solution, resulting in a large amount of active selenium on the carbon-based material. Adhesively attached to activated carbon or sponge, with low adsorption activity for mercury

[0016] ③After using this material to treat mercury-containing gas, the mercury-containing waste generated at the end is likely to cause secondary mercury pollution

[0017] ④In the above three patents, there is no mention of the state's limit value for the discharge of mercury and its compounds in mercury-containing tail gas from various mercury-related industries, nor does it explain the industrialization of the sponges loaded with nano-selenium and activated carbon loaded with nano-selenium. Whether the mercury content in the tail gas after mercury-containing flue gas can reach the mercury emission limit stipulated by the Ministry of Environmental Protection, therefore, cannot really be applied to the complex containing a large amount of water, sulfur dioxide, nitrogen oxides, particulate matter, carbon monoxide, carbon dioxide and other heavy metals. Mercury Fume Treatment