Ammonium Metatungstate Prepares Tephra Contained Tungsten Trioxide Denitration Catalyst

Tephra is defined as the gravel and mineral particles which are erupted from a volcano and the granule less than 2 mm in diameter. At the explosive of the volcanic activity, the solid rocks and lava are broken down into the fine particles and formed to volcanic ash. In the mix materials of some pozzolana, there are active ingredients, such as a certain number of active silica, activated titanium oxide.

The coal takes the domination of China's energy structure, and one of the main sources of air pollution is the nitrogen oxide which is produced by the consumption of coal; the nitrogen oxide will not only cause acid rain, photochemical smog and other issues which damages to the global environment, but also seriously endanger human health. Conventional manufacturing of honeycomb catalyst is taking tungsten trioxide and nanoscale titanium dioxide as the main raw material, and mixing with water, binders, extrusion aid, reaming, lubricants, glass fibers and so on to fully kneaded to obtain a plastic pug, then extruded to wet honeycomb catalyst, finally get the molded catalyst after drying and calcining.

tephra and denitration catalyst

Study has found that the tungsten trioxide denitration catalyst containing tephra which the components include: nano titanium dioxide powder 72~81, volcanic tephra 5~15, ammonium metatungstate 0.9~3, ammonium metavanadate 0.7~2, monoethanolamine 2~6, carboxymethyl cellulose 2, Polyoxyethylene of 2, 1~3 lanthanum nitrate (Remarks: the unit is part). The preparation method is as follows:

1. Mix the monoethanolamine, deionized water and ammonium metavanadate together, and fully dissolved by heating and stirring to prepare a solution of ammonium metavanadate;

2. Respectively dissolve lanthanum nitrate and ammonium metatungstate in water at room temperature, continually stirring for 1 hour to obtain the solution of ammonium metatungstate and lanthanum nitrate;

3. Mix the tephra, nano titanium dioxide with deionized water, ammonium metavanadate and ammonium metatungstate solution, polyethylene oxide, lanthanum nitrate solution for high-speed mixing evenly, then standing for 1-12 hours to obtain pug;

4. Warmed and dried the pug;

5. Calcine the dried pug, which is obtain the tungsten trioxide denitration catalyst products containing tephra after calcined at a maximum temperature of 600°C for 30 hours.

Studies have shown that it can reduce the high amount of conventional titanium dioxide by adding volcanic tephra, thereby reducing costs; tungsten trioxide decomposed from the calcination of ammoniummetatungstate in the production process; the cost will be reduced, compared with directly using nanoscale titanium dioxide which containing tungsten trioxide as a raw material; the added polyethylene oxide in calcined product improving pore volume and distribution of the products, increasing the specific surface area, thus to effectively improve the denitration performance; therefore, we will know this kind of tungsten trioxide denitration catalyst containing tephra has a low manufacturing cost, high specific surface area of catalyst products, wide operating temperature, and has the advantage of good catalytic denitration performance at the same time.

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