Ammonium Metatungstate Preparing Tungsten Trioxide

Ammonium metatungstate is a tungsten chemical in the form of highly soluble hydrated crystals, it is white or slightly yellow crystals which has no harmful components and slightly acidic. Due to its solubility in water, it can be used as raw material to produce tungsten trioxide.

ammonium metatungstate picture

Use ammonium paratungstate as raw material and heat to 220-280℃. After that it will lose ammonium and crystal water and transform into ammonium metatungstate. Continuously heat ammonium metatungstate to 600℃ until it loses all ammonium and crystal water, cool it down and crystallize, after spray drying it turns into yellow tungsten trioxide.

Ammonium metatungstate preparing tungsten trioxide is easy to operate, the finished product is of good uniformity. Tungsten trioxide can be used to made tungsten product and shielding materials which is widely used in industry.

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Ammonium Metatungstate for Tungsten Trioxide Based Ultra-Strong Acid Desulfurization Catalyst

The sulfide in the In the fuel will unavoidable release into the air in the form of gas when in the combustion process, which will probably causes a series of issues that destroying ecosystems like acid rain, damaging buildings. As the improving of people's awareness of environmental protection and vehicle fuel emission standards, increasingly strict restrictions on the sulfur content of fuel oil index has been worked out, therefore, the production and using of ultra-low sulfur fuel oil is imperative. In deep desulfurization, the application of traditional method of hydrodesulfurization (HDS) has been limited, because of its disadvantages such as harsh reaction conditions, equipment investment and higher operating costs.

desulfurization catalyst picture

Oxidative desulfurization is using an oxidizing agent to oxidize the sulfur compounds like thiophene in the fuel which are difficult to remove to sulfoxide or sulfone sulfur-containing materials with stronger polar in normal temperature, pressure and the presence of catalyst conditions, and then removing the sulfoxide or sulfone sulfur-containing materials by the methods like extraction, thus to achieve the goal of deep desulfurization. Oxidative desulfurization is considered to be a very attractive desulfurization technology, which usually consists of two steps: first, the fuel sulfide oxidation; second, removing the oxidized sulfur compounds from fuel oil by extraction, adsorption and distillation methods.

 The key of desulfurization method is developing an oxidative desulfurization catalyst with good properties of high desulfurization rate, oil yield, and low cost. Research indicates that a kind of zirconium hydroxide as a carrier, then immerse in the aqueous solution constitute of ammonium metatungstate after finely crushed; the immersion liquid placed in an ultrasonic generator ultrasonic to promote the dipping, evaporating the water, dried, and roasting at the high temperature to generate the WO3/ZrO2 solid ultra-strong acid desulfurization catalyst. This catalyst exhibits good activity and selectivity, and high desulfurization rate when used for the deep desulfurization of diesel fuel.
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Ammonium Metatungstate for Tungsten Trioxide Based Ultra-Strong Acid Desulfurization Catalyst

The sulfide in the In the fuel will unavoidable release into the air in the form of gas when in the combustion process, which will probably causes a series of issues that destroying ecosystems like acid rain, damaging buildings. As the improving of people's awareness of environmental protection and vehicle fuel emission standards, increasingly strict restrictions on the sulfur content of fuel oil index has been worked out, therefore, the production and using of ultra-low sulfur fuel oil is imperative. In deep desulfurization, the application of traditional method of hydrodesulfurization (HDS) has been limited, because of its disadvantages such as harsh reaction conditions, equipment investment and higher operating costs.

desulfurization catalyst picture

Oxidative desulfurization is using an oxidizing agent to oxidize the sulfur compounds like thiophene in the fuel which are difficult to remove to sulfoxide or sulfone sulfur-containing materials with stronger polar in normal temperature, pressure and the presence of catalyst conditions, and then removing the sulfoxide or sulfone sulfur-containing materials by the methods like extraction, thus to achieve the goal of deep desulfurization. Oxidative desulfurization is considered to be a very attractive desulfurization technology, which usually consists of two steps: first, the fuel sulfide oxidation; second, removing the oxidized sulfur compounds from fuel oil by extraction, adsorption and distillation methods.

 The key of desulfurization method is developing an oxidative desulfurization catalyst with good properties of high desulfurization rate, oil yield, and low cost. Research indicates that a kind of zirconium hydroxide as a carrier, then immerse in the aqueous solution constitute of ammonium metatungstate after finely crushed; the immersion liquid placed in an ultrasonic generator ultrasonic to promote the dipping, evaporating the water, dried, and roasting at the high temperature to generate the WO3/ZrO2 solid ultra-strong acid desulfurization catalyst. This catalyst exhibits good activity and selectivity, and high desulfurization rate when used for the deep desulfurization of diesel fuel.
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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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Ammonium Metatungstate Preparing Tungsten Trioxide

Ammonium metatungstate (AMT) is an appearance of white or slightly yellow crystalline powder, its water-soluble is 300g / 100ml, it slightly soluble in water; when the temperature reaches at 20 ℃, its solubility is less than 2%. Ammonium metatungstate is used in making metal tungsten, steel, fireproof fabric and for the ceramic industry. Usually, we take ammonium tungstate solution as raw material to obtain ammonium metatungstate solution by solvent extraction or ion exchange method, and then evaporate it to prepare crystals of ammonium metatungstate. Ammonium metatungstate is also used in the manufacture of various petrochemical catalysts and other tungsten compounds, and it is the main raw material refinery tungsten-based catalyst. According to the features of ammonium metatungstate slightly soluble in water, we prepare tungsten trioxide in this case.

AMT

Ammonium metatungstate preparing tungsten trioxide is based on taking ammonium metatungstate as raw materials, heating ammonium metatungstate to 220-280 ℃; it can be converted to ammonium metatungstate when it loses some ammonia and crystal water, and then continue to heat ammonium metatungstate to more than 600 ℃, when ammonium metatungstate loses all crystal water and ammonia, cooling and crystallization, the finished product is dried thoroughly into yellow tungsten trioxide.

There many methods of preparation of ammonium metatungstate, such as acid method, thermal decomposition method, ion exchange, solvent extraction method. The method of ammonium metatungstate preparing tungsten trioxide is simple and easy, and it meets the needs of industrial production.

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Ammonium Metatungstate for Tungsten Trioxide Denitration Catalyst with Dioxin Removable

Dioxins are a class of substances with persistent pollution, with its highly toxic, the small amount of them can cause serious damage to health or fatal, so they has become the focus of public attention in recent years. Dioxins are very stable compounds, which appear in a colorless solid at room temperature; it will accumulate in fat after entering human body with its high lipophilicity; In addition, it is extremely difficult to remove once the pollution occurs, because the strong bond between it and the soil or other particulate material.

de-dioxin and denitration catalyst

The most effective way to remove dioxins is still the selective oxidation-reduction, experimental proposed a preparing method of tungsten trioxide denitration catalyst which with dioxin removable; also the anti-sulfur poisoning is improved, and possess the good catalytic activity at the same time. It is prepared as the follow steps:

1. Successively add the equal amount of titanium dioxide powder and carbon nanotubes into the dilute ammonia to form the carrier mixture with stirring well, then transferred to the ultrasonic cleaning machine for an ultrasonic treatment;

2. Dissolve ammonium metavanadate, ammonium sulfate, ammonium metatungstate in the dilute aqueous ammonia in turns to form of a mixed solution of the active ingredient, then thoroughly stirred under heating, transferred into a rotary evaporator furnace for drying to give a mixture of the active ingredient;

3. Successively add the active ingredient mixture, glass fiber, cellulose and polyacrylic acid  into the mixed carrier to form a catalyst mixture, heat with stirring to dry and stop until the catalyst mixture of a moisture content of about 30%;

4. Get the tungsten trioxide denitration catalyst products with dioxins removable by extruding, drying, calcining the catalyst mixture.

This kind of catalyst is constituted by the following components: 1.2% of vanadium pentoxide, 7% of vanadium oxide sulfate, 1.5% of tungsten trioxide, 2.5% of glass fiber, 1.5% of polyacrylic acid cellulose, 1.1% of cerium sulfate, 14% of manganese sulfate, the rests are carriers (titanium dioxide and carbon nanotubes with the mass ratio of 1:1).

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