Ammonium Metatungstate Preparing WO3 Plate SCR Denitration Catalyst--Dry Powder Mixing Method

The main component of tungsten trioxide plate denitration catalyst is just similar to honeycomb denitration catalyst, both are based on vanadium pentoxide, tungsten trioxide as the main active substance, titanium dioxide as the carrier. Compared with cellular, it has a stronger capacity of ash anti-clogging, wear resistance, less consumption under dust and low pressure loss ect.; although its market share is only about 1/3 of the cellular, it will gradually expand with the further launch of high-dust flue gas denitration in China.

plate denitration catalyst

The process that dry powder mixing method prepares tungsten trioxide plate denitration catalyst is as follows:
1. Put the titanium dioxide powder, stearate acid, AK sugars, methyl cellulose into the kneader, stir for about 10 minutes;
2. Add pulp slurry and stir for about 10 minutes;
3. Add silica sol solution and continually stir for 10 minutes;
4. Add the lactic acid, ammonia, ammonium metavanadate and suitable amount of deionized water into the mixed solution prepared above, then stir for about 1 hour for sufficiently reacting;
5. Add glass fiber and tungsten compound containing with tungsten trioxide (ammonium paratungstate, ammonium metatungstate ect.), stirring for about 30 minutes to prepare a catalyst mud;
6. Forming to generate the wet catalyst;
7. Dry the catalyst at 100 °C to remove excess free water;
8. Roasting, the purpose of it is: at the same time titanium dioxide crystal transition does not occurred, decompose the organic matter and active ingredient precursors; studies have shown that the active ingredient precursors and organic substances are decomposed completely at 400°C, the polymerization of vanadium pentoxide has been improved as the temperature increasing, but the titanium dioxide crystalline transition may occur, thus will cause the properties of catalyst reduced; therefore, calcination at the proper temperature, we can finally get the best active tungsten trioxide plate denitration catalyst.

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Ammonium Metatungstate for WO3-Based Oxidative Desulfurization Catalyst

Oxidative desulfurization process consists of two steps: Firstly, oxidize the organic sulfur compounds in the oil into polar sulfone substance; secondly, separate the sulfone substances to achieve the purpose of desulfurization by adsorption, extraction and distillation methods s. Wherein the transformation of sulfone substance is the key step.

Sulfone is a group organic compound which contains sulfonyl, and often combined S with two carbon atoms (e.g. two hydrocarbons or simple divalent), generally the stable crystalline compounds, can be generated by the oxidation of organic sulfides or other methods.

WO3 desulfurization catalyst photo

Supported WO3-based oxidative desulfurization catalyst is achieving deep desulfurization by the oxidation catalyzed reaction of organic peroxide and sulfur heterocyclic aromatic compounds under mild conditions. The preparation program is under a hydrogen atmosphere or an inert gas atmosphere, plasma treatment supported tungsten trioxide based catalyst.

Preparation process are as follows:
1. The equal volume dipping method to prepare supported WO3/SiO2 catalyst: Weigh 0.852g of ammonium metatungstate and dissolved in 9ml of dubbed deionized water to form a solution and dripped drop by drop into the 3g silica with stirring;
2. Static in the room temperature for 12h, and then dried at 120°C for 4 hours;
3. Raise the temperature by the rate of 2V/min to 500 ° C, calcined for 5 hours to obtain the tungsten trioxide silica supported catalyst, wherein the loaded tungsten trioxide amount is 20% of the mass fraction of (of the total catalyst mass meter);
4. Under Ar atmosphere, treating the WO3/SiO2 catalyst with plasma;
Put 2mL of catalyst in the dielectric barrier discharge plasma reactor; control the Ar gas flow rate at 100mL/min under normal pressure; discharge frequency of plasma is about 10kHz; the input voltage of 50 volts; the input power of about 15 watts for 30min, and then get the supported WO3-based oxidative desulfurization catalyst.
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Ammonium Metatungstate Prepares WO3 Contained Hydrodesulfurization Catalyst

Boehmite is the main raw material to produce aluminum oxide. γ-Al₂O₃ obtained by the calcination of boehmite as the carrier, and load nickel oxide and tungsten trioxide, add a additive-fluorine, thus to produce tungsten trioxide hydrodesulfurization catalyst with high activity. The different purities of boehmite have a certain degree of influence on the activity of the desulfurization catalyst.

Boehmite 

Low-purity boehmite prepares WO₃ hydrodesulfurization catalyst

1. Take aluminum hydroxide powder generated by aluminum sulfate- sodium aluminate method from boehmite with a purity of 35% by weight, add the extrusion aid and water, extruded strip of 1.2 mm in diameter, dry in an oven at 120 ℃for 4 hours and then roasted at 550 ℃ in a tube furnace under the air for 4 hours to obtain γ-Al₂O₃ (A);

2. Dissolve ammonium fluoride in deionized water, add the carrier which is cooled down to room temperature for impregnation for 4 hours at room temperature;

3. Separate and dry the wet fluorinated alumina bar in an oven at 120 ℃ for 4 hours, then heated at 500 ℃ in a tube furnace with dry air for 4 hours to obtain fluorinated alumina strip, removed and cooled down to room temperature;

4. Add fluorided alumina to the deionized water containing with ammonium metatungstate and nickel nitrate, and separate after dip at room temperature for 4 hours to obtain wet catalyst;

5. Dry the wet catalyst in an oven at 120 ℃ for 4 hours, and calcine under the air in a tube furnace at 500 ℃ for 4 hours to obtain the catalyst A.

High-purity boehmite prepares WO₃ hydrodesulfurization catalyst:

1. Take aluminum hydroxide powder (obtained from the hydrolysis of aluminum alkoxide) with the boehmite purity of 70% by weight, add extrusion aid and water, then squeeze to a strip with a diameter of 1.2 mm, dry in an oven at 120 ℃ for 4 hours, then calcine at 550 ℃ for 4 hours in a tube furnace accompanying with the air to give γ-Al₂O₃ (B);

2. γ-Al₂O₃ (B) for the preparation of the carrier catalyst B, the same preparing method of the low purity boehmite.

Analysis showed that the aluminum oxide generated from high-purity of boehmite has the larger amount of acid, while the boehmite prepared by calcination has a larger amount of strong acid; tungsten desulfurization catalyst B prepared by aluminum alkoxide hydrolysis of a high-purity oxide boehmite has a higher activity.

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Ammonium Metatungstate Prepare WO3 Contained De-Dioxin and Denitration Catalyst

Dioxin refers to the collectively chlorine-containing organic compounds which contain one or two oxygen-bond connecting with two benzene rings, the carcinogen with most toxic, very stable and difficult to break down, besides, the dioxin has reproductive, immunity and endocrine toxicity. The main active ingredients of de-dioxin catalyst are titanium dioxide, vanadium pentoxide, tungsten trioxide, cobalt oxide and other transition metal oxides, or a noble metal (platinum, gold, etc.). The researches on an efficient, economic catalyst with both functions of de-dioxin and denitration catalyst is very necessary.

honeycomb denitration catalyst

Waste hydrodesulfurization catalyst generated by the refinery contains a lot of metals, such as aluminum, tungsten, nickel, cobalt, vanadium, which is a relatively inexpensive resource. The recycling of it can not only recycle the useful resources, but also reduce the environmental pressure, and thus become a hot topic. Experiments have shown that the waste hydrodesulfurization catalyst can be used to prepare tungsten trioxide contained of de-dioxin and denitration catalyst, and prepared as follows:

1. Waste hydrodesulfurization catalyst is carried out a pretreatment by washing with deionized water and drying;

2. Mix the carrier-titanium dioxide and the active ingredient-tungsten trioxide. The ammonium metatungstate and titanate are mixed according to mass ratio of 1: 9 to give a suspension, then filtered and the wet powder is calcined, to obtain the titanium dioxide loading with tungsten trioxide;

3. Ball grinding to mix the waste hydrodesulfurization catalyst and the carrier to obtain a raw material mixed powder, adding oxalic acid (or citric acid) and water to mix uniformly at the same time;

4. Dry and calcine the semi-finished products o give the finished-products--tungsten trioxide catalyst with the function of both de-dioxin and denitration.

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