Photoelectrochemical Cells Hydrogen Production (PEC) technology is based on solar energy and water, and the two substances are renewable with no byproduct, not pollution to the environment, and also can be applied to small as well as large scale development. Therefore, the technology is the most attractive way to produce hydrogen by solar energy. The property of photoelectric which is consisted of semiconducting materials determines the efficiency of PEC. Compared with the traditional semiconductor materials such as titanium dioxide and zinc oxide, W0₃ can be well applied with the advantages that narrow band gap (2.5ev), absorbing solar spectrum in a wavelength greater than 500nm in visible light, and low price, good chemical stability, non-toxic, no corrosion.



The method for preparing nano tungsten trioxide film using ammonium paratungstate (APT) as raw material we describes in this paper, has advantages that stable precursor solution, reuseable, production process simplified, cost reduced, high purity of the obtained product and so on.
The reagent used: apt, modifier (can be one of citric acid, polyethylene glycol octyl phenyl ether, oleic acid and acetyl acetone), deionized water, dispersing agent. The dispersing agent plays the role of constituting large numbers of mass weaving structures to make sure the crystals not easy broken in the dry, hot environment; and the modifier will increase stability of the precursor solution, also prevent the nano tungsten trioxide to reunion thus leading the film to peeling in the condition of high temperature.
Coating substrates: aluminum, stainless steel, glass, graphite or silicon wafers.

Currently, the prepared pyrochlore type tungsten trioxide (Pyrochlore-type H₂W₂O₇) is A-multi-bit deletion as the layered perovskite tissue. Pyrochlore type tungsten trioxide takes tungsten WO₆ distorted octahedral structural as motifs, it builds a layered structure having six-membered ring channels by the angle of the top of the tungsten trioxide rigid skeleton, and has a three-dimensional tunnel along the (111) direction. Pyrochlore tungsten trioxide is used in layered composite materials, sensing field, and be calcimined to prepared tungsten oxide.

Pyrochlore types of tungsten trioxide are pyrochlore type structure, it is also known as yellow-stone structure or pyrochlore structure. There will be more prominent pyrochlore out of tungsten trioxide used in the preparation of battery sensing field because it is hydrate, and its unique physical and chemical properties. Currently, it is widely used in the sensing field.

In the application process, we often make pyrochlore type tungsten trioxide in LiClO₄ electrolyte 1mol / L as the cathode, and we make lithium foil as anode, and uniformly embedding Li in the pyrochlore tungsten trioxide. Last, we have a process by ion exchange for pyrochlore type tungsten trioxide containing sodium. After testing, the result shows that the finished product has the lowest resistivity, good durability and repeatability, which can exhibits good electrochromic properties.

Oxalic acid is metabolite of the organism, it is widely distributed in plants, animals and fungi in the body, and it plays different functions in different living body. Industrial oxalic acid is colorless monoclinic crystal or prism sheet or white powder; it is usually odorless oxidation oxalic acid. Its sublime is in 150 ~ 160 ℃. Oxalic acid can be used as bleaching agent, reducing agent, mordant, and it has rust function.

Oxalic acid as an additive for preparing pyrochlore type tungsten trioxide, the first steep is configuring concentration of 100g / L of sodium tungstate solution 10mL, adding an appropriate amount of oxalic acid, adjusting the pH value of the solution about 7.0, the second steep , the sodium tungstate solution is transferred to a low pressure reaction vessel, maintaining constant temperature at 140 ℃ , conditions reaction 24h, measuring the reaction rate of the solution according to the concentration of tungsten trioxide. The resulting solution is filtered and treated; water as well as the spent ion alcohol is washed 2-3 times, drying it to obtain finished pyrochlore type tungsten trioxide.

It was found that the highest rate of decomposition of oxalic acid as an additive tungstate sodium in hot water system can reach about 60%, and the reaction is faster, the decomposition rate closes to the maximum. The decomposition rate has been around 60% of small amplitude fluctuations. It exploded a short time in the entire hot water system; it is suitable for industrial production applications.

A low cost method to prepare SCR denitration catalyst which can reduce the preparation and operation cost, improve the abrasion resistant property of catalyst. The weight composes are like bellows: grounded slag powder takes 52~55%, gypsum 2.7~2.9%, partial ammonium metavanadate 1.3~1.5%, ammonium paratungstate 5.5~5.7%, silica sol 2.6~2.8%, clay 1.6~1.8%, glass fiber yarn 2.5~3.0%, methyl cellulose 2.7 to 2.9%, poly ethylene oxide 1.3~1.5%, a glycol ammonium 2.7~3.0%, distilled water of 20~23%.

The preparation steps are as follows:
1. Grinding and activate the carriers
Send grounded slag powder and gypsum by weight ratio of 17.9~20.4:1 into grinding equipment, inlet the high temperature steam (100 to 120℃), grinding and activate to get the carrier;
2. Preparation of slurry
Send carriers and ammonium metavanadate, ammonium paratungstate, silica sol, clay, glass, fiber, methyl cellulose, poly ethylene Huan and ethanol ammonium into the mixer, adding distilled water while stirring, stirring more than 2 hours until the solution uniform, to generate slurry with water below 25%;
3. Molding catalyst
Form the slurry in the required prepared shape, then dry and calcine to get the products we needed. The calcine conditions are like bellows: first calcined in 250~255℃ for 45~50 hours, then 370~390℃ calcined for 23~25 hours, again calcined at 445~455℃for 11~13 hours.

We propose a honeycomb ammonia selective catalytic reductive SCR catalyst preparation method with simple process, high strength, and denitrification activity, continued for a long time in this paper. The catalyst  uses Ti0₂ as carrier, V₂0₅ as active component, W0₃  as co-catalyst. In which Ti0₂ anatase is used to be the raw materials of carrier, 80% content of the catalyst weight; V₂0₅ is added in the form of ammonium metavanadate, 0.1%-5% of the catalyst weight percent content; co-catalyst as W0₃ added in the form of ammonium paratungstate, 1%-20% of the catalyst weight percent content.

Steps are as follows:
1. Preparation of carrier stock
Take Ti0₂ powder, stirring in the water bath at the temperature of 60~80℃, get support slurry;
2. Join the loaded active component and other additives
Slowly add ammonium metavanadate and ammonium paratungstate into the carrier stock during the mixing process, and then add a variety of additives;
3. Mixing in the pug mill and being stale
Transfer the slurry obtained in step 2 to vacuum refining mud machine mixing, and stale in the constant humidity, continue to kneading. Pug kneaded for half an hour each time, the stale time is 8 hours, repeated several times to generate mud practiced;
4. Molding. Shaped the mud in the honeycomb;
5. Drying and roasting the catalyst
Dry the honeycomb for 3~6 days in drying box which the humidity and drying speed is controllable; and then roasted in the furnace of 300~600℃ for 12~24 hours, then to obtain the final honeycomb catalyst.

Theoretically, tungsten carbide ball rely on the role of the media between ball and seat have a mutual compression to achieve cut-off function. The valve seat ring at predetermined contact pressure localized plastic deformation and elastic region, so that it is possible to compensate for manufacturing precision and surface roughness of the sphere, in order to ensure the sealing performance of the ball valve. Then we introduce some common occasions of tungsten carbide ball valve:

1. In the two-position adjustment, sealing requirements of high performance, open and close rapidly (1/4 turn open and close), the larger the pressure, the operating torque, low flow resistance, cavitation or vaporization of the piping system should use tungsten carbide ball;

2. Pipeline with corrosive media;

3. In cryogenic apparatus or high-temperature and high-pressure piping systems;

4. Full bore welded carbide ball valve can be used in pipelines and gas pipelines need buried in the ground;

5. Specially designed V-shaped openings carbide ball structure may have regulatory function;

6. Petrochemical, power systems, metallurgical industry and other fields have a higher operating temperature;

7. Refined oil and natural gas transportation or storage of piping or equipment.

In addition, due to different connectors, it can be divided into carbide ball full bore or reduced diameter valve, welded ball valves, flanged ball valves, floating ball valve threaded connection. Among flanged ball valve (which is the two pipes, fittings or equipment, each fixed in a first flange, and then between the two flanges plus flange gasket, bolt the last two law Flanges tighten it closely combine a removable connector.) the most common, both in the metallurgical oxygen piping system, or in the city gas and natural gas pipeline systems have been widely used.

Application of carbide materials plus computer-aided design (CAD), computer aided manufacturing (CAM) and a flexible manufacturing system (FMS is controlled by a unified information system, material handling system and a set of digital control and processing equipment composition, can adapt to the introduction of automated machinery manufacturing system of the object transformed Flexible manufacturing system) and other related technology allows design and manufacturing efficiency and accuracy of the ball valve have been greatly improved.

Tungsten carbide ball valve without any abrasion and wear in the rapid process of opening and closing, and the flow resistance is small and close to zero infinitely when it fully opened, which can well endure the larger pressure difference fully closed. Therefore, equal diameter ball valve can be widely used in pipeline cleaning of oil and gas work. Most of tungsten carbide ball valve due to its ability to wipe a certain opening and closing process can be used in the medium with suspended solid particles. However, since the valve seat ring material (more common with Teflon, synthetic rubber, nylon, etc.) restricted, making it suitable for a temperature range subject to certain restrictions.

Porosity is a measure of the degree of dense objects, the pore volume of the object to a percentage of the total volume; it is the degree of sintering ceramics and refractories and other products, it is the determination of porous material such as activated carbon adsorption capacity, as well as to measure the technical properties of the foam material and so on. The size, temperature and pressure of porosity are related. Generally speaking, the higher the temperature, the greater the pressure, the greater the general porosity. Porosity ceramic material is dense level of characterization.

The test results in the following table:

The data of porosity in the table above shows that the sintering temperature is 1100 ℃ and 1180 ℃, the sintered samples are in loose state, heating 2h, tungsten trioxide dusting off the lumps in boiling water; and the porosity of the sintered samples sintered samples is lower than abroad when the temperature is 1200 ℃, porosity is smaller, and therefore can prove the porosity value increases at this temperature, the sintered density of the sample increase.