Tungsten Trioxide - Graphene Photocatalyst, Nemesis of Dye Pollutant

Not long ago, a kind of tungsten trioxide - graphene photocatalyst has been developed; this catalyst can degrade the dye Rhodamine B almost completely in 15 minutes. This is much faster than the degradation times that the single ingredient of tungsten trioxide or titanium dioxide photocatalyst can be achieved. This kind of photocatalyst is jointly discovered by Chinese and American scientists, and also, they imagined that this enormous potential invention shall be used in the visible light degradation of dye pollutant.

tungsten-trioxide-and-graphene
 
Because of the porous structure and special composition, the discovered tungsten trioxide - graphene photocatalyst has shown an excellent performance. The tungsten trioxide nano-framework can efficiently absorb the visible light due to multiple reflections in the pores. Also, the generated charges will quickly transfer to the graphene, thus to avoid the charge recombination. In addition, graphene nanosheets exposed on the surface of the photocatalyst, which guarantees the π-π contamination between graphene and dye pollutant, and thus lead to high absorption rate of catalyst material on the substrate. These combined features enhance the degradation of dye pollutants by the photocatalysis.
 
Tungsten trioxide is a transition metal oxide, which is widely used in gas sensors, photocatalysts, electrochromic device and so on, due to its special physical and chemical properties, and has a relatively broad application prospects. As a semiconductor photocatalyst, tungsten trioxide can produce holes with the strong oxidizing power and hydroxyl radicals in the reaction, and thus can be used to degrade pollutants in water. The researchers believed that, this very potential tungsten trioxide - graphene composite photocatalyst will have a widely concern, in the challenge of environmental remediation, and also will become the nemesis of dye pollutants; moreover, they highlight that this material is prepared by electrospinning method, which is suitable for industrial scale production.

 

Minmetals Published Tungsten Market Guide Price

Ganzhou Tungsten Industry Association yesterday announced the March 2016 market forecast average price of tungsten: tungsten concentrate 75,000 RMB/ton, APT 105,000.00 RMB/ton, middle size tungsten powder 168 RMB/kg. Compared to February, the price of tungsten concentrates unchanged, but APT raised 2,000 RMB for each ton and the middle size of tungsten powder raised 4 RMB for each kg. This showed Ganzhou Tungsten Industry Association has optimistic attitude about the spring tungsten market.

tungsten concentrate

Following Minmetals tungsten market guide price published in May, now re-released new tungsten market guidance in June, including tungsten concentrate 75,000/ton, scheelite 74,000/ton. Compared with the May guidance, the chain relative ratio were down 3,000 for each ton. And difference with May, this time Minmetals guide price of tungsten concentrate is similar to Ganzhou Tungsten Association tungsten concentrate forecast average price. Minmetals tungsten market guide price can be slightly higher than recent market transaction price, also showed Minmetals willingness to stabilize tungsten market.

The manufacturers of raw materials has optimistic attitude about tungsten market, so they reluctant to sale raw material and want to increase the price, but affected by low tungsten finished products demand the price acceptance is low and the turnover is limited. But supported by supply-side reform, mainly China domestic mining enterprises to suspend shipments, based on the policy is expected to continue to bring some benefit, so in the short-term the price of tungsten is difficult to fall down and will slight increase. 65% tungsten concentrate purchase price is not less than 75,000 RMB/ton and APT purchase price is not less than 115,000.00 RMB/ton. Besides, the market is still upside.

China's economic is gradually recovery, but tungsten finished products industry demand is shrinking, and the industry has been going on downturn for a long time. The end of January this year, eight large tungsten enterprises of China met in Chaozhou decided in 2016 tungsten concentrate reduction of output more than 15%. Reduced supply is good for industry rebound.

Tungsten Trioxide Denitration Catalyst Regeneration Technology

Recently, the State Environmental Protection Bureau delegation went to Jiangsu, Shanghai investigagion selective catalytic reduction denitration catalyst recycling and subsequent disposal. The study is mainly to promote the selective catalytic reduction denitration resource utilization and safe disposal of the catalyst after elimination, rational planning its whereabouts, thus to reduce the running cost of environmental protection, resolve the environmental issues.

tungsten trioxide and denitration system
 
Denitration system has already become an important part of coal-fired power plant, wherein the tungsten trioxide denitration catalyst is the core part of SCR system which takes the higher proportion of total investment. Currently, the denitration catalyst commonly used in the market are based on titanium dioxide as the carrier, vanadium pentoxide as the main active ingredient, tungsten trioxide (and / or molybdenum trioxide) as the anti-oxidant, anti-sulfide, anti-toxic auxiliary component. Theoretically, as the catalyst, it doesn’t as a reactant and cannot be consumed, so its effect is supposed to be permanent. However, in China, the catalyst market is now really staying in a relatively chaotic situation; usually, the catalyst will be deactivation after about three years. The main reasons which cause catalyst deactivation are sintering, poisoning, intoxication, calcium, alkali metal poisoning, and poisoning of sulfur trioxide, and the voids plug fouling of catalyst, ect..
 
The regeneration or replacement of denitration catalyst will directly affect the running costs of the SCR system, therefore, the research on SCR catalyst deactivation and regeneration has an important practical significance. In practical applications, the regeneration techniques of failure tungsten trioxide denitration catalyst are generally the two kinds of live regeneration and plant regeneration. Since the site regeneration will pollute the around environment and water quality of the plant, also the quality and performance of catalyst which regenerated in the site are poor, and therefore, plant regeneration is the development direction. SCR catalyst is impregnated plant regeneration during a series of cleaning, ash removal, ultrasonic treatment, the active ingredient (vanadium, tungsten, molybdenum, etc.), and finally achieve the goal of restoring catalyst activity.

 

Foreign Carbide Circular Blade Industry Focus on Brand Building

Tungsten carbide circular blade is a kind of super-hard composite material that mainly composed of refractory metal compound and the binder metal fabricated by PM (Powder Metallurgy). Due to it has many advantages, such as high hardness, high strength, excellent wear and corrosion resistance and is able to keep better performance at high temperature, etc, which becomes indispensable in cutting tool materials. Its appearance was circular, with a hole in the middle for easy fixing, generally used for the equipment cutting, trimming and other operations. According to the shape of the circular blade, it can be specifically divided into flat edge, sharp edge, and irregular edge. Conventional carbide circular blade size diameter φ300-1000mm, thickness 0.5-300mm, common in many industries slitting blades, such as paper making, paper products processing, adhesive tape products, films, wire and cable, rubber, aluminum, chemical fiber , non-manufacturing cloth, composite packaging materials, telecommunications appliances, cigarettes, leather, printing, food, clothing and other industries.

Since tungsten carbide circular blade has many advantages, domestic enterprises also works on that. However, They stressed by low prices, the price war to attract customers, which to some extent led to the cutting tool market vicious competition, low prices can not guarantee the quality of products, but ultimately customers on the domestic carbide circular blade lose confidence, a huge loss of customers caused. Take automobile industry as an example, it has higher requirements on the efficiency and service life of cutting tools. In order to avoid change blades cause the entire production line shut down and causing huge economic losses, usually mandatory unified tool change mode, if the blade quality problems, will affect the entire batch of products. By comparison, foreign tungsten carbide circular blade industries more focus on the brand building, and set the quality and the requirements of customers as first place, which build good foundation for the developments. In aerospace, military aspects of the field of production parts, molds and some large turbines, steam turbines, generators, and its not only high precision machining, material is also difficult to process (such as high temperature alloys, nickel-titanium alloy), high-quality carbide circular blade can perfectly meet the needs.

tungsten carbide circular blade

 

Tungsten Trioxide Denitration Catalyst Creates a Myth of Clean Diesel Technology

Recently, a report said Volkswagen had altered diesel engines to beat emissions tests, which immediately caused the great anger of the consumers. The agency reported that some diesel powered vehicles made by Volkswagen and its subsidiaries Audi and Porsche contained software which can lower the emissions during tests; however, during the normal driving, the software has gone. On the discharge gate event, Mullen, the CEO of Volkswagen expressed they had especially tough to come through the past few months. On the road, the emissions of some vehicles can even reach up to 40 times as much NOx—a combination of nitric oxide and nitrogen dioxide—as allowed, which has caused enormous pressure on the environment protection.

Volkswagen CEO Murren denitration catalyst
 
In the atmosphere, nitrogen dioxide contributes to the formation of ground-level ozone and particulate matter, which create further negative health effects. A recent study estimated that the excess NOx can cause the additional unexpected deaths and damages compared with the regular emissions. In Europe, however, the excess NOx from the altered cars may have little impact, which shows the high NOx emissions have already upset the region, because it has weaker emissions regulations and more diesel powered cars. So the issue of balancing the NOx emissions control with fuel efficiency is a tough nut to crack.
 
In addition, the exhaust of diesel powered vehicles contains a lot of sulfur, which not only causes air pollution, but also causes the poisoning of the denitration catalyst for automotive exhaust gas, and influence the effect of exhaust treatment. Tungsten trioxide denitration catalyst makes the clean diesel technology not a myth. Since tungsten trioxide can improve the sulfidation resistance of the catalyst, it is widely used in the denitration catalyst. In addition, tungsten trioxide can also broaden the operating temperature of the catalyst, and make it suitable for the denitration catalyst under lean burn conditions; therefore, the denitration catalyst which contains tungsten trioxide has very broad prospect in the clean fuel technologies.

 

 

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