Vanadium emission

Anthropogenic vanadium emissions are indicated even years after the closure of the vanadium source, as was demonstrated in the vicinity of cement and phosphate factories (Anke et al. 1998). 

Schildhauer T, Elsener M, Krdcher O, Moser J, Begsteiger I, Chatteijee D, Rusch K (2012) Measurement of vanadium emissions from SCR catalysts Method development and temperature dependency. Paper presented at the 7th International Exhaust Gas and Particulate... 

Chemical reduction. The injection of ammonia reduces NO emissions by the reduction of NO , to nitrogen and water. Although it can be used at higher temperatures without a catalyst, the most commonly used method injects the ammonia into the flue gas upstream of a catalyst bed (typically vanadium and/or tin on a silica support). 

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned ia utility boilers. Coal ash ia the atmosphere also coataias vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m, whereas air samples from Los Angeles and Honolulu contained 1—12 ng V/m. Adverse pubHc health effects attributable to vanadium ia the ambieat air have aot beea deteroiiaed. lacreased emphasis by iadustry oa controlling all plant emissions may have resulted ia more internal reclamation and recycle of vanadium catalysts. An apparent drop ia consumption of vanadium chemicals ia the United States since 1974 may be attributed, in part, to such reclamation activities. 

Tin plate, thickness of tin coating on, determination by x-ray spectrography, 148, 149, 157, 158 Tissues, determination of dry weight by absorptiometry, 297-300 Tissue sections, biological, determination of mineral elements in, 301-305 Titanium, as internal standard in vanadium determination, 188 determination by x-ray emission spectrography, 222, 329 trace analysis by x-ray emission spectrography, 163, 225-229 Topaz, as analyzing crystal, 116-118, 220, 318-327 Total reflection, 112, 117... 

Vanadium, determination by x-ray emission spectrography, 188, 329 trace analysis by x-ray emission spectrograph y, 228, 229... 

The presence of asphaltenes, originating in the fuel, acts as a trap for vanadium, nickel, and sodium (which promote slagging and sulfur corrosion)-, these asphalthenes often contain sulfur compounds, which simply add to the contaminant load. Additionally, asphaltenes act as precursors to spherical stack solids (cenospheres), which are exhausted with the flue gases as stack emissions. 

A wide range of catalytic materials have been investigated for the selective catalytic reduction of NOx. For stationary emissions, NH3-SCR using vanadium-tungsten oxides supported on titania is the most used method however, when there is a simultaneous emission of NO and NOz (in tail gas from nitric acid plants), copper-based zeolites or analogous systems have been proven to be preferable [31b], In fact, there are two main reactions for NH3-SCR ... 

If flame emission is based on excitation of atoms formed by combustion in the flame, why does flame emission work well for sodium, potassium, cesium and some of the transition metals but not vanadium, molybdenum or the lanthanides ... 

Elemental composition H 4.11%, Mo 48.94%, N 14.29% O 32.65. (NH4)2Mo04 is digested with nitric acid and the molybdenum metal is analyzed by atomic absorption or emission spectrophotometry. It is dissociated to ammonia, which may be measured by titration or by an ion-specific electrode technique (see Ammonia). Ammonium molybdate reacts under acid conditions with dilute orthophosphate solution to form molybdophosphoric acid which, in the presence of vanadium, forms yellow vanadomolybdophosphoric acid the intensity of the yeUow color may be measured by a spectrophotometer at 400 to 490 nm and is proportional to the trace amount of ammonium molybdate. 

As was already mentioned, the narrow lines at 692 and 710 nm in the luminescence spectrum of zoisite have been connected with element emission, while Cr and were considered as the possible candidates (Koziarsca et al. 1994). Laser-induced time-resolved luminescence spectra of zoisite reveal the same lines (Fig. 4.59). We are inclined to connect these lines with for the reason that vanadium concentration in our sample is much higher than the chromium concentration. 

The blue emission band in the beryl liuninescence spectrum with a short decay time of 1 ps (Fig. 4.52a) can be connected with the (V04) complex, especially because a similar emission has been foimd in the radioluminescence spectrum of beryl with an elevated concentration of vanadium (Chithambo et al. 1995). 

---