(Mo,W)Si2 composite powders with the grain size of about 1 ?m were synthesized at 1150? for 2 h. The high purity molybdenum concentrate (with the main component of MoS2), W and Si powders were ...utilized as raw materials and lime as desulfurizer. The graphite felt was laid between the compact (made of MoS2, W and Si) and the lime to facilitate the separation of the produced composite powders from desulfurization product. The phase composition, microstructure evolution, and residual sulfur content during the silicothermic reduction reaction were evaluated. The experimental results showed that the reaction could be completed after a reaction time of 1150? for 2 h, and the residual sulfur content of the product was 0.087 wt.%. It was concluded that the interactions between Si and the intermediate products of SiS and SiS2 are crucial for the preparationof (Mo,W)Si2 composite powders at low temperatures. The preparation process could be divided into three stages: solid state reactions between MoS2, W and Si to produce MoSi2, WSi2 and gaseous SiS; gas-solid reaction between MoS2, W and gaseous SiS to generate MoSi2, WSi2 and gaseous SiS2; and gas-solid reaction between gaseous SiS2 and Si to form SiS gas. With this short flow process, fine-grained (Mo,W)Si2 composite powders can be produced at low cost at low temperature, which has great application potential.
MFI zeolite materials (ZSM-5) with crystal sizes in the range from 0.10 to 1.70 μm have been synthesized. Acidic and surface properties, phase and morphological composition of the prepared zeolites ...have been studied by the IR sprectroscopy, nitrogen porosimetry, XRD, and scanning electron microscopy. Increasing crystal size was shown to decrease the general acidity of the zeolite. Synthesized zeolites served as supports for molybden-containing catalysts for methane aromatization prepared by using the solid phase synthesis approach. Diffuse reflectance IR spectroscopy, thermoprogrammed desoption of ammonia and
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Al NMR spectroscopy were used to characterize the physicochemical properties of the catalysts. An increase in the crystallite size of the zeolite favors a decrease in the acidity of the catalysts and inhibits the formation of alumina molybdate during the catalyst preparation. As a result, a tendency to coke formation is suppressed and the performance of the catalysts in methane aromatization improved: methane conversion and aromatic hydrocarbon yield increase.
Molibden jest jednym z podstawowych mikroelementów dla roślin, ale jego nadmiar w glebach przy niedoborze miedzi może prowadzić do produkcji pasz, które mogą być toksyczne dla zwierząt i powodować ...molibdenozę. Łupki menilitowe występujące na obszarze Beskidów Wschodnich charakteryzują się podwyższoną zawartością tego pierwiastka. W próbkach skał podłoża, gleb oraz roślin (rośliny Trifolium hybridum L. i Plantago major L.) pobranych na terenie występowania łupków menilitowych oraz piaskowców z Otrytu oznaczono zawartości molibdenu i miedzi. Zawartość molibdenu w skałach wynosi od 0,80 mg/kg do 40 mg/kg, w glebach jest w zakresie 1,97-19,58 mg/kg, a w materiale roślinnym jest w przedziale od 0,54 do 11,76 mg/kg. Zawartość miedzi zmieniała się w skałach od 11 mg/kg do 111 mg/kg, w glebach od 23 do 76 mg/kg i badanych roślinach do 20 mg/kg. Średnia zawartość Mo we wszystkich rodzajach roślin jest zdecydowanie wyższa na terenie występowania łupków menilitowych niż na obszarze gdzie dominują piaskowce z Otrytu. Z wyższą zawartością Mo w próbkach koniczyny wiąże się niższa wartość stosunku Cu/Mo, co może skutkować występowaniem molibdenozy u zwierząt w badanym rejonie.
Molybdenum is one of the major trace elements for plants, but its excess and the deficiency of copper in soils can lead to the production of feed that may be toxic to animals and cause molybdenosis. ...Menilite shales that occur in the Eastern Beskids Mts. are characterised by an elevated content of this element. The concentration of molybdenum and copper has been determined in samples of bedrock, soils and plants (Trifolium hybridum L. and Plantago major L. plants), taken in the area of occurrence of menilite shales and the Otryt Sandstones. The molybdenum concentration in rocks varies from 0.80 to 40 mg/kg, in soils - from 1.97 to 19.58 mg/kg, and in plant material - from 0.54 to 11.76 mg/kg. The copper concentration in rocks ranges from 11 to 111 mg/kg, in soils - from 23 to 76 mg/kg, and in plants - up to 20 mg/kg. The average Mo concentration in all kinds of plants is significantly higher in the area of occurrence of menilite shales than in the area where the Otryt Sandstones are dominant. The higher content of Mo in the samples collected from clover was accompanied by the lower Cu/Mo ratio, which may cause a molybdenosis disease in animals in the study area.
Molibden jest jednym z podstawowych mikroelementów dla roślin, ale jego nadmiar w glebach przy niedoborze miedzi może prowadzić do produkcji pasz, które mogą być toksyczne dla zwierząt i powodować molibdenozę. Łupki menilitowe występujące na obszarze Beskidów Wschodnich charakteryzują się podwyższoną zawartością tego pierwiastka. W próbkach skał podłoża, gleb oraz roślin (rośliny Trifolium hybridum L. i Plantago major L.) pobranych na terenie występowania łupków menilitowych oraz piaskowców z Otrytu oznaczono zawartości molibdenu i miedzi. Zawartość molibdenu w skałach wynosi od 0,80 mg/kg do 40 mg/kg, w glebach jest w zakresie 1,97-19,58 mg/kg, a w materiale roślinnym jest w przedziale od 0,54 do 11,76 mg/kg. Zawartość miedzi zmieniała się w skałach od 11 mg/kg do 111 mg/kg, w glebach od 23 do 76 mg/kg i badanych roślinach do 20 mg/kg. Średnia zawartość Mo we wszystkich rodzajach roślin jest zdecydowanie wyższa na terenie występowania łupków menilitowych niż na obszarze gdzie dominują piaskowce z Otrytu. Z wyższą zawartością Mo w próbkach koniczyny wiąże się niższa wartość stosunku Cu/Mo, co może skutkować występowaniem molibdenozy u zwierząt w badanym rejonie.
Micronutrient deficiency is widespread in many Asian countries due to the calcareous nature of soils, high pH, low organic matter, salt stress, continuous drought, high bicarbonate content in ...irrigation water, and imbalanced application of fertilizers. Some of the adverse effects of micronutrient deficiency-induced stress in plants include low crop yield and quality, imperfect plant morphological structure (such as fewer xylem vessels of small size), widespread infestation of various diseases and pests, low activation of phytosiderophores, and lower fertilizer use efficiency. The absence of micronutrient fertilizers results in inadequate absorption of trace elements by plants, which causes substantial yield losses in different crops and forages, and eventually results in poor health for domestic animals and humans. Calcareous soil research results of the last decade show that at the present time, among micronutrients, Zn deficiency is the most detrimental to effective crop yield. Other important micronutrients that increase crop yield (most to least effect) are Fe, B, Mn, Cu, and Mo. In the case of calcareous soils, the conventional notion that micronutrients increase crop yield by 15%-30% is an underestimated range. In fact, in some cases, especially with inefficient cultivars such as durum wheat (Triticum durum L.), micronutrients can increase grain yield up to 50%, as well as increase macronutrient use efficiency. By supplying plants with micronutrients, either through soil application, foliar spray, or seed treatment, increased yield and higher quality, as well as macronutrient use efficiency, could be achieved. In consideration of the important role micronutrients have in promoting and maintaining human health, more research is needed to determine the advantages of using the optimum level of micronutrients instead of their critical level as an indicator with regard to yield, quality, and enrichment objectives for the future.
S ciljem poboljšanja karakteristika katalizatora na bazi kroma, u ovom su se istraživanju kombinirano primijenile poluempirijske računalne metode i metode temeljene na teoriji funkcionala gustoće. ...Nastojao se dobiti uvid u katalitički potencijal izmjene kroma molibdenom i volframom u katalizatoru CrXO3 (gdje X označava krom, molibden i volfram) za dehidrogeniranje propana pri proizvodnji propilena. Rezultati su potvrdili da površina modificirana molibdenom pokazuje bolju selektivnosti u usporedbi s površinom modificiranom volframom, usporavajući dehidrogenaciju, pucanje i koksiranje propilena. Utvrđeno je da upotreba molibdena olakšava proizvodnju propilena zbog njegova nižeg afiniteta prema adsorbatima koji potiču pucanje i koksiranje, uključujući i lakšu desorpciju propilena te višu barijeru potpune dehidrogenacije što sprječava nastanak neželjenih produkata; to nije bio slučaj kod volframa. Ovo istraživanje stoga preporučuje upotrebu molibdena za poboljšanje svojstava katalizatora, što bi moglo rezultirati većim iskorištenjem u proizvodnji propilena te pomoći zadovoljavanju rastuće tržišne potražnje za propilenom.
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