Molybdenum disulfide, hydrogen

Moissanite, see Silicon carbide Molybdenite, see Molybdenum disulfide Molybdite, see Molybdenum(VI) oxide Molysite, see Iron(III) chloride Montroydite, see Mercury(II) oxide Morenosite, see Nickel sulfate 7-water Mosaic gold, see Tin disulfide Muriatic acid, see Hydrogen chloride, aqueous solutions... 

Metal sulfides play an important role in catalyzing a wide variety of hydrogenations (e.g., of fats, coal, or olefins) and also desulfurization reactions, which are used in pretreatment of fossil fuels to reduce the emission of sulfur oxides during combustion (Section 8.5). Molybdenum disulfide, an important defect catalyst, can be made to function as an n-type (Moi+xS2) or p-type (Mo1 xS2) semiconductor by exposure to an appropriate mixture of H2S and hydrogen at temperatures on the order of 600 °C. The equilibrium... 

T T ydroformylation of olefins to aldehydes over cobalt carbonyl catalysts is the first step in the industrial synthesis of oxo alcohols (1, 2). Reaction conditions require temperatures above 150 °C and pressures up to 3000 psig. Subsequent aldehyde hydrogenation occurs over supported cobalt or molybdenum disulfide catalysts. 

In these experiments a sample of cobalt/molybdenum disulfide was mounted on the heater ribbon in close proximity to a cobalt/graphite specimen, which was positioned in the path of the electron beam. All specimens were initially treated in 1.0 Torr hydrogen for l.Q hours at 360°C. and under these conditions the cobalt film nucleated to form particles. 2.5 - 5.0 nm diam. on the graphite surface. At the same time these particles were being exposed to hydrogen disulfide produced during the cobalt catalyzed hydrogenation of molybdenum disulfide, a reaction which had been previously found to proceed at appreciable rates at ten ratures above 250°C (ref. 16). 

In a complementary series of experiments the cobalt/molybdenum disulfide samples were initially treated in hydrogen at S00°C for O.S hours. Under these conditions metal particles which had accumulated at edges were observed to catalyze the removal of material from these regions. When such specimens were subsequently heated in the presence of acetylene there was no evidence for the formation of carbon filaments. It was apparent that when specimens were treated in the hydrocarbon for extended periods at 6S0°C then many of the surface features were obscured by the build up of carbon deposits resulting from uncatalyzcd hydrocarbon decomposition reactions. 

From these experiments it is clear that in the presence of relatively high levels of hydrogen sulfide, produced by catalytic hydrogenation of molybdenum disulfide, cobalt is poisoned by sulfur and loses its ability to catalyze the growth of carbon filamems. 

Early in situ STM (and AFM) of nucleobases focused on adenine and guanine on molybdenum disulfide and highly oriented pyrolytic graphite [131-133]. Other early studies addressed all the nucleobases and Au(lll) electrode surfaces. The bases were concluded to form planar hydrogen-bonded networks on the surfaces... 

The publications are listed in two different ways Table A4.1 is alphabetical by common or systematic name, thus acetone not propanone, propylene not propene. The formula is given in the usual style, thus Fe(CO)s not FeCsOs. Catalyst studies are listed in two ways under the name of the adsorbate, with the entry starting with. Thus the next entry after thiophene is M0S2, showing that thiophene on M0S2 has been studied. Catalyst studies are also listed under the name of the catalyst so there is an entry for molybdenum disulfide with H2 and thiophene. The two types of entry allow the reader to find all the molecules that have been studied on a particular catalyst or all the catalysts a particular molecule has been studied on. Hydrogen is subdivided into systems where H2 was the species studied e.g. H2 on Ru/C or... 

Molybdenum disulfide, M0S2, can be prepared by chemical vapor deposition using M0CI5 [116, 117], MoFf, [117] or Mo(CO)6 (9) [118] as the molybdenum source. The sulfur source in each case is hydrogen sulfide. The molybdenum tetrakis(thiolate) compound, Mo(S-f-Bu)4, is a unimolecular precursor to M0S2 and decomposes at temperatures as low as 100°C [111]. 

Hydrogen sulfide can react with M0O2 to produce molybdenum disulfide and water. The stabilities of the dioxide and disulfide depend upon the relative partial pressures of hydrogen sulfide and water vapor. Estimates of the effect of temperature upon the equilibrium are summarized in Fig. 7. 

PEG-8 cocoate PEG hydrogenated castor oil PEG-20 hydrogenated castor oil PEG-60 hydrogenated tallowate PEG-12 ricinoleate PEG-2 stearate PEG-2 tallowate lubricant, dry powders Molybdenum disulfide lubricant, dry skin care Propylene glycol dioctanoate lubricant, dry-film Barium fluoride lubricant, drying rubber Zinc stearate lubricant, dye baths Butyl oleate Octyl palmitate lubricant, dye leveling compounds PEG-5 soyamine lubricant, dyeing... 

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