Solution-processed metal oxides molybdenum oxide

Some of the earliest catalysts for this transformation were heterogeneous metal oxides (typically of tungsten, molybdenum or rhenium) on a support such as silica or alumina. These are still the catalysts employed for all current large scale industrial processes. Ill-defined homogeneous systems comprising alcohol solutions of a metal halide in conjunction with a promoter were also employed extensively in the early years, and are currently still used for the... 

The validity of the description of this patented procedure was also challenged on the grounds that molybdic oxide needs to be present in the plated film for the conversion to take place. It is interesting, therefore, that C E Vest introduced an important modification to the process in order to electrodeposit molybdenum trioxide instead of molybdenum metal when studying the application of the technique to the lubrication of spacecraft components. Vest s modification was to use a mixed plating bath of molybdenum trioxide in an alkali salt solution such as ammonium formate. The component being coated formed the cathode, and the molybdenum was probably present in the bath in the form of ammonium molybdate. 

Molybdenum is released from rocks by the processes of weathering (Mitchell, 1964), which involve one or more cycles of solution, oxidation, and precipitation before the Mo from a given rock either appears in the soil formed from that rock or is transported to ocean sediments as part of the sedimentary cycle. Molybdenum is fairly readily released from primary minerals by weathering, and, as compared with other metals, it remains relatively mobile as potentially soluble molybdates (Mo +). Consequently, transport of Mo via leaching is likely unless iron, aluminum, or manganese oxides interfere under conditions appropriate for occlusion by those minerals (Davies, 1956). 

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