Formation by Hydrolysis of Metal Phosphides

The interrelation between structure and hydrolytic behavior of metal phosphides is reviewed in [1]. Of the numerous phosphides that release PH3 when hydrolyzed, Ca3P2 and AlP have been predominantly used to prepare the compound on a laboratory scale. 

ZnaPa is not hydrolyzed by neat water, but only in acidic or basic solution or at pH 7 in a phosphate buffer solution. The rate of PH3 formation was found to depend mainly on the pH and temperature [12]. Finely dispersed Zn3P2, obtained by reduction of Zn3(P04)2 with carbon powder or petroleum coke at 1000 to 1300 C, is hydrolyzed by 20 to 85 wt% H3PO4 at 20 to 200°C to give PH3 ( 95 vol%) and H2. The regenerated zinc phosphate can be dehydrated at around 250°C and recycled [13]. Zn3P2 mixed with clay oxide soils of volcanic origin (pH 5.4, 5.7, or 6.9) at various moisture levels decomposes with liberation of variable amounts of PH3 [12]. 

Dilute acids hydrolyze LaPj to give PH3, P2H4, and solid yellow phosphanes. The slower hydrolysis in dilute bases begins with polycrystalline fragments of LaP2 yielding only PH3 [14]. 

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