GB942831A - Process for the production of purified phosphorus or sulphur - Google Patents

Abstract

Impure phosphorus or sulphur is purified by passage of its vapour through a gas chromatographic column. The impure substance may be vaporized with an inert entraining gas e.g. Ar2He, N2 or H2 and the mixture passed through the column operated at 250-550 DEG C., e.g. at least 280 DEG C. for P, and at least 450 DEG C. for S. The column may be stainless steel, carbon, zirconium oxide, rhenium, tantalum, tungsten, silicon carbide, molybdenum, niobium, ruthenium or iridium. The stationary phase can be a liquid metal, e.g. tin, bismuth, lead, thallium or zinc, or a fused salt e.g. a nitrite, such as a mixture of potassium and sodium nitrites, supported on a packing, which can be one of the materials used for the column, or magnesia, and may be foamed or sintered to give a large surface area. The stationary phase may also be a solid, e.g. silicon carbide, aluminium, or a silica aerogel having a large surface area. The column may be heated by an electrically heated rod or winding, or by induction or resistance heating, and may have an external layer of thermal insulation, e.g. graphite, magnesia, foamed silicon carbide, or vermiculite fire-brick. The purified phosphorus vapour may be passed into indium vapour to form indium phosphide, and the purified sulphur vapour may be passed into cadmium vapour to form cadmium sulphide.ALSO:Impure phosphorus or sulphur is purified by passage of its vapour through a gas chromatographic column. The impure substance may be vaporized with an inert entraining gas e.g. Ar, He, N2 or H2 and the mixture passed through the column operated at 250-550 DEG C., e.g. at least 280 DEG C. for P and at least 450 DEG C. for S. The column may be stainless steel, carbon, zirconium oxide, rhenium, tantalum, tungsten, silicon carbide, molybdenum, niobium, ruthenium or iridium. The stationary phase can be a liquid metal, e.g. tin, bismuth, lead, thallium or zinc, or a fused salt, e.g. a nitrite, such as a mixture of potassium or sodium nitrites, supported on a packing, which can be one of the materials used for the column, or magnesia, and may be foamed or sintered to give a large surface area. The stationary phase may also be a solid, e.g. silicon carbide, aluminium, or a silica aerogel having a large surface area. The column may be heated by an electrically heated rod or winding, or by induction or resistance heating, and may have an external layer of thermal insulation, e.g. graphite, magnesia, foamed silicon carbide or vermiculite firebrick. The purified phosphorus vapour may be passed into indium vapour to form indium phosphide, and the purified suphur vapour may be passed into cadmium vapour to form cadmium sulphide.