Process and composition for drying of gaseous hydrogen halides

Claim 1

A process for drying a gaseous hydrogen halide of the formula HX, wherein X is selected from the group consisting of bromine, chlorine, fluorine, and iodine, to remove water impurity therefrom and produce an essentially completely water-free gaseous hydrogen halide effluent characterized by residual water concentration of below 0.1 part per million by volume, said process comprising the steps of: (a) providing an alkylated precursor composition comprising: a support having a vapor pressure of less than 1 part per million by volume, and having associated therewith (i) partially or fully alkylated metal alkyl compounds dispersed in the support and/or (ii) partially or fully alkylated metal alkyl pendant functional groups convalently bonded to the support, which are reactive with gaseous hydrogen halide to form corresponding (i) metal halide compounds dispersed in the support, of the formula MX y , and/or (ii) metal halide pendant functional groups convalently bonded to the support, of the formula --MX y-1 , wherein: M is a y-valent metal selected from the group consisting of lithium (I), beryllium (II), magnesium (II), calcium (II), strontium (II), barium (II), cadmium (II), nickel (I), iron (II), iron (III), zinc (II), and aluminum (III); y is an integer whose value is from 1 to 3; M is selected such that the heat of formation of its hydrated halide, MX y ·(H 2 O) n , is greater than or equal to 10.1 kilocalories per mole of such hydrated halide compound for each hydrated water molecule, wherein n is the number of water molecules bound to the metal halide in the metal halide hydrate; (b) contacting gaseous hydrogen halide with said alkylated precursor composition for reaction of the gaseous hydrogen halide with said partially or fully alkylated compounds and/or partially or fully alkylated pendant functional groups associated with the support to yield a scavenger composition wherein said support has associated therewith (i) said metal halide compounds dispersed in the support, of the formula MX y , and/or (ii) said metal halide pendant functional groups covalently bonded to the support, of the formula --MX y-1 ; (c) contacting water impurity-containing gaseous hydrogen halide with said scavenger composition for reaction of said metal halide compounds and/or metal halide pendant functional groups with the water impurity to yield the corresponding hydrates and/or oxides of the metal halide compounds and/or metal halide pendant functional groups; and (d) recovering an essentially completely water-free gaseous hydrogen halide effluent characterized by residual water concentration of below 0.1 part per million by volume.