THE THERMAL-DECOMPOSITION OF HYDROGEN-SULFIDE OVER ALKALI-METAL SULFIDES AND POLYSULFIDES

The decomposition of hydrogen sulfide and sulfur on alkali metal sulfides M//2S (M equals Li, Na and K) and polysulfides M//2S//x (x equals 2-4; M equals Na and K) has been studied in a flow system at 400-800 degree C. Hydrogen yields were measured as a function of temperature in order to compare the effectiveness of the alkali metal (poly)sulfides in promoting the decomposition. It was found that both Na//2S and K//2S are rapidly sulfided by H//2S to give the corresponding disulfides M//2S//2, whereas Li//2S acts as a catalyst for the thermal decomposition of H//2S. Although Na//2S//2 was further sulfided by H//2S, sodium polysulfides were not effective in enhancing hydrogen yields and all polysulfides produced an amorphous product of approximate composition of Na//2S//2//. //4//-//2//. //6.