GAS-COMPOSITION EFFECT ON THE PROPERTIES OF VANADIUM CATALYST FOR SULFUR-DIOXIDE OXIDATION UNDER CALCINATION

Gas composition effect on the stage of preliminary calcination for two typical cases of sulphuric acid vanadium catalyst synthesis at pH 5 and pH 0.5 was studied. It was stated that for the samples synthesized in acid medium gas composition didn't practically effect the properties of the catalyst prepared, the differences in phase composition and texture of intermediates disappeared under reaction conditions. For the samples, synthesized at pH 5 calcination in the air stimulated intensive sintering of supporter under the effect of potassium polyvanadate and blocking of the latter in thin pores of a supporter. Calcination in nitrogen and sulphur dioxide substantially inhibits these processes, that promotes the increasing of the catalyst activity. There is also given an explanation of these peculiarities on the basis of the complex study of texture formation and phase composition at different stages of catalyst synthesis.