| 摘要 |
571,207. Sulphur trioxide. CATHALA, J. Feb. 24, 1941, No. 2516. [Class 1 (i)] A gas mixture containing at least 15 per cent. of sulphur dioxide and oxygen not in excess is subjected to catalysis under at least 3 atmospheres pressure and the products are cooled to condense a mixture of sulphur trioxide and dioxide, which is separated by fractional distillation. The mixture may be obtained by the evaporation of liquid sulphur dioxide at a controlled temperature into air under pressure. The condensation may be effected in stages, yielding mixtures with successively higher sulphur dioxide content, which are fed into the rectifying column at appropriate places. The sulphur dioxide fraction may be liquefied and recirculated. The exit gases undergo a final purification by washing or adsorption. Specifications 467,298 and 519,570 are referred to. |
