Abstract: A method for preparing chlorine gas through catalytic oxidation of hydrogen chloride is carried out by one-time hydrogen chloride feeding and multi-stage oxygen feeding, one-time oxygen feeding and multi-stage hydrogen chloride feeding, or both, returning a product gas stream without separation thereof, and optionally carrying out heat insulation means. In the present invention, excessive reaction heat concentration is prevented, therefore, the method of the present invention is a chlorine gas recovery method implemented through the Deacon catalytic oxidation of hydrogen chloride that may be industrialized.

Abstract: Clean process for preparing a chloroformyl-substituted benzene by oxidation of a tail gas hydrogen chloride from a chlorination reaction and a chloroacylation reaction and recycling of the resulting oxidation product chlorine gas into the chlorination reaction. The present invention provides a clean process for preparing a polymer-grade chloroformyl-substituted benzene.