US 12,404,172 B2
Hydrogen chloride dehydration method
Junya Sakai, Yamaguchi (JP); and Shoji Iiyama, Yamaguchi (JP)
Assigned to TOKUYAMA CORPORATION, Yamaguchi (JP)
Appl. No. 17/771,532
Filed by TOKUYAMA CORPORATION, Yamaguchi (JP)
PCT Filed Sep. 4, 2020, PCT No. PCT/JP2020/033526
§ 371(c)(1), (2) Date Apr. 25, 2022,
PCT Pub. No. WO2021/095329, PCT Pub. Date May 20, 2021.
Claims priority of application No. 2019-205560 (JP), filed on Nov. 13, 2019.
Prior Publication US 2022/0371886 A1, Nov. 24, 2022
Int. Cl. C01B 7/07 (2006.01); B01D 53/26 (2006.01); C01B 33/107 (2006.01)
CPC C01B 7/0706 (2013.01) [B01D 53/26 (2013.01); C01B 33/10763 (2013.01); B01D 2257/30 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method of dehydrating hydrogen chloride gas through a multi-step process, the method comprising:
a first dehydration step of bringing hydrogen chloride gas and concentrated sulfuric acid into contact with each other; and
a second dehydration step of bringing hydrogen chloride gas that has been obtained through the first dehydration step into contact with concentrated sulfuric acid,
wherein a concentration of the concentrated sulfuric acid used in the second dehydration step is higher than a concentration of the concentrated sulfuric acid used in the first dehydration step,
wherein at least part of the concentrated sulfuric acid that has been used in the second dehydration step is reused in the first dehydration step,
wherein the multi-step process consists of the first dehydration step, the second dehydration step, and a third dehydration step carried out after the second dehydration step,
wherein at least part of concentrated sulfuric acid that has been used in the third dehydration step is reused in the second dehydration step,
a concentration of the concentrated sulfuric acid reused in the second dehydration step after having been used in the third dehydration step is not lower than 96 wt %,
a concentration of the concentrated sulfuric acid reused in the first dehydration step after having been used in the second dehydration step is not lower than 85 wt % and lower than 96 wt %, and
a concentration of the concentrated sulfuric acid after having been used in the first dehydration step is not lower than 75 wt % and lower than 85 wt %.