Mateo_swe,
This was covered earlier in the thread.
You can do this absorption with water and sulfur trioxide.
It is messy but workable, the water winds up in the sulfur trioxide side forming oleum but it coats the surfaces.
If you have 84.5% H2SO4 and oleum, you can mix them directly but slowly dropwise adding oleum to acid.
If your acid isn't concentrated enough heat it to drive off water.
You can use a water bath to keep it cool and use an addition funnel to add it.
There might be a way around it such as absorbing the sulfuric acid on activated silica gel to absorb the vapor but then your sulfuric acid is
solidified
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