From my googling it appears that the particular chemical the OP was transporting may be permitted in limited quantities on passenger aircraft,
however, there are pretty specific IATA packaging and labeling requirements, which are certainly not met by placing the item in a suitcase.
OP, just because something came via air freight, does not mean you can take it in your suitcase on a passenger aircraft. A shipper sending this item via USPS for example, would have to comply with several regulations regarding how the item is packed and labeled, in order to legally mail it. It is certainly possible to mail it legally. See
https://pe.usps.com/text/pub52/pub52c3_023.htm, which also mentions that items in this hazard class (5.1) are not internationally mailable.