Decomposition and kinetic studies of AdBlue using thermogravimetric and mass spectrometric (TG-MS) analyses

Evolved gases from AdBlue decomposition with different catalysts (Ti, Zr, Pt, SiO 2 , and γ-Al 2 O 3 ) were analyzed with a thermogravimetric analyzer coupled to a mass spectrometer (TG-MS). Kinetic parameters of AdBlue decomposition process were calculated by Kissinger–Akahira–Sunoe (KAS) and Flynn–Wall–Ozawa (FWO) methods. The results show that γ-Al 2 O 3 is the best pyrolysis catalyst, and it promotes the decomposition of urea. The gaseous products (H 2 O, NH 3 , CHNO, CO 2 ) were detected by MS at different reaction stages, resulting from the decomposition of urea and the formation of intermediate products. With the KAS method, the calculated activation energies with the same fractional conversion for three stages are 133.20 ± 3.71–151.14 ± 7.78 kJ/mol, 128.93 ± 3.13–186.09 ± 3.92 kJ/mol, and 326.00 ± 17.58–465.09 ± 17.62 kJ/mol, respectively.