Thermal Decomposition of Tricresyl Phosphate on Ferrous Surfaces

A Khajeh and FH Bhuiyan and JE Mogonye and RA Pesce-Rodriguez and S Berkebile and A Martini, JOURNAL OF PHYSICAL CHEMISTRY C, 125, 5076-5087 (2021).

DOI: 10.1021/acs.jpcc.0c10789

Tricresyl phosphate (TCP) forms protective films on moving mechanical components through thermally driven decomposition and interactions with the ferrous surfaces of the components. These reactions are hidden from view in moving interfaces, but are known to be sensitive to both the surface material and the isomeric form of the TCP. Here, temperature- programmed reaction spectroscopy (TPRS) and gas chromatography-mass spectroscopy (GC-MS) are complemented by reactive molecular dynamics (MD) simulations to investigate the thermal decomposition of meta and para isomers of TCP reacting with ferrous materials. Key observations are that the primary decomposition product of TCP is cresol, more cresol is generated on Fe2O3 than on Fe3O4, and that para-TCP isomers are more reactive than meta-TCP isomers. These trends are explained using the simulations to identify multiple reaction pathways leading to cresol formation. The likelihood of each pathway is quantified and correlated to surface material and TCP isomer trends in terms of energy barriers for the rate-limiting steps in the decomposition reactions.

Return to Publications page