Corrosion rate study of aqueous 2-amino-2-hydroxymethyl-1,3- propanediol (AHPD) and its mixture with piperazine (PZ)

Carbon dioxide emission has been a worldwide concern around the globe due its
greenhouse effect that leads to global warming. Current amine treating plant is used to
remove C02 by absorption process using alkanolamines as an absorbent. Recently
sterically hindered amines such as AHPD many others have grown interest in C02
absorption area due to its high C02 solubility (up to 1 mol C02/mol AHPD). Piperazine
is a chemical derivative added to AHPD to enhance its absorption capacity to even more
than 1 mol C02/mol AHPD. However, all amine solutions whether it is lean or saturated
with C02 is corrosive. This has caused all plants that operate C02 absorption using
amine solution encounter severe corrosion problems. The corrosion problem has a big
impact on the plant's economy and also the safety of the workers around it.
This present study provides information on the corrosion rate of AHPD at different
concentrations and also the effect of mixing ratio of AHPD/PZ blends. An
electrochemical testing of Linear Polarization Method is used to evaluate the corrosion
rate. The corrosion rate of AHPD solution is found to be increasing with increasing
concentration of AHPD. For AHPD/PZ blends, it is found that when amount of PZ
added to AHPD is increased, the rate of corrosion decreases which shows that PZ acts as
a corrosion inhibitor when mixed with AHPD. Comparison among the AHPD solution
with C02 loading and its fresh solution is also presented in this study.