Oxygen scavenging performance of carboxylic acids formed during the degradation of monoethylene glycol regeneration products

Abstract

Previous studies have demonstrated that formic and glycolic acids could scavenge oxygen from aqueous solutions via complex radical mechanisms similar to that of erythorbic acid. Therefore, it is important to study the feasibility of using these common thermal degradation products obtained from the regeneration of monoethylene glycol (MEG). By replacing commercially used oxygen scavengers, such as sulfites, with these organic acids, the toxicity and subsequent environmental impact of oil and gas products could be easily reduced. Furthermore, these organic acids are rapid oxygen scavengers at low concentration, and they could be cost-effective; in addition, the chemical inventory could be reduced and project costs could be further optimized. The experimental results confirmed the potential of formic and glycolic acids to be used as oxygen scavengers downstream of the MEG regeneration process in the presence of manganese (II) ions as catalyst. Of the two commercial aqueous industrial oxygen scavengers tested, diethylhydroxylamine was an extremely rapid oxygen scavenger in salty aged lean MEG solutions under alkaline conditions, whereas methyl ethyl ketoxime exhibited extremely poor performance under similar conditions; therefore, it was ruled out as potential oxygen scavenger.