Roles of major alloying elements in steels and alloys on corrosion under biomass hydrothermal liquefaction (HTL) conversion

Hydrothermal liquefaction (HTL) is a promising thermochemical technology to convert wet biomass and biowaste streams into bioenergy products. Significant knowledge gaps exist due to reactors' corrosion damage. This study investigated the roles of alloying elements (Cr, Fe, Ni and Mo) on corrosion in simulated HTL environments via thermodynamic calculation and autoclave tests. Cr acts as the dominant alloying element, and the tested Fe-based steels and Ni-based alloys with Cr content over about 16% exhibit satisfied resistance to the HTL environments. Influences of alloying elements Ni and Mo are different depending on Cr content in the steels and alloys.