Abstract
Biomass-derived pyrolysis oils are rich in carbon and can be used as such or can be processed to produce oil compatible with crude oils to be used in production of fuel and chemicals in petroleum refineries. However, pyrolysis oils can be significantly more corrosive compared to traditional fuels. As-produced pyrolysis oils contain a significant amount of oxygen, primarily as a component of water, carboxylic acids, phenols, ketones and aldehydes. As a result of these constituents, bio oils are generally more acidic with a total acid number (TAN) that can reach levels as high as 100mgKOH/g, with the measured pH of bio-oils between 2.3 to 3.5. There is a significant variation in the chemical composition of bio-oils due to the source and procedures used to produce these oils. Extent and mode of corrosion attack also depends on the alloy composition, microstructure, and environmental parameters. If pyrolysis oils are to be successfully used in an existing or a new process stream, it is very important to know their effect on the performance of different alloys used in that equipment. To study this effect, six materials, aluminum Al 1100, copper (Cu), brass (Cu-Zn), carbon steel (CS) 516-G70, austenitic stainless steel (SS) 316L, and two duplex stainless steels (DSS) 2205 and 2101 were tested in different pyrolysis oils. Corrosivity of pyrolysis oils depends on its water content, carboxylic acids, as well as other constituents affecting their TAN.
