Performance of Structural Alloys in Bio-oil Production, Upgrading, and Storage Systems

Selection of corrosion-resistant, cost-effective structural materials for the process and containment vessels required for the production, upgrading, and storage of biomass-derived oils has been the subject of study in our laboratory for many years. The wide variety of biomass resources and the many liquefaction techniques and processing conditions result in products with a broad range of properties and compositions. This paper will address the materials issues in three distinct areas. In production, materials are exposed to temperatures that range from 350 to 550 degrees C depending upon the process. Generally, austenitic stainless steels have performed reasonably well, although thicker oxide scales and intergranular attack have sometimes been observed. For storage and transport of the bio-oil products, temperatures experienced by the containment materials are not expected to exceed 50 degrees C. Our studies have shown that most raw bio-oils contain significant concentrations of organic acids, and low-molecular-weight organic acids were quite corrosive to carbon and low alloy steels. For some applications, subsequent processing is required, which includes hydrotreating or co-processing with a petroleum-derived liquid. These processes utilize a catalyst that requires periodic retreatment with a sulfidizing gas, and the exposure to this gas at elevated temperatures can cause appreciable corrosion to the more common austenitic stainless steels. The materials considered most cost-effective and sufficiently corrosion-resistant for each of these environments were identified.

Automated summary

The selection of corrosion-resistant and cost-effective structural materials for biomass-derived oil production, upgrading, and storage has been extensively studied in our laboratory. The wide variety of biomass resources and liquefaction techniques result in products with diverse properties. This paper discusses the materials challenges in three distinct areas. Austenitic stainless steels have generally performed well in the production process at temperatures ranging from 350 to 550 degrees C, although issues such as thicker oxide scales and intergranular attack have been observed. For storage and transport of bio-oil products, organic acids present in the raw bio-oils can cause corrosion to carbon and low-alloy steels. Furthermore, certain subsequent processing methods can lead to corrosion of common austenitic stainless steels during exposure to sulfidizing gas at elevated temperatures. The study identifies cost-effective and sufficiently corrosion-resistant materials for each environment.