Research progress on corrosion behavior in methanol and methanol-gasoline blended transport systems

Objective Pipeline transport of methanol and methanol-gasoline blends increases the risk of corrosion and stress corrosion cracking in metallic materials, posing significant threats to the safety and integrity of energy infrastructure. Investigating corrosion behavior in these transport systems is essential for advancing the safe and efficient development of “methanol-hydrogen” energy infrastructure.

Methods Through review of the domestic and international research progress on the corrosion of metals caused by methanol and methanol-gasoline blends, the corrosion mechanism of methanol was summarized. The corrosion laws of different metals in methanol and methanol-gasoline blends were comprehensively examined, and feasible suggestions for the future key research directions of corrosion in methanol and methanol-gasoline blended systems were put forward.

Results The corrosion environment of methanol pipelines is more complex, with corrosion influenced by impurities, stress, and other factors. Corrosion primarily occurs via electrochemical processes and stress corrosion cracking. Methoxy anions (CH₃O^-) from methanol dissociation react with metals to form passivation layers, which dissolve under high potential, leading to electrochemical corrosion. Stress accelerates intergranular corrosion and crack propagation, promoting stress corrosion cracking. Chlorides and sulfides in methanol exacerbate corrosion, while adding 0.5％ water by volume can form a stable passivation film, inhibiting corrosion. Higher methanol-gasoline blending ratios increase metal corrosion. Compared to steel, aluminum, and cast iron, copper and brass exhibit greater corrosion sensitivity in methanol-gasoline environments.

Conclusion Given the unclear corrosion mechanisms of methanol and methanol-gasoline in complex transport environments, the following suggestions are put forward: (1) further investigate the corrosion behavior and mechanisms of methanol and methanol-gasoline for metals under the combined effects of impurities, materials, and stress; (2) accelerate research on critical failure thresholds of pipe materials and corrosion risk assessment systems, aligned with large-scale storage and transport demands and actual pipeline conditions.