Conversion of Enteromorpha prolifera to high-quality liquid oil via deoxy-liquefaction

• Enteromorpha prolifera was converted into liquid oil by deoxy-liquefaction.
• Zeolite catalysts can improve the yield, distribution and properties of the products.
• Total contents of long-chain alkanes and aromatics increased greatly.
• A distinct decrease in oxygen contents was achieved.

The marine green macroalgae, Enteromorpha prolifera, was converted into liquid oil through deoxy-liquefaction in a stainless steel microreactor. Mn/H-ZSM-5 and Fe/H-ZSM-5 catalysts were employed to investigate the yield, distribution and properties of the liquefaction products. With Fe/H-ZSM-5 catalyst, a maximum yield of 14.81% oil was obtained at 350 °C, and the higher heating value was up to 44.69 MJ/kg. In both the presence and absence catalysts, the liquefaction products were similar and mainly composed of aromatics, phenols, alkanes, etc. However, their contents were quite different. With the addition of Mn/H-ZSM-5 and Fe/H-ZSM-5 catalysts, the long-chain alkanes and aromatics increased, while those phenols and nitrogen containing species decreased, contributing to a distinct decrease in oxygen content. The results suggested that deoxy-liquefaction technique may be an effective way to convert macroalgae E. prolifera into high-quality liquid oil, which should be beneficial for environmental protection and renewable energy development.