Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a Catalyst

Abstract

Biocrude from Chlorococcum sp. algae was hydrotreated in batch autoclaves in the presence and absence of Al-SBA-15 supports and NiMo/Al-SBA-15 catalysts with different Si/Al ratios and hence different acidities. Reaction time (0−15 min), temperature (425−500 °C), and H2 pressure (3−9 MPa cold) were varied. The nitrogen content of the biocrude was approximately halved in all of the reactions, regardless of temperature, H2 pressure, or the presence of the support/catalyst. Product aromaticity increased with reaction temperature. The presence of the supports, especially those of lower acidity, decreased product yields (CH2Cl2 solubles and hydrocarbon gases) due to severe coking. Incorporation of NiMo introduced a pressure dependence of the product yield. For 425 °C reactions, NiMo could more than make up for the coking effect of the support, increasing the product yield to up to 65 wt % (6−9 MPa H2 (cold)) and the proportion of liquid products in the kerosene-boiling-point range (C12−C17). Higher-acidity supports gave higher product yields, and their superiority was maintained when NiMo was incorporated.