Results of the hydrogenation of bio-crude oil produced from army food waste through hydrothermal liquefaction

Hydrothermal liquefaction (HTL) offers a promising, but limited in terms of technology readiness level, alternative route for converting food waste into energy‐dense liquid fuels. The objectives of the study were to examine the effect of temperature, residence time and solid loadings on the quantitative and qualitative characteristics of bio-crude from army food waste through HTL including the effect of three catalysts on the quality of bio-crude derived through hydrogenation. Army food waste with an average moisture content of 72% was treated at temperatures between 280 and 320 °C, residence times from 30 to 60 min, and solid loadings of 5–20 wt%. The maximum bio-oil yield of ∼30 wt% on a dry basis was obtained at ∼310 °C. The produced bio-crude exhibited high heating values from 20.5 to 39 MJ/kg which was the optimal at 320 °C. On the other hand the experiments regarding the hydrogenation of the produced bio-crude revealed that among the catalysts and conditions used, nickel (II) nitrate hexahydrate at 320 °C represented the optimal catalytic and operational condition for producing high-quality, energy-dense bio-oil from food waste. Aluminum (III) oxide offered a moderate improvement, while zeolite shows limited effectiveness under the conditions investigated.