Biocrude Production by Hydrothermal Liquefaction from Rugulopterix Okamurae Brown Macroalgae

Abstract

Nowadays, some populations of invasive marine macroalgae species cause environmental problems due to their excessive growth beyond their original niche. There are currently several investigations that are aimed at giving a possible valorization to the algal biomass waste that accumulates in coastal deposits. One of the technologies that are being applied to the treatment of algal biomass is Hydrothermal Liquefaction (HTL). This technology allows the transformation of organic matter into biocrude by means of a reaction in aqueous medium and at high temperature and pressure conditions. Rugulopteryx okamurae, an invasive macroalgae found on the coasts of many countries, has been used for the production of bio-oil by hydrothermal liquefaction. Although there are many variables that influence the process, the objective of this study is to carry out preliminary hydrothermal liquefaction tests of the mentioned algal biomass, without being subjected to previous pre-treatment. HTL experiments were carried out in water sub-critical conditions at a temperature range of 270–330 °C for reaction times between 5 and 60 min and with an initial biomass load between 5-15 % w/w. Maximum bio-crude yield (26.3 wt%) was obtained at 300 °C, 30 min, and 10 % w/w, while the highest HHV (8456.9 kcal/kg) was obtained at 330 ºC, 30 min, and 10 % w/w. The solid residue yields decreased continuously from 30.6 wt% to 12.1 wt% as the temperature increased from 270 to 330 °C.