Year: 2015
Type: article
Abstract: In the research of the renewable liquid fuels production, hydrothermal liquefaction (HTL) of algal biomass has received increasing attention. This thesis aims to study the effects of co solvents and acids on product distribution from HTL processes of macroalgae N- Oedogonium, in both small scale batch and pilot-scale continuous reactors. This work also provided further insights into the process scaling effects. The effects of polar solvent additions were found to depend on the solvent concentration – adding ethanol at 10 wt.% had little impact on the bio-crude yield, but at 30 wt.% led to an increase of 10% in the fraction of the biomass reporting as bio-crude. With the addition of non-polar solvents (anisole, heptane, toluene and their mixture), although the total bio-crude yield and elemental analysis were generally unchanged; the opportunity of tailoring the yield and quality of bio-crude oil which produced in-situ by forming a second organic phase from the primary aqueous phase was explored. In the continuous operations, approximately 7.5-25wt.% oil was found in solvent phase, increasing with higher solvent polarity; while the reduction of nitrogen and oxygen flowed an opposite trend. The greatest reductions of nitrogen (to ~1%) and oxygen (to ~12.5%) was obtained from heptane-phase oil, associating with a lowest yield of 7.5wt.%. The addition of acids (formic, lactic and sulphuric acid) to the algal HTL process was found to accelerate the hydrothermal reactions in a pH range of 1.6-3.2. Additionally, the preliminary study of the addition of 10wt.% CO2, as a green non-polar solvent and weak acid in the continuous HTL, however showed little impact on the bio-crude production. The carbon loss in this work was suggested to be ~0–24%, varying significantly with the reaction conditions and additives. Anisole exhibited a great ability to improve the process recovery efficiency and enhancing the carbon recovery close to 100%.
Author: Yaya He
Language: English
Subfield: Fuel Technology
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1103424509