The presence of a negligible quantity of biocrude within the kerosene fraction at longer RT might not necessarily result in more economical operating conditions. The longer RT, lower gravimetric biocrude yield and only a small increase in overall deoxygenation does not seem advantageous enough to pursue considering the KU-0060648 penalty.
3.6. Chemical characterisation – GC–MS
Table 1 (Supplementary Information 2) shows the list of detected compounds for biocrude produced at three different reaction conditions. Spectra with total chromatogram peak area of greater than 1% were identified using the NIST database. It should be noted that only a proportion of the biocrude produced lies within the temperature range in which the GC–MS operates and thus only a fraction of the components in the biocrude can be deciphered. Additionally, there might have been some loss of lighter compounds during solvent extraction and sample preparation.
From the list of compounds in Table 1 (Supplementary Information 2) it becomes apparent that under severe conditions there is more degradation of macromolecules present in algal biomass. It would be expected that proteins, lipids and carbohydrates will rapidly break down to their subsequent products under HTL conditions. The CN bond present in proteins will easily hydrolyse to form its primary product amino acids along with some hydrocarbons, amines, aldehydes and acids (Brunner, 2009). At longer RTs, these degradation/hydrolysis products can react with carbohydrate hydrolysis product, monosaccharide, to produce a range of products. Thus, there is a larger pool of compounds present at 380 °C and 4 min RT.