Nitrogen distribution in the products from the hydrothermal liquefaction of Chlorella sp. and Spirulina sp.

Review on Nitrogen Transformation during Microalgae Thermochemical Liquefaction: Recent Advances and Future Perspectives

“…Proteins consist of at least one peptide chain and most nitrogen elements in microalgae . During HTL, the components of microalgae went through dynamic processes or complex interconversions such as hydrolysis, dehydration, breaking chemical bonds, and stepwise rearrangement or sometimes simultaneous conversion to four-phase products, such as biocrude, liquid, solid, and gas, in which N transformation pathways were also complex and element N was distributed in the final substances in different forms depending on various conditions including microalgae properties and operating conditions. − In this review, the effect of microalgae properties will be discussed based on species and biochemical compositions, respectively.…”

“…Nearly 40 sets of data from the literature ,,,,,,,− were collected to generalize and analyze the general pattern of interactions between the three biochemical compositions of microalgae on the N distribution in biocrude (N bio ) as shown in Table S1 and Figure . All three components (protein, lipid, and carbohydrate) presented in this figure were normalized to ensure they sum to 1 (daf %).…”

“…Most of the remaining N may end up in aqueous products in the form of ammonia-N and organic nitrogen or other phases . Practically, it is expected that more N can be transferred into the aqueous phase for recycling and utilization, while more carbon and hydrogen can be converted to biocrude for high heating value. ,, However, technically controlling the N distribution during HTL is not only affected by the microalgae property but also determined by operational condition which is stated in the next section.…”

“…A favorable solid loading rate for microalgae HTL depends on many factors, such as microalgae species, the scale of the reactor, and economics . Generally, most of the studies selected a solid loading rate of 10–30 wt % and observed that the lower N bio was easily obtained when it was 20 ± 5 wt % …”

“…at the same reaction time (60 min) and obtained the same T min (260 °C), although the solid loading rate was 20 and 11.1 wt %, respectively. However, Bao et al and Jena et al observed totally different T min , 260 and 200 °C, respectively, for the same species ( Spirulina sp. ) and the same retention time (60 min) when the solid loading rate was 10 and 20 wt %, respectively.…”