Hydrothermal liquefaction of Cyanidioschyzon merolae and the influence of catalysts on products

Abstract

This work investigates the hydrothermal liquefaction (HTL) of Cyanidioschyzon merolae algal species under various reaction temperatures and catalysts. Liquefaction of microalgae was performed with 10% solid loading for 30min at temperatures of 180-300°C to study the influences of two base and two acid catalysts on HTL product fractions. Maximum biocrude oil yield of 16.98% was obtained at 300°C with no catalyst. The biocrude oil yield increased to 22.67% when KOH was introduced into the reaction mixture as a catalyst. The algal biocrude and biochar has a higher heating values (HHV) of 32.22MJkg and 20.78MJkg respectively when no catalyst was used. Gas chromatography time of flight mass spectrometry (GC/TOFMS) was employed to analyze the biocrude oil composition, and elemental analysis was performed on the algae, biocrude and biochar samples. Analysis of the HTL aqueous phase revealed the presence of valuable products.

Characterization of biofuel production from hydrothermal treatment of hyperaccumulator waste (Pteris vittata L.) in sub- and supercritical water

“…[6][7][8] Through series of complex chemical reactions under subor supercritical conditions, the process converts diverse biomass feedstocks into four types of products, as shown in Scheme 1: energy-dense bio-crude oil with higher heating value (HHV) of up to 35-40 MJ kg À1 ; 9,10 biochar, which can be used as a solid fuel, adsorbent or catalysis support; 11,12 biogas (e.g., combustible hydrogen and methane) and nutrient-rich aqueous products. 13 More importantly, during HTL process, particularly operating at pressures higher than 22.1 MPa and temperatures above 374 C, the decomposition of organic substances in biomass could result in the release of heavy metals into the liquid phase and their subsequent translation into stable solidphase fractions due to the changes in the water's physical properties (i.e., its diffusivity, solubility, density and dielectric constant). 14,15 Thus, these advantages make HTL a suitable technique for treating hazardous biomass with particular value from an energy exploration and environmental protection standpoint.…”

Co-liquefaction of mixed culture microalgal strains under sub-critical water conditions

“…Cyanidioschyzon merolae and Galdieria sulphuraria and the mixture of two species were selected in this study to run under subcritical water conditions and investigate the quantitative and qualitative performance of mixed microalgal strains. C. merolae & G. sulphuraria are unicellular, thermo-tolerant acidophilic red alga adapted to grow in extreme conditions (pH 0.5-4, 56 ˚C) (Muppaneni et al, 2017;Selvaratnam et al, 2014). (Jin et al, 2013) have evaluated the effect of co-liquefaction of microand macro-algae in subcritical water conditions and reported a positive synergistic effect.…”

Effect of cosolvent and addition of catalyst (HZSM‐5) on hydrothermal liquefaction of macroalgae

“…52 The catalyst (HZSM-5) activity may intensify the reaction of the small molecules in the later stage of polymerization, and some small molecule can be repolymerized to form carbon, thus leading to the increase in the solid residue yield. In general, macromolecules in algae are first decomposed into respective monomers such as glucose, amino acids, fatty acids, and so on.…”

“…These monomers are then further dehydrated, decarboxylated, and dehydroxylated to form small molecular compounds which are then polymerized, condensed, and cyclized to form new compounds of bio-oil, gas, and water. 52 The catalyst (HZSM-5) activity may intensify the reaction of the small molecules in the later stage of polymerization, and some small molecule can be repolymerized to form carbon, thus leading to the increase in the solid residue yield. 53 In the hydrothermal liquefaction experiment of EN, the presence of the catalyst affects both on the bio-oil quantity and the quality of the bio-oil product.…”