Evaluation of Storage Stability for Biocrude Derived from Hydrothermal Liquefaction of Microalgae

Abstract

The instability of hydrothermal liquefaction (HTL) biocrude has impeded the broader utilization of fuel and chemical feedstock. In this paper, we investigated the storage stability of biocrude produced from HTL of microalgae. The biocrude showed good stability in phase homogeneity and water content, whereas the viscosity and average molecular weight increased by 48.4 and 41.9%, respectively, after storing for 12 months. Thermogravimetric analysis (TGA) and asphaltene content analysis indicated more high-boiling-point fraction, and asphaltene fraction appeared in biocrude during storage. Further elemental analysis and increased total acid numbers (TANs) demonstrated that oxidization acidic-compound-forming reactions occurred, and the gas chromatography–mass spectrometry (GC–MS) results evidenced this guess. However, the mechanism of biocrude storage instability still needs further analysis. The current biocrude assuredly requires stabilization refining for future applications.

Coupling hydrothermal liquefaction and aqueous phase reforming for integrated production of biocrude and renewable H2

“…First of all, the wastewater treatment cost would be reduced if the organic load is converted into a valuable product, with the remaining one being recycled; secondly, it compensates the environmental cost of the fossil H 2 ; moreover, if a green H 2 source is proposed (i.e., electrolysis powered by renewable energy), it would currently have higher costs. Furthermore, partial deoxygenation of the BC would be beneficial for the storage properties and avoid the increase of the viscosity 49,50 . In fact, several research groups showed that partially upgraded BCs could be processed together with fossil‐derived fuels in conventional refineries 51 …”

“…Furthermore, partial deoxygenation of the BC would be beneficial for the storage properties and avoid the increase of the viscosity. 49,50 In fact, several research groups showed that partially upgraded BCs could be processed together with fossilderived fuels in conventional refineries. 51 Other technologies investigated for the production of H 2 via the processing of HTL-AP are, among the others, supercritical water gasification (SCWG), also called hydrothermal gasification (HTG) and electrochemical oxidation (EO).…”

Enhanced biocrude production from hydrothermal conversion of municipal sewage sludge via co-liquefaction with various model feedstocks

“…11,12 The HTL process is advantageous in saving on the feedstock drying cost, requiring a lower heating energy input, and reducing the requirement for special facilities, compared with other thermochemical conversion processes (pyrolysis, gasication, and carbonization). 13,14 Moreover, the HTL operating conditions provide a sub/supercritical water environment to kill pathogens and passivate the heavy metals in MSS. 6 Hence, the HTL conversion of MSS could be a promising method for the disposal and recycling of municipal sludge waste.…”

Factors Affecting the Sensitivity of Hydroxyl Group Content Analysis of Biocrude Products via Phosphitylation and 31P NMR Spectroscopy

“…Compared to petroleum crudes, biocrudes are more compositionally complex, more reactive, and more susceptible to aging . The compositional complexity of biocrudes creates challenges for their refining or coprocessing with petroleum feedstocks. − Biocrudes also tend to be quite corrosive to metallic surfaces (especially at elevated temperatures), which adversely impacts their transportation, storage, and processing. − The corrosivity of biocrudes has been attributed to various protic oxygen containing molecular components, including alcohols, phenolics, carboxylic acids, and water. Such Brønsted acids are also known to catalytically accelerate dehydrative condensation − and oligomerization/polymerization reactions to form larger molecules and polymeric structures with reduced solubility, which lead to biocrude instability .…”

“…The compositional complexity of biocrudes creates challenges for their refining or coprocessing with petroleum feedstocks. − Biocrudes also tend to be quite corrosive to metallic surfaces (especially at elevated temperatures), which adversely impacts their transportation, storage, and processing. − The corrosivity of biocrudes has been attributed to various protic oxygen containing molecular components, including alcohols, phenolics, carboxylic acids, and water. Such Brønsted acids are also known to catalytically accelerate dehydrative condensation − and oligomerization/polymerization reactions to form larger molecules and polymeric structures with reduced solubility, which lead to biocrude instability . In addition, condensation reactions may occur during biocrude aging, causing precipitation of deposits associated with clogging and fouling of process equipment. − An improved understanding of relationships between biocrude’s corrosivity or instability and its native hydroxyl group containing populations is needed to inform production best practices and aid further integration of biocrude into the energy industry.…”