Aqueous phase recycling in catalytic hydrothermal liquefaction for algal biomass and the effect on elemental accumulation and energy efficiency. (20th March 2021)

• Record Type: Journal Article
• Authors: Taghipour, Alireza; Hornung, Ursel; Ramirez, Jerome Atillo; Brown, Richard John; Rainey, Thomas James
• Is Part Of: Journal of cleaner production. Volume 289(2021)
• Publication Date: 2021-03-20
• Subjects: Biomass -- Aqueous phase -- Catalytic hydrothermal liquefaction (HTL) -- Biofuel -- Recycling; ANOVA Analysis of variance -- DCM dichloromethane -- EA Elemental analysis -- EC Energy consumption -- ECR Energy consumption recovery -- ER energy recovery -- HHV Higher heating value -- HTL hydrothermal liquefaction -- NOx Nitrogen Oxides -- WGS water-gas shift reaction -- WSO water-soluble organics; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2020.125582
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Generating green-based liquid fuels using hydrothermal liquefaction is a promising method for fossil fuel replacement. This study investigates the impact of recycling the aqueous phase in hydrothermal liquefaction processing on fuel yield, quality and energy efficiency using algae as the feedstock. Recycling the aqueous phase in algal hydrothermal liquefaction increased biocrude production yield by 18.9% at 350 °C, although a 12.2% increase in the biocrude nitrogen content was observed. In the second recycling, the nitrogen content increased to 17.6%, which is not environmentally favourable for direct usage in diesel engines due to the possible increase in Nitrogen Oxides (NOx) emissions. Recycling the aqueous phase in Spirulina Platensis feedstock liquefaction led to a 19–30% increase in yields for different recycling numbers, which was influenced by increasing the temperature and by applying catalysts. The heterogeneous catalyst showed a considerable increase (17.8%) in yield, a decrease (9.5%) in nitrogen content, and an improved energy consumption recovery by 30.8% after single recycling. However, a slight increase (2.7%) in nitrogen content was observed after recycling twice. It is vital to reduce the amount of energy used in the hydrothermal liquefaction process to be comparable with conventional fuels. Recycling the aqueous phase reduced the energy usage considerably. Applying the homogeneous catalyst and recycling the aqueous phase twice had the highest energy efficiency (36.8%) and production yield (51.4%) for the hydrothermal liquefaction process. The generated aqueous phase in single and double recycling experiments had up to 77% and 166% more phosphate, which may be of interest for agricultural applications. Graphical abstract: Image 1 Highlights: The aqueous phase of HTL was applied as the solvent in a new simple/catalytic test. Recycling of the aqueous phase increased the biocrude yield for most experiments. Energy consumption reduced notably for double recycling HTL with Na2 CO3 catalyst. Using Pt/Al2 O3 catalyst decreased the nitrogen content after recycling. Potential to reapply the residue for agricultural use due to phosphate.