A review of recent developments of pre-treatment technologies and hydrothermal liquefaction of microalgae for bio-crude oil production

Hu, Yingtao; Gong, Mengyue; Feng, Shanghuan; Xu, Chunbao; Bassi, Amarjeet

doi:10.1016/j.rser.2018.11.037

Cited by 121 publications

(64 citation statements)

References 165 publications

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“…11 The utilisation of microalgae often requires pretreatment to acquire the desired product with high efficiency. The treatment of microalgae can easily be divided into mechanical and nonmechanical methods such as ultrasonication, microwave, through acid and alkali treatment, and osmotic shocks 12,13 etc. Cell wall rupture is the main concern during pretreatment, and microwave pretreatment was found to be most effective and economical; however, barriers in the commercial application are still unknown.…”

Section: Introductionmentioning

confidence: 99%

Carbon conversion and stabilisation of date palm and high rate algal pond (microalgae) biomass through slow pyrolysis

et al. 2019

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Summary The processing of waste through pyrolysis technology is gaining momentum worldwide and is considered to be a green technology to reduce CO2 emissions. This study is devoted to analysing the lignocellulosic biomass (date palm) and wastewater‐derived microalgae and the carbon‐rich char produced between temperature range (400°C‐600°C) from these biomass types. The properties of microalgae char showed that significant variation with date palm char exhibited high heating values (24‐28 MJ/kg), low ash content (11%‐16%), and high energy yield (48%‐42%). Algal biomass char showed considerably high nitrogen content (6%‐7%) as compared with date palm char (<1%), lower stability, and more significant influence on the price with respect to treatment temperature. Quaternary, pyrrolic, and pyridinic nitrogen species were found on the surface of the microalgae char, whereas no nitrogen species detected on date palm char due to low nitrogen content. The activation energy was also noted to be high for algal char during pyrolysis and combustion process. It can be concluded that date palm char is suitable for energy applications, whereas, algal char can be used for soil amendment, wastewater treatment, and applications requiring nitrogen‐doped char.

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Section: Introductionmentioning

confidence: 99%

Carbon conversion and stabilisation of date palm and high rate algal pond (microalgae) biomass through slow pyrolysis

et al. 2019

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“…Hydrothermal liquefaction (HTL) of algae is usually conducted in a pressurized water environment (4-28 MPa) at a relatively moderate temperature (200-450 • C) [3,37,38,81,82]. At elevated temperature and pressure, the properties (e.g., solubility) of water change, which promote the degradation of macromolecules in algae to small molecular compounds [5,37].…”

Section: Biocrude From Direct Hydrothermal Liquefactionmentioning

confidence: 99%

“…The water-insoluble phase of liquid products can be recovered by extraction using organic solvents, and the obtained oil-like products are called biocrude. The water-soluble phase separated from liquid products containing nutrients (e.g., N, P, Mg and K) makes up a large fraction, which can be recycled for microalgae cultivation and anaerobic digestion [81,[83][84][85][86].…”

Section: Biocrude From Direct Hydrothermal Liquefactionmentioning

confidence: 99%

Catalytic Thermochemical Conversion of Algae and Upgrading of Algal Oil for the Production of High-Grade Liquid Fuel: A Review

Zhou

2020

Catalysts

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The depletion of fossil fuel has drawn growing attention towards the utilization of renewable biomass for sustainable energy production. Technologies for the production of algae derived biofuel has attracted wide attention in recent years. Direct thermochemical conversion of algae obtained biocrude oil with poor fuel quality due to the complex composition of algae. Thus, catalysts are required in such process to remove the heteroatoms such as oxygen, nitrogen, and sulfur. This article reviews the recent advances in catalytic systems for the direct catalytic conversion of algae, as well as catalytic upgrading of algae-derived oil or biocrude into liquid fuels with high quality. Heterogeneous catalysts with high activity in deoxygenation and denitrogenation are preferable for the conversion of algae oil to high-grade liquid fuel. The paper summarized the influence of reaction parameters and reaction routes for the catalytic conversion process of algae from critical literature. The development of new catalysts, conversion conditions, and efficiency indicators (yields and selectivity) from different literature are presented and compared. The future prospect and challenges in general utilization of algae are also proposed.

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“…A moderate temperature (250-375 • C), pressure (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), and reaction time within the range of 5-60 min are commonly used in HTL [9,14,15]. Under these conditions, the aqueous medium, near the critical point, promotes the degradation of macromolecules present in the algal biomass, as well as the polymerization of the resultant smaller molecules [13].…”

Section: Introductionmentioning

confidence: 99%

“…In order to decrease the N and O contents of the biocrude, different strategies can be devised. One of them is a low temperature HTL (<200 • C), which has been evaluated as a previous pretreatment to increase the quality of the final biocrude and to enhance the energy efficiency of the overall process [14,[20][21][22]. This is an advantageous option, because it allows for the hydrolysis of proteins into small molecules, which remain solubilized in the aqueous phase, diminishing the N content in the pretreated residue and consequently reducing the N content in the final biocrude.…”

Section: Introductionmentioning

confidence: 99%

Mild Hydrothermal Pretreatment of Microalgae for the Production of Biocrude with a Low N and O Content

et al. 2019

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A hydrothermal pretreatment of the microalga Nannochloropsis gaditana at mild temperatures was studied in order to reduce the N and O content in the biocrude obtained by hydrothermal liquefaction (HTL). The work focused on the evaluation of temperature, reactor loading, and time (factors) to maximize the yield of the pretreated biomass and the heteroatom contents transferred from the microalga biomass to the aqueous phase (responses). The study followed the factorial design and response surface methodology. An equation for every response was obtained, which led to the accurate calculation of the operating conditions required to obtain a given value of these responses. Temperature and time are critical factors with a negative effect on the pretreated biomass yield but a positive one on the N and O recovery in the aqueous phase. The slurry concentration has to be low to increase heteroatom recovery and has to be high to maximize the pretreated microalga yields. Response equations were obtained for the analyzed responses, which facilitated the accurate prediction of the operating conditions required to obtain a given value of these responses.

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A review of recent developments of pre-treatment technologies and hydrothermal liquefaction of microalgae for bio-crude oil production

Cited by 121 publications

References 165 publications

Carbon conversion and stabilisation of date palm and high rate algal pond (microalgae) biomass through slow pyrolysis

Carbon conversion and stabilisation of date palm and high rate algal pond (microalgae) biomass through slow pyrolysis

Catalytic Thermochemical Conversion of Algae and Upgrading of Algal Oil for the Production of High-Grade Liquid Fuel: A Review

Mild Hydrothermal Pretreatment of Microalgae for the Production of Biocrude with a Low N and O Content

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