Hydrothermal Liquefaction of Microalga Using Metal Oxide Catalyst

Sánchez-Bayo, Alejandra; Rodríguez, Rosalía; Morales, Victoria; Nasirian, Nima; Bautista, Luis Fernando; Vicente, Gemma

doi:10.3390/pr8010015

Cited by 18 publications

(21 citation statements)

References 46 publications

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“…The relation between denitrogenation and hydrogenation can be better understood by means of a modified van Krevelen plot in terms of H/C and N/C atomic ratios [19,48]. From Figure 5, it is clear that temperature has a significant effect on both nitrogen removal and the reduction of the aromatic content (especially in Spirulina).…”

Section: Tablementioning

confidence: 99%

Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage

Haider

Castello

Rosendahl

2020

Biomass and Bioenergy

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ACCEPTED MANUSCRIPT When citing this work, please refer to the final version published in "Biomass and Bioenergy" (Elsevier), which is available through the following bibliographic details:M.S. Haider, D. Castello, L.A. Rosendahl, Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage.Abstract: Effective catalytic hydrotreatment of highly nitrogenous biocrudes derived from the hydrothermal liquefaction (HTL) of primary sewage sludge and microalga Spirulina biomass was explored. A critical issue is the lack of thermal stability of raw HTL biocrudes at the severe conditions (~400 °C) required for hydrodenitrogenation. This fact suggests the need for a two-stage approach, involving a first low-temperature stabilization stage followed by another one operated at higher temperature. In this study, DSC was successfully used to indicate the thermal stability of both biocrudes. During hydrotreating, it was observed that complete deoxygenation was already achieved in the first stage at 350 °C, with limited coke formation.Moreover, after second stage up to 92% denitrogenation associated with the higher hydrogen consumption (39.9 g kg -1 for Spirulina and 36.9 g kg -1 for sewage sludge) was obtained for both biocrudes. Consequently, comparable oil yields but significantly less coke yields were recorded during two-stage upgrading (1.0% for Spirulina and 0.7% for sewage sludge), compared to direct processing at 400 °C (9.1% for Spirulina and 3.4% for sewage sludge). In addition, the properties of the upgraded oils were enhanced by increasing the temperature in the first stage (310 °C, 330 °C and 350 °C respectively). Finally, the results indicated that remarkable drop-in fuel properties were obtained, with respect to heteroatom (O and N) removal, HHV, and H/C ratio during the two-stage hydrotreatment. Two-stage hydrotreating is therefore proposed as a successful approach for the upgrading of HTL biocrudes with high nitrogen content.

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Section: Tablementioning

confidence: 99%

Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage

Haider

Castello

Rosendahl

2020

Biomass and Bioenergy

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“…Processes 2020, 8, x FOR PEER REVIEW 16 of 21 biodiesel (0.0004) and the conventional diesel (0.0048) [72]. Furthermore, all the values obtained were between the limits found in the literature (0.056-0.1) [73].…”

Section: Analysis Of Biocrudementioning

confidence: 55%

“…These decreases were due to the high yields obtained from the aqueous phases. The H/C ratios of the P. tricornutum-derived biocrudes were higher than the H/C ratio for a biocrude from N. gaditana (1.25) [72]. Therefore, the H/C values of the biocrude from P. tricornutum were closer to those of the reference diesel (1.84).…”

Section: Analysis Of Biocrudementioning

confidence: 71%

“…The biofuel properties were significantly affected by their H/C, N/C and O/C ratios, as it is well known. The above ratios for the biocrudes, along with those of a petroleum diesel, a biodiesel and a biocrude obtained from the microalgae N. gaditana [72], were plotted in Van Krevelen diagrams (Figure 6) for comparison purposes. The results showed that the O/C and N/C ratios decreased in our biocrudes with respect to the initial biomass, which were due to the denitrogenation and decarboxylation reactions taking place during the HTL process [27].…”

Section: Analysis Of Biocrudementioning

confidence: 99%

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Scale-Up Cultivation of Phaeodactylum tricornutum to Produce Biocrude by Hydrothermal Liquefaction

et al. 2020

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Phaeodactylum tricornutum is an interesting source of biomass to produce biocrude by hydrothermal liquefaction (HTL). Its biochemical composition, along with its biomass productivity, can be modulated according to this specific application by varying the photoperiod, the addition of CO2 or the variation of the initial nitrate concentration. The lab-scale culture allowed the production of a P. tricornutum biomass with high biomass and lipid productivities using a 18:6 h light:dark photoperiod and a specific CO2 injection. An initial concentration of nitrates (11.8 mM) in the culture was also essential for the growth of this species at the lab scale. The biomass generated in the scale-up photoreactor had acceptable biomass and lipid productivities, although the values were higher in the biomass cultivated at the lab scale because of the difficulty for the light to reach all cells, making the cells unable to develop and hindering their growth. The biocrudes from a 90-L cultivated microalga (B-90L) showed lower yields than the ones obtained from the biomass cultivated at the lab scale (B-1L) because of the lower lipid and high ash contents in this biomass. However, the culture scaling-up did not affect significantly the heteroatom concentrations in the biocrudes. A larger-scale culture is recommended to produce a biocrude to be used as biofuel after a post-hydrotreatment stage.

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“…[ 71 ] Catalysts such as Na 2 CO 3 or CaO may be used to improve yields, but only for some strains and under particular reaction conditions. [ 72,73 ]…”

Section: Harvesting Microalgaementioning

confidence: 99%

Harvesting Microalgae for Food and Energy Products

et al. 2020

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their size and physiology, and they belong to many different phylogenetic groups that are distinct from plants. [1] Microalgae are the subset of algae that are unicellular and range in size from several to a few hundred micrometers. Most microalgae diversity resides in freshwater or marine systems. Microalgae can grow in extreme environments such as deserts and polar regions, [2] and often show greater efficiency in synthesizing bioproducts compared to land plants. [3] Moreover, algae produce oxygen and sequester the greenhouse gas carbon dioxide at globally relevant scales, [4] and account for half of the oceans' net primary production. [5] They grow fast and can produce high-value biomass. [6] While microalgae are phylogenetically diverse, most biotechnology interest applies to the green algae (Chlorophyceae), diatoms (Bacillariophyceae), blue-green algae (Cyanobacteria), and Eustigmatophyceae (including Nannochloropsis), which are well-characterized species for valuable bioproducts. 1.2. Microalgae as Sustainable Biofactories Microalgae have the potential to produce large amounts of valuable products sustainably, since they do not require arable land and can be produced using seawater, wastewater, or brackish water. Reduction in environmental impacts of fuels and food products will be important for the mitigation of climate change. [7] Microalgae are also being used in powerplants as a means to capture carbon dioxide and sequester it into biomass, which may provide opportunities for large-scale production of carbon-neutral energy and products. [8] Vaccines and other pharmaceutical proteins are among the most high-value products that microalgae are used to produce, as well as effectively store and orally administer those products. [9] Other high-value products derived from microalgae include cosmetics, [10] food supplements and additives, [11] cooking oils, [12] and animal feed. [13,14] These have been developed as potentially more sustainable alternatives to synthetic or animal-derived products. Microalgae also provide feedstocks for biodiesel [15] and ethanol, [16] contributing to renewable and sustainable energy resource developments that may displace fossil fuels and food-derived fuels. Genetic and synthetic biology approaches can accelerate the development of microalgae strains capable of producing novel specialty products [17-19] or producing conventional products with improved lipid content, [20] growth rate, and production efficiency. [21,22] Unlike field-grown transgenic crops, multi ple Microalgae are promising biological factories for diverse natural products. Microalgae tout high productivity, and their biomass has value in industrial products ranging from biofuels, feedstocks, food additives, cosmetics, pharmaceuticals, and as alternatives to synthetic or animal-derived products. However, harvesting microalgae to extract bioproducts is challenging given their small size and suspension in liquid growth media. In response, technologic developments have relied upon mechanical, chemical, thermal, and b...

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Hydrothermal Liquefaction of Microalga Using Metal Oxide Catalyst

Cited by 18 publications

References 46 publications

Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage

Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage

Scale-Up Cultivation of Phaeodactylum tricornutum to Produce Biocrude by Hydrothermal Liquefaction

Harvesting Microalgae for Food and Energy Products

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