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Development of catalysts for the conversion of microalgae into biofuels

The use of biomass (agricultural and forest residues, energy crops, etc.) as a renewable energy source can reduce the dependence on fossil fuels, as well as reduce its impact on climate change. Among the existing biomass types, microalgae have a series of peculiarities that convert them in a good candidate for their conversion into biofuels in a sustainable way. Among them, can be highlighted the ability to grow on marginal lands, and the use of wastewater and CO2 as a source of energy and nutrients. Isochrysis sp. is a type of microalgae that has been shown to be a promising candidate as a raw material in the so-called biorefineries (due to its rich composition in carbohydrates and proteins) given the possibility of converting it into numerous by-products through different biological and thermochemical processes (e.g. pyrolysis).

The fast pyrolysis process is one of the thermochemical processes with the largest potential for the conversion of biomass into liquid products, such as biofuels and/or other high added-value products to the chemical industry due to its relative low cost and simplicity of operation. However, the properties of bio-oil directly obtained from biomass (microalgae) pyrolysis must be improved by means of catalytic processes that require the removal of heteroatoms (oxygen and nitrogen), giving rise to the formation of high added-value compounds to the chemical industry (e.g. aromatic hydrocarbons).

In this work (*), the senior assistant researcher of the Thermochemical Processes Unit of IMDEA Energy, Javier Fermoso, has collaborated with the Advanced Biofuels Lab of the Heriot-Watt University (Edinburgh), led by Dr. Aimaro Sanna, in which the use of the zeolite Li-LSX as a catalyst for the selective removal of oxygen and nitrogen from the pyrolysis bio-oil obtained from microalgae (Isochrysis sp) has been investigated. In addition, the effect the inorganic matter, naturally present in microalgae, has on the catalytic pyrolysis process has been studied. In summary, Li-LSX zeolite was effective maintaining a certain deoxygenation activity during several consecutive microalgae pyrolysis cycles. On the other hand, the partial removal of the microalgae mineral matter (which can work as natural catalysts) reduced the catalytic activity of the zeolite, so such pre-treatment is not recommended simplifying the process and saving costs.

(*) Nur Adilah Abd Rahman, Javier Fermoso, Aimaro Sanna. Stability of Li-LSX Zeolite in the Catalytic Pyrolysis of Non-Treated and Acid Pre-Treated Isochrysis sp. Microalgae. Energies 2020, 13(4), 959; https://doi.org/10.3390/en13040959

More information: Javier Fermoso, Senior Assistant Researcher of the Thermochemical Processes Unit, javier.fermoso@imdea.org

Event Date: 
Wednesday, June 3, 2020