The Role of Ionic Liquids on Biomass Liquefaction—A Short Review of the Recent Advances

Abstract

Biomass is recognised as one of the most attractive feedstocks among the alternative resources, having a high potential for the sustainable production of valuable chemicals and biofuels. Due to its abundance, convenience, carbon neutrality and eco-friendliness, biomass is believed to positively impact the current environmental crisis caused by the extensive use of petroleum resources. For this reason, the search for processes that can convert this feedstock, resolving some inherent drawbacks, is needed. Biomass liquefaction using ionic liquids (ILs) as catalysts has received appreciable attention in renewable fuels and chemicals production. With the potential for a substantial number of anion and cation pairings, ILs can be an attractive medium towards reusability and sustainability for these processes due to the unique and tunable combinations of their functional groups-and, therefore, their properties. In this review, several studies using ILs in biomass liquefaction are compared and discussed. With a particular emphasis on the last five years, advantages and disadvantages will be discussed using this class of liquids addressing essential issues such as yields, reusability and conversion, among others.

Importance of Microalgae and Municipal Waste in Bioenergy Products Hierarchy—Integration of Biorefineries for Microalgae and Municipal Waste Processing: A Review

“…Due to the complex nature of biomass compositions, various reactions occur at once to transform biomass feedstocks into bio-oil. During the reaction, phase separation takes place spontaneously, resulting in carbon dioxide gas, solid bio-char trace, bio-oil, and traces of aqueous phase [30]. Most importantly, the great majority of the product is bio-oil and only a small amount is other unwanted by-products.…”

Bio-Oil: The Next-Generation Source of Chemicals

“…With similar outcomes, there is also the possibility to generate bio-oil fractions through pyrolysis with two or more steps [165], supercritical CO 2 fractioning [166][167][168], or separations using ionic liquids [169,170].…”

Investigation of the Liquefaction Kinetics of the PolyE-IL-Catalyzed Catalytic Thermo Liquefaction Process for Organic Biodegradable Municipal Solid Waste

“…Ionic liquids (ILs) have received attention as a potential homogeneous catalyst for HTL of biomass due to their distinctive properties, including the low melting point, low flammability, solubility in a wide range of solvents, high thermal stability, structural adaptability, and controllable acidity and basicity. , Abushammala and Mao have investigated the use of imidazolium-based ILs for the dissolution and fractionation of wood and lignocelluloses . Similarly, Cristino et al have assessed the role of ILs in biomass liquefaction . Amarasekara and Reyes have reported the usage of 1-(3-propylsulfonic)-3-methylimidazolium chloride and 1-(4-butylsulfonic)-3-imidazolium chloride ILs as catalysts for liquefaction of corn cob .…”