Techno-Economic Assessment and Sensitivity Analysis of Glycerol Valorization to Biofuel Additives via Esterification

Upcycling glycerol into succinic acid: sustainable integration with biodiesel mills

This study explores the industrial potential of producing bio-based succinic acid (SA) from crude glycerol, a low-value byproduct of Brazil's biodiesel industry. By integrating green chemistry and biotechnology, the research aims to upcycle crude glycerol into high-value SA. Using Yarrowia lipolytica as a natural SA producer, the study assesses standalone facilities and systems integrated into biodiesel mills. Results show that producing SA from crude glycerol (S1) reduces climate change impact by 47% compared to using pure glycerol (S2), despite lower productivity. Integrating SA production with biodiesel operations (S3) improves economic performance but raises CO2 emissions by 54% relative to standalone biodiesel production (S1). All scenarios are economically feasible, with payback periods under seven years. Energy use and solvent recovery optimization remain essential to boost competitiveness. This work underscores the potential to upcycle crude glycerol, supporting circular economy strategies and informing sustainable biorefinery development and policy.

Co-upcycling of Plastic Waste and Biowaste via Tandem Transesterification Reactions

Polyethylene terephthalate (PET) and glycerol are prevalent forms of plastic and biowaste, necessitating facile and effective strategies for their upcycling treatment. Herein, we present an innovative one-pot reaction system for the concurrent depolymerization of PET plastics and the transesterification of glycerol into dimethyl terephthalate (DMT), a valuable feedstock in polymer manufacturing. This process occurs in the presence of methyl acetate (MA), a byproduct of the industrial production of acetic acid. The upcycling of biowaste glycerol into glycerol acetates renders them valuable additives for application in both the biofuel and chemical industries. This integrated reaction system enhances the conversion of glycerol to acetins compared with the singular transesterification of glycerol. In this approach, cost-effective catalysts, based on perovskite-structured CaMnO3, were employed. The catalyst undergoes in situ reconstruction in the tandem PET/glycerol/MA system due to glycerolation between the metal oxides and glycerol/acetins. This process results in the formation of small metal oxide nanoparticles confined in amorphous metal glycerolates, thereby enhancing the PET depolymerization efficiency. The optimized coupled reaction system can achieve a product yield exceeding 70% for glycerol acetates and 68% for PET monomers. This research introduces a tandem pathway for the simultaneous upcycling of PET plastic waste and biowaste glycerol with minimal feedstock input and maximal reactant utilization efficiency, promising both economic advantages and positive environmental impacts.

Nanostructured Solid/Liquid Acid Catalysts for Glycerol Esterification: The Key to Convert Liability into Assets

Owing to the growing concerns about the dwindling fossil fuel reserves, increasing energy demand, and climate emergency, it is imperative to develop and deploy sustainable energy technologies to ensure future energy supply and to transition to the net-zero world. In this context, there is great potential in the biorefinery concept for supplying drop in biofuels in the form of biodiesel. Biodiesel as a fuel can certainly bridge the gap where electrification or the use of hydrogen is not feasible, for instance, in heavy vehicles and in the farm and marine transportation sectors. However, the biodiesel industry also generates a large amount of crude glycerol as the by-product. Due to the presence of several impurities, crude glycerol may not be a suitable feedstock for all high-value products derived from glycerol, but it fits well with glycerol esterification for producing glycerol acetins, which have numerous applications. This review critically looks at the processes using nanostructured solid/liquid acid catalysts for glycerol esterification, including the economic viability of the scale-up. The homogeneous catalysts reviewed herein include mineral acids and Brønsted acidic ionic liquids, such as SO3H-functionalized and heteropoly acid based ionic liquids. The heterogeneous catalysts reviewed herein include solid acid catalysts such as metal oxides, ion-exchange resins, zeolites, and supported heteropoly acid-based catalysts. Furthermore, the techno-economic analysis studies have shown the process to be highly profitable, confirming the viability of glycerol esterification as a potential tool for economic value addition to the biorefinery industry.