Technological assessment of glycerol carbonate (GC) synthesis via direct conversion of carbon dioxide: An examination of process design, techno-economic analysis, life cycle assessment, and safety evaluation

The synthesis of glycerol carbonate (GC) via the direct conversion of carbon dioxide (CO2) and glycerol (GLY) represents an innovative approach that transforms two waste materials into a valuable product. Although significant experimental research has been conducted, the technological viability for the development of this process has yet to be thoroughly investigated. To tackle this issue, the present study introduces two processes for the production of GC via the direct conversion pathway. Scheme 1 features photothermal catalytic conversion, while Scheme 2 employs thermal catalytic conversion with the addition of a chemical dehydrant (2-cyanopyridine, 2-CP) to enhance reaction performance. Rigorous separation strategies were proposed for both schemes. Subsequently, both processes were optimized and compared with other GC production pathways (i.e., indirect conversion and reactive-distillation-based transesterification) in the aspects of economics, environment, and safety. Overall, the techno-economic analysis indicates a lack of economic feasibility based on current technologies, reporting a minimum selling price (MSP) of $8.15 per kg for Scheme 1 and $15.76 per kg for Scheme 2. However, these values can be improved to $1.57 per kg for Scheme 1 and $1.38 per kg for Scheme 2, provided that the capital cost of the reactor is reduced and the expense of 2-CP can be offset through either regeneration or the sale of the hydration product, 2-picolinamide (2-PA). A cradle-to-gate life cycle assessment (LCA) indicates that both Schemes 1 and 2 are less sustainable compared to the indirect pathway. However, should the yield of the product in Scheme 1 be improved, the overall sustainability could potentially align with that of the indirect process. Finally, both direct conversion schemes have lower values for the inherent safety index (ISI). This, in turn, provides supportive evidence for the further development of this pathway. Overall, this study underscores the potential advantages and obstacles linked to this conversion pathway. It may serve as a valuable resource for subsequent research focused on process development.