(731g) Evaluating Glycerol Carbonate Production from CO2 and Glycerol: An Integrated Process Analysis

The decarbonization of the chemical industry stands as one of the most important challenges in the transition towards a renewable-based system. Currently, fossil resources serve a dual role: as energy supplier (accounting for around 42% of the total usage) and as feedstock for the different processes (representing the remaining 58%) (Kätelhön et al., 2019). Among the alternatives proposed for establishing a sustainable chemical industry, CO₂ utilization has attracted great attention in the last years as feedstock. The aim extends beyond a mere substitution of current fossil resources, encompassing the creation of novel chemical products in accordance with the principles of green chemistry and engineering. In this context, Glycerol Carbonate (GC) emerges as a key green chemical that is gaining increasing attention (Pirzadi & Meshkani, 2022). GC offers two main benefits: its wide reactivity involving an extended range of applications including the synthesis of green polymers or surfactants and the possibility of valorising glycerol, a by-product of the biomass-based industry. Different pathways have been explored in the production of GC. The most straightforward approach (at least theoretically) is the direct combination of glycerol and CO₂ (Luo et al., 2022). However, this route is highly constrained by thermodynamics, offering low performance results. Presently, the most promising alternative lies in transcarbonation, involving the reaction between an alcohol (glycerol) with a carbonate (highlighting dimethyl carbonate) (Christy et al., 2018).

In this work, an integrated process assessment for the synthesis of GC is performed employing CO₂ and glycerol as the primary raw materials. The selected synthesis follows the transcarbonation reaction between glycerol and Dimethyl Carbonate (DMC). The overall process consists of three main stages. The first one involves the production of urea via the combination of CO₂ and ammonia. Subsequently, in the second step, the alcoholysis reaction between the produced urea and methanol synthesizing DMC. Finally, the DMC is combined with glycerol for the final synthesis of GC. The entire process is modelled using ASPEN Plus V14 including some experimental equations for this particular synthesis using Fortran statements. A comprehensive techno-economic evaluation is performed for the proposed process obtaining the final technical and economic results toward the implementation of this green route to produce GC.

The techno-economic evaluation reveals promising results. The two main raw materials of the GC production are glycerol and CO₂ with a global yield in the synthesis of 0.78 kg glycerol/kg GC. Some small amounts of ammonia and methanol are required to mitigate process losses. The capital cost, for a facility with an operating capacity of 166,870 t of GC/year, is estimated at 171.5 M$. The total operating cost for GC produced by this integrated green process amounts to 1558 US$/t of GC where the utilities and the raw materials constitute the two most important contributions. These results demonstrate competitiveness with other alternative processes for the synthesis of GC showing the potential of process integration in designing a new efficient green chemical industry.

References

Christy, S., Noschese, A., Lomeli-Rodriguez, M., Greeves, N., Lopez-Sanchez, J.A. (2018). Recent progress in the synthesis and applications of glycerol carbonate. Current Opinion in Green and Sustainable Chemistry, 14, 99–107

Kätelhön, A., Meys, R., Deutz, S., Suh, S., Bardow, A. (2019). Climate change mitigation potential of carbon capture and utilization in the chemical industry. Proceedings of the National Academy of Sciences, 116, 11187–11194.

Luo, C., Wang, J., Lu, H., Wu, K., Liu, Y., Zhu, Y., Wang, B., Liang, B. (2022). Atmospheric-pressure synthesis of glycerol carbonate from CO2 and glycerol catalyzed by protic ionic liquids. Green Chemistry, 24, 8292–8301.

Pirzadi, Z., Meshkani, F. (2022). From glycerol production to its value-added uses: A critical review. Fuel, 329, 125044.

Acknowledgements

The authors are grateful to the PSEM3 research group for its support in the development of this work, the funding received from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 778168 (IProPBio proyect), and also acknowledge the funding received from the CONAHCYT and the FPU, Spain grant (FPU21 /02413) to C.P.