(4gn) Process Systems Engineering for Sustainable Chemicals

During the past decades, researchers in Process Systems Engineering (PSE) have been developing powerful tools for decision-making in process industries and chemical supply chains (Chen and Grossmann, 2017; Mujkic et al., 2018; Pistikopoulos et al., 2021). While past efforts were devoted to optimize and integrate individual processes and their supply chains, in the last few years we have experienced a move towards sustainable development via interplant integration, industrial symbiosis, and circular economy. In this search of more sustainable chemical production new manufacturing patterns and technologies need to be adopted to improve the efficiency of production processes and utilize sustainable raw materials and renewable energy sources. However, this transition presents new challenges to the PSE community regarding, among others, the modeling and optimization of new technologies and routes and their integration into existing chemical supply chains.

My research focuses on applying and extending the most recent tools and methods in PSE to solve the technical challenges that arise because of the paradigm shift towards sustainable development, with a special focus on material upcycling. Here, waste-to-resource and emissions-to-resource processes will be key to close material lifecycles and thus lead to a more efficient use of resources. Due to their emerging status, most of these technologies are at low technology readiness levels and require evaluation and scale-up procedures before the traditional synthesis and operation stages. Thus, decision support tools (supply chain optimization, process integration, process control...) have to be paired with techno-economic and life cycle assessment, and process modeling methods to ensure these problems are solved systematically to create economic value in the chemical industry by sustainable means. I will focus this approach on solving two of the main challenges related to sustainable development: the accumulation of plastic waste and carbon dioxide emissions.

Building circular plastic economies to enhance the use of materials

Plastics represent the main product of the chemical industry on a mass basis but are one of the most challenging ones to recycle due to collection and sorting stages and material degradation during recycling. Thus, overcoming these limitations will play a major role in building future sustainable chemical supply chains. The main advantages of applying a circular economy perspective to plastic supply chains include enhancing material and energy conservation, reducing the costs for the acquisition of fresh raw materials and treatment of side products, and decreasing the environmental footprint (Somoza-Tornos et al., 2020). These benefits are increased if, apart from direct waste-to-resource matching, transformation opportunities are also considered as a way to convert otherwise unusable waste into new profitable materials (Somoza-Tornos et al., 2021). PSE tools need to be extended to address the new challenges that circular systems pose: expand the scope of current models to include interplant exchanges and the particularities of using recycled materials, use game theory approaches to deal with the different stakeholders involved, and manage knowledge and uncertainty via ontologies and stochastic optimization, among many others. These methods will be integrated in a multi-scale framework to allow holistic decision-making.

The decarbonization of chemical synthesis via carbon dioxide utilization

Another key development towards sustainable development is carbon capture and utilization (CCU) to decarbonize hard-to-abate sectors (e.g., shipping, aviation, and industrial applications). A coordinated effort towards the cost-effective integration of CCU pathways (biochemical, bioelectrochemical, electrochemical, photocatalytic, photosynthetic, and thermo-catalytic processes) into the process chain and energy systems will be needed to drive the shift towards a low carbon economy, relying also on the integration of carbon neutral energy sources into the industrial and chemical sectors. Building a roadmap for the implementation of emerging technologies can also benefit from a multi-scale approach, from a complete design and assessment at the process level to the potential substitution of traditional technologies at the supply chain level (Zhang et al., 2020). Here, one of the main challenges to address is the modeling and assessment of emerging technologies with low technology readiness level, requiring full techno-economic and life cycle assessments paired with hybrid simulation methods. These models will have to be integrated into multi-period process network optimization models to assess the large-scale implementation of CCU and guide the transition to carbon-free chemicals.

References

Chen, Q., Grossmann, I.E., 2017. Recent Developments and Challenges in Optimization-Based Process Synthesis. Annu. Rev. Chem. Biomol. Eng. 8, 249–283. https://doi.org/10.1146/annurev-chembioeng-080615-033546

Mujkic, Z., Qorri, A., Kraslawski, A., 2018. Sustainability and Optimization of Supply Chains: a Literature Review. Oper. Supply Chain Manag. An Int. J. 186–199. https://doi.org/10.31387/oscm0350213

Pistikopoulos, E.N., Barbosa-Povoa, A., Lee, J.H., Misener, R., Mitsos, A., Reklaitis, G. V, Venkatasubramanian, V., You, F., Gani, R., 2021. Process systems engineering – The generation next? Comput. Chem. Eng. 147, 107252. https://doi.org/10.1016/j.compchemeng.2021.107252

Somoza-Tornos, A., Gonzalez-Garay, A., Pozo, C., Graells, M., Espuña, A., Guillén-Gosálbez, G., 2020. Realizing the Potential High Benefits of Circular Economy in the Chemical Industry: Ethylene Monomer Recovery via Polyethylene Pyrolysis. ACS Sustain. Chem. Eng. 8, 3561–3572. https://doi.org/10.1021/acssuschemeng.9b04835

Somoza-Tornos, A., Pozo, C., Graells, M., Espuña, A., Puigjaner, L., 2021. Process screening framework for the synthesis of process networks from a circular economy perspective. Resour. Conserv. Recycl. 164. https://doi.org/10.1016/j.resconrec.2020.105147

Zhang, Z., Pan, S.-Y., Li, H., Cai, J., Olabi, A.G., Anthony, E.J., Manovic, V., 2020. Recent advances in carbon dioxide utilization. Renew. Sustain. Energy Rev. 125, 109799. https://doi.org/10.1016/j.rser.2020.109799