Distillation is widely used for separation in chemical industries, but accounts for a half of operational costs and 40% of the energy usage due to its low energy efficiency. Process intensification could effectively enhance the energy efficiency and reduce the energy requirement of the distillation processes by integrating unit operations or functions. However, there is no general methodology that enables to choose the best intensified distillation technologies among all available choices for a given separation task. This study generates a conceptual de-composed selection and decision approach by first identifying the process bottlenecks and intensification targets, and then select the most promising intensified techniques via a selection framework and decision matrix based on the identified bottlenecks and intensification targets. Two separation cases are illustrated to demonstrate the developed methodology, and the outcomes are verified with conceptual designs reported in the literature.@en

Process Intensification (PI) is an effective way to enhance process efficiency and sustainability at affordable costs and efforts, attracting particular interest in the European area, as one of the most important chemical production areas in the world. PI primarily contributes by developing and testing new processing technologies that once integrated within a process improve the overall process performance substantially but as a result, it may alter the overall process (flowsheet) structure and its dynamic behavior. As such PI plays a key role in improving energy efficiency, optimizing resource allocation, and reducing environmental impact of industrial processes, and thereby leading to a cost-effective, eco-efficient, low-carbon and sustainable industry. However, along with opportunities, the PI new technologies have challenges related to failures in longer-term performance. In this respect, Process Systems Engineering (PSE) stance is more on integration aspects of new PI technologies into processes by making process (re)designs, doing operability studies, and performance optimizations within a supply chain setting. PSE contributes to overcoming the challenges by providing systematic approaches for the design and optimization of PI technologies. This perspective paper is a lightly referenced scholarly opinion piece about the status and directions of process intensification field from a PSE viewpoint. Primarily, it focuses on PSE perspectives towards sustainable lower energy usage process systems and provides a brief overview of the current situation in Europe. It also emphasizes the key challenges and opportunities for (new) PI technologies considering their integration in a process in terms of process synthesis and design, process flowsheet optimization, process and plantwide control, (green) electrification, sustainability improvements. Potential research directions on these aspects are given from an industrial and academic perspective of the authors.

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CO₂ from carbonate-based capture solutions requires a substantial energy input. Replacing this step with (bi)carbonate electrolysis has been commonly proposed as an efficient alternative that coproduces CO/syngas. Here, we assess the feasibility of directly integrating air contactors with (bi)carbonate electrolyzers by leveraging process, multiphysics, microkinetic, and technoeconomic models. We show that the copresence of CO₃^2- with HCO₃^- in the contactor effluent greatly diminishes the electrolyzer performance and eventually results in a reduced CO₂ capture fraction to ≤1%. Additionally, we estimate suitable effluents for (bi)carbonate electrolysis to require 5-14 times larger contactors than conventionally needed contactors, leading to unfavorable process economics. Notably, we show that the regeneration of the capture solvent inside (bi)carbonate electrolyzers is insufficient for CO₂ recapture. Thus, we suggest process modifications that would allow this route to be operationally feasible. Overall, this work sheds light on the practical operation of integrated direct air capture with (bi)carbonate electrolysis.

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Distillation is widely used for fluid separation in chemical industries, but accounts for a half of the operational cost and 40–50 % of the energy usage due to its low energy efficiency. Process intensification could effectively enhance the energy efficiency as well as improve the economic performance of distillation processes by integrating unit operations or functions. However, matching suitable intensified distillation techniques systematically with given separation tasks remains a challenge. This study is the first to generate a conceptual multi-step selection and decision approach by first going through several high level questions with corresponding suggested solutions for a separation task, then identifying the process bottlenecks and intensification targets via a list of evaluation criteria. Each of the technologies goes through a pre-filled process intensification (PI) matrix, and the most promising intensified technologies are recommended, and potential solutions are compared against the task specifications. The PI matrix proposed in this work yields a short list of appropriate solutions to be designed and economically assessed, proposing a screening framework for fluid separations in order to make a rapid selection at an early stage. Several binary, ternary, and multicomponent zeotropic and azeotropic mixture separations are carried out as case studies to illustrate the application of the proposed methodology, being validated using literature data. The proposed methodology can also help reduce the search space before carrying out rigorous optimization for the synthesis and design of the distillation.@en

As the urgency of reducing greenhouse gas emissions increases, the chemical industry is moving towards more sustainable applications, such as substituting fossil feedstock with renewable ones. The development and implementation of novel technologies will entail momentous, system-wide changes to allow for the production of chemicals and fuels. This work aims at providing an overview of the energy requirements for the production of several chemicals by means of electrochemical reduction of CO2 (ECO2R), in order to aid the decision-making process to select the products on which further research and development efforts should focus.

The results demonstrate that the production of C1 oxygenated molecules, such as carbon monoxide and methanol, via ECO2R would have significantly lower requirements in terms of renewable energy generation when compared to fully reduced hydrocarbons (methane, ethylene) and ethanol. This would lead to a less demanding implementation of electrochemical CO2 utilisation technologies, allowing for a more streamlined deployment of ECO2R within existing supply chains.@en

Despite the huge efforts devoted to the development of the electrochemical reduction of CO2 (ECO2R) in the past decade, still many challenges are present, hindering further approaches to industrial applications. This paper gives a perspective on these challenges from a Process Systems Engineering (PSE) standpoint, while at the same time highlighting the opportunities for advancements in the field in the European context. The challenges are connected with: the coupling of these processes with renewable electricity generation; the feedstock (in particular CO2); the processes itself; and the different products that can be obtained. PSE can determine the optimal interactions among the components of such systems, allowing educated decision making in designing the best process configurations under uncertainty and constrains. The opportunities, on the other hand, stem from a stronger collaboration between the PSE and the experimental communities, from the possibility of integrating ECO2R into existing industrial productions and from process-wide optimisation studies, encompassing the whole production cycle of the chemicals to exploit possible synergies.@en

The constant development of new alternatives to treat waste aids in closing material loops towards the circular economy and improving sustainability through the use of new renewable materials and energy. This fact leads to the increasing need for decision-making tools for process synthesis and assessment, which can be addressed with an integrated framework that employs ontologies for knowledge management and optimization tools to perform a hierarchical assessment of alternatives. The systematization of these procedures raises the need for tools to automate techno-economic and life cycle analyses. In this work, such a challenge is addressed through the additional integration of add-on modules such as the CapEx-Opex estimation tools and surrogate modeling within this framework. A case study on plastic waste is proposed with the inclusion of several pyrolysis and gasification alternatives. Results show pyrolysis, followed by the subsequent purification of its products, as the best alternative and helped identify main drivers for technologies feasibility such as feedstock purity and energy consumption.

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An educational workshop for developing Process Systems Engineering (PSE) courses will be held during ESCAPE-33, following the model workshop that was run during the CAPE Forum 2022 held at the University of Twente, in the Netherlands. This 3-hour workshop distributes the participants into four teams working together to develop the outline of a course on a novel application area in PSE motivated by a selected plenary or keynote talk at the conference, with each team led by authors of this contribution. This paper provides an overview of the approach used in the workshop for the effective development of a PSE course.

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As energy systems across the globe transition toward net-zero emissions, the decarbonization of hard-to-decarbonize sectors, e.g., industry and transportation, is becoming more crucial. Renewable power-driven carbon dioxide (CO₂) electrolysis has the potential to facilitate this transition by (1) substituting carbon-intensive petrochemical and fuel production and (2) using CO₂ otherwise emitted from industrial processes or CO₂ from the atmosphere; however, because of existing technical and economic challenges, the industrial deployment of this technology is not yet imminent. Here, we present an overview of CO₂ electrolysis technologies to identify key hurdles in view of the industrial deployment of this technology in net-zero emissions energy systems. From the technology standpoint, catalysts should be developed with enhanced activity, selectivity, and stability/durability as well as membranes and reactors that prevent carbonate formation or crossover, achieve higher reaction rates, e.g., >1 A/cm², and demonstrate long-term stability, e.g., >5 years. Conversely, from the system integration standpoint, impurity-tolerant CO₂ electrolysis systems need to be developed and tested under relevant conditions, e.g., CO₂ streams with traces of impurities (NO_x, SO_x, O₂, N₂, H₂S, etc.). Additionally, the quantification of pros and cons of different integration pathways for CO₂ capture and CO₂ electrolysis requires further research. Moreover, the integration with variable renewable power sources—e.g., wind and solar photovoltaic power—and electricity markets requires a better understanding. For instance, the value of CO₂ electrolysis flexibility in view of variable renewable power supply or dynamic electricity prices is not well understood.

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Defossilizing the chemical industry using air-to-chemical processes offers a promising solution to driving down the emission trajectory to net-zero by 2050. Syngas is a key intermediate in the chemical industry, which can be produced from electrolytic H2 and air-sourced CO2. To techno-economically assess possible emerging air-to-syngas routes, we develop detailed process simulations of direct air CO2 capture, proton exchange membrane water electrolysis, and CO2 electrolysis. Our results show that renewable electricity prices of ≤$15 per MW h enable the replacement of current syngas production methods with CO2 electrolysis at CO2 avoidance costs of about $200 per t-CO2. In addition, we identify necessary future advances that enable economic competition of CO2 electrolysis with traditional syngas production methods, including a reverse water gas shift. Indeed, we find an improved CO2 electrolysis process (total current density = 1.5 A cm−2, CO2 single-pass conversion = 54%, and CO faradaic efficiency = 90%) that can economically compete with the reverse water gas shift at an optimal cell voltage of about 2.00 V, an electricity price of $28–42 per MW h, a CO2 capture cost of $100 per t-CO2, and CO2 taxes of $100–300 per t-CO2. Finally, we discuss the integration of the presented emerging air-to-syngas routes with variable renewable power systems and their social impacts in future deployments. This work paints a holistic picture of the targets required to economically realize a defossilized syngas production method that is in alignment with net-zero goals.@en

The need to transform economic models to implement a circular use of resources is crucial due to the current waste accumulation crisis. New waste-to-resource alternatives are constantly emerging to close material loops; therefore, tools are needed to identify the best synergies to upcycle waste. An approach has been developed to identify and assess waste-to-resource processing routes not currently implemented at the industrial level to valorize waste. The proposed framework consists of several interconnected modules that include ontologies for knowledge management, graph theory and short-path algorithms for the generation of paths and pre-assessment of processes, a Mixed-Integer Linear Programming (MILP) model for superstructure optimization; and the rigorous design, simulation, and optimization exclusively of those alternatives that show the best performance in previous steps. A case study for the treatment of mixed plastic waste reveals chemical recycling and the production of pyrolytic fuels as tentatively favorable options, both environmentally and economically.

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