(63d) The ASSF Tool – an Automated Systematic Synthesis Framework for Determining Feasible Reaction Pathways Prior to Extensive Design Procedures

With reactor unit operations considered to be the core of any chemical process, a considerable amount of design resources has been focused on optimizing its associated operating conditions, flow rates and catalyst composition, with the sole focus of this optimization centering around its economic and environmental feasibility. Therefore, when developing and analyzing existing, and new chemical process structures, the critical step involves determining the most efficient reactive system. While there may be a number of feasible pathways, there is always a possibility that a novel reaction system, or combination thereof, could potentially improve the efficiency of the process, or lower its operational costs.

However, with the proliferation of reaction pathways focused on the production of a single product, it has become increasingly difficult and time-consuming to develop economically and environmentally sound manufacturing processes. Whilst a novel, catalytic reaction pathway may exhibit feasibility on a laboratory scale, this may not hold true when scaled to an industrial level, leaving the potential plant application of these pathways with much uncertainty. One of the major concerns with scaling up a chemical reaction to an industrial scale, lies in the cost of unit operations required to meet the reaction’s operating conditions, as well as the necessary separation conditions. These downstream processing (DSP) techniques are of particular importance to the feasibility of a process, as it determines the purity achieved from the process structure, and its associated market value.

Additionally, to increase the feasibility of a process, it is possible that the product of one reactive system be treated as an intermediate in the overall process, thereby allowing for the production of a secondary product with a greater economic value. Whilst this expansion of the process boundaries cannot guarantee a more economically and environmentally feasible solution, the possibility of such cannot be negated, and is often overlooked during the initial stages of process design.

The Automated Systematic Synthesis Framework tool (ASSF tool) developed and presented herein, is a novel, rapid screening tool that bridges the gap between the analysis and scale up of laboratory systems. This tool, focused on the automated analysis of a reaction pathway database, considers the economic and environmental impacts of a process design by; (1) providing generic process structures, (2) determining the cost and environmental implications associated with the scale up of a reactive system, and (3) systematically searching for, and identifying, the possibility of pairing reaction systems, as consecutive reactor vessels in a chemical plant, attempting to increase the overall feasibility of the process structure.

The uses of the novel ASSF tool, presented herein, include:

• Quick, automated simulations of chemical plants given only the reaction pathway involved in the process,
• Determining the likely optimum operating condition range of a reaction pathway, given experimental data,
• Systematically designing and analyzing potential chemical plants associated with a reaction pathway database, accounting for potential reaction pathway combinations, and
• Reducing the potential search space of the reaction pathway database using economic and environmental search space reduction criteria.

Whilst the ASSF tool is not designed to develop novel reaction pathway systems, it is a useful analytical tool that speeds up the search for the most promising, and suitable, reactive systems. It is also able to highlight bottlenecks, and thus aid in strategic decisions and allocation of resources. The advantage of the ASSF tool in the existing engineering software space lies not only in its automated approach, but also in its simplified, generic design that minimized the level of detail required to analyse a reactive system/s, only requiring the balanced stoichiometric equation and the reaction’s operating conditions. This improves the efficiency of the tool, whilst increasing its usability in conceptual design stages, where streamlined and limited input data is available.

Once the reactions are inputted in a guided, predefined database format, the ASSF tool systematically searches for any potential reaction pathway combinations, registering each combination as a separate case study for analysis. Each reactive system/case study then undergoes a basic, generic process design, costing the unit operations required in, and leading up to, the reaction and separation systems. These plant structures are then analysed using economic and environmental criteria, with the final, reduced search space being ranked in order of its expected industrial feasibility.

It is important to note, however, that the ASSF tool is not designed as a replacement for existing chemical engineering software, but rather acts as a precursory, screening tool, with the ability to automatically narrow down large reaction pathway search spaces in a fraction of the time that would have previously been needed if these pathways were individually simulated in the existing software packages. Once the search space has been reduced and ranked in order of their predicted feasibilities, the user can utilize intricate software platforms, such as Aspen ® Plus, to perform a detailed design of its process structure. This allows for more efficient use of design resources, with users now only needing to focus on the intricate design of pathways that are likely to exhibit feasibility on an industrial scale. This is also beneficial in avoiding committing expensive resources from the onset.

To ensure the accuracy of the results obtained from the ASSF tool, the developed tool was verified against published simulation platforms, such as CHEMCAD ® and the Web-based Economic Cogeneration Modular Program (W-EcoMP). These comparisons show a minor deviation in capital costs of less than 6%, which is well within the ±30% range for preliminary design procedures. Furthermore, the ASSF tool was tested with a reaction pathway database developed by Jugmohan, et al. (2020), focused on the production of methanol and dimethyl via the hydrogenation of carbon dioxide. This study noted an analysis period of 10 months. This lengthy analysis period was due to the manual design and transfer of data between four intricate software platforms. Using the ASSF tool, the database was completely analysed in under 5 hours, concluding an identical final search space of 5 potentially feasible reactive systems. This application reiterates the use and uniqueness of the ASSF tool in identifying promising reactive systems at the early onset of the design procedure, allowing resources to be more focus driven.