Abstract
A technical evaluation on the production of sustainable formaldehyde was presented in this report, including process design, advanced simulation, economic analysis, and environmental analysis. Three process configurations to produce formaldehyde were developed: a base-case with no capture of carbon, a post-combustion capture (PCC) process, which utilized 14 wt.% MEA solution-based process, and a direct air capture (DAC) route which used NaOH. Sequestered CO₂ was used as a major feedstock for methanol production via an electrocatalytic reactor (ECR), after which was converted into formaldehyde via a FORMOX process. Large-scale simulations were carried out, demonstrating a yearly methanol production capacity of approximately 62 million kilograms, with a fixed formaldehyde-to-methanol conversion ratio of 1.4 kg per kg of methanol. Economic models were developed using Aspen Process Economic Analyser, indicating that the base-case option (without capture) would involve a capital expenditure (CAPEX) of approximately $108 million and an operating expenditure (OPEX) of $427 million per year. In comparison, the PCC design was associated with a CAPEX of $120 million and a reduced OPEX of $395 million annually. The DAC option was found to require a similar CAPEX ($119 million), but a significantly higher OPEX of $519 million due primarily to the cost of reagents and electricity penalties in calcium looping. A grid-search optimisation was conducted over 10,000 data points to compare reactor geometry, with a feasible optimum identified at a diameter of 0.02 m, length of 1.00 m, at 400°C and 1 bar. Under these conditions, high selectivity in formaldehyde synthesis was achieved with very minimal side reactions, which was deemed significant as around 68% of the total CAPEX and 66% of the total OPEX were attributed to the ECR alone. Heat integration analysis using Aspen Energy Analyser was performed, and the most utilised heat exchanger (E-129) was found to manage approximately 52 million kJ/h thermal load, with a cost exceeding $841,000, reaffirming the importance of energy recovery within the design. Furthermore, a life cycle assessment (LCA) based on the ReCiPe Midpoint method was conducted, showing that the global warming potential of the reference process was around 3.90 kgCO2eq following process optimisation and carbon capture integration. A sustainable process design was therefore proposed, featuring a payback period of approximately 6 years and projected cumulative profits of $245 million by year 20, based on a formaldehyde base price of €2.16/kg and an ECR cost share of 20%.