Suppressing undesired solid byproducts formation in Maleic anhydride processing

• Maleic anhydride (MA) processes are limited by MA decomposition to polymeric solids. • Improved mixing is demonstrated to mitigate solids formation. • Droplet size and time scale analysis confirm transport outpacing solids formation. • ‘Chemical mixing’ via emulsification is proposed as novel, scalable alternative. Maleic Anhydride (MA) is a versatile molecule that serves as a precursor for numerous intermediates and consumer products. However, it is thermally unstable, decomposing at higher temperatures (>130 °C) in the presence of other hydrocarbons via decarboxylation to undesired polymeric byproducts. These solid byproducts not only compromise product quality but also pose severe operational challenges in industrial practice due to reactor fouling. The present study focuses on the production of polyisobutenyl succinic anhydride (PIBSA) from polyisobutene (PIB) and MA as an industrially important process, to demonstrate that this formation of solid byproducts can be suppressed via improved mixing (Fr > 0.073) in batch reactors and the resulting enhancement of the desired reaction over the undesired decomposition of MA. The mixing behavior of the reactor is characterized by dimensionless number and characteristic time scale analysis based on droplet size estimation of the dispersion, including the first estimate of interfacial tension between PIB and MA. Further, an alternative ‘chemical mixing’ approach via emulsification of PIB and MA with the product, PIBSA, was assessed as a reactor-size independent approach for scaling up mixing even under poor mechanical agitation. The reported results demonstrate that solids suppression through improved mixing leads to an increase in product yield as MA loss to solid byproduct formation is minimized. Mitigation of solid byproducts further mitigates reactor fouling and thus enables operation at higher temperatures, facilitating process intensification via accelerated reaction kinetics and hence significantly reduced production times.