Evaluation on the intensified hydroxypropyl acrylate (HPA) production processes: Rigorous design, optimization, techno-economic and environmental analysis, and control

This work firstly proposed novel processes synthesizing hydroxypropyl acrylate (HPA) from diluted aqueous acrylic acid (AA) and propylene glycol (PG). As both AA and HPA dimerize, the key in process design is to hold the one-pass conversion low, and the product selectivity high. Herein, three process schemes using different strategies in enhancing selectivity, or handling recycle streams, were investigated. These include the conventional reaction/distillation configuration (Scheme 1), the intensified process using a side reactor (Scheme 2), or multiple side reactors with feed splitting (Scheme 3). After optimization, it was found that scheme 3 exhibits the greatest economic and environmental attractiveness, which reduces 43.4 % of cost, and 13.8 % of CO2 emission from scheme 1. From the optimized scheme 3, the minimum required selling price (MRSP) of HPA (Target: 20 % internal rate of return, or IRR) is in between 1.904 and 2.797 USD/kg under varying raw material prices (i.e. diluted AA= 0.566–1.140 USD/kg; PG = 1.148–1.403 USD/kg). These results reveal the improvement from the current technology of producing HPA (i.e. current price: 2.725 USD/kg). Finally, a control structure was proposed onto the optimized Scheme 3. It satisfactorily rejects the disturbances from feed flowrate, feed composition and catalyst deactivation.