Batch-to-continuous process design and economic, energy, exergy, and environmental analyses of Claisen ester condensation based on diethyl 2-ethyl-2-phenylmalonate synthesis

Abstract

Abstract Batch operation is commonly used for the Claisen ester condensation reaction, resulting in relatively high energy consumption. For the industrial production of diethyl 2-ethyl-2-phenylmalonate, the key productivity-limiting factor is the Claisen ester condensation reaction via batch operation, which requires ＞ 22 h. In this study, the optimum reaction conditions were determined experimentally and a novel reactor and process to produce diethyl 2-ethyl-2-phenylmalonate are proposed, enabling continuous operation. The time required to produce a single output unit was reduced from 34 h to 5 h, while the process energy consumption was reduced by approximately 80%. All solutions used during the production process can be recycled and modeling and simulation of the process were extensively performed to determine the economic, energy, exergy, and environmental costs of the new process according to the principles of green chemistry. The analysis showed that the exergy loss of separation and purification unit is the largest, accounting for 48.1% of the entire process. The operating cost of the newly developed process with an annual output of 1400 t of product is $1.389 × 107 per year. The consumption per unit of output products was significantly lower than those of existing processes. The environmental emissions of the new production process provide a reliable basis for further optimization. The realization of continuous process operation provides a useful reference for other synthetic reactions currently achieved using batch reactors.