(248e) Systematic Process Design of Cumene Process

Cumene is produced industrially by the alkylation of benzene with propylene, and is one of the primary uses of benzene. Production of cumene is gaining more interest due to increasing market demands, and is used almost exclusively as a chemical intermediate for production of phenol and acetone [1].

In this work, a sustainable conceptual design of a cumene process has been developed, using a systematic, hierarchical, twelve step approach [2]. The process design has an annual cumene production of 4.1â??10⁵ metric tons, with a purity of 99.97 wt%. The process includes an alkylation reactor, and a transalkylation reactor. Benzene and propylene (which contains a 5% propane impurity) are fed to the alkylation reactor in a ratio of 3:1, where the main alkylation reaction occurs, as well as two side reactions producing di-isopropylbenzene (DIPB) and 1-hexene. In the transalkylation reactor, DIPB reacts with benzene to form additional cumene, thus increasing the yield [3]. The alkylation reactor outlet consists of a multi-component mixture of propane, propylene, 1-hexene, benzene, cumene and DIPB. First, a flash separation is performed for the separation of propane and 1-hexene. The overhead of the flash also contains benzene, and is sent to a distillation column where benzene is recovered in the bottom product and recycled to the alkylation reactor, and the overhead is further sent to another distillation column to separate propane from 1-hexene. Propane is sold as LPG and 1-hexene is purged. The bottom product of the flash is sent to a distillation column to separate benzene from cumene, and benzene is recycled back to the alkylation reactor. The bottom product is sent to another distillation column to separate cumene from DIPB, and DIPB is sent to the transalkylation reactor, where additional benzene is also fed in a ratio of 1:1. The effluents of the transalkylation reactor consists of benzene, cumene and DIPB, and is recycled back into the separation train, where it is mixed with the bottom product of the flash. This design will be considered the base case design of the process, and has been evaluated for further improvement.

The base case process design was subjected to an analysis including economics, sustainability indicators and life cycle assessment factors, where targets of improvement were identified. The targets were addressed through targeted process re-design, process optimization and heat-mass integration, in order to improve the economics of the process. Through a sustainability analysis and life cycle analysis, targets of improvement related to sustainability of the process were identified. Based on these targets, the sustainability of the process design was improved. The final process design has thus been improved w.r.t. both economic viability and sustainability, including an assessment of the environmental impacts. This poster will present systematic design of the process, including economic and sustainability results of the base case design as well as optimized cases.

References:

[1] R. M. Pandia, â??the Phenol-Acetone Value Chain: Prospects and Opportunities,â? 2013.

[2] D. K. Babi, Teaching Sustainable Process Design Using 12 Systematic Computer-Aided Tasks, vol. 37, no. June. Elsevier, 2015.

[3] M. Weber, W. Pompetzki, R. Bonmann, and M. Weber, â??Acetone,â? Ullmanâ??s encyclopedia of industrial chemistry. INEOS Phenol GmbH, p. 6, 2013.