Optimal synthesis of p-xylene separation processes based on crystallization technology

Ricardo M. Lima, Ignacio E. Grossmann

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


This article addresses the synthesis and optimization of crystallization processes for p-xylene recovery for systems with feed streams of high concentration, a case that arises in hybrid designs where the first step is commonly performed by adsorption. A novel superstructure and its corresponding mixed-integer nonlinear programming (MINLP) model are proposed. The distinct feature of this superstructure is the capability to generate optimum or near optimum flow sheets for a wide range of specifications of p-xylene compositions in the feed stream of the process. To cope with the complexity of the MINLP model, a two-level decomposition approach, consisting of the solution of an aggregated model and a detailed model, is proposed. The results obtained show good performance of the decomposition strategy, and the optimal flow sheets and p-xylene recoveries are in agreement with the results reported in patents.

Original languageEnglish (US)
Pages (from-to)354-373
Number of pages20
JournalAIChE Journal
Issue number2
StatePublished - Feb 2009
Externally publishedYes


  • Crystallization
  • MINLP optimization
  • Process synthesis
  • p-xylene separation

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • General Chemical Engineering


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