(31b) Methodology and Development of a Process for Extractive Distillation Using a Novel Ionic Liquid for the Recovery of Olefin From Paraffin Mixtures

A methodology and a proposal for the design of an extractive distillation process based upon using a novel ionic liquid as the heavy solvent to separate olefins from paraffins is presented. The ionic liquid is silver(I)/N,N-dimethylbenzoamide bis(trifluoromethylsulfonyl) imide [Ag(DMBA)₂+Tf₂N-], and was synthesized by the Oak Ridge National Laboratory. This ionic liquid takes advantage of the special ability of silver to form pi-bonds with the double bonds in the olefin. The process is designed using the ASPEN PLUS? process simulation tool, and the steps that are required for the process development are described.

The application that will be discussed is the recovery of higher olefins from paraffins. In this case, the discussion will center on the separation of 1-octene from the binary mixture of n-octane and 1-octene. The model is based on experimental infinite dilution data that were generated and recently published by The Dow Chemical Company in the Industrial & Engineering Chemistry Research journal. However, the steps and data requirements in the development of the process are broadly applicable to the development of a broad variety of processes using ionic liquids as the heavy solvent in an extractive distillation process.

The development of the information and the evaluation of the potential benefits of using ionic liquids is a necessary step for these relatively new class of components to gain wide commercial acceptance. Any broad application of these materials must involve an understanding of the economic benefits and economic hurdles yet to be overcome. In an effort to understand the economic impact of an extractive distillation using an ionic liquid, the proposed extractive distillation scheme using ionic liquid is compared with a conventional process using traditional heavy solvent like N-methyl pyrrolidone.