THE USE OF IONIC LIQUIDS AS EFFICIENT MEDIA IN OLEFIN/PARAFFIN SEPARATIONS

Sustainable process-product development & green chemistry

Modelling, Design & Analysis of Processes with Ionic Liquids (T1-1P)

Ing Alfredo Ortiz
University of Cantabria
Dpt. of Chemical engineering and Inorganic Chemistry
Departamento Ingeniería Química y Quimica Inorgánica. (Lab 456). ETSIIT Universidad de Cantabria. Av Castros s/n 39005 Santander Cantabria (Spain)
Spain

Ing Alicia Ruiz Perez
Universidad de Cantanbria
Ingenieria Química y Química Inorgánica
Universidad de Cantabria, Avda. de los Castros s/n 39005 Santander, Spain
Telf: +34 942 201585; fax: +34 942 201591
Spain

Dr Daniel Gorri
Universidad de Cantabria
Ingenieria Quimica y Quimica Inorganica
Avda. de los Castros s/n. 39005 Santander
Spain

Prof Inmaculada Ortiz
University of Cantabria
Chemical Engineering

Spain

Keywords: Ionic liquids, π-complexation, separation, olefins, paraffins

The separation of alkenes from hydrocarbon mixtures is one of the most important processes in the petrochemical industry. Their separation, a difficult process due to the similarity in molecular sizes and physical properties, is currently carried out by distillation, a high energy intensive process (Eldridge, 1993). Hence, there is a strong incentive to develop new processes for their separation with lower energy cost. To improve the energy efficiency of this separation process, absorption using chemical complexing agents such as copper or silver salts for selective olefin removal has been investigated (Krekeler et al., 1963).

Separation by π-complexation, Fig. 1, is a subgroup of chemical complexation where the mixture is contacted with the second phase, which contains a complexing agent. The advantage of chemical complexation is that the bonds formed are stronger than those by van der Waals forces alone, so it is possible to achieve high selectivity and high capacity for the component to be bound; at the same time, the bonds are still weak enough to be broken by using simple engineering operations such as raising the temperature , decreasing the pressure or using a sweep gas (A.E. Wentink, 2005).

Recently, considerable attention has been drawn to room temperature ionic liquids (RTIL) as green alternative to common organic solvents. RTIL are organic salts with melting points at or below room temperature. They have substantial potential as diluents in separations and their application is an important step in the design of environmentally safe separation processes, because ionic liquids are considered to be non-flammable, non-toxic and non-volatile.
In this work we present two case studies; first the removal of cyclopentadiene from cyclohexane, liquid solvent used in the manufacture of synthetic rubber, and second the separation of a gaseous mixture propane/propylene. In both cases the silver salt AgBF4 dissolved in the RTIL BminBF4 was used as a selective agent for complexation of the olefin.

Presented Monday 17, 13:30 to 15:00, in session Modelling, Design & Analysis of Processes with Ionic Liquids (T1-1P).