Final Report: Ionic Liquids as Alternative Solvents for Industrial Alkylation Chemistry

EPA Contract Number: 68D00273
Title: Ionic Liquids as Alternative Solvents for Industrial Alkylation Chemistry
Investigators: Carter, Michael T.
Small Business: Eltron Research & Development Inc.
EPA Contact: Richards, April
Phase: II
Project Period: September 1, 2000 through September 1, 2002
Project Amount: $224,997
RFA: Small Business Innovation Research (SBIR) - Phase II (2000) Recipients Lists
Research Category: SBIR - Pollution Prevention , Pollution Prevention/Sustainable Development , Small Business Innovation Research (SBIR)

Description:

This Phase II project demonstrated and characterized the production of several economically important alkylbenzenes from ambient temperature ionic liquids by Friedel-Crafts alkylation. The products were generated by a reusable catalytic medium that minimizes environmental impact and disposal costs while increasing the value added to the products. Friedel-Crafts alkylation of benzene to ethylbenzene, cumene, and long-chain linear alkylbenzenes (LABs) was investigated. Products were characterized by fourier transform infrared spectroscopy, nuclear magnetic resonance imaging, and gas chromatography-mass spectroscopy analysis. Dependence of product and side product yield was examined as a function of acidity and other reaction conditions in AlCl3:triphenylmethylammonium chloride, AlCl3:1-ethyl-3-methylimidazolium chloride, and AlCl3:1-butyl-3-methylimidazolium chloride.

Summary/Accomplishments (Outputs/Outcomes):

Alkylations of benzene by ethylene, propene, 1-dodecene, 1-tetradecene, and 1-hexadecene successfully were carried out in a variety of Lewis acidic chloroaluminate ionic liquids. Products formed and their relative yields were consistent with the Friedel-Crafts alkylation mechanism, where olefins are the source of the alkyl group. LAB preparation was affected by rearrangement of a reactive intermediate to form a mixture of branched products in alkylation reactions, but this problem was remedied by performing the corresponding acylation reaction. Continuous production of products without loss of bulk ionic liquid or need to add catalyst was demonstrated. Ethylbenzene and cumene yields could be maximized by manipulation of melt acidity, concentration of starting benzene reactant, and the nature of the cation component of the ionic liquid.

Eltron Research, Inc., clearly demonstrated the feasibility of Friedel-Crafts benzene alkylation in an ambient temperature chloroaluminate ionic liquid for a wide variety of useful products. The concept of long-term reuse of the catalytic ionic liquid medium for the production of large quantities of product and minimal use of catalyst was demonstrated in principle in small bench-scale experiments. The ionic liquid medium can be applied without substantial modification to three major classes of extremely economically important alkylbenzene production. The Friedel-Crafts alkylation process can be cycled indefinitely in the catalytic acidic melt without loss of melt, addition of catalyst, or loss of catalytic activity. The demonstrated ability of the ionic liquid to be reused indefinitely could enable the production of large quantities of product per unit of ionic liquid catalyst. This would provide a substantial increase in ratio of product value to cost of production. Additionally, because catalyst is not lost or consumed during the process, addition of fresh catalyst is not necessary, in contrast to current methods of alkylbenzene production. The ability to indefinitely reuse catalyst could substantially reduce the amount of waste generated and lower the cost of disposal and environmental impact of the process.

Conclusions:

The reusable, catalytic ionic liquid medium was used to generate high value-added products including ethylbenzene, cumene, and LABs, which are used as feedstocks for polystyrene, phenol, and biodegradable surfactant production, respectively. The ionic liquid allowed a small amount of catalyst to be reused for a long time period, significantly decreasing the environmental impact of these materials, as well as waste-disposal costs. Yields in alkylation reactions depended on the nature of the ionic liquid, suggesting that the production of these materials can be tuned by selection of appropriate ionic liquid constituents.

Supplemental Keywords:

ionic liquid, ambient temperature molten salt, benzene alkylation, ethylbenzene, cumene, linear alkylbenzenes, styrene, phenol, SBIR, RFA, Scientific Discipline, Toxics, Sustainable Industry/Business, National Recommended Water Quality, Chemical Engineering, cleaner production/pollution prevention, Environmental Chemistry, Sustainable Environment, Chemistry, HAPS, Technology for Sustainable Environment, Chemistry and Materials Science, 33/50, Environmental Engineering, alkylation , alkylbenzenes, Cumene, Ethyl benzene, alternative solvents, alkylbenzene, benzene, alkylation, Ethylbenzene, ionic liquids, chloroaluminate, Benzene (including benzene from gasoline)


SBIR Phase I:

Ionic Liquids as Alternative Solvents for Industrial Alkylation Chemistry  | Final Report