Final Report: Ionic Liquids as Alternative Solvents for Industrial Alkylation ChemistryEPA Contract Number: 68D99042
Title: Ionic Liquids as Alternative Solvents for Industrial Alkylation Chemistry
Investigators: Carter, Michael T.
Small Business: Eltron Research & Development Inc.
Project Period: September 1, 1999 through March 1, 2000
Project Amount: $69,997
RFA: Small Business Innovation Research (SBIR) - Phase I (1999) RFA Text | Recipients Lists
Research Category: SBIR - Pollution Prevention , Pollution Prevention/Sustainable Development , Small Business Innovation Research (SBIR)
Description:This Phase I program demonstrated feasibility for continuous production of several economically important alkylbenzenes from an ambient temperature ionic liquid by Friedel-Crafts chemistry. The goal of this program was to demonstrate that these products could be generated by an indefinitely reusable catalytic medium to minimize environmental impact and disposal costs, while increasing value added of the products.
Friedel-Crafts alkylation of benzene to ethylbenzene, cumene and long-chain linear alkylbenzenes (LABs) was investigated in an ambient temperature ionic liquid. Products were characterized by FTIR, NMR and GC-MS analysis. Continuous production of products from a single batch of ionic liquid without loss of catalytic activity or need for addition of catalyst was demonstrated.
Summary/Accomplishments (Outputs/Outcomes):Alkylation of benzene by ethylene, propene and 1-dodecene were successfully carried out in a Lewis acidic chloroaluminate ionic liquid. Products formed and their relative yields were consistent with a standard Friedel-Crafts alkylation mechanism using the olefins as the source of the alkyl group. Ethylbenzene selectivity up to 34% and cumene selectivities as high as 48% could be attained in single pass reactions without following transalkylation. LAB preparation was affected by rearrangement of a reactive intermediate to form a mixture of branched products. Continuous production of products without loss of ionic liquid bulk or need to add catalyst was demonstrated for cumene and LABs.
Work accomplished during the Phase I program clearly demonstrated feasibility of Friedel-Crafts benzene alkylation in an ambient temperature chloroaluminate ionic liquid. The concept of long-term reuse of the catalytic ionic liquid medium for production of large quantities of product and minimal use of catalyst was demonstrated in principle in small scale bench experiments. Syntheses demonstrated included production of cumene, ethylbenzene and linear alkylbenzenes. 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. We have demonstrated this by running 10-15 consecutive preparations of 1-phenyldodecane and cumene from a single ionic liquid batch. While we arbitrarily halted the process after 10-15 batches, there was no indication of loss of the bulk medium or catalytic activity, indicating that many more cycles could have been accomplished if desired. The demonstrated ability of the ionic liquid to be reused indefinitely will enable production of large quantities of product per unit ionic liquid catalyst. This will provide a substantial increase in ratio of product value to cost of production. Additionally, since 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 will also substantially reduce the amount of waste generated and will substantially lower the cost of disposal and environmental impact of the process.
These findings satisfied all proposed Phase I Technical Objectives and demonstrated feasibility of the proposed approach. Especially significant here were the demonstrations of production of the two most most economically important of the three alkylbenzene classes, ethylbenzene and cumene. During the Phase II program, we will demonstrate efficient and selective production of cumene and ethylbenzene in a continuous process from the ambient temperature ionic liquid through appropriate manipulation of experimental conditions.