Document Type

Working Paper

Date of this Version



A plant that uses three major stages to convert natural gas to produce a 1MMM lb of mixed xylenes stream a year, which contains 68 wt% of para-xylene, was designed for this project. The three main stages are the dehydrocyclization stage, where methane is converted to benzene; the alkylation stage, where benzene is alkylated to form xylenes; and the post- processing stage that separates para-xylene from the mixed xylene stream. The goal of the project was to produce a billion pounds of BTX while maximizing profits. This report provides a detailed design and economic analysis for the production of para- xylene and mixed xylenes on the Gulf Coast. Process flow sheets, energy and utility requirements, and equipment summaries have been provided and analyzed. The process is currently unprofitable with an IRR of 5.77% and a net present value of $(327,000,000) at a discount rate of 20%. The financials for this venture are highly sensitive to the price of natural gas, which is currently $0.02/lb. A few major reasons that make this venture unprofitable are the extremely high costs for the two proprietary processes, namely the Sulfolane process and the Parex process, high use of utilities, and low conversion of methane to benzene. After in depth analysis of the financials, we recommend that this project should not be executed unless the proprietary process costs are significantly reduced or a better conversion of methane to benzene is achieved.



Date Posted: 25 July 2014