(555c) An Alternative Process for Oxidative Methane Coupling for Ethylene, Electricity and Formaldehyde Production

Oxidative coupling of methane (OCM) is a promising route for the production of ethylene by utilizing methane, the main constituent of natural gas. OCM is a reaction of two methyl radicals coupled after the abstraction of one hydrogen atom from the methane molecule. This reaction is highly exothermic. The conventional processes are endothermic, energy intensive and low in C2 selectivity, depending on the choice of the feedstock. However, the development of the industrial process still remains in its very early stage with the main efforts focused on the search for a sufficiently selective, active, and stable catalyst. The motivating force of this work is to design an alternative process for ethylene production via OCM and the co-generation of electricity and formaldehyde that can make the process economically attractive and designed so as to be industrially implemented. The total project investment, based on total equipment cost (TEC), as well as variable and fixed operating costs, was developed based on mass and energy balance information taken from ASPEN ICARUS® simulation results. With these costs, a discounted cash flow analysis was used to determine the production cost of ethylene, electricity and formaldehyde, when the net present value of the project is zero. The feasibility was evaluated in terms of energy savings, CO2-emission reductions, and costs, in comparison to the separate production of ethylene with conventional OCM technology alone. In addition, the process was screened to look for possible future technology developments. The economics have been reviewed and compared to the classical OCM process. Capital requirements and the potential to enhance cash margins are the primary focus of the analysis. The basis of the analysis is a world-scale conventional OCM plant that converts 2750 Mm3 per day of methane into 320 metric tons per day of ethylene, 17 MW of electricity and 77 metric tons per day of formaldehyde. Capital and operating costs are for an arbitrary remote location where natural gas is available at 246.9 ? per 1000 m3. Payout time for this process, with OCM plant, is less than ten years. This payout time is generally much higher, which indicates that the OCM process alone currently is not candidate for commercialization without consideration of special incentives, such as power generation and formaldehyde production. The analysis also includes an evaluation of the effects of process yields on the economics for two potential technologies: oxidative coupling to ethylene and co-generation of electricity as well as formaldehyde production. This analysis suggests areas for research focus that might improve the profitability of natural gas conversion.

Acknowledgment The authors acknowledge support from the Cluster of Excellency ?Unifying Concepts in Catalysis? coordinated by the Berlin Institute of Technology and funded by the German Research Foundation ? Deutsche Forschungsgemeinschaft.