(83f) Performance Targets for Oxidative Coupling of Methane from Techno-Economic Profiling | AIChE

(83f) Performance Targets for Oxidative Coupling of Methane from Techno-Economic Profiling


Ashour, F. - Presenter, Texas A&M University at Qatar
Al-Rawashdeh, M., Texas A&M University at Qatar
Linke, P., Texas A&M University at Qatar
The Oxidative Coupling of Methane (OCM) route to convert methane to ethane and ethylene (C2) has been investigated as a potentially promising path for natural gas monetization for more than 40 years. Significant research efforts have been invested in the field of catalysis accompanied by considerably less efforts in process design and analysis to establish economic performance. The current state-of-the-art in catalysis and reaction engineering still results in drastic degradations of C2 selectivity with increases in conversion. This poses challenges for economic process performance as value addition to the methane feed through conversion to C2 products, which is generally bounded by the price difference between reactants and products, is offset by the high costs associated with low conversion.

This work introduces a systematic method to explore the minimum performance requirements for OCM reactors that could enable commercial viability through techno-economic profiling. The multi-level methodology aims to determine the minimum requirements for the key reactor level performance indicators selectivity and conversion based on high-level economic analysis. At the initial level, high-level value added calculations considering raw material, product and energy prices as well as carbon taxes at the input-output level of an OCM process are performed to establish minimum selectivity requirements and visualize the OCM process in the form of ‘value addition/destruction maps’ that shows revenues, costs and gross value added as functions of C2 selectivity for ranges of ethylene to ethane selectivity. This analysis sets an absolute minimum requirement for reactor selectivities that must be achieved at full conversion within a no capital cost OCM process. The presented work will show how most published studies already remain below the absolute minimum selectivity requirement and will lead to value destruction. At the next level, major additional costs related to separations and recycling form incomplete conversions are included to set a corresponding lower bounds for both selectivity and reactor conversions that must always be exceeded by a potentially profitable process. Minimum energy requirements for separations and recycling are calculated for complete ranges of selectivity and conversions to determine the conversion—selectivity frontier that bounds the value destruction domain. Analysis shows that reported OCM reactor performances are exclusively located within the value destruction regime. Further levels of analysis explore sensitivities of the selectivity-conversion frontier to deviations from the idealized performance assumptions towards efficiencies and costs of real systems to generate aspirational targets be exceed by future efforts in catalysis and reaction engineering to achieve profitable OCM.

While the presented method of techno-economic profiling is illustrated for the OCM route, it is generally applicable to the study of any reaction route. The quick analysis enables an early and clear understanding of process economics and reactor level performance bounds that can be used to steer time and resource intensive development efforts in catalysis and reaction engineering from a process perspective.