(430d) Production of Benzene, Toluene, and Xylenes from Natural Gas Via Methanol: A Process Synthesis and Global Optimization Approach
We present a deterministic global optimization based process synthesis framework to perform a comprehensive technoeconomic and environmental assessment of a natural gas based aromatics refinery.  Several direct and indirect natural gas conversion technologies, including autothermal reforming, steam reforming, and partial oxidation to methanol, are investigated. Numerous novel, commercial, and/or competing technologies are modeled within the framework, including methanol-to-aromatics, toluene alkylation with methanol, selective toluene disproportionation, toluene disproportionation and transalkylation with heavy aromatics, para-xylene separation via adsorptive separation or crystallization, isomerization of xylenes, and dehydrocyclodimerization of liquefied petroleum gas, among others. To address the economic barriers often associated with the utilization of alternative feedstocks, we develop a novel branch-and-bound global optimization algorithm that is capable of determining the optimal technologies to produce aromatics from natural gas at the highest profit. [6,7] Our approach provides an adequate baseline for comparing competing technologies and identifying bottlenecks for natural gas conversion based technologies. Several key aspects of the algorithm are discussed, multiple case studies are presented to investigate the effect of refinery capacity and product output, and the key topological decisions are described.
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 Niziolek, A. M.; Onel, O.; Floudas, C. A. Production of Benzene, Toluene, and Xylenes from Natural Gas via Methanol: Process Synthesis and Global Optimization. AIChE Journal 2016, 62 (5), 1531 â?? 1556.
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