Plant-wide Modeling and Techno-Economic Analysis of a Direct Non-Oxidative Methane Dehydroaromatization Process Via Conventional and Microwave-Assisted Catalysis

Direct non-oxidative methane dehydroaromatization (DHA) process via conventional and microwave (MW)assisted thermo-catalytic catalysis is studied. Rate models for methane DHA reactions, including the effect of catalyst deactivation, are developed by using the in-house experimental data. Model results for gas concentration profile and catalyst deactivation are in good agreement with the experimental data. This rate model is then used for the development of dynamic multi-scale, multi-physics commercial-scale reactor models. Total number of fixed bed reactors desired for a cyclic steady state process is estimated. Plant-wide models are then developed for conventional and MW-assisted processes for producing products of desired specifications. Techno-economic analysis of the methane DHA process is undertaken. Economics of these methane DHA processes are compared with the typical multi-step natural gas to aromatics production process via methanol synthesis. Sensitivity of internal rate of return (IRR) and net present value (NPV) to various economic and process parameters such as plant scale, desired rate of return, reactor cost, feedstock and utility cost, catalyst variable cost, and MW reactor cost is studied. Electric equivalent efficiency of the conventional methane DHA process is found to be 69.2 % and 67.3 % at 750 degrees C and 800 degrees C, respectively, while the MW-assisted methane DHA process has the electric equivalent efficiency of 48.9 % at 800 degrees C. IRRs of the conventional methane DHA process at 750 degrees C and 800 degrees C, and MW-assisted process are 15.2 %, 17.5 %, and 18.8 %, respectively for a methane feed flowrate of 19,782 kg/h, while the IRR of the multi-step natural gas to aromatics production process is estimated to be 0 % for the same plant scale. Impact of change in the methane price, electricity price, and catalyst cost is found to be considerable on the process economics, while the cost of the MW reactor is found to have negligible impact.