System-Level Analysis of Methanol Production from Shale Gas Integrated with Multibed-BTX Production

The production of benzene, toluene, and xylene (BTX) is an energy-efficient subprocess that produces highly pure CH₄ from shale gas by coaromatizing shale gas-derived C₂H₆ and C₃H₈; this method is considered a feasible option for replacing conventional cryogenic distillation. Moreover, a rationally designed proof-of-concept co-production of BTX and methanol production is proposed. Our proposed BTX production process from shale gas consists of multiple beds, each of which undergoes five sequential processes, including carburization, reaction, cooling, regeneration, and heating in a continuous cyclic mode. Also, the switching time of the reaction/regeneration process is optimized with fixed-bed reactor experiments, and the general algebraic modeling system was used to develop the corresponding nonlinear programming-optimized catalyst regeneration strategy. Our Mo/HZSM-5-based BTX production method enables continuous BTX production from shale gas and shows relatively high yield of BTX (10.0%) compared to conventional methane dehydroaromatization process (∼5%). Furthermore, the method leads to an increased amount of produced CH₄ with a high BTX yield owing to the cracking of C₂H₆ and C₃H₈, thereby resulting in increased methanol production. Most importantly, the technoeconomic analysis revealed that the estimated minimum selling price of methanol production is approximately 0.321 $/kg methanol for 24.4% improved methanol production, which is comparable to that obtained with the current most mature methanol production process. The proposed process also lower CO₂ emission compared to that of the conventional process. The results of this analysis support the feasibility of the integrated BTX and methanol production process for energy-efficient shale gas conversion into high-value products.