(308a) Techno-Economic Analysis of Direct Methane Aromatization for Natural Gas Upgrading with Mini-Plant Construction for Remote Deployment

Authors: 
Sees, M., Texas Tech University
Ward, L., Texas Tech University
Chen, C. C., Texas Tech University
Khatib, S. J., Texas Tech University
Inexpensive sources of natural gas have led to a boom in development of technologies taking advantage of C1 chemistry; however, a significant number of potential natural gas sources are stranded and lack the infrastructure for economically-feasible transportation. The resulting gas, which is normally flared can, in theory, be recovered at the well-site, purified, and then processed to a product which is easier to transport. Gas-to-liquid (GTL) processes exist which can convert the feed to liquid products which can be more easily transported, although there are process constraints due to the need for deployment in remote locations, and several are being commercialized.1 One such process, direct methane aromatization (DMA), produces significant amounts of benzene, a valuable commodity chemical, and hydrogen. The benzene can be purified on-site and then transported by truck; the hydrogen can be dealt with on-site as well by either transforming it to another transportable chemical, such as ammonia or cyclohexane, or using it to provide heating or electricity.

Previous economic studies of DMA have been reported which either invoke unrealistic assumptions in the process model,2 do not consider processing of the gaseous hydrogen,2, 3 or do not consider the limitations imposed on the process due to remote deployment.4 With these issues in mind, a DMA mini-plant processing 20 MMSCFD of natural gas was designed with currently available technology to provide a platform for the investigation of process intensified alternatives. The reactor section of the plant uses a DMA catalyst developed at Texas Tech which deactivates at a significantly slower rate than previous catalysts.5 The unit was investigated for economic feasibility and sustainability. In particular, the analysis identifies four particular areas which can benefit from intensification: aromatics yield (ie. one-pass conversion), coke selectivity, hydrogen recovery, and separation and purification of the aromatic products. Although intensified reactor technology for the DMA process is already being investigated for improving the yield with6, 7 and without integrated hydrogen recovery8, 9, the process model framework should provide opportunities for investigating additional intensification technologies, particularly in separations.

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