Wednesday, November 18, 2020
Catalysis and Reaction Engineering Division (20) (PreRecorded+)
Xinwei Bai1, Terence Musho2, Chirag Mevawala1, Victor Abdelsayed3, Dushyant Shekhawat4, Debangsu Bhattacharyya1 and Jianli Hu1, (1)Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, (2)Mechanical & Aerospace Engineering, West Virginia University, Morgantown, WV, (3)Leidos Research Support Team, Morgantown, WV, (4)US Department of Energy, National Energy Technology Laboratory, Morgantown, WV
The challenges in direct methane conversion to higher-value chemicals include rapid catalyst deactivation and comparatively low single-pass conversion. The most important step in direct methane conversion is the activation of strong C-H bonds. In this presentation, we integrate microwave irradiation with heterogeneous catalysis to enable a higher methane conversion to C2 and aromatics at low temperature. The results show that methane conversion can reach 18% at 550 °C under microwave irradiation, while 800 °C is required to achieve the same level of conversion in a traditional fixed-bed reactor. The microwave irradiation facilitates heterogeneous catalysis process both thermally and non-thermally. Thermal effect, as known as “hot spots”, can be characterized experimentally, and the result indicates that the “hot spot” temperature can reach 800 °C while the bulk temperature stays at 550 °C. However, the non-thermal effect is difficult to characterize due to the limitations of existing in-situ instrumentations.
Finite-element modeling can be a powerful engineering tool to simulate and understand complex physic fields. In this report, three-dimensional finite-element models based on Maxwell’s equations were developed to study the non-thermal effects of microwave irradiation on direct methane conversion process. The simulation results show the local ultra-high electric field exists between catalyst particles and at the metal-support boundary. With the existence of electric field between catalyst particles, stable methane molecules can be activated. The local high electric field at the metal-support boundary further facilitates the collapse of activated C-H bond and form C2, which is an important intermediate and product for this process. These field distributions explain the non-thermal effects of microwave-assisted catalytic chemical reactions, which significantly affect the final product distribution that higher C2 selectivity was observed in microwave reactor, and the intrinsic reaction pathway.
Extended Abstract: File Not Uploaded
