Effect of solid acids in methane aromatization

Title : Effect of solid acids in methane aromatization

Abstract:

Methane dehydroaromatization (MDA) reaction is typically catalyzed by a bifunctional Mo/H-ZSM-5 catalyst to produce benzene from methane (6CH₄ → C₆H₆ + 9H₂; ΔG^o=432.5 kJ/mol). This reaction is one of the most complex problems of catalysis because of thermodynamic limitations (carbonaceous depositions) which are inevitable in deactivation. MDA is catalyzed by two sites: (a) a metal (typically Mo), and (b) an acid (typically H-ZSM-5). In this presentation, we will describe what solid superacids are, their main characteristics, and introduce the use of Mo/WO₃/ZrO₂ (Mo/W/Z) solid superacid catalysts in MDA instead of the widely used H-ZSM-5 with experimental results with three different molybdenum loadings (1% (wt.) Mo, 3% (wt.) Mo, and 6% (wt.) Mo). For this purpose, a series of reactions (TOS = 1000 min) were completed in two stages. Mo carburization (MoO₃→Mo₂C) was the first step. The second step involves MDA with CH₄ as the only reactant at temperature ranges from 600°C to 800°C at 50°C intervals, constant pressure (atmospheric) and 1500 mL/g?h (space velocity). The main organic products at each temperature were ethylene, ethane, propylene, and benzene. The fresh, carburized, and spent samples were characterized by XRD, XPS, BET, NH₃-TPD, pyridine DRIFTS, EXAFS, and XANES. Partial results show the conversion drops drastically in all the samples after 400 min. 6% (wt.) Mo/W-Z at 600°C has the highest CH₄ conversion (12.3% at TOS = 50 min), but it shows more thermostability and lower deactivation rate at 650°C. The conversion achieved by methane within the first 100 minutes (at the same space velocity) is 15.8%^1,2 with H-ZSM-5 which shows a big potential of WO₃/ZrO₂ catalyst.

Audience Take Away: 

• Recognize about the importance of Benzene in the chemical industry.
• Learn about the Methane aromatization reaction.
• Understand what solid super acids are.
• Comprehend the application of solid super acids in methane aromatization reaction (specifically the use of Mo/WO₃-ZrO₂ catalyst).

Biography:

Jhonattan Manosalvas finished his undergrad program of Chemical Engineering at Central University of Ecuador in 2018. He joined the graduate program of Department of Chemical Engineering at LSU in spring 2021. Since then he has worked in the methane aromatization reaction within the research group of Dr. James Spivey.