Towards more sustainable natural gas utilization processes through catalyst design and process intensification

Increasing global competition, stringent environmental regulations, and concerns over long-term sustainability drive the development of more efficient and sustainable chemical and fuel processing technologies. Towards this goal, responsible and more sustainable natural gas utilization will be key for the immediate future. The present dissertation applies catalyst design and process intensification to two natural gas utilization processes: (i) methane upgrading through methane dehydroaromatization (MDA) and (ii) utilization of methane-derived low-purity H2 streams for the hydrogenation of small hydrocarbons. MDA is a promising methane upgrading route that converts methane directly into benzene and hydrogen. However, methane activation in MDA requires high temperatures, which lead to severe coking and rapid catalyst deactivation. Furthermore, MDA suffers from slow catalyst activation, further lowering process efficiency. In the present work, we evaluated the possibility of overcoming the first challenge via microwave-assisted catalysis. We found that microwave heating allows tailoring the temperature of different catalyst components separately and thus opens new avenues for the design of thermocatalytic processes. We furthermore find that Fe speciation in Fe-ZSM-5 catalysts has a large impact on catalyst activation, yielding a guide for the design of more efficient MDA catalysts. The second part of this dissertation focuses on using low-purity hydrogen for hydrogenation reactions. Hydrogen is primarily produced via methane steam reforming, resulting in the formation of synthesis gas, a mixture of CO and H2. Utilization of the H2 currently requires costly and energy-intensive purification steps. We demonstrate that a "chemical looping" derived approach, which uses Pt-WO3 as a H carrier, allows uptake and release of H even in high levels of CO impurity and enables highly selective partial hydrogenation of acetylene to ethylene. Our work constitutes the first extension of chemical looping to hydrogen transport and utilization, which is key to a wide range of chemical processes. Overall, this work combined process intensification principles with catalyst design toward developing next-generation methane utilization processes that are cleaner, safer, and more resource-efficient