(144c) Process Intensified Conversion of Stranded Energy Resources to Value-Added Liquid Products for Distributed Production

Over 200 billion ft³/year of natural gas at remote production sites is flared in the U.S. due to the limitations in pipeline transportation capacity. This wastes valuable resources, increases air emissions, and burns profits. Similarly, renewable electricity (wind and solar) in some disadvantaged locations becomes stranded due to the limitations in power transmission capacity and intermittent nature of the renewable electivity. This presentation introduces the applications of microwave catalysis for the conversion of these stranded energy resources into liquid transportable chemicals such as aromatics and ammonia. Microwave irradiation has shown a profound impact on catalyzed and uncatalyzed gas-solid reactions. In particular, it has been demonstrated that microwave-specific effects can manifest themselves through the enhancement of reaction rates, changes in the position of equilibria and the distribution of products.

Methane must be activated to a high-energy transition state before it can further react to produce stable products. The high reaction temperatures (>700^oC) required to activate methane’s strong C-H bonds usually results in rapid and extensive coke formation that blocks catalyst micropores, deactivating the catalyst. The gaps in scientific understanding of the direct, non-oxidative methane conversion process preclude the design of highly selective catalysts and reactors to make desired higher value products. Technical hurdles include catalyst stability and thermodynamic limitations that constrain the desired product yields. In this study, methane conversion reaction is enhanced with microwave irradiation to demonstrate microwave reaction chemistry at catalyst-reactant interface for selective C-H bond activation

Stranded electricity can be converted to liquid ammonia under ambient pressure and 320^oC using water and air as feedstock. Conventional ammonia synthesis process, i.e. Haber-Bosch process, cannot be scaled down economically due to the high temperature and high pressure operation and the intermittent nature of renewable electricity that requires frequent startup and shutdown. Catalytic ammonia synthesis was conducted under two microwave irradiation scenarios: microwave and microwave plasma. Other than selective activation of dinitrogen to metastable radicals, the most obvious advantage that microwave irradiation affords in driving a heterogeneously catalyzed reaction is the ability to locally heat the catalytic sites. Many industrial processes utilizing heterogeneous catalysts are high-temperature processes wherein both components of the reaction (i.e., catalyst and medium) are heated to the temperature required for the reaction to occur. Specifically discussed in this presentation are the effects of electromagnetic properties of catalysts, microwave frequency and microwave energy absorbed on the conversion of nitrogen and ammonia yield.

Technoeconomic analysis was carried out to compare microwave catalytic processes with the state-of-the art. The comparisons are made to focus on process intensification elements such as energy efficiency, energy productivity and capital cost reduction. Sensitivity analysis was made to evaluate various scenario and different plant sizes. The resulting engineering innovation includes plant siting flexibility due to smaller scale, lower capital and operating costs, higher energy efficiency, lower carbon footprint, no or low environmental emissions.

The potential for a dramatic transformation in the chemical process industries is emerging from the rapid development of process intensification. This can potentially yield substantial economic and environmental benefits in combination with advanced manufacturing by significantly reducing the size of chemical process plants. This presentation aims to revolutionize the chemical process industries by enabling the development of intensified and, where appropriate, modular process plants.