Ramirez A, Hueso J L, Abian M, Alzueta M U, Mallada R, Santamaria J
Department of Chemical and Environmental Engineering, University of Zaragoza, 50018 Zaragoza, Spain.
Institute of Nanoscience of Aragon (INA), University of Zaragoza, 50018 Zaragoza, Spain.
Sci Adv. 2019 Mar 15;5(3):eaau9000. doi: 10.1126/sciadv.aau9000. eCollection 2019 Mar.
Research in solid-gas heterogeneous catalytic processes is typically aimed toward optimization of catalyst composition to achieve a higher conversion and, especially, a higher selectivity. However, even with the most selective catalysts, an upper limit is found: Above a certain temperature, gas-phase reactions become important and their effects cannot be neglected. Here, we apply a microwave field to a catalyst-support ensemble capable of direct microwave heating (MWH). We have taken extra precautions to ensure that (i) the solid phase is free from significant hot spots and (ii) an accurate estimation of both solid and gas temperatures is obtained. MWH allows operating with a catalyst that is significantly hotter than the surrounding gas, achieving a high conversion on the catalyst while reducing undesired homogeneous reactions. We demonstrate the concept with the CO-mediated oxidative dehydrogenation of isobutane, but it can be applied to any system with significant undesired homogeneous contributions.
固-气多相催化过程的研究通常旨在优化催化剂组成，以实现更高的转化率，尤其是更高的选择性。然而，即使使用选择性最高的催化剂，也会发现一个上限：在一定温度以上，气相反应变得重要，其影响不可忽视。在这里，我们将微波场应用于能够直接微波加热（MWH）的催化剂-载体体系。我们采取了额外的预防措施，以确保（i）固相没有明显的热点，（ii）能够准确估计固相和气相的温度。微波加热允许使用比周围气体温度高得多的催化剂进行操作，在催化剂上实现高转化率，同时减少不需要的均相反应。我们用CO介导的异丁烷氧化脱氢来证明这一概念，但它可应用于任何存在大量不需要的均相贡献的系统。
