Читать книгу Engineering Solutions for CO2 Conversion - Группа авторов - Страница 60

A clear example of the contribution of membranes toward chemical production and process intensification is the direct conversion of methane‐containing sources, i.e. natural gas or biogas, into valuable petrochemicals using MDA reaction [123]. This reaction, normally carried out at 700 °C, suffers from some drawbacks, and rapid catalyst deactivation occurs because of the accumulation of polyaromatic‐type coke, impeding the access to the catalyst‐active sites and the limitation imposed by thermodynamics of the per‐pass conversion to aromatics [124]. In order to overcome the abovementioned disadvantages, a recent publication reports a CMR for MDA process intensification [125]. The system is composed of an electrochemical BaZrO₃‐based tubular membrane that exhibits proton and ion conductivity. Figure 3.9 depicts a representation of the MDA reaction and the different components/materials that form the CMR.

In this case, methane is converted to benzene and hydrogen using a Mo/H‐MCM‐22 catalyst. Protons are transported to the sweep side, whereas oxide ions are transported to the reaction chamber and react with H₂ to form water that will subsequently react with coke to form CO and H₂, enhancing catalyst stability. The authors observed that the electrochemically driven simultaneous extraction and injection of proton and oxide ions, respectively, allows obtaining high aromatic yields while drastically reducing the catalyst deactivation rate by coking.