| Popis: |
The electronic structure and reactivity of Cu- and Zn-promoted wet-kneaded MgO/SiO2 catalysts was interrogated during ethanol reaction to 1,3-BD. A multimodal nature of characterization, including in situ or operando X-ray, electron, light spectroscopies, and steady state reactivity measurements demonstrated critical information on the temporal evolution of the catalyst active sites including key measurements performed in operando conditions using synchrotron techniques (EXAFS and XANES). In situ DRIFT spectroscopy allowed decoupling of the aldol condensation and dehydrogenation reactive steps due to the promotion with enhanced ability to carry out aldol condensation, as correlated with the steady state reactivity experiments. In situ UV–vis spectroscopy presented a complex picture of the adsorbates with π–π* electronic transitions due to the allylic cations, cyclic or aromatic species while also suggesting oligomeric CuO species were formed. Operando X-ray measurements combined with ab initio multiple sc... |
