Over 70 years, silica-magnesia catalyst prepared by wet-kneading method has been a benchmark for one-step ethanol-to-butadiene Lebedev process. Recent studies showed that wet-kneading provides an environment for the concomitant dissolution and cross-deposition of silicon and magnesium subunits, which can lead to the formation of not only the beneficial sites (Si on MgO), but also the detrimental ones (Mg on SiO2) for the Lebedev process. The use of conventional silica sources to formulate the silica-magnesia catalysts should be revisited, as they will be eventually dissolved and redispersed on MgO and the remaining SiO2 particles would be used for the formation of detrimental sites. In this regard, we demonstrated core-shell structured MgO-SiO2 catalysts as a second generation of Lebedev catalyst, where the Si subunits were selectively deposited on the MgO nanoparticles as surface magnesium silicates. Compared to the conventional wet-kneaded silica-magnesia catalyst system, we could reduce the amount of Si source by similar to 40 times with the enhanced catalytic performance towards butadiene.
