Zr-SBA-15 acid catalyst: Optimization of the synthesis and reaction conditions for biodiesel production from low-grade oils and fats

Zr-SBA-15 Lewis Acid Catalyst: Activity in Meerwein Ponndorf Verley Reduction

“…Zr-SBA-15 catalyst was prepared according to the method previously described in literature [27]. In a typical synthesis, ZrCl2Cp2 is dissolved in a P123-containing hydrochloric acid aqueous solution at 40 °C.…”

“…Our previous investigations on the synthesis and use of Zr-SBA-15 have revealed a highly active catalyst in several acid-driven reactions [25][26][27][28]. The high activity of this material has been attributed not to the acid strength of the supported active species weak Lewis acid sites, but to the high accessibility of the same, which occupy accessible locations on the surface of the mesopores.…”

“…calculated from NH3 TPD analysis. This fact could be attributed to the formation of zircon (ZrSiO4) and zirconium dioxide (ZrO2) particles, whose presence onto the Zr-SBA-15 material is evident in XRD ( Figure 1B) [27]. In this way, although quite a high proportion of the zirconium species added to the synthesis media are successfully supported onto the Zr-SBA-15 material, a fraction of the same would not be active in MPV reactions.…”

“…The high activity of this material has been attributed not to the acid strength of the supported active species weak Lewis acid sites, but to the high accessibility of the same, which occupy accessible locations on the surface of the mesopores. This feature is due to the synthesis method and the used metal precursor, which facilitates the interaction between the hydrophobic core of the structure directing agent micelles and the zirconium precursor, zirconocene dichloride [27]. In this way, upon surfactant removal by calcination, the metal sites are settled on the surface of the mesostructured support occupying accessible locations.…”

Potential applications of Zr-KIT-5: Hantzsch reaction, Meerwein–Ponndorf–Verley (MPV) reduction of 4-tert-butylcyclohexanone, and Prins reaction of citronellal

“…Zirconium-containing mesoporous silica composites have been investigated as solid acid catalysts based on the presence of Lewis acid sites created by Zr 4? incorporation in the framework and the large surface area, pore volume, and uniform pore size distribution [1][2][3][4]. Since the discovery of mesoporous silicates such as MCM-41 and SBA-15, two-and three-dimensional mesostructured silica materials containing Zr have been synthesized including Zr-MCM-41 [5,6], Zr-MCM-48 [7,8], Zr-SBA-15 [1,3,9], and Zr-SBA-16 [10].…”