No abstract

Glycerol carbonate (GC) and glycidol (GD) are commercial products possible from glycerol transformation, which has become a subject of great importance. Among several basic catalysts screened in this work, BaO showed the highest glycerol conversion of 71% with almost complete selectivity to GC. A tandem synthesis of GD with a selectivity as high as 80% with 98% glycerol conversion could be achieved with mixed oxides of Ba and lanthanides (La and Ce) prepared by the coprecipitation method. Although BaO alone showed the highest basicity as measured by CO 2 TPD, tuning of basicity by incorporation of CeO 2 resulted in the formation of GD. Incorporation of Ba into the ceria matrix induced oxygen vacancies in the cerium oxide material. The presence of u″/v″ doublets at 888.7 and 903.2 eV, respectively, in XPS of the Ba−Ce sample also confirmed the oxygen vacancies in the lattice. In this tandem approach to GD, the subsequent decarboxylation of initially formed GC was due to the presence of a CeO 2 lattice with defects, which is known to be the best for CO 2 adsorption. Increase in both catalyst loading and temperature showed a dramatic enhancement in GD selectivity. A plausible reaction pathway for the transesterification of glycerol with DMC to give GC followed by its decarboxylation to GD is also proposed based on the structural characterization and activity studies.

No abstract

Etherification of furanic compounds such as furfuryl alcohol (FA) and 5-(Hydroxymethyl) furfural (5-HMF) to the corresponding ethers was successfully achieved over Zr-SBA-15 catalyst. For this purpose, various Zr-SBA-15 catalysts with different Zr/Si molar ratios in self-generated acidic environment were prepared by one-pot strategy in self-generated acidic environment. XRD analysis revealed the increase in the d-spacing from 9.021 nm for parent SBA-15 to 11.66 nm for Zr-SBA-15, confirming the incorporation of Zr into the framework without disturbing the mesoporous structure of SBA-15. For the lowest Zr concentration of 0.09 M, hexagonally ordered porous structure was found to be retained as confirmed by TEM while, increase in Zr/Si molar ratio to 0.14, resulted in loss of long range order mesoporosity. The presence of both Lewis and Brønsted acid sites in Zr-SBA-15 catalyst as evidenced by py-IR, were due to the introduction of Zr in the frame work of SBA-15. The co-existence of Lewis and Brønsted acid sites in Zr-SBA-15 was responsible to catalyze etherification of FA and esterification of levulinic acid producing 2-(Ethoxymethyl) furan and ethyl levulinate selectively, both of which are bio-derived fuel additives.