CO2 cycloaddition of styrene oxide over MOF catalysts

Zirconium-containing metal organic frameworks as solid acid catalysts for the esterification of free fatty acids: Synthesis of biodiesel and other compounds of interest

“…23% of the amount adsorbed at 50ºC). Both results indicate that UiO-66 contains twice as much Lewis acid centers than UiO-66-NH 2 , and their acid strength is higher, in agreement with the conclusions drawn in previous studies [23,30,31]. < Insert Figure 1 near here> …”

“…Furthermore, experimental evidences by TPD of CO 2 [23] and FTIR of adsorbed CDCl 3 [31] also revealed the presence of basic sites of medium strength in UiO-66-NH 2 , which are absent in UiO-66. In the present work, we have used FTIR spectroscopy of adsorbed cyclohexanone to evaluate comparatively the acid properties of the UiO-66 and UiO-66-NH 2 samples that will be later used in the catalytic studies.…”

“…As commented above, the acid character of UiO-66 type materials has been indirectly established for several acid catalyzed reactions [23][24][25], as well as directly determined experimentally by means of CO adsorption FTIR and microcalorimetry [30], FTIR spectroscopy of adsorbed 5-nonanone [31], temperature programmed desorption (TPD) of NH 3 [23], and has been theoretically evaluated by DFT [25].…”

Conversion of levulinic acid into chemicals: Synthesis of biomass derived levulinate esters over Zr-containing MOFs

“…This could be due to a cooperative action of the (basic) amino groups that are located adjacent to the (acid) Zr sites of UiO-66-NH 2 , thus leading to a bifunctional acid-base catalyst, as already proposed for cross-aldol condensation (Vermoortele et al, 2011), CO 2 cycloaddition to styrene oxide (Kim et al, 2013), or fatty acid esterification over UiO-66-NH 2 materials (Cirujano et al, 2014). This could lead to a dual activation mechanism, in which levulinic acid would adsorb onto the Zr acid sites, thus increasing the electrophilic character of the carboxylic carbon atom.…”

Lewis Base Catalytic Properties of [Nb10O28]6− for CO2 Fixation to Epoxide: Kinetic and Theoretical Studies

“…Selectivity to SC remained high (> 90 %) throughout the reaction, but close inspection revealed that it decreased gradually with time after 4h.T he 1 HNMR spectrum of the reactionm ixture after 12 h (conversion 88 %) exhibited three intense peaks assignedt o SC, three minor peaks assigned to SO and unassigned minor peaks likely due to epoxide polymerization products (Figure S5). The ESI mass spectrum of the reactionm ixture after 8h(conversion 64 %) exhibited aseries of mass peaks assigned to (TBA) According to previous reports on the CO 2 fixation by metal oxides, [21][22][23] MOFs, [28] and organic bases, [29] we assume that CO 2 fixation catalyzed by [Nb 10 O 28 ] 6À proceeds via the Eley-Rideal mechanism in which SO reacts with CO 2 adsorbed on the base sites (Scheme1).…”