Acidic ionic liquid based UiO-67 type MOFs: a stable and efficient heterogeneous catalyst for esterification

Abstract

A facile strategy for the synthesis of acidic ionic liquid based UiO-67 type MOFs was developed in this study.Brønsted acids (H 2 SO 4 , CF 3 SO 3 H and hifpOSO 3 H (hexafluoroisopropyl sulfuric acid)) were introduced into UiO-67-bpy (bpy ¼ 2,2 0 -bipyridine-5,5 0 -dicarboxylic acid) frameworks by reacting with bipyridyl nitrogen to introduce the properties of an acidic ionic liquid into the frameworks. The prepared catalysts, denoted as UiO-67-HSO 4 , UiO-67-CF 3 SO 3 and UiO-67-hifpOSO 3 , were characterized by XRD, SEM, FT-IR, EA, TGA and N 2 adsorption-desorption studies. The relatively high surface area was still maintained and acidic active groups were uniformly dispersed in the frameworks. The catalytic performance of UiO-67-HSO 4 , UiO-67-CF 3 SO 3 and UiO-67-hifpOSO 3 was evaluated by the esterification of acetic acid with isooctyl alcohol. The prepared catalysts showed good catalytic activities in the esterification, of which UiO-67-CF 3 SO 3 gave the maximum isooctyl alcohol conversion of 98.6% under optimized conditions. The catalyst could be reused five times without a significant decrease in the conversion of isooctyl alcohol, and almost no active species were leached, indicating the excellent stability and reusability of the catalyst. Our study provides one effective way to synthesize heterogeneous acidic ionic liquid catalysts consisting of isolated, well defined acidic groups that will probably attract interest in acid catalyst chemistry.

Ionic‐Liquid‐Functionalized UiO‐66 Framework: An Experimental and Theoretical Study on the Cycloaddition of CO2 and Epoxides

“…[21][22][23][24] Ionic liquids( ILs), [25] that is, salts comprising an organic cation and inorganic anion, have gained prominence in the field of catalysis due to their elite physicochemical properties such as meltingp oint, immiscibility with organic solvents, liquid state at room temperature,n onvolatility even at high temperature, viscosity,a nd structural versatility with various functional groups. [38][39][40][41] Recently,t he developmento fI L/metal-organic framework (IL@MOF) heterogeneous catalyst systemsh as attracted much attention owing to the ability of these systemsf or CO 2 capture and conversion. [28][29][30][31][32][33][34][35][36][37] In the liquid-phase reactions, leaching of the IL reduces the reactivity and stability of the material.…”

Fast Catalytic Esterification Using a Hydrophobized Zr‐MOF with Acidic Ionic Liquid Linkers

“…The XRD pattern of PDMS@UiO-67-CF 3 SO 3 matches well with that of UiO-67-CF 3 SO 3 , [10] and the main diffraction peaks still remain sharp ( Figure S4(d)), indicating the crystal structure of UiO-67-CF 3 SO 3 is well maintained. The XRD pattern of PDMS@UiO-67-CF 3 SO 3 matches well with that of UiO-67-CF 3 SO 3 , [10] and the main diffraction peaks still remain sharp ( Figure S4(d)), indicating the crystal structure of UiO-67-CF 3 SO 3 is well maintained.…”

“…The derived hydrophobized PDMS@UiO-67-CF 3 SO 3 exhibited excellent catalytic performance in the esterification of acetic acid and isooctyl alcohol, it only needed 4 h to reach the reaction equilibrium, while for UiO-67-CF 3 SO 3 , it was 18 h. The decrease in reaction time was mainly attributed to the accelerated the removal of water and isooctyl acetate, resulting the increase rate in the forward reaction. [10] They all showed good catalytic activities in the esterification of acetic acid and isooctyl alcohol, of which UiO-67-CF 3 SO 3 performed best. [1] Esters are widely utilized as fragrances in essential oils, [2] and raw materials for lubricants, plasticizers and paints, [3] In order to improve the greenness and efficiency of current esterification technologies, engineers and researchers are mainly focused on the following aspects.…”

“…One is to design novel reactors, such as pervaporation reactors and reactive distilled reactors, which will shift the reaction equilibrium toward ester production side by accelerating the removal of side products. [10] They all showed good catalytic activities in the esterification of acetic acid and isooctyl alcohol, of which UiO-67-CF 3 SO 3 performed best. To date, many solid acid catalysts have been developed to replace the conventional homogenous catalysts to avoid corrosion and separation issues, [5] such as zeolites, [6] metal oxides, [7] heteropolyacids, [8] and Amberlyst.…”

“…[4] Another is to develop green and effective acidic catalysts. [10] They all showed good catalytic activities in the esterification of acetic acid and isooctyl alcohol, of which UiO-67-CF 3 SO 3 performed best. [9] Recently, we have developed three acidic ionic liquids based Zr-MOF (UiO-67-HSO 4 , UiO-67-CF 3 SO 3 and UiO-67-hifpOSO 3 ) which can be utilized as efficient catalysts in esterification.…”