Comparative research on three types of MIL-101(Cr)-SO₃H for esterification of cyclohexene with formic acid

Abstract

MIL-101(Cr)-SO3H was prepared with three different mineralizers, namely HCl, HF and NaAC, respectively. And catalytic performance and stability of three samples catalyzing the esterification of cyclohexene with formic acid were compared.

Metal–organic frameworks as catalysts for fructose conversion into 5‐hydroxymethylfurfural: Catalyst screening and parametric study

“…The diffraction peaks corresponding to reflection planes are indexed, and the obtained samples exhibited strong diffraction peaks at 2θ 5.50 0 , 8.55 0 , and 9.90 0 , which correspond to the crystal‐plane diffraction of 311, 531, and 606, which are typical diffraction peaks for MIL‐101(Cr) and indicating that the synthesized material has the MIL‐101(Cr) phase having good crystallinity. [ 72 ] The results also show the crystalline structures of MIL‐101(Cr), MIL‐101(Cr)‐NH 2 , and MIL‐101(Cr)‐SO 3 H, and it can be seen that they have incredibly similar diffraction patterns. The ligand used in NH 2 ‐MIL‐101(Cr) was 2‐aminoterephthalic acid (H 2 BDC‐NH 2 ), which is structurally identical to the 1,4‐benzenedicarboxylate (BDC) ligand used in MIL‐101(Cr), and hence, it can be concluded that they have the same crystal structure.…”

“…Hence, the FTIR spectrum confirms the successful grafting of the −SO 3 H functional group on the MIL‐101(Cr) framework. [ 72 ] Figure 5 demonstrates the characteristic peak of the amine stretching vibration, which appeared at 3490 and 3378 cm −1 for MIL‐101‐NH 2 . Another characteristic peak was observed for the asymmetric for C–N bonds at 1360–1290 cm −1 .…”

“…[87] The diversity of Lewis acidity of the chromium open metal-organic framework (OMS) offers the potential to selectively functionalize those sites with different electron-rich functional groups such as sulfonic or amino groups to enhance fructose dehydration. [72] Hence, the introduction of sulfonic groups into inorganic carriers gives rise to additional ÀSO 3 H Brønsted acid sites.…”

“…The obtained XRD patterns of each MOF, as given in Figure 6, show that the crystalline structures are comparable with those reported in the literature. [72,[74][75][76] Other than the structural analysis powder XRD patterns were also used to identify phases by searching the standard patterns (peak positions) provided from the International Center for Diffraction Data (ICDD) structure databases. The peaks were compared with database peaks from Powder Diffraction File-4 (PDF-4) organic database such as ZIF-8 (reference ID: 00-062-1030) [77] and UiO-66 (ref ID: 02-002-6797).…”

Versatile Hybrid Niobium Pentoxide‐Based Catalyst Applied in Reactions of the Fuels Industry: Oleic Acid Esterification and Quinoline Oxidation

“…However, thermal treatment of these materials directly influences their acidity and consequently their catalytic activity, since at high temperatures hydrated niobium oxide loses its surface hydroxyl groups, and thus its Brønsted acidity is reduced 20. However, several studies have been carried out aiming at modification of the catalyst surface by the insertion of acid functional groups such as sulfonic acids (–SO 3 H) or organic acids to increase the catalyst efficiency for several applications 7, 21, 22.…”