Synthesis of a highly dispersed CuO catalyst on CoAl-HT for the epoxidation of styrene

Abstract

A highly dispersed CuO catalyst was prepared by the deposition-precipitation method and evaluated for the catalytic epoxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant under solvent acetonitrile conditions. Compared with MgAl hydrotalcite (MgAl-HT)-, MgO-, TiO-, C-, and MCM-22-supported catalysts, CuO/CoAl-HT exhibited preferable activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion) due to its high dispersion of CuO and surface area of Cu. The improved dispersion of CuO/CoAl-HT could be ascribed to the nature of HT support, especially the synergistic effect of acidic and basic sites on the surface, which facilitated the formation of highly dispersed CuO species. A structure-performance relationship study indicated that copper(ii) in CuO was the active site for the epoxidation and oxidation of styrene, and that Cu of rich electronic density favored the improvement of selectivity of styrene oxide. Based on these results, a reaction mechanism was proposed. Moreover, the preferred catalytic performance of CuO/CoAl-HT could be maintained in five reused cycles.

Hierarchical 0D/2D Co3O4 hybrids rich in oxygen vacancies as catalysts towards styrene epoxidation reaction

“…Under this condition, the SO yield can achieve 70.9% with 99.3% styrene conversion and 71.4% SO selectivity. This yield value of 70.9% is better or comparable to those of the reported heterogeneous co-balt-containing catalysts under similar reaction conditions, such as mesoporous Co3O4 (8.3%) [31], Co-NH2-KIT-6 (33.0%) [48], CoO (34.6%) [49], CoOx/TiO2/SBA-15 (54.3%) [22] and CuO/CoAl-HT (71.6%) [50].…”

“…Previous studies have demonstrated that the formation of M-peroxo species should be responsible for the SER [16,30,50,53]. Based on this understanding and the above dis- cussions, the possible reaction pathways for the SER over the Co3O4-based catalysts were reasonably proposed.…”

Recent Developments in Heterogeneous Catalyzed Epoxidation of Styrene to Styrene Oxide

“…He et al. synthesized a highly dispersed CuO on CoAl‐HT (hydrotalcite) by the deposition–precipitation method and used for catalytic epoxidation of styrene with TBHP as an oxidant and acetonitrile as a solvent at 85 °C . This catalyst exhibited good activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion), as compared with MgAl hydrotalcite (MgAl‐HT)‐, MgO‐, TiO 2 ‐, C‐, and MCM‐22‐supported catalysts.…”

Instant and quantitative epoxidation of styrene under ambient conditions over a nickel(ii)dibenzotetramethyltetraaza[14]annulene complex immobilized on amino-functionalized SBA-15

“…We can notice that the Nitmtaa@N-SBA-15 catalyst provides a quantitative conversion of styrene to cyclohexene immediately at room temperature which is much better than all reported catalysts. [45][46][47][48][49][50][51][52] While, heat at around 80 C with prolonged reaction time ($6 h).…”

“…Fe, Cr, Ru, Mn, Ni, with facilely accessible high oxidation states, include porphyrin transition metal complexes, and using peroxycarboxylic acids such as m-CPBA as oxygen donor, this reaction probably operates by redox mechanism involving the formation of Ni II -OOAr and Ni-Oxo activated species, which transfer the oxygen to the olen either directly or by the intermediacy of a metallacycle, a radical, cation species, or via concerted transition state. 10,49,53,54 For porphyrins complexes, this mechanism was named by Groves as oxygen-rebound mechanism. 55 In this mechanism, an oxygen atom is transferred from the oxidant to the metal ion to form metal-oxo species (M-Oxo) with high oxidation state, which in turn transfers this oxygen atom to the olenic substrate.…”