Perlite Supported Cobalt Oxide Catalyst for a Series of Liquid‐Phase Esterification Reactions

Abstract

Thermally activated perlite-supported cobalt oxide (Co-TAP) catalyst has been synthesized via the deposition-precipitation method. FTIR peaks at around 663 and 565 cm -1 and XRD peaks arise from diffraction of FCC planes of CoO crystals confirm the presence of Co 3 O 4 crystallites on Co-TAP surface. UV-Vis DRS studies reveal the presence of octahedrally coordinated Co 3+ and tetrahedrally coordinated Co 2+ ions. EDX analysis of Co-TAP clearly shows the enhanced percentage of silica and cobalt oxide. All characterization studies suggest the presence of Lewis acidic sites on Co-TAP which have been utilized in a series of liquid-phase esterification reactions of benzoic acid with various alcohols over three different reaction media (conventional, microwave, and sonication). The reactions are carried out in one-pot, single-step, solvent-free reaction conditions, and the catalyst is filtered easily, regenerated, and reused up to five reaction cycles with analogous efficiency suggesting that acidic sites of the catalyst remain stable in all reaction mediums. The stability of regenerated Co-TAP catalyst after the fifth reaction cycle is confirmed by FTIR spectrum which resembles the FTIR of fresh catalyst.

Mott–Schottky contact synergistically boosts the electroreduction of nitrate to ammonia under low-nitrate concentration

“…For CoO x , two broad peaks in the ranges of 400–550 nm and 650–800 nm correspond to octahedrally coordinated Co 3+ and tetrahedrally coordinated Co 2+ , respectively. 44 By applying Tauc's equation ( αhν = A ( hν − E g ) n /2 ), 45 the E g of CoO x was calculated to be 1.70 eV, which is larger than that of Co–B@CoO x (1.05 eV) (Fig. 3d).…”

Vapor Phase Alkylation of Isomeric Cresols with Tert-Butyl Alcohol over Perlite Supported Sulfated Zirconia Catalyst

“…Hence, in recent years, perlite was also utilized as an effective substrate in the synthesis of heterogeneous acid catalysts in different organic transformations, i.e., Fenton reactions of organic compounds [9], the production of aryl/alkyl methane [10], photocatalysis [11], synthesis of xanthenes [12], transesterification reactions [13], condensation reactions [14], the degradation of azo-dyes [15], hydrogenation reactions [16], etc. We recently reported the synthesis of perlite supported catalysts and their catalytic activities in a series of different types of condensation and esterification reactions [17][18][19]. Due to its rough surface and low density, relatively low price, stability in various reaction media, high thermal, chemical, and mechanical stability, perlite acts as suitable support in the development of potential heterogeneous catalysts for catalyzing vapor phase organic transformations at an industrial scale and can replace solid catalysts traditionally used in this field.…”