Control of the Interphases Formation Degree in Co₃O₄/ZnO Catalysts

Abstract

ZnO supported Co3O4 nanoparticles are highly active in the transformation of renewable materials through carbonylation of glycerol with urea. The activity of the nanoparticles is modulated by their interaction with the ZnO support, which remarkably depends on the impregnation method. One catalyst series was impregnated by conventional impregnation of a ZnO support with an aqueous solution of Co(NO3)2⋅6 (H2O), while the second set was obtained using a novel room‐temperature low‐energy dry nanodispersion method. This work focuses on the characterization and catalytic activity of both series of catalysts and describes the nature of the active sites required for the carbonylation of glycerol with urea. Raman spectroscopy and HRTEM were used to proof the nature of the interphase interaction between ZnO and Co3O4 particles in both catalyst series. Thus, it was verified such interphases are present in the catalysts prepared through the dry mixing method. Co3O4/ZnO system prepared with the dry mixing method at room temperature exhibited a catalytic behavior in the production of glycerol carbonate reaching conversion values up to 69 % in 4 h affording nearly total selectivity. There was a clear correlation between the amount of the phase and the catalytic activity. Therefore, the catalytic activity can be tuned by controlling interphase formation in Co3O4/ZnO catalysts. Upon thermal treatment, both series rearranged into inactive phases such as ZnxCo1−xCo2O4, decreasing the number of free Co3O4 related sites, which decreased the catalytic activity. Therefore, the preparation stage of the Co3O4/ZnO catalysts played an important role in the formation of this phase.

Towards three-dimensional hierarchical ZnO nanofiber@Ni(OH)2 nanoflake core–shell heterostructures for high-performance asymmetric supercapacitors

“…1 Generally, carbonaceous materials, 2-8 metal oxides/hydroxides, 9,10 and conducting polymers are commonly used as available types of electrode materials for supercapacitors. [17][18][19][20][21][22] For instance, it has been demonstrated to be effective to incorporate metal oxides/hydroxides with conductive carbon materials such as graphene and carbon nanotubes, conducting polymer, 23 and construct core-shell structures such as Co 3 O 4 @MnO 2 , 18 Ni(OH) 2 @MnO 2 , 24 Ni 3 S 2 @Ni(OH) 2 , 25 and ZnO@NiO/MoO 2 . However, the high specific capacitance and increase in energy density commonly come at the cost of lower power density, poorer rate capability and inferior cycling stability of the pseudocapacitive materials as a result of their poor electrical conductivity and the undesirable shrinking and swelling during the charge/discharge process, which have dramatically limits their wide application in high-performance energy storage devices.…”

Value-Added Products from Urea Glycerolysis Using a Heterogeneous Biosolids-Based Catalyst

“…Among them, zinc-based catalysts play a major role. As reported by several authors [12,[36][37][38], use of different zinc salts induced different conversion and glycerol carbonate selectivity during urea glycerolysis. Zinc-halogen binary salts showed a close relationship between anions and zinc activity with an increase in conversion from 64.3% using ZnF 2 to 81.4% using ZnBr 2 at 150 • C for 4 h. The increased mobility of bromine with respect to fluorine also affected glycerol carbonate selectivity with an increase from 84.1% to 97.2% [36].…”

Progress of Catalytic Valorization of Bio-Glycerol with Urea into Glycerol Carbonate as a Monomer for Polymeric Materials

“…To further develop the environmentally friendly catalytic protocols for GC synthesis from glycerol and urea, heterogeneous catalysts of environmental value synthesized by an important preparation stratagem should be considered first and foremost. Motivated by the residue-free and solvent-free synthetic manner that can fabricate the hierarchical nanoscaled catalyst dispersed on microparticles [47][48][49][50][51] decisive role in GC production efficiency [58,59]. With respect to this, the novel zinc-tin composite oxide was prepared using three different means including coprecipitation, solid-state, and evaporation methods, and investigated in producing GC [60].…”