Fabrication of nanosized SO42−/Co–Al mixed oxide via solution combustion method used in esterification reaction: effect of urea-nitrate ratio on the properties and performance

Abstract

Recently, mixed metal aluminate as a highly active, stable, and reusable nanocatalyst was extremely used in chemical reactions such as esterification. The preparation of the samples via a simple, rapid, and cost-effective method is one of the main problems on the front of the industrial application of these materials. For this purpose, the solution combustion method (SCM) was assessed for the fabrication of spinel CoAl 2 O 4 , and the effects of fuel-to-oxidizer (F/O) ratio on crystalline structure, surface functional groups, surface area, morphology, and porosity were analyzed. The activity of the samples, which was impregnated by the sulfate group was evaluated in the esterification reaction. Morphology and texture properties of the samples indicated the crystallinity, surface area, and pore diameter of CoAl 2 O 4 were enhanced by increasing the F/O ratio. It can be related to increasing the combustion reaction time and temperature. However, at F/O ratios above two, due to limited diffusion of oxygen into the reaction medium, the reaction terminated immaturely. Sulfated cobalt aluminate fabricated at F/O ratio of two was successfully synthesized in nanoscale with same particle size. Moreover, it did not show impurity in its structure that is related to the ability of the combustion method for the fabrication of pure nanocatalyst. Evaluation of the catalytic activity of the SO 4 2− /CoAl 2 O 4 nanocatalysts in the esterification reaction confirmed the results of physicochemical studies. For instance, the sample prepared at F/O ratio of two presented the highest conversion (96.7%) at methanol/oleic acid molar ratio of nine, catalyst amount of 3 wt. %, and reaction temperature and time of 120 °C and 4 h, respectively. In addition to preserving its activity for four runs (conversion > 85%), its activity was simply recovered upon regeneration by sulfate group, making it a promising alternative for industrial production of biodiesel.

Synthesis and E-metric Studies of an Economically Viable Heterogeneous Acid Catalyst for Production and Upscaling of Solketal

“…Besides these, other small reflection peaks at 27.3, 34.1, 38.5, 43.2, and 54.9 with the Miller indices (201), (121), (221), (202), and (040), respectively, confirmed the existence of α-CoSO 4 (JCPDS no. 46-0004). , All of these diffraction peaks were observed in the SCAT catalyst, showing the sulfate group’s successful impregnation. The intensity of diffracted peaks was changed by varying the molar concentration of these two components.…”

“…46-0004). 42,44 All of these diffraction peaks were observed in the SCAT catalyst, showing the sulfate group's successful impregnation. The intensity of diffracted peaks was changed by varying the molar concentration of these two components.…”

“…In contrast, this broad peak was not observed in SCAT spectra, possibly due to an intense band of Co−O and Al−O stretching vibrations. The stretching vibration in the 545 to 683 cm −1 range explains the Al−O bond, while the peaks observed below 500 cm −1 are responsible for the Co−O vibration peak for CoAl 2 O 4 spinel in all SCAT catalysts 44. Another characteristic peak at 1651 cm −1 is ascribed to the bending vibration of the O−H group of water molecules, whose intensity decreases with increasing loading percentage of TiO 2 .…”

Optimizing the Production of Biodiesel from Waste Cooking Oil Utilizing Industrial Waste‐Derived MgO/CaO Catalysts

“…The broad band at 596 cm −1 is caused by the stretching vibration of S=O and the interaction of SiO 2 with the CaO surface, which inefficiently links the CaO 28. The small bands at 674 and 1124 cm −1 describe CaO bonds and SiO 2 29, 30. The bands at the wavenumber of 1158 cm −1 belong to SO 31.…”

Modelling and Optimisation of the Sol-Gel Conditions for Synthesis of Semi-Hexagonal Titania-Based Nano-Catalyst for Esterification Reaction

“…Moreover, the mean pore size (greater than 3 nm) was sufficient for the diffusion of large molecules of oleic acid into the pores, and for maximal availability of the reactants to the external and internal surface areas [60]. The N2 adsorption-desorption plot is also shown in (Figure 6d), and relates to Type IV and H1 hysteresis loop which are typically associated with capillary condensation within cylindrical mesopores [61]. The pore size distribution profile (inset in Figure 6d) can clarify the porous structure of the synthesized material, in which the pore sizes were greater than 2 nm.…”