Abstract
Herewith, we report on the synthesis and characterization of multicationic inorganic perovskites SrMo1-xNixO3-δ and CaTi1-xSnxO3-δ using the soft-templating method. They were successfully synthesized and characterized wholly using various techniques. These perovskites were intended for use as catalysts that drive some organic reactions. Of the many properties metal oxides and other heterogeneous catalysts have, surface area (SBET) has been used to describe the activity of the catalyst. This is because in heterogeneous catalysis the reaction occurs on the surface of the catalysts and as such, a large SBET would infer that the catalyst is or will be more active. The soft-templating method was purposely selected to design and synthesize perovskites with small SBET. The largest and smallest SBET obtained for the SrMo1-xNixO3-δ obtained were 5.5 m2/g and 1.9 m2/g for when x = 0.3 and x = 0.5, respectively. The amounts of Ni and Mo incorporated into the perovskite system held no significant influence on the SBET, which had no influence on the activity of these perovskites in the reductive etherification of benzaldehyde and methanol and even in the cross-aldol condensation reaction between benzaldehyde with diethyl ketone.
In the reductive etherification of benzaldehyde and methanol in the presence of the multicationic SrMo1-xNixO3-δ perovskite catalyst, good conversions of the benzaldehyde were observed with 100% selectivity towards the desired ether product. The activity of the perovskite was not influenced by the SBET of the material but rather, the amount of oxygen vacancies in the material. Introducing new metal cations into the crystal lattice of the perovskite induced more distortions in the structure and therefore created these oxygen vacancies that had an influence on the rate of catalysis. These perovskites no effect in utilizing secondary alcohols and in the conversion of ketones and carboxylic acid. This feature of the perovskite catalyst speaks to the selective nature of the perovskite.
Albeit the rate of conversion in the reductive etherification reaction was found to be governed by the amount of oxygen vacancies, this is not observed for aldol condensation reaction. Nor did SBET influenced this reaction. However, the multicationic SrMo1-xNixO3-δ perovskite show great promise as heterogeneous catalysts for the solvent-free aldol condensation of benzaldehyde with diethyl ketone. This demonstrates that these perovskites can be utilized in the pharmaceutical industry. The aldol product obtained must undergo a round of hydrodeoxygenation in the synthesis of petrochemically active hydrocarbons.
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Acetalization of glycerol has attracted a considerable amount of attention owing to the beneficiation of the by-product of biodiesel, glycerol. In this work, we investigate the effect of the inorganic CaTi1-xSnxO3-δ perovskite as a catalyst for acetalization and examine their traits and influence on catalysis. We found that the two metal cations in the B-site of this perovskite, have a combine effect that can boost the perovskite’s activity as a catalyst. This establishes perovskites as catalysts applicable in the acetalization of polyols.
There has been a noticeable shift towards using biomass-derived sources of energy as opposed to fossil fuels. In this study, we examine organic reactions used for synthesizing fuels and fuel additives. We found that multicationic inorganic perovskites, specifically SrMo1-xNixO3-δ and CaTi1-xSnxO3-δ, exhibit high activity in these reactions.