Preparation of Zirconia Supported Basic Nanocatalyst: A Physicochemical and Kinetic Study of Biodiesel Production from Soybean Oil

Zirconia-based nanomaterials: recent developments in synthesis and applications

In the last decade, the whole scientific community has witnessed great advances and progress in the various fields of nanoscience. Among the different nanomaterials, zirconia nanomaterials have found numerous applications as nanocatalysts, nanosensors, adsorbents, etc. Additionally, their exceptional biomedical applications in dentistry and drug delivery, and interesting biological properties, viz. anti-microbial, antioxidant, and anti-cancer activity, have further motivated the researchers to explore their physico-chemical properties using different synthetic pathways. With such an interest in zirconia-based nanomaterials, the present review focuses systematically on different synthesis approaches and their impact on the structure, size, shape, and morphology of these nanomaterials. Broadly, there are two approaches, viz., chemical synthesis which includes hydrothermal, solvothermal, sol-gel, microwave, solution combustion, and co-precipitation methods, and a greener approach which employs bacteria, fungus, and plant parts for the preparation of zirconia nanoparticles. In this review article, the aforementioned methods have been critically analyzed for obtaining specific phases and shapes. The review also incorporates a detailed survey of the applications of zirconia-based nanomaterials. Furthermore, the influence of specific phases, morphology, and the comparison with their counterpart composites for different applications have also been included. Finally, the concluding remarks, prospects and possible scope are given in the last section.

High Conversion of CaO-Catalyzed Transesterification of Vegetable Oils with Ethanol

Fatty acid ethyl esters (FAEEs) derived from vegetable oils and ethanol are promising bio-based chemicals for various applications such as biofuel, monomers for polyesters, and fine chemicals. However, the limited conversion and yield are obtained in the conventional methods due to low boiling point of ethanol that thus requires conducting the reaction at low temperature. This work demonstrates high yield of FAEEs from soybean, rice bran and palm oil with ethanol by performing the transesterification at high temperatures of 150-200°C by using CaO catalyst in a high pressure reactor. The results demonstrate the complete reaction for all vegetable oils with low ethanol to oil molar ratio of 6:1 and 1 wt.% CaO catalyst. Higher reaction temperature results in faster reaction while keeping high conversion of ≥ 99.0%. The unsaturated components in FAEE products are consistent with their original fatty acid chain. Moreover, the high conversion can be achieved even in the reaction conducted with low ethanol to oil molar ratio of 4.5:1 and 0.5 wt.% CaO catalyst at 180 °C in the palm oil transesterification. The catalyst can be reused for at least 3 times with the conversion higher than 94.0%. In addition, the activation energy (E_a), enthalpy of activation (ΔH^‡), entropy of activation (ΔS^‡) and Gibbs free energy of activation (ΔG^‡) are also obtained.