• Energy Research

Agricultural waste-based heterogeneous catalysts are emerging as efficient and green catalysts. The present study explored the agricultural waste-based heterogeneous catalyst utilized in the production of biodiesel. The plant waste is composed of organic compounds and various metals which, on combustion, produces ashes that mainly consist of various metal carbonates and oxides. The most commonly employed approach for the solid catalyst preparation from plant materials is the calcination process, and it is performed at temperatures ranging from 300 to 1200°C. It is known that the temperature employed for calcination plays a vital role in the composition and development of the morphology of the catalyst. The variation in alkalinity, porosity, and, accordingly, the catalytic activity of the catalyst is significantly influenced by the calcination temperature. It was found that the potassium present in the form of oxide and carbonate as the main constituent in such catalysts played a significant role in delivering catalytic efficacy. Therefore, a number of agricultural waste-based catalysts were reported as efficient catalysts. The selection of the catalyst may be one of the important issues for application in large-scale biodiesel production. Thus, the present study was undertaken for the preparation of a rank list among the reported catalysts by following the VIKOR (Višekriterijumsko Kompromisno Rangiranje) multicriterion decision-making approach. In this work, the ranking study was performed considering the reported optimum reaction conditions (ORCs) of biodiesel synthesis reactions. The study was conducted strictly on the basis of the parameters, viz., catalyst concentration ( C 1 ), MTOR ( C 2 ), reaction temperature ( C 3 ), reaction time ( C 4 ), and biodiesel yield ( C 5 ). The parameters are considered good if C 1 , C 2 , C 3 , and C 4 are low or minimum and if C 5 is high or maximum. The catalyst prepared from plantain peel showed the best performance and ranked as the first one followed by Musa paradisiaca peel and cocoa pod husk catalysts which are ranked second. Thus, the VIKOR method can be useful for comparison and ranking purposes if there are a large number of data, and this may be expanded for thorough study by considering more criteria which may give more fruitful results.

The study focuses on the preparation of an inexpensive, ecocompatible, and effective catalyst from the Bharatmoni (Musa AAA) plant for biodiesel synthesis using Jatropha curcas oil. The burnt ashes obtained from the Bharatmoni fruit peel, stem, and rhizome were calcined at 550°C for 2 h and characterized by analytical techniques. Utilization of CBS‐550 catalyst achieved a higher yield of biodiesel (96.97%) within 12 min compared to CBP‐550 (96.89% in 16 min) and CBR‐550 (96.53% in 18 min) catalysts under optimum reaction parameters of 5 wt% of catalyst and 9 : 1 MTOMR at 65°C. This study described that catalyst having a higher concentration of potassium in its oxide and carbonate form has higher catalytic activity. The surface morphology of the prepared catalysts revealed mesoporous in nature. The kinetic and thermodynamic studies of the reactions catalyzed by the present catalysts follow the pseudo‐first‐order kinetic model exhibiting a nonspontaneous and endothermic process. The reaction catalyzed by the CBS‐550 catalyst revealed the lowest Ea of 44.36 kJ mol-1 and is known to be the superior catalyst among the derived catalysts of this study.

Hydrogen fuel cell vehicles (FCVs) are expected to have a significant impact in meeting both energy security and environmental concerns globally. Public and private support is however essential for successful transition to a sustainable energy system. Several studies have looked into the issues and considered the purchase behaviour of related Alternative Fuel Vehicles (AFCs) and more research momentum is seen towards hydrogen FCV. The article aims to critically review and identifies gaps of acceptance, preferences and attitudes of hydrogen FCV and examine whether attitudes, subjective norms (SNs) and perceived behaviour control (PBC) have significant associations with customer purchase intention (PI) and purchase behaviour of hydrogen FCV in Malaysia. This is a timely study to address useful policies for decarbonizing the transportation sector.

Abstract In this work, bifunctional magnetic nano-catalyst was successfully derived from rice husk char doped with potassium oxide and nickel oxide by impregnation techniques, and their catalytic ability was tested via transesterification of used cooking oil (UCO). The catalyst was characterized by thermogravimetric analyzer (TGA), X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), Temperature programmed desorption (TPD), Brunauer–Emmett–Teller (BET), Scanning electron microscopy equipped with energy dispersive x-ray analyzer (FESEM-EDX), and Vibrating sampling magnetometer (VSM) for magnetic properties. The optimized nanomagnetic bifunctional catalyst (RHC/K2O-20%/Ni-5%) had 3.014 mmol g − 1 & 4.485 mmol g − 1 of acidity and basicity, respectively, with the magnetic strength was recorded at 2.312 emu g−1. For the catalytic evaluation, a maximum biodiesel yield of 98.2% was accomplished with 4 wt% of catalyst loading, 12:1 methanol to UCO molar ratio at 65 °C within 2 h of reaction time. The catalyst was reused for up to 5 reaction cycles and producing 70% of biodiesel at the last cycles. The fuel properties of optimized biodiesel were measured using Biodiesel - American Standard Testing Method (ASTM) D6751. Due to the magnetic properties of the catalyst, it was easily recovered by an external magnetic device and has the potential to improve the separation and purification processes.