Sulfonated SnO2 nanocatalysts via a self-propagating combustion method for esterification of palm fatty acid distillate

Glycerol-Based Retrievable Heterogeneous Catalysts for Single-Pot Esterification of Palm Fatty Acid Distillate to Biodiesel

The by-product of the previous transesterification, glycerol was utilised as an acid catalyst precursor for biodiesel production. The crude glycerol was treated through the sulfonation method with sulfuric acid and chlorosulfonic acid in a reflux batch reactor giving solid glycerol-SO₃H and glycerol-ClSO₃H, respectively. The synthesised acidic glycerol catalysts were characterised by various analytical techniques such as thermalgravimetric analyser (TGA), infrared spectroscopy, surface properties adsorption-desorption by nitrogen gas, ammonia-temperature programmed desorption (NH₃-TPD), X-ray diffraction spectroscopy (XRD), elemental composition analysis by energy dispersive spectrometer (EDX) and surface micrographic morphologies by field emission electron microscope (FESEM). Both glycerol-SO₃H and glycerol-ClSO₃H samples exhibited mesoporous structures with a low surface area of 8.85 mm²/g and 4.71 mm²/g, respectively, supported by the microscopic image of blockage pores. However, the acidity strength for both catalysts was recorded at 3.43 mmol/g and 3.96 mmol/g, which is sufficient for catalysing PFAD biodiesel at the highest yield. The catalytic esterification was optimised at 96.7% and 98.2% with 3 wt.% of catalyst loading, 18:1 of methanol-PFAD molar ratio, 120 °C, and 4 h of reaction. Catalyst reusability was sustained up to 3 reaction cycles due to catalyst deactivation, and the insight investigation of spent catalysts was also performed.

Indigenous Materials as Catalyst Supports for Renewable Diesel Production in Malaysia

High energy demand from the market due to the rapid increment of the human population worldwide has urged society to explore alternatives to replace non-renewable energy. Renewable diesel produced from biomass could be the next potential energy source for its high stability, long-term storage, and comparable performance with diesel fuels. In producing renewable diesel, the application of catalyst is essential, and the catalyst support is synthesized with the catalyst to enhance the reaction rate and catalytic properties. In this review, the type of catalyst support will be reviewed along with a brief introduction to biodiesel and renewable diesel production, especially focusing on zeolites as the catalyst support. The enhancement of catalyst support will be critically discussed to improve the catalytic performance of support in renewable diesel production and important aspects such as the stability and recyclability of the supported catalyst are included. The application of the supported catalyst in increasing the selectivity and yield of renewable diesel is significant, in which the catalytic properties depend on the interaction between catalyst and catalyst support. The supported catalyst as a favorable substance to assist in enhancing renewable diesel yield could lead to a sustainable and greener future for the biofuel industry in Malaysia.

Biodiesel Production Using Homogeneous, Heterogeneous, and Enzyme Catalysts via Transesterification and Esterification Reactions: a Critical Review

The excessive utilization of petroleum resources leads to global warming, crude oil price fluctuations, and the fast depletion of petroleum reserves. Biodiesel has gained importance over the last few years as a clean, sustainable, and renewable energy source. This review provides knowledge of biodiesel production via transesterification/esterification using different catalysts, their prospects, and their challenges. The intensive research on homogeneous chemical catalysts points to the challenges in using high free fatty acids containing oils, such as waste cooking oils and animal fats. The problems faced are soap formation and the difficulty in product separation. On the other hand, heterogeneous catalysts are more preferable in biodiesel synthesis due to their ease of separation and reusability. However, in-depth studies show the limited activity and selectivity issues. Using biomass waste-based catalysts can reduce the biodiesel production cost as the materials are readily available and cheap. The use of an enzymatic approach has gained precedence in recent times. Additionally, immobilization of these enzymes has also improved the statistics because of their excellent functional properties like easy separation and reusability. However, free/liquid lipases are also growing faster due to better mass transfer with reactants. Biocatalysts are exceptional in good selectivity and mild operational conditions, but attractive features are veiled with the operational costs. Nanocatalysts play a vital role in heterogeneous catalysis and lipase immobilization due to their excellent selectivity, reactivity, faster reaction rates owing to their higher surface area, and easy recovery from the products and reuse for several cycles.