Simultaneous Conversion of Triglyceride/Free Fatty Acid Mixtures into Biodiesel Using Sulfated Zirconia

A comprehensive review on nanocatalysts and nanobiocatalysts for biodiesel production in Indonesia, Malaysia, Brazil and USA

Biodiesel is an alternative to fossil-derived diesel with similar properties and several environmental benefits. Biodiesel production using conventional catalysts such as homogeneous, heterogeneous, or enzymatic catalysts faces a problem regarding catalysts deactivation after repeated reaction cycles. Heterogeneous nanocatalysts and nanobiocatalysts (enzymes) have shown better advantages due to higher activity, recyclability, larger surface area, and improved active sites. Despite a large number of studies on this subject, there are still challenges regarding its stability, recyclability, and scale-up processes for biodiesel production. Therefore, the purpose of this study is to review current modifications and role of nanocatalysts and nanobiocatalysts and also to observe effect of various parameters on biodiesel production. Nanocatalysts and nanobiocatalysts demonstrate long-term stability due to strong Brønsted-Lewis acidity, larger active spots and better accessibility leading to enhancethe biodiesel production. Incorporation of metal supporting positively contributes to shorten the reaction time and enhance the longer reusability. Furthermore, proper operating parameters play a vital role to optimize the biodiesel productivity in the commercial scale process due to higher conversion, yield and selectivity with the lower process cost. This article also analyses the relationship between different types of feedstocks towards the quality and quantity of biodiesel production. Crude palm oil is convinced as the most prospective and promising feedstock due to massive production, low cost, and easily available. It also evaluates key factors and technologies for biodiesel production in Indonesia, Malaysia, Brazil, and the USA as the biggest biodiesel production supply.

Utilization of Ficus carica leaves as a heterogeneous catalyst for production of biodiesel from waste cooking oil

Biodiesel appears to be a possible substitute for non-renewable fossil fuels; however, its production requires the presence of a catalyst to accelerate the reaction. Serving the purpose of finding effective, cheap and environmentally safe, heterogeneous catalysts, this research used the fig leaves in three different forms, calcined, activated by KOH, and activated by both K₂CO₃ and CaCO₃. Their efficiency in biodiesel synthesis, from spent cooking oil, was examined and compared with that of activated carbon which has been previously investigated. The properties of different catalyst forms were specified using X-ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy. Operating parameters studied for the three catalysts were reaction time (from 30 to 180 min), alcohol-to-oil molar ratio (from 4:1 to 10:1), catalyst loading (from 0.5 to 5% by wt.), and stirring speed (from 100 to 400 rpm). The increase in reaction time, molar ratio, and catalyst loading proved to have a favorable effect on % conversion to biodiesel but to a certain degree; increasing the stirring speed augmented the conversion. At optimum conditions (2 h of heating, 6:1 alcohol-to-oil molar ratio, 1% by wt. catalyst loading, and 400 rpm stirring), fig leaves activated by KOH provided the highest conversion to biodiesel (92.73%). The measured properties of the produced biodiesel (density, viscosity, flash point, cloud point, and pour point) yielded encouraging results. Graphical Abstract.

Heterogeneous alkaline earth metal–transition metal bimetallic catalysts for synthesis of biodiesel from low grade unrefined feedstock

A bimetallic alkaline earth metal–transition metal oxide, synthesized through a method of direct low-temperature decomposition of the bimetallic complex, is reported for the synthesis of biodiesel.

One-pot transesterification and esterification of waste cooking oil via ethanolysis using Sr:Zr mixed oxide as solid catalyst

Prepared 2Sr:Zr-650 catalyst possesses both acidic and basic sites, hence it was able to catalyze the simultaneous esterification and transesterification of free fatty acid containing vegetable oils.

One-step production of biodiesel from rice bran oil catalyzed by chlorosulfonic acid modified zirconia via simultaneous esterification and transesterification

Due to the high content (25-50%) of free fatty acid (FFA), crude rice bran oil usually requires a two steps conversion or one step conversion with very harsh condition for simultaneous esterification and transesterification. In this study, chlorosulfonic acid modified zirconia (HClSO3-ZrO2) with strong acidity and durability is prepared and it shows excellent catalytic activity toward simultaneous esterification and transesterification. Under a relative low reaction temperature of 120 °C, HClSO3-ZrO2 catalyzes a complete conversion of simulated crude rice bran oil (refined oil with 40 wt% FFA) into biodiesel and the conversion yield keep at above 92% for at least three cycles. Further investigation on the tolerance towards FFA and water reveals that it maintains high activity even with the presence of 40 wt% FFA and 3 wt% water. It shows that HClSO3-ZrO2 is a robust and durable catalyst which shows high potential to be commercial catalyst for biodiesel production from low grade feedstock.

A new generation of zirconia supported metal oxide catalysts for converting low grade renewable feedstocks to biodiesel

A new class of zirconia supported mixed metal oxides (ZnO-TiO(2)-Nd(2)O(3)/ZrO(2) and ZnO-SiO(2)-Yb(2)O(3)/ZrO(2)) has demonstrated the ability to convert low quality, high free fatty acid (FFA) bio-oils into biodiesel. Pelletized catalysts of ZrO(2) supported metal oxides were prepared via a sol-gel process and tested in continuous flow packed bed reactors for up to 6 months. In a single pass, while operating at mild to moderate reaction conditions, 195 °C and 300 psi, these catalysts can perform simultaneous esterification and transesterification reactions on feedstock of 33% FFA and 67% soybean oil to achieve FAME yields higher than 90%. Catalytic activity of the ZrO(2) supported metal oxide catalysts was highly dependent on the metal oxide composition. These heterogeneous catalysts will enable biodiesel manufacturers to avoid problems inherent in homogeneous processes, such as separation and washing, corrosive conditions, and excessive methanol usage.

Triglyceride cracking for biofuel production using a directly synthesised sulphated zirconia catalyst

In this study, sulphated zirconia was directly synthesised and compared to the conventional wet method of preparation. The surface areas and pore sizes were 169 m(2)/g, 0.61 μm (directly synthesized) and 65 m(2)/g, 0.24 μm (conventional method), respectively. Directly synthesized sulphated zirconia was amorphous, whereas conventionally prepared sulphated zirconia is polycrystalline. Their IR spectra were broadly similar, although the area of the 1250 to 950 cm(-1) band was larger for directly synthesised sulphated zirconia. Not only were conversions greater for directly synthesised sulphated zirconia (63% vs. 42% after 4h), but it exhibited significantly greater yield for fatty acid methyl esters. The percentage yield (after 1h) of methyl esters was 43% for the directly synthesised catalyst and 15% for the conventionally synthesised.