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Heterogeneous catalysts for biodiesel production

9:1 alcohol-to-oil molar ratio, this catalyst showed showed that biodiesel production increased with higher
outstanding performance, producing a 93% biodiesel KOH loading, indicating that the catalyst containing
yield in 1.5 h. The catalytic qualities of bovine and chicken KOH exhibited greater activity than the catalyst
bones, in addition to fish bones, have been investigated made from virgin calcined bone. Similarly, Olajide
in the process of producing biodiesel. The preparation of et al., reported enhanced catalytic activity in palm
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bone-derived catalysts is shown in Figure 3. oil transesterification when calcined scrap pig bone
Ni et al. obtained a 96.31% biodiesel yield was used as a catalyst impregnated with potassium
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using CaO derived from discarded chicken bones carbonate, although some leaching of K⁺ ions occurred
to transesterify waste cooking oil that was calcined during each cycle. Masango and Ngema developed
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at 800°C. According to them, lower calcination a bimetallic CaO-CeO₂ catalyst (1:1 ratio) supported
temperatures resulted in lower biodiesel yields. on hydroxyapatite derived from calcined waste pig
The ideal calcination temperature must be established bones. This catalyst showed outstanding performance in
due to its significant impact on the catalyst’s surface transesterification, reaching a maximum biodiesel yield
area and catalytic activity. Farooq et al. examined the of 91.84%. Lattice distortion from Ca and Ce ions
2+
2+
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process of transesterifying soybean oil with catalysts caused less catalyst leaching in future cycles. Waste
made from leftover bovine bones that were calcined at canola oil was transesterified using a catalyst made from
temperatures between 350°C and 1,100°C. According leftover chicken bones that included lithium, zinc, and a
to their findings, the ideal calcination temperature range lithium/zinc hybrid combination. With an alcohol-to-oil
was between 650°C and 950°C, while catalysts produced molar ratio of 18:1, a catalyst concentration of 4wt%,
at lower calcination temperatures showed less catalytic and a temperature of 60°C, the lithium/zinc catalyst in a
activity. Surface area and catalytic performance were 2:2 ratio produced the best results, yielding 98% methyl
both decreased by higher temperatures. They found a esters in 3.5 h. 174
clear association between surface area and calcination In addition to modifying catalysts, other approaches
temperature after calcining leftover chicken bones at should be explored to boost the efficiency of
800°C, 900°C, and 1,000°C for 4 h. Marzbali et al. heterogeneous catalysts made from bone with an 18:1
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found that the highest performance was obtained by molar ratio of methanol to oil, a 4 wt% concentration of
the catalyst that was calcined at 900°C. The findings catalysts, 800 W of microwave power, and a temperature
revealed that extremely high temperatures were of 65°C. Khan et al., used microwave heating to
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detrimental, even if catalytic activity rose with greater create a catalyst derived from the bones of Guinea fowls
calcination temperatures. A biodiesel yield of 89.5% was to produce biodiesel from Annona squamosa (custard
produced in approximately 1.54 h under a 10:1 alcohol- apple seed) oil. They were able to convert 95.82% of
to-oil molar ratio, 1.98% w/v catalyst concentration, FAME in 20 min.
and a reaction temperature of 65°C using a combination Table 5 presents an analysis of the efficiency of bone-
of fish and chicken bones that have been calcined at based catalysts derived from various animal origins for
1,000°C in identical weight ratios. the transesterification process in biodiesel production.
Nisar et al., used discarded quail beaks calcined These catalysts, primarily CaO or hydroxyapatite,
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at 900°C to create an extremely effective catalyst made are synthesized by calcining animal bones at specific
on heterogeneous hydroxyapatite. According to their temperatures to enhance their catalytic properties.
research, the catalyst’s ability to effectively transesterify Calcined ostrich bone catalysts have been utilized in
was caused by the increases in particle size and basic transesterifying waste cooking oil, achieving a biodiesel
strength that occurred during calcination. yield of 90.56% under a 15:1 methanol-to-oil molar
Although bone-derived catalysts are reasonably ratio and 5% catalyst load for 4 h at 60°C. Similarly,
efficient in transesterification processes, their high quail waste head-derived catalysts have been employed
molar ratio of methanol to oil, long reaction times, for the transesterification of canola oil, rapeseed oil,
and large catalyst requirements make them unfeasible and waste cooking oil, yielding 89.4%, 91%, and 91.7%
for large-scale biodiesel synthesis. Catalysts produced biodiesel, respectively, under a 1:12 methanol-to-oil
from bone have been modified to increase catalytic molar ratio and 7% catalyst load for 4 h at 65°C. Fish
activity by improving their surface characteristics or bone-derived CaO catalysts have demonstrated high
fundamental strength. To transesterify pre-esterified efficiency, with yields ranging from 89.33% to 94.3%
Jatropha oil, Chen et al. employed KOH supported for waste cooking oil and palm oil under varying
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on animal waste that has been calcined. Their study methanol-to-oil ratios, catalyst loadings, reaction times,

Volume 22 Issue 5 (2025) 13 doi: 10.36922/AJWEP025130095