Page 31 - AJWEP-22-5

Heterogeneous catalysts for biodiesel production

yields. Reaction periods were 1.4 to 4 h, and reaction of biodiesel produced with the catalysts examined in
temperatures usually fell between 65°C and 70°C, much this research often satisfy the needs of the industry. The
as in uniform basic catalysis. Although higher ratios of type of catalyst, feedstock properties, and operating
methanol to oil were occasionally employed, methanol circumstances are some of the variables that affect
recovery and reuse do not present any issues. Given their these outcomes. A comparison of homogeneous and
high conversion efficiency, eggshells are among the heterogeneous catalysis for the manufacture of biodiesel
most often utilized catalyst pre-cursors. However, few reveals that the economic feasibility of heterogeneous
researchers have thoroughly investigated the practical catalysis is mostly dependent on the number of cycles
applications of these catalysts, and many studies do not and the yield per cycle. Although heterogeneous
establish a clear connection between the catalyst source catalysts sometimes have greater upfront costs, their
and the feasibility of large-scale biodiesel production. total biodiesel production and cycle count make them a
Eggshells, for instance, may not be a viable pre-cursor viable alternative. The subsequent section delves more
for large-scale biodiesel manufacturing because of into the impact of cycling efficiency on catalyst lifespan.
supply chain issues. To support a circular economy, a Table 8 provides a comprehensive overview of
more sustainable strategy would be to use agro-industrial biodiesel synthesis efficiencies using heterogeneous
wastes as catalyst pre-cursors, such as J. curcas or palm catalysts derived from various biomass sources.
oil leftovers. These catalysts, often calcined at high temperatures,
Figure 4 shows encouraging outcomes for catalysts facilitate the transesterification of oils into FAME under
based on biomass ash and biochar. In contrast to CaO- optimized conditions. For instance, catalysts derived
based catalysts, biomass ash catalysts drastically shorten from seed cakes, such as sunflower, castor, jatropha,
reaction durations and methanol-to-oil ratios. However, and palm oil cakes, with catalyst loadings ranging from
the yields of biodiesel produced by catalysts based on 5% to 20%, achieved biodiesel yields between 84%
charcoal are often somewhat lower. Activated carbon- and 94% under a 12:1 methanol-to-oil molar ratio at
derived catalysts often outperform the other biomass 60°C for 2 h. Similarly, palm stearin-derived catalysts,
pre-cursors examined, reducing the temperature, particularly those from palm oil shells, demonstrated a
catalyst consumption, methanol-to-oil proportions, and high yield of 95.3% under a 20:1 molar ratio at 60°C
the duration of reaction while preserving 92 – 98% for 4 h. Animal-derived catalysts, including those from
biodiesel yields. Given that it is influenced by variables, mussels, shrimps, snails, and clam shells, exhibited
including catalyst type, alcohol, temperature, catalyst impressive yields, with some reaching up to 99%.
quantities, and reaction duration, biodiesel yield is an For example, shrimp shell-derived catalysts achieved
essential metric for evaluating catalyst performance. a yield of 89.1% under a 9:1 molar ratio at 65°C for
The best results are obtained by homogeneous basic 3 h. Eggshell-derived catalysts consistently produced
catalysis and ash-based catalysts, with the data showing yields between 95% and 98% across various feedstocks,
no discernible difference in FAME production across showcasing their versatility and efficiency. Ash-based
the different catalysts. The least amount of catalyst catalysts, such as those from coconut husk, banana
is needed by homogeneous basic catalysis, followed peels, and Azadirachta indica, also demonstrated
by biochar-activated carbon catalysts. To obtain high catalytic activity. Coconut husk-derived catalysts
comparable FAME yields, other catalyst types typically achieved yields up to 99% under a 12:1 molar ratio at
need 6.1 – 7.5 wt% catalyst loading. Since they use 45°C for 45 min. Banana peel-derived catalysts produced
biomass pre-cursors, biomass-based catalysts provide yields of 98%, highlighting the potential of agricultural
considerable economic savings and less environmental waste as a sustainable catalyst source. Biochar-
effect than HBC, but often require more material for supported catalysts, including those from canola, rice
comparable performance. husk, and palm fatty acid distillate, exhibited varying
The type of catalyst has minimal effect on the quality efficiencies. For instance, canola-derived catalysts
of biodiesel produced using heterogeneous catalysts achieved yields between 89% and 92% under an 18:1
since catalysts primarily affect reaction kinetics. The molar ratio at 65°C for 3 h, while rice husk-derived
quality of biodiesel can be impacted by downstream catalysts reached a yield of 87.6% under a 20:1 molar
processes, such as separation and purification, which ratio at 110°C for 15 h. These variations underscore the
are impacted by catalysts. The biodiesel synthesis importance of optimizing reaction conditions for each
efficiency of heterogeneous catalysts generated from catalyst type. The data presented in Table 8 underscores
biomass is given in Table 8. The quality characteristics the significant impact of catalyst source, preparation

Volume 22 Issue 5 (2025) 25 doi: 10.36922/AJWEP025130095