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Heterogeneous catalysts for biodiesel production

Table 8. (Continued)
Source Catalyst Loading Time Temperature Molar-to-oil Yield References
(wt%) (h) (°C) ratio (%)
Cerbera Coconut husk 10 3 60 6:1 88.6 377
manghas
Palm oil Eggshell 7 4 65 9:1 91.5 378
Canola Harwood 5 3 65 18:1 89 – 92 379
Wood Canola 5 3 150 6:1 48 380
Frying oil Rice husk 5 15 110 20:1 87.6 381
Palm fatty acid Palm waste 2.5 2 60 9:1 96.1 382
distillate
Oleic acid Corn straw 7 4 60 7:1 98 383
Palm oil Palm oil trunk 2 0.75 65 - 93 384
Sugarcane bagasse 2 0.75 65 - 94 385

method, and reaction conditions on biodiesel yield. mild reaction settings. In contrast to other heterogeneous
The use of biomass-derived heterogeneous catalysts catalysts, CaO has been shown to exhibit a reduced rate
not only enhances biodiesel production efficiency of reactivity. 390
but also promotes the utilization of renewable and For the manufacture of biodiesel, CaO has been
waste materials, contributing to sustainable energy employed as an alkaline solid catalyst in several
solutions. experiments. Research has shown that CaO is a viable
391
choice for recyclable catalysts since it is extremely
6.1. Heterogeneous solid catalysts derived from soluble in methanol. In addition, other research has
392
biomass looked at biodiesel production using various feedstocks,
Alkali metals, metal oxides, and alkaline earth metals including soybeans, and catalysts with mixed oxide
are examples of heterogeneous catalysts that are heterogeneity, including calcium-doped silicates.
frequently employed in the manufacture of biodiesel. Mesoporous calcium silicate and pectin methyl
393
These catalysts are frequently accompanied by pre- esterase-templated calcium structures (PMCS1-9)
cursors that offer a large surface area. Since solid are notable CaO catalysts that incorporate silicates as
386
acid catalysts provide several active sites with both references.
Lewis and Brønsted acidity, they are preferred over
liquid acid catalysts. Table 8 summarizes a variety 6.2. Biodiesel production using zeolite-based
387
of feedstocks, catalyst preparation techniques, and catalysts
solvents utilized in the manufacture of biodiesel, along Zeolite catalysts are made up of crystalline
with examples of mixed-metal solid acid catalysts. aluminosilicate compounds with a microporous, three-
The performance of these catalysts is highlighted dimensional structure composed of tetrahedra connected
in Table 8, with special attention to the normalized by oxygen atoms. In accordance with criteria, such
394
time and biodiesel yields, as reported in different as molecular size, ion exchange characteristics, and
investigations. internal acidity, these catalysts are selective, permitting
Despite being extensively researched for biodiesel only certain hydrocarbon molecules to pass through
production, solid alkaline catalysts face several their pores while obstructing others. 64,395 Since the
limitations, including slower reaction rates and the 1970s, zeolites have garnered substantial commercial
possibility of side reactions, which have prevented attention, expanding on discoveries made in the
their wider use. 388,389 Over the past 10 years, substantial 1950s. Their varied uses, including catalytic cracking,
progress has been achieved in developing solid alkaline alkylation, and isomerization, have had a major impact
catalysts despite these obstacles. Among them, CaO, on the petrochemical industry. 396
which can be obtained from both conventional and Zeolites work well in esterification reactions with
biomass sources, has gained popularity due to its carboxylic acids. However, only large-pore zeolites
extended operational life and strong catalytic activity in work well in such reactions, and their reaction rates

Volume 22 Issue 5 (2025) 27 doi: 10.36922/AJWEP025130095