Preparation of solid heterogeneous catalysts for biodiesel production from palm-based feedstock
Palm fatty acid distillate (PFAD) and palm stearin (PS) are side products from physical refining of crude palm oil, and it can be a good alternative feedstock for biodiesel production. In this study, PS and PFAD were chemically converted into biodiesel using solid base and acid catalysts. The rea...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/91299/1/FS%202015%2090%20-%20IR.pdf http://psasir.upm.edu.my/id/eprint/91299/ |
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| Summary: | Palm fatty acid distillate (PFAD) and palm stearin (PS) are side products from physical
refining of crude palm oil, and it can be a good alternative feedstock for biodiesel
production. In this study, PS and PFAD were chemically converted into biodiesel using
solid base and acid catalysts. The reaction parameters of the catalytic reaction were
thoroughly investigated and optimized via Response Surface Methodology. The
optimal values of these factors were found to be related to the chemical and physical
properties of the feedstock. Four catalysts were synthesized and used to produce
biodiesel and these were (i) nanoscale calcium methoxide (eMS), (ii) zirconia
supported calcium methoxide (eMSS), (iii) sulfated zirconia (SZ) and, (iv) ball-milled
sucrose-derived carbon acid catalyst (S400M). eMS catalyst possesses a novel
morphology due to the sonication treatment during preparation of the catalyst. The
nanoscale particles gave a high surface area which may provide more active sites for
reactants to anchor and react. The results showed that eMS has excellent basicity and
high catalytic ability as a heterogeneous solid base catalyst. This catalyst gave 94.7 %
of biodiesel yield within 3 hours at temperature of 70'C, methanol molar ratio and
catalyst loading of 6 and 1 wt% of PS, respectively. Besides, eMSS catalyst gave the
highest biodiesel yield of 98 % at temperature of70'C, reaction time of 125 min, using
3 % catalyst loading and methanol to PS molar ratio of 11:1. Furthermore, the
recycling experiment results showed it had a longer catalyst lifespan, and the zirconia
support had proven to be the good stabilizing agent to the calcium methoxide catalyst.
This catalyst appeared to be a promising candidate to replace the existing homogeneous
catalysts for biodiesel production as it requires short reaction time with high reusability.
Moreover, SZ has been extensively studied and optimized as catalyst for the
esterification of free fatty acid in PFAD with methanol. The effect of sonication on the
phase structure and its catalytic activity was investigated. TPD-NH3 coupled with mass
spectrometer analysis revealed that the first thermal desorption peak of SZ represented
the actual acidity of the catalyst. SZ catalyst exhibited a good catalytic performance as
a heterogeneous solid acid catalyst which used to esterify PFAD and 97 % of free fatty
acid (FFA) conversion was achieved with 2 hours of reaction time, despite its low
surface area. A noticeable deactivation of catalyst has been experimentally detected
under the optimized reaction conditions. The characterization results showed that the
deactivation is due to the leaching of sulfate groups from the catalyst. Furthermore, the
other heterogeneous solid acid catalyst i.e. S400M was prepared in the present study
which aims to improve the esterification process and reduce the generation of waste
from biodiesel production. The experimental results showed that S400M exhibited good catalytic activity in the esterification of PFAD, providing maximum FFA
conversion of 94% at optimum parameters. The good catalytic activity of the
aforementioned catalyst in the biodiesel reaction could be attributed to the presence of
optimal number of catalytically active acid site density on its surface. The
mechanochemical treatment was the good tool to improve the catalytic activity of
carbon catalyst by adding extra active sites for esterification of FFA and to intensify
the acid strength of the catalyst. |
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