Synthesis and characterization of mesoporous base catalyst for transesterification of palm oil
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Date
2009
Authors
Razali, Noraini
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Abstract
Due to environmental and economic concerns, current research trend in
catalysis has been shifting from homogeneous into heterogeneous systems in which
the active centers are supported on a solid. The pursuit of solid base catalyst has been
recently focused on mesoporous silica substrates due to very high surface area,
uniformity in pore size and hydrothermal stability which promising great opportunity
for application as catalysts and catalytic supports. In the present study, SBA-15
(mesoporous material) was studied as a catalyst support. The synthesis of SBA-15
support was studied by varying different process parameters i.e. effects of reaction
temperature, tetraethylorthosilicate/triblock copolymer (TEOS/TCP) ratio, pH of solgel
solution and hydrothermal treatment time. The SBA-15 materials were subjected
to surface analyzer, XRD, TEM and SEM in order to study BET surface area,
crystallinity and morphology of the support, respectively. The optimum conditions
for the SBA-15 were chosen based on the characterization results. The optimum
conditions were obtained at 60 oC synthesis temperature, 1.52 TEOS/TCP ratio, pH
1.7 and 36 h of hydrothermal treatment time. Mesoporous base catalysts were
developed by incorporating three different potassium compounds (KI, KNO3, KOH)
loaded on SBA-15 by impregnation method with heating at a temperature of 350 oC
for 3 h. All of these three types of catalyst were used in the transesterification
process and the yield of FAME was investigated. The highest yield was obtained
using KOH/SBA-15 catalyst and the optimum KOH loading was found to be at 20
wt. %. Otherwise, the different supports were also studied i.e. HZSM-5 and Al2O3.
The optimization study of the transesterification process encompassed the effect of
temperature (50-90 oC), methanol to oil ratio (6:1-14:1), weight of catalyst (1-5 wt.
%) and reaction time (2-6 h). Response surface methodology (RSM) was employed
for the optimization process to achieve the highest FAME yield and to evaluate the
interaction between the parameters at the same time. The optimum conditions were
found to give the best activity of 84.3 % of FAME yield at 70 oC of reaction
temperature with a methanol to oil ratio of 11.6, 3.91 wt. % of catalyst and 4.54 h of
reaction time. Besides showing high catalytic activity, KOH/SBA-15 could be reused
for one more run with an activity drop of merely 15.6 %. Beside that, the catalyst
also can be used in the transesterification process of waste cooking oil with 77 % of
FAME yield. Furthermore, low activation energy of 46.37 kJ/mol was obtained for
the transesterification process. From this study, it was demonstrated that the
KOH/SBA-15 was an effective catalyst for the transesterification process of palm oil.
Description
Master
Keywords
Chemical science , Mesoporous base catalyst , Palm oil