Synthesis, characterization and catalytic activity of supported sugar catalysts
The process of synthesizing sugar catalyst is started by incomplete carbonization of Dglucose. It is followed by sulphonation to incorporate the sulphonic group (-SO3H). However, despite of its excellence catalytic performance, the current form of sugar catalyst is in powder form with non-porous str...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2017
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/38884/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/38884/2/FULLTEXT.pdf |
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| Summary: | The process of synthesizing sugar catalyst is started by incomplete carbonization of Dglucose. It is followed by sulphonation to incorporate the sulphonic group (-SO3H). However, despite of its excellence catalytic performance, the current form of sugar catalyst is in powder form with non-porous structure maybe lack of applicability in commercial scale biodiesel production due to the potential of large pressure drop in a packed bed reactor. Hence, it is anticipated that the industrial applicability of sugar catalyst can be enhanced if its particle size can be increased. This study was conducted to investigate the feasibility of attaching sugar catalyst on different surfaces by depositing the char on external surfaces of aluminum (SCDCAI), glass (SCDCSi) and clay (SCDCCI) via dip coating method ( ex-situ) followed by sulphonation. The sulfonation of char embedded naturally in different types of supports namely, rice husk, rice straw, and rice husk were also studied (in-situ). Rice husk and rice straw were pyrolyzed in a controlled condition, whereas rice husk ash, a combustion waste, was acquired from a local paddy mill. Synthesized supported sugar catalysts via ex-situ were sulphonated using fuming sulphuric acid via vapor-phase sulphonation and supported catalysts via in-situ were sulphonated via liquid phase sulphonation. The ratio of char deposited on SCDCAI, SCDCSi and SCDCCI were 0.900 gJgs, 0.040 gJgs, and 0.014 gc/gs, respectively. The total acidity for SCDCAI, SCDCSi, and SCDCCI were 0.9 mmol/g, 0.2 mmol/g, and 0.4 mmol/g, respectively. SCDCAI and SCDCGI had surface area of 3.38 m2/g and 1.2 m2/g, respectively compared to powder sugar catalyst which has less than <1 m2/g. The catalysts were stable up to 673.15 K. Meanwhile, the total acidity of in-situ sulfonation of rice straw (RSC), rice husk (RHC) and rice husk ash (RHAC) were 3.60 mmol/g, 3.53 mmol/g and 2.28 mmol/g, respectively. FTIR data indicated the presence of silica bonded to carbon in the samples. The supported catalysts via in-situ undergone two stages of weight loss from T = 303.15 K to 673.15 K. The catalytic activity of SCDCAI was tested in a packed bed reactor and conversion of oleic acid was below than 1 %. The catalytic activity of RSC, RHC and RHAC on esterification of oleic acid with methanol were studied in a batch reactor at 333.15 K, 343.15 K, and 353.15 K under reflux, molar ratio (oleic acid: methanol) of 1:10, 3 wt.% catalyst. The conversion of oleic acid using RHC and RHAC were linearly proportional to temperature. RSC had the highest oleic acid conversion compared to RHC and RHAC. Ea for esterification reaction catalyzed by RSC, RHC and RHAC were 25.952 Kj.moI-1 , 38.760 Kj.mo1-1 and 10.842 Kj.moI-1 respectively. The kinetic model was studied using the integral method. Based on the regression of best fit line, RSC, RHC and RHAC followed second order reaction. In conclusion, sugar catalyst can barely be deposited externally on aluminum, clay and glass via ex-situ process with weak adhesion strength. Meanwhile, the sulfonated carbon-silica catalyst prepared via in-situ had high total acidity that likely due to the presence of carbonsilica bond. It had shown high catalytic activity on esterification of oleic acid with methanol. |
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