Garba, Kabir (2018) Thermal And Catalytic Slow Pyrolysis Of Lignocellulosic Oil Palm Wastes Using Zeolite And Hydroxyapatite Based Catalysts. PhD thesis, Universiti Sains Malaysia.
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Abstract
The concern associated with industrial wastes motivated the production quality bio-oils from pyrolysis of lignocellulosic oil palm wastes with viable mesoporous catalysts derived from waste steel-slag. This study investigated the thermal and catalytic pyrolysis of LOPW over zeolite and zeolite-hydroxyapatite based catalysts to produce quality bio-oils in a slow-heating fixed-bed reactor. Also, the kinetics of the thermal and catalytic pyrolysis of the LOPW was investigated by using the Coats- Redfern methods. The reactor was maintained at 450-600 oC pyrolysis temperatures, 200 mL/min N2 flowrate, 10 oC/min heating rate and 0.5-2.5 g catalyst load was used for the catalytic pyrolysis. The pyrolysis was performed over zeolite and zeolitehydroxyapatite, as catalysts prepared from electric arc furnace slag. The BET textural characteristics suggested that the catalysts are hierarchical and highly mesoporous with average pore diameter ranging from 23-25 nm. The zeolite catalyst has crystallite structure consistent with that of Faujasite-Ca zeolite, based on authentication by XRD analysis. Whereas, Faujasite-Ca zeolite and hydroxyapatite crystallite formed the composite structure of hydroxyapatite-zeolite-based catalysts. The thermal pyrolysis produced crude bio-oils (CBO) at maximum yield of 40-47 wt% under 500-550 oC pyrolysis temperatures, whereas, the catalytic pyrolysis over 0.5 g catalyst is 40-47 wt%. The CBO have high heating values from 21-24.68 MJ/kg higher than that of the corresponding LOPW and comprised of conglomerate of bulky and reactive oxygenated compounds. But, the catalysts facilitated secondary reactions, which produced bio-oils pervaded with small and stable oxygenated compounds of specific families. The phenolics, acids, benzene derivative, esters among others constitute the light and stable compounds in the bio-oils that the catalysts were selective to. The decomposition profiles and kinetics of the pyrolysis of LOPW were determined via thermogravimetry. The thermographs from the thermogravimetric analysis inferred that pyrolysis reactions decomposed LOPW via stage-wise mode. The kinetics analysis based on the Coats-Redfern’s methods revealed that diffusion kinetics best described the second stage (active stage) of thermal and catalytic pyrolysis. While, the geometrical correlation kinetics best described the second and third stages, conversely kinetics govern by Avarami-Erofe'ev and Power law described the third stages of the LOPW pyrolysis. From the kinetics parameters, the catalytic pyrolysis exhibited the lowest activation energies compared to the corresponding thermal pyrolysis. Therefore, the pyrolysis of LOPW can be best described to follow complex multi-step mechanisms. The characteristic decomposition index (D) for the pyrolysis of LOPW and Fe/HAPAZ blend were higher than those for the LOPW thermal pyrolysis. The index D revealed that the Fe/HAPAZ profoundly influences the LOPW thermal pyrolysis.
| Item Type: | Thesis (PhD) |
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| Subjects: | T Technology T Technology > TP Chemical Technology > TP155-156 Chemical engineering |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Kimia (School of Chemical Engineering) > Thesis |
| Depositing User: | Mr Mohamed Yunus Mat Yusof |
| Date Deposited: | 02 Nov 2020 08:50 |
| Last Modified: | 17 Nov 2021 03:42 |
| URI: | http://eprints.usm.my/id/eprint/47839 |
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