Ethylene production from ethanol dehydration over mesoporous SBA-15 catalyst derived from palm oil clinker waste

Cheng, Y.W. and Chong, C.C. and Cheng, C.K. and Ng, K.H. and Witoon, T. and Juan, J.C. (2020) Ethylene production from ethanol dehydration over mesoporous SBA-15 catalyst derived from palm oil clinker waste. Journal of Cleaner Production, 249.

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Abstract

The silica-rich palm oil clinker (POC) from oil palm agroindustry is often dumped in landfill. This work investigated the valorisation of POC into Santa Barbara Amorphous-15 (SBA-15) catalyst, the modulation of its surface acidity, and its application in dehydration of ethanol to ethylene. With commercial SBA-15 SBA-15(Comm.) as reference, the successful fabrication of POC-derived SBA-15 POC-SBA-15(pH = 3, 5, and 7) were validated by spectroscopic and microscopic characterisation. From the results of temperature-programmed desorption of ammonia, the SBA-15(Comm.) have high strong acidity while POC-SBA-15 exhibit enriched weak-moderate acidity. For ethanol dehydration over SBA-15 at 200�400 °C, the ethanol conversion (XC2H5OH) and ethylene selectivity (SC2H4) rise with temperature. The catalytic activity was ranked as SBA-15(Comm.) < POC-SBA-15(3) < POC-SBA-15(7) < POC-SBA-15(5). Spent catalysts characterisation unanimously confirms the least carbon deposition on POC-SBA-15(5), which subsequently used to study the effect of initial ethanol concentration and liquid hourly space velocity (LHSV). When 99.5 wt% ethanol diluted to 50 wt%, the competitive adsorption between ethanol and water reduces XC2H5OH but enhances SC2H4. Further ethanol dilution (�30 wt%) deteriorates SC2H4 following remarkable ethanol steam reforming at elevated temperature (�350 °C). For 50 wt% ethanol dehydration over POC-SBA-15(5) at 400 °C, a greater LHSV furnishes a higher ethanol partial pressure that increases XC2H5OH but decreases SC2H4. When LHSV >16 mL/g·h, the saturation of finite active sites with adsorbates renders the drastic declination of XC2H5OH and SC2H4. For ethanol dehydration over POC-SBA-15(5), the optimal conditions are temperature of 400 °C, initial ethanol concentration of 50 wt%, and LHSV of 16 mL/g·h. Fresh POC-SBA-15(5) steadily catalyses the optimal process (73.33% XC2H5OH and 84.70% SC2H4) up to 105 h. Meanwhile, regenerated POC-SBA-15(5) achieves a lower catalytic activity (71.95% XC2H5OH and 81.96% SC2H4). © 2019 Elsevier Ltd

Item Type: Article
Impact Factor: cited By 11
Uncontrolled Keywords: Ammonia; Catalyst activity; Dehydration; Ethylene; Palm oil; Silica; Steam reforming; Temperature programmed desorption, Ethanol dehydration; Mesoporous SBA-15; Operating condition; Palm oil clinkers; Surface acidity, Ethanol
Depositing User: Ms Sharifah Fahimah Saiyed Yeop
Date Deposited: 19 Aug 2021 07:20
Last Modified: 19 Aug 2021 07:20
URI: http://scholars.utp.edu.my/id/eprint/23445

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