Bioresource Technology xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Bioresource Technology journal homepage: www.elsevier.com/locate/biortech
Short Communication
Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME) Yong Nie ⇑, Ying Duan, Ruchao Gong, Shangzhi Yu, Meizhen Lu, Fengwen Yu, Jianbing Ji Zhejiang Province Key Lab of Biofuel, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
h i g h l i g h t s A continuous microwave-assisted
pyrolysis system was developed. UAME was produced from methyl ricinoleate using the system. The maximum UAME yield could reach 77 wt.% at 500 °C with atomization feeding.
g r a p h i c a l a b s t r a c t Metering pump Condenser Preheater
Quartz reactor
Microwave generator
Liquid products
Atomizer Infrared thermometer
Methyl ricinoleate Temperature controller
SiC bed Temperature recorder
Microwave-assisted pyrolysis system
a r t i c l e
i n f o
Article history: Received 11 February 2015 Received in revised form 12 March 2015 Accepted 13 March 2015 Available online xxxx Keywords: Methyl ricinoleate Undecylenic acid methyl ester (UAME) Microwave Pyrolysis Atomization feeding
a b s t r a c t Undecylenic acid methyl ester (UAME) was continuously produced from methyl ricinoleate using a microwave-assisted pyrolysis system with atomization feeding. The UAME yield of 77 wt.% was obtained at 500 °C using SiC as the microwave absorbent and heating medium. The methyl ricinoleate conversion and UAME yield from microwave-assisted pyrolysis process were higher than those from conventional pyrolysis. The effect of temperature on the pyrolysis process was also investigated. The methyl ricinoleate conversion increased but the cracking liquid yield decreased when the temperature increased from 460 °C to 560 °C. The maximum UAME yield was obtained at the temperature of 500 °C. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Undecylenic acid (UA), an important fatty acid derived from castor oil (Ogunniyi, 2006), owing to its bifunctional nature, can be used in sustainable material and chemical synthesis, including polyurethane polymers (Nylon11), flavors and fragrances, pharmaceuticals, and etc. (Van der Steen, 2009; Theimer, 1982). UA is mainly obtained from undecylenic acid methyl ester (UAME) via hydrolysis, while UAME is produced through pyrolysis of the methyl esters of castor oil, i.e., methyl ricinoleate. Gregory ⇑ Corresponding author.
et al. (1956) carried out the pyrolytic process of methyl ricinoleate by contacting with molten Pb bath, quartz sand, or refractory bricks which are heated by an electric furnace to 480–650 °C. However, the yield to UAME is low due to the uneven heating. Tang and Yuan (2014) conducted pyrolysis of methyl ricinoleate using a stainless steel tubular reactor heated by a temperaturecontrolled furnace. There is a temperature gradient from the inner wall to the center of the reaction tube, which would result in secondary cracking reactions and coke formation on the inner wall of the reaction tube. The coking can influence the heat transfer and thus the reaction temperature for the pyrolysis process in the tubular reactor.
http://dx.doi.org/10.1016/j.biortech.2015.03.076 0960-8524/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Nie, Y., et al. Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME). Bioresour. Technol. (2015), http://dx.doi.org/10.1016/j.biortech.2015.03.076
2
Y. Nie et al. / Bioresource Technology xxx (2015) xxx–xxx
Unlike conventional conductive heating which is driven by temperature gradient, microwave heating provides uniform internal heating for microwave absorbers which can be quickly heated without direct contact with the heat source. The direct conversion of the electromagnetic energy into heat at the molecular level makes microwave an alternative heating source for biomass pyrolysis, which has attracted increasing interest in recent years (Sobhy and Chaouki, 2010; Du et al., 2011; Bu et al., 2012; Wang et al., 2012; Xie et al., 2014). Microwave radiation is a fast and efficient heating method, with very high heating rate especially when being absorbed by some microwave absorbents (Du et al., 2011; Xie et al., 2014). In this study, a microwave-assisted system with continuous liquid feeding was developed for UAME production from pyrolysis of methyl ricinoleate. Silicon carbide (SiC) was used as the microwave absorbent and heat medium due to its high microwave absorptive capacity, chemical inertia, high specific heat capacity and thermal conductivity (Hasegawa et al., 2000; Kremsner and Kappe, 2006; Borges et al., 2014). Atomization feeding was employed for the introduction of methyl ricinoleate. In addition, the effect of pyrolysis temperature on methyl ricinoleate conversion and UAME yield was investigated. This work may provide a promising strategy to prepare UAME continuously from methyl ricinoleate for chemical industry. 2. Methods 2.1. Materials Methyl ricinoleate prepared by the transesterification of castor oil (Wuxi Haishuo Biological Co. Ltd. Jiangsu, China) was purified to 99 wt.% using a packed tower distillation unit under reduced pressure (
Contents lists available at ScienceDirect
Bioresource Technology journal homepage: www.elsevier.com/locate/biortech
Short Communication
Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME) Yong Nie ⇑, Ying Duan, Ruchao Gong, Shangzhi Yu, Meizhen Lu, Fengwen Yu, Jianbing Ji Zhejiang Province Key Lab of Biofuel, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
h i g h l i g h t s A continuous microwave-assisted
pyrolysis system was developed. UAME was produced from methyl ricinoleate using the system. The maximum UAME yield could reach 77 wt.% at 500 °C with atomization feeding.
g r a p h i c a l a b s t r a c t Metering pump Condenser Preheater
Quartz reactor
Microwave generator
Liquid products
Atomizer Infrared thermometer
Methyl ricinoleate Temperature controller
SiC bed Temperature recorder
Microwave-assisted pyrolysis system
a r t i c l e
i n f o
Article history: Received 11 February 2015 Received in revised form 12 March 2015 Accepted 13 March 2015 Available online xxxx Keywords: Methyl ricinoleate Undecylenic acid methyl ester (UAME) Microwave Pyrolysis Atomization feeding
a b s t r a c t Undecylenic acid methyl ester (UAME) was continuously produced from methyl ricinoleate using a microwave-assisted pyrolysis system with atomization feeding. The UAME yield of 77 wt.% was obtained at 500 °C using SiC as the microwave absorbent and heating medium. The methyl ricinoleate conversion and UAME yield from microwave-assisted pyrolysis process were higher than those from conventional pyrolysis. The effect of temperature on the pyrolysis process was also investigated. The methyl ricinoleate conversion increased but the cracking liquid yield decreased when the temperature increased from 460 °C to 560 °C. The maximum UAME yield was obtained at the temperature of 500 °C. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Undecylenic acid (UA), an important fatty acid derived from castor oil (Ogunniyi, 2006), owing to its bifunctional nature, can be used in sustainable material and chemical synthesis, including polyurethane polymers (Nylon11), flavors and fragrances, pharmaceuticals, and etc. (Van der Steen, 2009; Theimer, 1982). UA is mainly obtained from undecylenic acid methyl ester (UAME) via hydrolysis, while UAME is produced through pyrolysis of the methyl esters of castor oil, i.e., methyl ricinoleate. Gregory ⇑ Corresponding author.
et al. (1956) carried out the pyrolytic process of methyl ricinoleate by contacting with molten Pb bath, quartz sand, or refractory bricks which are heated by an electric furnace to 480–650 °C. However, the yield to UAME is low due to the uneven heating. Tang and Yuan (2014) conducted pyrolysis of methyl ricinoleate using a stainless steel tubular reactor heated by a temperaturecontrolled furnace. There is a temperature gradient from the inner wall to the center of the reaction tube, which would result in secondary cracking reactions and coke formation on the inner wall of the reaction tube. The coking can influence the heat transfer and thus the reaction temperature for the pyrolysis process in the tubular reactor.
http://dx.doi.org/10.1016/j.biortech.2015.03.076 0960-8524/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Nie, Y., et al. Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME). Bioresour. Technol. (2015), http://dx.doi.org/10.1016/j.biortech.2015.03.076
2
Y. Nie et al. / Bioresource Technology xxx (2015) xxx–xxx
Unlike conventional conductive heating which is driven by temperature gradient, microwave heating provides uniform internal heating for microwave absorbers which can be quickly heated without direct contact with the heat source. The direct conversion of the electromagnetic energy into heat at the molecular level makes microwave an alternative heating source for biomass pyrolysis, which has attracted increasing interest in recent years (Sobhy and Chaouki, 2010; Du et al., 2011; Bu et al., 2012; Wang et al., 2012; Xie et al., 2014). Microwave radiation is a fast and efficient heating method, with very high heating rate especially when being absorbed by some microwave absorbents (Du et al., 2011; Xie et al., 2014). In this study, a microwave-assisted system with continuous liquid feeding was developed for UAME production from pyrolysis of methyl ricinoleate. Silicon carbide (SiC) was used as the microwave absorbent and heat medium due to its high microwave absorptive capacity, chemical inertia, high specific heat capacity and thermal conductivity (Hasegawa et al., 2000; Kremsner and Kappe, 2006; Borges et al., 2014). Atomization feeding was employed for the introduction of methyl ricinoleate. In addition, the effect of pyrolysis temperature on methyl ricinoleate conversion and UAME yield was investigated. This work may provide a promising strategy to prepare UAME continuously from methyl ricinoleate for chemical industry. 2. Methods 2.1. Materials Methyl ricinoleate prepared by the transesterification of castor oil (Wuxi Haishuo Biological Co. Ltd. Jiangsu, China) was purified to 99 wt.% using a packed tower distillation unit under reduced pressure (
