The study of ultrasound-assisted oxidative desulfurization process applied to the utilization of pyrolysis oil from waste tires Teng-Chien Chen a, e , Yun-Hwei Shen a , Wen-Jhy Lee b, e , Chih-Chung Lin c , Meng-Wei Wan d, * a Department of Resources Engineering, National Cheng KungUniversity, No.1, Ta-Hsueh Road, 701 Tainan, Taiwan, ROC b Department of Environmental Engineering, National Cheng Kung University, No.1, Ta-Hsueh Road, 701 Tainan, Taiwan, ROC c Department of Environmental Engineering and Science, National Ping Tung University of Science and Technology,1 Hseuh-Fu Road, Nei Pu, 912, Ping Tung, Taiwan, ROC d Department of Environmental Engineering and Science, Chia Nan University of Pharmacy and Science, 60, Erh-Jen Road, Sec.1, Jen-Te, 717, Tainan, Taiwan, ROC e Resource Recycling And Management Research Center, National Cheng Kung University, No.500, Sec. 3, Anming Road, Tainan 709, Taiwan, ROC article info Article history: Received 13 March 2010 Received in revised form 17 July 2010 Accepted 17 July 2010 Available online 24 July 2010 Keywords: Oxidative Desulfurization Ultrasound Pyrolysis oil Waste tires Clean Energy abstract In recent years, the increasing world population and rapid industrial development has increased the consumption of fossil fuel-derived oils. In response to the resulting exhaustion of fossil fuel energy, many countries around the world are investigating methods of waste energy recovery and reuse, including oil recovery from the pyrolysis process of waste tires. This study investigates the efficiency of an ultrasound- assisted oxidative desulfurization (UAOD) process in sulfur reduction from diesel oil and the pyrolysis oil from waste tires treatment. The results indicate that the oxidation efficiency increases as the doses of transition metal catalyst are increased. Longer sonication time also enhances the oxidation process, apparently through the biphasic transfer of oxidants, which results in a high yield of organic sulfur oxidation products. The best desulfurization efficiency was 99.7% (2.67 ppm sulfur remaining) and 89% (800 ppm sulfur remaining) for diesel and pyrolysis oils, respectively, via a process executed by two UAOD units connected in series and combined with solid adsorption using 30 g of Al 2 O 3 in 6 cm columns. These batch experiment results demonstrate clean waste energy recovery and utilization, while fulfilling the requirements of Taiwan EPA environmental regulations (sulfur concentrations less than 5000 ppm). Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction In the past three decades, the increasing world population and rapid industrial developments have drastically increased the consumption of fossil fuel-derived oils. The current use of fossil fuels in various sectors for heat and power generation continues to threaten global stability and sustainability (Dovì et al., 2009; Battaglini et al., 2009). Thus, countries around the world have devoted their resources to solving the shortage of fossil fuel energy and lowering energy costs. In general, the predominant energy policies have been divided into two categories: 1) the development of renewable energy resources and 2) the recycling and reuse of waste energy. Though by-products, industrial and municipal solid wastes may still possess economic value as energy sources, depending on their quality and market accessibility (Tsai and Chou, 2004; Tsai, 2010). For this reason, researchers have begun to develop chemical treatments for recycling solid wastes to recover their leftover energy (Dodbiba et al., 2008; Stehlik, 2009). The pyrolysis process utilized for oil recovery from the waste of rubber and polymer production and cotton ginning procedures is receiving marked attention in some developed countries (Zabaniotou and Andreou, 2010). However, there is a serious environmental concern that the recovered oils from the pyrolysis of waste tires contain high organic sulfur concentrations in their final products. Upon combustion, the organic sulfur compounds (OSCs) in pyrolysis- recovered oil produces SO 2 and sulfate particulate matter (PM) emissions that endanger public health and welfare (Wan and Yen, 2007). Previous research has shown that such OSCs in petro- leum can poison catalytic converters, corrode parts of internal combustion engines, and lead to air pollution. Because the sulfur compounds poison the shift catalyst in the hydrocarbon conversion Abbreviations: BTs, Benzothinphenes; DBTs, Dibenzothiophenes; GC/SCD, Gas Chromatograph equipped with a Sulfur Chemiluminescence Detector; HDS, Hydro- Desulfurization; ODS, Oxidative Desulfurization; OSCs, Organic Sulfur Compounds; PM, Particulate Matter; PTA, Phase Transfer Agent; Taiwan EPA, Taiwan Environ- mental Protection Administration; TMC, Transitional Metal Catalyst; Ts, Thio- phenes; UAOD, Ultrasound-Assisted Oxidative Desulfurization. * Corresponding author. Tel.: þ886 6 2660615; fax: þ886 6 3662668. E-mail address: peterwan@mail.chna.edu.tw (M.-W. Wan). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro 0959-6526/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jclepro.2010.07.019 Journal of Cleaner Production 18 (2010) 1850e1858