Catalytic Coprocessing of Low-Density Polyethylene with VGO Using Metal Supported on Activated Carbon Selhan Karago ¨z, †,§ Jale Yanik,* ,‡ Suat Uc ¸ ar, † and Chunshan Song § Fuel Science Program, The Pennsylvania State University, 209 Academic Project Building, University Park, Pennsylvania 16802, Refinery and Petrochemical Program, Dokuz Eylul University, IMYO, 35160 Buca-Izmir, Turkey, and Chemistry Department, Faculty of Science, Ege University, 35100, Bornova-Izmir, Turkey Received March 12, 2002 The main objective of this study was to explore nonacidic catalysts for recycling of low-density polyethylene (LDPE) by coprocessing with vacuum gas oil (VGO). The focus of this study is to investigate processability of coprocessing LDPE with VGO, and to obtain environmentally friendly liquid fuels from such coprocessing. LDPE and VGO were cracked over activated carbon-supported metal catalysts (M-Ac) and acidic catalysts (HZSM-5, DHC-8) using a batch autoclave at 425, 435, and 450 °C under hydrogen atmosphere. In hydrocracking of LDPE in VGO, the most suitable temperature was found to be 435 °C. The amount of sulfur in liquid products obtained from hydrocracking over activated carbon-supported metal catalysts was lower than that over HZSM- 5. Activated carbon-supported metal catalysts acted as an absorbent for sulfur compounds and H 2 S and also facilitated hydrodesulfurization (HDS). The hydrocarbon types in liquids were determined by nuclear magnetic resonance (NMR) analysis. In the cases of activated carbon- supported metal catalysts, aromatic species were found between 4% and 8.9%, whereas the liquid product obtained over HZSM-5 has 28% aromatic species. In the presence of activated carbon- supported metal catalysts, the isoparaffin index was found to be between 0.32 and 0.66. However, the isoparaffin index was 0.01 in the liquid obtained over HZSM-5. The presence of lower aromatics and higher isoparaffin index in liquid products obtained over the activated carbon-supported metal catalysts suggest an improved hydrocarbon fuel from an environmental viewpoint. Introduction Plastic materials are present in almost every area of daily life. However, the significant growth of plastic consumption also led to increasing amounts of waste plastics. The disposal of plastic wastes is an important environmental problem all over the world. Europe is generating about 15 million tons of post consumer plastic waste 1 while the United States alone generates more than 20 million tons of plastic wastes each year. 2 Recently, the degradation of polymers into liquid hy- drocarbons has attracted much attention from the viewpoint of the utilization of waste plastics as an energy resource. There have been many reports on the conversion of plastics to fuels using solid acid catalysts, especially on polyethylene (PE) and polypropylene (PP). 3,8 Solid acid catalysts generally have been pre- ferred for polymer degradation because of their high cracking abilities. 9 On the other hand, it was reported that in the use of nonacidic mesoporous silica catalyst (FSM) which pos- sesses no acid sites the degradation rates of PE and PP were as fast as that over an acid catalyst (SA-1), and the liquid yields were higher. 10 Recently carbon-sup- ported metal catalysts have become popular for hy- drodesulfurization (HDS), 11-13 hydrogenation, 14,15 and hydrodenitrogenation (HDN) 16 reactions because of their high surface area and because they can function as an absorbent for sulfur and nitrogen compounds. In addi- tion, in the fine chemical industry, precious metals loaded on activated carbon supports are frequently used, because such systems exhibit interesting features with * Author to whom correspondence should be addressed. Fax: +90 232 388 82 64. E-mail: jyanik@sci.ege.edu.tr; jryanik@yahoo.com. † Dokuz Eylul University. ‡ Ege University. § The Pennsylvania State University. (1) Williams, P. T.; Williams, E. A. J. Anal. Appl. Pyrolysis 1999, 51, 107-126. (2) Ramdoss, P. K.; Tarrer, A. R. Fuel 1998, 77 (4), 293-299. (3) McCaffrey, W. C.; Cooper, D. G.; Kamal, M. R. Polym. Degrad. Stab. 1998, 62, 513-521. (4) Garforth, A. A.; Lin, Y.-H.; Sharratt, P. N.; Dwyer, J. Appl. Catal. A: General 1998, 169, 331-342. (5) Shabtai, J.; Xiao, X.; Zmierczak, W. Energy Fuels 1997, 11, 76- 87. (6) Sharratt, P. N.; Lin, Y.-H.; Garforth, A. A.; Dwyer, J. Ind. Eng. Chem. Res. 1997, 36, 5118-5124. (7) Park, D. W.; Hwang, E. Y.; Kim, J. R.; Choi, J. K.; Kim, Y. A.; Woo, H. C. Polym. Degrad. 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