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Energy & Fuels 2004, 18, 1770-1774
Recovery of Useful Hydrocarbons from Petroleum Residual Oil by Catalytic Cracking with Steam over Zirconia-Supporting Iron Oxide Catalyst Eri Fumoto, Teruoki Tago,* Toshiro Tsuji, and Takao Masuda Division of Materials Science and Engineering, Graduate School of Engineering, Hokkaido University, N13 W8, Kita-Ku, Sapporo 060-8628, Japan Received April 14, 2004
To reduce the consumption of hydrogen when converting heavy oil to light oil, the catalytic cracking of a heavy oil (residue of atmospheric distillation) with steam was examined. Two iron oxide-based catalystsshematite (R-Fe2O3) and goethite (FeOOH, denoted herein as FeOX catalyst)swere used. It was found that the heavy oil was converted to a mixture of useful light hydrocarbons (i.e., gasoline, kerosene, and gas-oil) over iron oxide-based catalysts. Moreover, because the FeOX catalyst possessed mesopores with diameters of 6-10 nm, it exhibited higher activity than the R-Fe2O3 catalyst without the production of carbonaceous residue. The catalytic activity could be enhanced by loading ZrO2 on the FeOX catalyst. From the X-ray diffraction analysis and Mo¨ssbauer measurement, it was considered that the active oxygen species generated from H2O over ZrO2 particles spilled over the FeOX surface, where the oxidized decomposition of heavy oil occurred.
1. Introduction Human society has developed by utilizing fossil energy. However, the demands for light hydrocarbons such as gasoline, kerosene, and gas-oil are increasing, although half of the primitive petroleum deposits have already been consumed. Thus, there is a pressing need for the development of alternative energy resources. Huge amounts of carbonaceous resources, including heavy oils such as atmospheric- and vacuum-distillated residual oils, are generated as the byproducts in petroleum refinery process. Accordingly, the physical and/or chemical methods that convert heavy oils to useful hydrocarbons have been recognized as potentially useful approaches for obtaining alternative fuels. However, these carbonaceous resources are not in a useable form, and it is difficult to convert them to useful chemicals. Several groups have reported methods for the degradation of heavy oil by thermal cracking,1,2 hydrocracking,3 and catalytic cracking.4-6 In all these methods, however,
the carbonaceous residue is formed both in the reactor and on the catalysts, and this formation leads to serious difficulties.7,8 To offset this problem, the amount of carbonaceous residue is usually reduced by increasing the hydrogen pressure in the hydrocracking process. The resource of this hydrogen, however, is produced from the petroleum deposits remaining as half of its primitive amount. It would therefore be desirable to utilize alternative hydrogen resources. Moreover, to convert the heavy oil to useful light hydrocarbons without the carbonaceous residue, hydrogenation and oxidized decomposition of the heavy oil, which means an increase in the hydrogen-to-carbon ratio (H/C ratio) of the heavy oil, are required. For all of the aforementioned reasons, the catalytic cracking of heavy oil with steam seems to be a promising solution.9,10 The chemical processes to convert the heavy oil to useful light hydrocarbons under steam require catalysts with the following properties: (i) a high ability to decompose heavy oil; (ii) stable activity in a steam atmosphere at high temperature; (iii)
* Author to whom correspondence should be addressed. E-mail address:
[email protected]. (1) Schlepp, L.; Elie, M.; Landais, P.; Romero, M. A. Pyrolysis of Asphalt in the Presence and Absence of Water. Fuel Process. Technol. 2001, 74, 107-123. (2) Kawai, H.; Kumata, F. Free Radical Behavior in Thermal Cracking Reaction Using Petroleum Heavy Oil and Model Compounds. Catal. Today 1998, 43, 281-289. (3) Radwan, A. M.; Zhang, Z. G.; Chambrion, P.; Kyotani, T.; Tomita, A. Hydrocracking of Orinoco Tar over Metal-Free USY Zeolite. Fuel Process. Technol. 1998, 55, 277-284. (4) Bianco, A. D.; Panariti, N.; Carlo, S. D.; Beltrame, P. L.; Carniti, P. New Development in Deep Hydroconversion of Heavy Oil Residues with Dispersed Catalysts. 2. Kinetic Aspects of Reaction. Energy Fuels 1994, 8, 593-597. (5) Panariti, N.; Bianco, A. D.; Piero, G. D.; Marchionna, M. Petroleum Residue Upgrading with Dispersed Catalysts, Part 1. Catalysts Activity and Selectivity. Appl. Catal., A 2000, 204, 203213.
(6) Serrano, D. P.; Aguado, J.; Escola, J. M.; Garagorri, E. Performance of a Continuous Screw Kiln Reactor for the Thermal and Catalytic Conversion of Polyethylene-Lubricating Oil Base Mixtures. Appl. Catal., B 2003, 44, 95-105. (7) Masuda, T.; Mukai, S. R.; Akiyama, T.; Fujikata, Y.; Hashimoto, K. Deactivation of REY Zeolite during Catalytic Cracking of Heavy Oil Obtained from the Pyrolysis of Waste Plastics. Kagaku Kougaku Ronbunshu 1995, 21, 1133-1139. (8) Masuda, T.; Tomita, P.; Fujikata, Y.; Hashimoto, K. Deactivation of HY-type Zeolite Catalyst due to Coke Deposition during Gas-Oil Cracking. Stud. Surf. Sci. Catal. 1999, 126, 89-96. (9) Masuda, T.; Kuwahara, H.; Mukai, S. R.; Hashimoto, K. Production of High Quality Gasoline from Waste Polyethylene Derived Heavy Oil over Ni-REY Catalyst in Steam Atmosphere. Chem. Eng. Sci. 1999, 54, 2773-2779. (10) Masuda, T.; Kushino, T.; Matsuda, T.; Mukai, S. R.; Hashimoto, K.; Yoshida, S. Chemical Recycling of Mixture of Waste Plastics Using a New Reactor System with Stirred Heat Medium Particles in Steam Atmosphere. Chem. Eng. J. 2001, 82, 173-181.
10.1021/ef0499067 CCC: $27.50 © 2004 American Chemical Society Published on Web 09/01/2004
Recovery of Useful Hydrocarbons from Residual Oil
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lack of, or good resistance to, coke deposition; and (iv) resistance to the deposition of sulfur compounds and heavy metals, such as vanadium and tungsten, contained in the heavy oil. Pereira and co-workers11-13 developed an aquaconversion process for degrading heavy oil by catalytic cracking with steam. We similarly showed that poly(ethylene terephthalate) could be decomposed over goethite (FeOOH) catalysts in a steam atmosphere.14,15 In a subsequent paper, we showed that ZrO2-supporting FeOOH catalysts were effective for catalytic cracking of oil palm waste with steam.16 In this study, iron oxide-based catalysts and ZrO2-supporting iron oxide catalysts were applied to the catalytic cracking of a residue of atmospheric distillation with steam, and the effect of the amount of ZrO2 loading on the catalytic activity and behavior is investigated. 2. Experimental Procedure 2.1. Catalyst Preparation and Characterization. Iron oxide catalysts (herein denoted as FeOX catalysts) were obtained by treating FeOOH at 773 K for 1 h under a steam atmosphere. ZrO2-supporting FeOX catalysts were prepared via a conventional impregnation method, using an aqueous solution of ZrOCl2, followed by steam treatment at 773 k for 1 h. The catalyst thus obtained will be denoted hereafter as Zr(X)/Fe, where X is the amount (in weight percent) of the supported ZrO2. All the catalysts were pelletized without any binders and crushed and sieved to yield catalyst particles with diameters of 212-355 µm before use in the following experiments. The structure of the catalysts was observed using transmission electron microscopy (TEM; model JEM1010, JEOL) and X-ray diffractometry (XRD; model XD-610, Shimadzu). The amount of ZrO2 supported on the FeOX was measured by inductively coupled plasma (ICP) analysis (model ICP 1000IV, Shimadzu). The surface areas and pore volume distributions of the catalysts were evaluated from nitrogen sorptions measured at 77.4 K (model BELSORP 18PLUS; BEL Japan). The Mo¨ssbauer spectra of the catalysts prior to and after reactions were recorded at room temperature on a constant acceleration spectrometer with a cobalt-57/rhodium source. 2.2. Catalytic Cracking of Heavy Oil with Steam over Zr(X)/Fe Catalyst. Figure 1 shows a schematic of the experimental apparatus. A residual oil of atmospheric distillation from a petroleum process (denoted as AR) was diluted with benzene, to reduce the viscosity of AR. The 10% solution of AR with benzene thus obtained was used as a feedstock. Catalytic cracking with steam over the Zr(X)/Fe catalyst was performed in a fixed-bed reactor loaded with 1.0 g of the (11) Pereira, P.; Marzin, R.; Zacarias, L.; Trosell, I.; Hernandez, F.; Cordova, J.; Szeoke, J.; Flores, C.; Duque, J.; Solari, B. AQUACONVERSION (TM): A New Option for Residue Conversion and Heavy Oil Upgrading. Vision Tecnol. 1998, 6, 5-14. (12) Pereira, P.; Flores, C.; Zbinden, H.; Guitian, J.; Solari, R. B.; Feintuch, H.; Gillis, D. Aquaconversion Technology Offers Added Value to E. Venezuela Synthetic Crude Oil Production. Oil Gas J. 2001, 99, 79-85. (13) Higuerey, I.; Rogel, E.; Pereira, P. Residue Stability Study in a Thermal Catalytic Steam Cracking Process through Theoretical Estimation of the Solubility Parameter. Pet. Sci. Technol. 2001, 19, 387-401. (14) Masuda, T.; Niwa, Y.; Hashimoto, K.; Ikeda, Y. Recovery of Oil from Waste Poly(ethylene terephthalate) without Producing Any Sublimate Materials. Polym. Degrad. Stab. 1998, 61, 217-224. (15) Masuda, T.; Niwa, Y.; Tamagawa, A.; Mukai, S. R.; Hashimoto, K.; Ikeda, Y. Degradation of Waste Poly(ethylene terephthalate) in a Steam Atmosphere To Recover Terephthalic Acid and To Minimize Carbonaceous Residue. Polym. Degrad. Stab. 1997, 58, 315-320. (16) Masuda, T.; Kondo, Y.; Niwa, M.; Shimotori, T.; Mukai, S. R.; Hashimoto, K.; Takano, M.; Kawasaki, S.; Yoshida, S. Recovery of Useful Hydrocarbons from Oil Palm Waste Using ZrO2 Supporting FeOOH Catalyst. Chem. Eng. Sci. 2001, 56, 897-904.
Figure 1. Schematic of the experimental apparatus. catalyst at a reaction temperature of 773 K and one atmospheric pressure. The time factor (W/F) ranged from 0.5 to 2.7 h, where F is the flow rate of the residual oil (AR). The benzene solution of AR was fed to the reactor using a syringe pump. A mixture of steam and nitrogen was introduced as a carrier gas at a flow rate of 5 cm3/min-steam and 72 cm3/min-N2. The Zr(X)/Fe catalyst was confirmed to be inactive in regard to benzene in a preliminary experiment. The reaction products were separated into liquid and gas fractions through a series of two ice traps. The gas product collected using a sampling bag was quantitatively analyzed by a thermal conductivity detector (TCD; model GC-8A, Shimadzu, Ltd.) and a flame ionization detector (FID; model GC-12A, Shimadzu, Ltd.) gas chromatograph, equipped with columns of activated carbon and Porapak-Q, respectively. The analysis of liquid product was conducted using a liquid chromatograph (model CTO-10A, Shimadzu, Ltd.), a capillary gas chromatograph (model GC-18A, Shimadzu, Ltd.) and a GCMS chromatograph (model QP-5000, Shimadzu, Ltd.). The liquid products with a carbon number of
