The chlorination of toluene produces two primary products, ortho-chlorotoluene and para-chlorotoluene. The latter is much more valuable, and as a consequence, the development of para-selective catalysts would represent a significant breakthrough. The focus of this project was to study the potential of zeolite catalysts for improving the selectivity of toluene chlorination. The chlorination reaction generates HCl as a byproduct, and this was challenging because many zeolites experience structural degradation when exposed to HCl. Our work used sulfuryl chloride as the chlorinating agent, so one of the first things we investigated was whether the sulfuryl chloride reacts directly or whether it first decomposes giving chlorine which subsequently reacts with the toluene.

Before studying the chlorination process, the effect of drying the zeolites was examined. This was done because the literature suggested that some zeolites would not degrade structurally in the presence of HCl as long as the system free of water. Our studies with X, Y, L and ZSM-5 revealed that each of them deactivated severely during reaction. Characterization showed that for X, Y and L zeolites, the degradation was at least partially irreversible, resulting from structural damage. However, for ZSM-5, the deactivation was found to be reversible. The lower the Al/Si ratio of the zeolite, the less likely it was to undergo structural degradation. Apparently, there was also deactivation due to fouling of the catalyst. While we were able to identify a regeneration procedure that fully restored the activity of ZSM-5, that procedure was not practical for commercial use.

We also studied the chlorination of toluene using AlCl₃ as the catalyst. Using computational chemistry we found that the mechanism changes as the dielectric constant of the solvent decreases. In more polar solvents, the reaction proceeds via the textbook arenium cation mechanism, but in less polar solvents, and when run neat, the reaction involves a direct bimolecular reaction between toluene and an AlCl₅ complex. Both computational studies and experimental work additionally showed that trace amounts of water were necessary to activate the catalyst. We believe that this water assisted in the decomposition of Al₂Cl₆ dimers into active AlCl₃ monomers.

“A Computational Study of Aluminum Chloride Activation for Toluene Chlorination,” S. R. Spencer, M. Zhang and C. R. F. Lund, J. Phys. Chem. A, 107 (48), 10335-10345 (2003). [more info]

“An Experimental and Computational Study of Solvent Effects in Toluene Chlorination,” M. Zhang and C. R. F. Lund, J. Phys. Chem. A, 106 (43), 10294-10301 (2002). [more info]

“Zeolite-Catalyzed Chlorination of Toluene by Sulfuryl Chloride: Activity, Selectivity and Deactivation of NaKL Zeolite,” M. C. Hausladen, R. C. Cyganovich, H. Y. Huang, and C. R. F. Lund, Appl. Catal. A: General, 219 (1-2), 1-12 (2001). [more info]

“Zeolite-Catalyzed Chlorination of Toluene by Sulfuryl Chloride: Activity, Selectivity and Deactivation of ZSM-5,” Chen-Chang Chang, M. J. Burger, G. M. Faitar, and C. R. F. Lund, J. Catal., 202, 59-67 (2001). [more info]

“Zeolite-Catalyzed Chlorination of Toluene by Sulfuryl Chloride: Activity, Selectivity and Deactivation of NaX and NaY Zeolites,” M. C. Hausladen and C. R. F. Lund, Appl. Catal. A: General, 190 (1-2), 269-281 (2000). [more info]

“Zeolite-Catalyzed Chlorination of Toluene by Sulfuryl Chloride: The Effect of Zeolite Drying,” M. C. Hausladen, B. W. Satterley, M. J. Burger, and C. R. F. Lund, Appl. Catal. A, 166 (1), 55 (1998). [more info]

“Zeolite-Catalyzed Chlorination of Toluene by Sulfuryl Chloride: The Role of Sulfuryl Chloride Decomposition in Chlorination,” B. W. Satterley, M. C. Hausladen, and C. R. F. Lund, Zeolites, 19, 434 (1997). [more info]

“The Role of Water in the Activation of Aluminum Chloride Halogenation Catalysts,” AIChE Annual Meeting, San Francisco, CA, November 2003.

“Development of Catalysts and Processes for Environmentally Benign Aromatic Chlorination,” ESI Spring Symposium, Buffalo, NY, April 2003.

“Pathways in Homogeneous Catalytic Chlorination,” AIChE Annual Meeting, Reno, NV, November 2001.

“Selective Chlorination of Toluene using Zeolites: Activity, Selectivity and Deactivation,” GE Corporate Research & Development, Schenectady, NY, October 12, 2001.

“Uncatalyzed and AlCl₃-catalyzed chlorination of toluene,” AIChE Annual Meeting, Los Angeles, CA, November 2000.

“Chlorination of Toluene Using ZSM-5,” AIChE Annual Meeting, Dallas, TX, November 1999.

“On the Role of the Lewis Acid in Electrophilic Substitution,” AIChE Annual Meeting, Dallas, TX, November 1999.

“DFT Studies of the Chlorination of Toluene using AlCl₃,” Jaguar/MacroModel Users Group Meeting, Forrestal Marriott Hotel, Princeton, NJ, August 1999.

“Selective Toluene Chlorination Using ZSM-5 Catalysts,” 16^th North American Catalysis Society Meeting, Boston, June 1999.

“Catalytic Chlorination of Toluene Using Zeolite Catalysts,” Pittsburgh-Cleveland Catalysis Society Meeting, Mercer, PA, December 1998.

“Catalysts for Selective Electrophilic Substitution,” Annual AIChE Meeting, Miami, November 1998.

“Zeolite-Catalyzed Chlorination of Toluene Using Sulfuryl Chloride,” 15^th North American Catalysis Society Meeting, Chicago, May 1997.

“Zeolite Catalysts for Enhanced para-Selectivity during Toluene Chlorination,” Workshop on Advances in Homogeneous and Heterogeneous Catalysis and Surface Science, June 1996, Nanjing, China.

“Selectivity and Activity in Zeolite-Catalyzed Chlorination,” Annual AIChE Meeting, Miami, November 1995.

Mang Zhang, “An Experimental Investigation of Promoted Iron Based Oxide for High Temperature Water Gas Shift Reaction Catalysts at Membrane Reactor Conditions and an Experimental and Computational Study of Solvent Effects in Toluene Chlorination,” Ph. D. Dissertation, University at Buffalo, SUNY, Dept. of Chemical Engineering (2003). [more info]

Chen-Chang Chang, “Selective Chlorination of Aromatic Hydrocarbons,” PhD Dissertation, University at Buffalo, SUNY, Dept. of Chemical Engineering (2001). [more info]

Michael Conrad Hausladen, “Zeolite-Catalyzed Chlorination of Toluene By Sulfuryl Chloride: Zeolite Activity, Selectivity and Stability,” PhD Dissertation, University at Buffalo, SUNY, Dept. of Chemical Engineering (1996). [more info]

Scott R. Spencer, “Ab-Initio Study of the Aluminum Chloride Catalysis of the Chlorination of Toluene,” M. S. Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (2001). [more info]

Gheorghita Mihaela Faitar, “K/ZSM5 Catalyzed Chlorination of Toluene Using Sulfuryl Chloride,” M. S. Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (1999). [more info]

Richard Cale Cyganovich, “A Kinetic Study of the Catalytic Chlorination of Toluene By Sulfuryl Chloride Using Zeolite L and Aluminum Chloride,” M. S. Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (1998). [more info]

Yaping Huang, “Chlorination of Toluene — Zeolite L Catalyst Deactivation and Regeneration Study,” MS Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (1997).

Matthew James Burger, “Toluene Chlorination Catalysis Using Zeolite ZSM-5,” M. S. Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (1997). [more info]

Brian Wayne Satterley, “The Effect of the Decomposition of Sulfuryl Chloride on the Zeolite-Catalyzed Chlorination of Toluene,” M. S. Thesis, University at Buffalo, SUNY, Dept. of Chemical Engineering (1996). [more info]