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 Figure 7. HPLC analysis of a model fuel before and after ODS treatment. (a) model fuel (b) model fuel extracted with methanol (c) oxidized model fuel (d) model fuel after catalytic oxidation and extraction with methanol.

The figures to the left depict the effect of a metalloporphyrin catalyst on our oxidation reactions. The catalyzed reactions showed almost complete reactant to product conversion while negligible conversion was observed for the uncatalyzed reactions. These results indicate that the metalloporphyrin was indeed catalyzing the reactions.

Initial experimental results of a model fuel, as seen to the right, showed our reaction could modestly oxidize some of the β-alkyldibenzothiophenes. Using HPLC data, we were then able to determine the relative ratios of substrate to product.

Our initial reaction conditions often led to incomplete oxidation of the substrate. As we refined technique, our reaction allowed us to oxidize over 95% of the problematic β-alkyldibenzothiophenes. As shown on the right, the sulfoxides and sulfone products could be removed from the model fuel by exploiting polarity differences between the starting materials and the reaction products.

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Figure 3. HPLC analysis of the uncatalyzed (daashed) and Fe(TPFPP)Cl catalyzed reaction(solid) of DBT with hydrogen peroxide.

Figure 4. HPLC analysis of the uncatalyzed (dashed) and Fe(TPFPP)Cl catalyzed reaction (solid) of BT with hydrogen peroxide.

Figure 5. HPLC analysis of the uncatalyzed (dashed) and Fe(TPFPP)Cl catalyzed reaction (solid) of 4-MDBT with hydrogen peroxide.

Figure 6. HPLC analysis of the uncatalyzed (dashed) and Fe(TPFPP)Cl catalyzed reaction (solid) of 4,6-DMDBT with hydrogen peroxide.

Diesel fuels typically containsulfur (.7-1% by weight)

Sulfur combustion products contribute to acid rain and poisoning of modern emission control systems.

US and EU governments call for lowered concentration of sulfur in all fuels2.

The current method, hydrodesulfurization, struggles to remove β- alkyldibenzothiophenes2.

ODS is a promising alternative orsupplementary process.1

This two step process uses an oxidant in a catalytic system to achieve the oxidation of a substrate and then removes the substrate based on polarity differences.A variety of catalysts are known to work in ODS.3

Will metalloporphyrins work as catalysts in the ODS process?

F F

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ODS using a metalloporphyrin catalyst was successful in removing β-alkyldibenzothiophenes, but the results suggest the catalytic system could be further optimized. Many aspects of the reaction including solvent system, catalyst structure, and substrate to oxidant ratio will be further explored to optimize the reaction.

The improvement of the metalloporphyrin catalyst is a key factor in the efficiency and viability of the reaction. Future work will include modifying the porphyrin ligand to improve its durability and effectiveness.

Kinetic studies will also address the broader question of the viability of this reaction in industry. The initial results presented here indicate that the metalloporphyrin catalyzed reaction could augment the desulfurization process in the future.

Figure 2. UV-visible spectra collected during the Fe(TPFPP)Cl catalyzed reaction of DBT with hydrogen peroxide. The reaction conditions were 312 mM DBT, 310 mM H 2O2 and 1% Fe(TPFPP)Cl in CH2Cl2/CH3CN/alcohol.  Insert: Absorbance as a function of time at lmax= 285 nm for reaction performed in CH2Cl2/CH3CN/methanol (black) and CH2Cl2/CH3CN/butanol (red).

Oxidative Desulfurization of Thiophene Derivatives using Metalloporphyrins 

Daniel Swediena, Erin Stuckerta, Michael Williamsb, Amy Bundyc, Dr. Alan Gengenbach University of Wisconsin-Eau Claire Department of Chemistry

 1. De Filippis, P.; Scarsella, M. Energy Fuels 17 (2003) 1452-1455.

2. Gary, J.H. and Handwerk, G.E. (1984). Petroleum Refining Technology and Economics, 2nd Edition, Marcel Dekker, Inc.

3. Tam, P. S.; Kittrell, J. R.; Eldridge, J. W. Ind. Eng. Chem. Res. 29 (1990) 321-324.

4. Stephenson, N. A.; Bell, A. T. Inorg. Chem., 45 (2006) 2758–2766  

FundingNSF – Erin and AmyPRF – Dan and MichaelORSPDr. Carney – Catalyst synthesisDr. Boulter – Repairing

instrumentationa- juniors at UWEC majoring in

Chemistryb- Graduated in Fall 2009 as

Chem/Businessc- junior at North Dakota

majoring in chemistry and forensic science

Dibenzothiophene sulfone, a desired product in our reaction, was commercially available. Therefore, DBT was chosen as the substrate for our initial experiments. The commercially available product facilitated analysis of the reaction results by UV-vis, GC-MS, and HPLC.

UV-visible spectra were taken to observe the effect of amount of oxidant. The results showed slightly more product for 2 equivalents than for 1equivalent.

Solvent effects are known for metalloporphyrins4. Similarly, a solvent effect was observed in the oxidation of DBT.

Discussion

Literature Cited 

Acknowledgments

Introduction

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Figure 1. UV-Visible spectra for DBT (black) and DBT sulfone (green).

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