Hetero-Polyaromatic Ring-Opening Reactions in scCO2

Gregory C. Curtis,*b ,Sarah A. Brough,a Crystal L. Allen,a

Christopher D. Willson,b and G. Sean McGrady*a

a Department of Chemistry, University of New Brunswick, PO Box 4400, Fredericton, NB, Canada E3B 5A3; Email: smcgrady@unb.cab HSM Systems, Inc., 364 York St., Fredericton, NB, Canada E3B 3P7

The Challenge

• Production of cleaner fuels from increasinglylow-grade feedstocks and non-edible biomasssources.

• In the EU, planned reduction of sulfur levelsin gasoline and diesel to 10 wt ppm for 2009will require elaborate new processes or theoptimization of existing ones.1

The main objective of this project is to explore the utility of scCO2 for upgrading and hydrotreatment of oil sand ,coal ,

biomass and transportation fuels using less energy than conventional processes.

ScCO2 has the potential to play several crucial roles in bitumen upgrading and the advancement of integrated clean coal

and biomass technologies.

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BT 1,2-DHBT EB Total Products

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Total Conversion T1P1P ECH DBT

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I 1,2-DHI EB ECH Total Products

Synthesized transition metal catalysis under investigation Superior HDS/HDN conversions are obtained in scCO2 incomparison to conventional solvents. Ring-opening and HDS/HDN observed under remarkably mild conditions (100-200oC lower than comparativeconventional processes).4

Encouraging ground work paves the way for productionof ultra-clean fuels.

References

NiMoW/Al2O3CoMoS4/TiO2-Al2O3

Superior in HDS/HDN experiments

CoMoS4/Al2O3

For bitumen upgrading

NiW/TiO2-Al2O3

For high sulfur diesel HDS experimentsNiMo/MCM-48

NiMo/Al-MCM-48

Model Compounds for HDS/HDN in scCO2

Benzothiophene HDS and indole HDN reactions were performed inscCO2 using various heterogeneous catalyst. For benzothiophene, HDSproducts were predominant using Pd/Al2O3, whereas thehydrogenation pathway was observed when using Rh/Al2O3. Reactionswere performed over the temperature range of 100-225 oC, with theoptimal HDN temperature being 200 oC. The fully hydrogenated HDNproduct (ECH) was observed in scCO2 only with the commercialcatalysts; however no such product was observed when using hexaneas the reaction medium.

Combined HDS/HDN in scCO2

Combined HDS/HDN experiments on 2(2-pyridyl)benzothiophene and(NH4)2S2O3 as the sulfiding agent were performed using far lowertemperatures than conventional processes.4 These reactions showedhigh levels of hydro-cracking products, with the major one beingethylcyclohexane. Up to 76% ethylcyclohexane was observed; anunprecedentedly high yield. In this case, the synthesized catalyst[CoMoS4/TiO2-Al2O3] performed as well as the commercial catalyst.

Hydrogenolysis Results forHPHs in n-Hexane and scCO2

Conclusions

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Heterocycle

n-Hexane Carbon dioxide 8.6 MPa

• The essential component of ultra-deep HDS is thedevelopment of highly active hydrogenating catalysts in amedium that supports this activity. To achieve energysustainability that satisfies current and impendingenvironmental regulations of sulfur and nitrogen levels intransportation fuel, a clean conversion technology andmethodology is fundamental.

• In January 2007 the EuropeanUnion agreed on a target to makebiofuels 10% of fuels consumedin the transport sector by 2020.2

• Biomass fuels are derived fromindustrial processing, such asforestry and wood products,agriculture residues and wastes,municipal solid wastes and fastgrowing energy crops.

• Biomass electrical generation orbiopower is second only tohydropower as a renewableenergy source.3

DBT T1P1P ECH

4,6-DMDBT 3-MVB 1,3-DMCH

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1,3,5-teb (5) PCH (4) Total Products

1) Off. J. Eur, Commun. L76 (2003) 102) www.energysavers.gov3) http://ec.europa.eu/environment

4) R.G. Leliveld, S.E. Ejisbouts, Catal. Today 130 (2008)183

Hydrotreating processes must havethe capacity to desulfurize highlyrefractory alkyl-dibenzothiophenes(alkyl-DBTs) while performing thecomplete hydrogenation of aromaticmolecules.5

5) Baldovino-Medrano, V.G., Giraldo, S.A., Centeno, A.; J Mol Cat(2009) 127-133

Results

Future Work