Group 12 Mark Lucas Trent Benefield Robert Stroud

 Review  Background  Mechanisms  Types of Catalysts  Data  Applications  Conclusion

 Thermodynamics controls if a reaction will occur or not  Does not determine the rate

 Kinetics is described by the speed of the reaction  Catalyst speeds up the process by lowering the activation energy of a reaction

 Catalysts are important in industry because they are used to develop specific reactions  Catalyst make processes more efficient  Common example is the catalytic converter in an automobile

 Homogeneous  Where the reactants and the products are in the same phase  Heterogeneous  Where the reactants and the products are in different phases  Catalysts can be metals or solutions  Examples:

 The reactant adheres to the catalyst, and creates a temporary weak bond  After the attachment to the catalyst the molecule becomes a radical or unstable compound  Then the radical reacts with another reactant or with itself to create the product, leaving the catalyst the same

 Olefins are unsaturated organic compounds that have at least one carbon-carbon double bond aka alkenes  Lower olefins have 2 to 4 carbons total in the compound  Very important because they are widely used in the petrochemical industry

 Fischer-Tropsch synthesis, a type of cracking, takes crude oil or other fossil fuels and produces olefins  The problem with this synthesis is that conventional catalysts tend to be mechanically unstable

Mechanism of FT synthesis Many different mechanisms theorized “M” is iron carbide (Fe x C) active site “R” group is what is already on active site  Either hydrogen or (CH) x chain 2-4 carbon chain is desired 46

Catalyst types Iron catalysts disfavor methane production in comparison to other metals like cobalt Unsupported iron oxide (“bulk”)  High selectivity toward light olefins with addition of promoters  Mechanically unstable at high temperature Can cause plug catalyst bed and foul separators used Necessary to steer reaction towards lower olefins Boudouard reaction happens in these conditions  Deposits carbon on active sites

Supported iron catalysts  Inert support material needed High surface area alumina prevents conversion of iron oxide to iron carbide Iron oxide on activated carbon had high activity, but low production of light olefins  Carbon nanofibers (CNF), β -silicon carbide, and α - alumina were used as supports ml x.php?topic= nce/article/pii/S X

Picture “A” is fresh Fe/ α-alumina catalyst  Large amount of iron oxide dispersion on support  Small crystal size ~14 nm Picture “B” is fresh “bulk” catalyst with (Fe-Ti-Zn-K) promoters  Clustering of iron oxide, large crystal size (~400 nm)

Picture “C” is spent Fe/ α-alumina catalyst  Small amount of coagulation in iron oxide  Increase in crystal size to ~17 nm Picture “D” is spend “bulk” promoted catalyst  Fragmentation and carbon filament growth Indicates poor mechanical stability of “bulk” catalysts

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Selectivity towards C2-C4 olefins is more important than the activity (iron time yield)  >30% selectivity towards methane production is undesirable

Experiment on iron content of Fe/ α-alumina

The 25 wt% Fe has lowest selectivity towards methane Outweighs low iron time yield Although 6 wt% Fe has high activity, low selectivity towards desired products Confirms earlier statement of inverse relationship between activity and selectivity

 Chemical Industry  Polymers  Solvents  Drugs  Cosmetics  Detergents blog.changeanything.com

 Ethylene  Synthesis of para- xylene from glucose  Completely Renewable  Precursor to polyethylene terephthalate (PET)  Solvent wable-xylene.html

 Butylene  Synthesis of Butyl Rubber (polyisobutylene)  Chewing gum  Tires  Explosives

 Ethylene  Synthesis of polyethylene glycol  Skin creams  Toothpaste  Heat transfer fluid  Solid rocket fuel

 Lower Olefins are key building blocks for plastics, cosmetics and drugs  Renewable lower olefins allows for decreased dependence on oil and decreased carbon emissions  Renewable lower olefin production is feasible using supported iron nanoparticles  Increased C 2 -C 4 selectivity over traditional renewable methods  Selectivity towards low olefins more important than activity /S X

1. Burtron H. Davis, Fischer–Tropsch Synthesis: Reaction mechanisms for iron catalysts, Catalysis Today, Volume 141, Issues 1–2, 15 March 2009, Pages 25-33, ISSN , /j.cattod ( 2. B. Büssemeier, C. D. Frohning, G. Horn, W. Kluy, U.S. Patent (1986). 3. A. P. Steynberg, M. E. Dry, Eds., Fischer-Tropsch Technology (Elsevier, Amsterdam, 2004). 4. M. D. Shroff et al., J. Catal. 156, 185 (1995). 5. J. Barrault, C. Forquy, J. C. Menezo, R. Maurel, React. Kinet. Catal. Lett. 15, 153 (1980). 6. K. P. de Jong, Oil Gas Sci. Technol. 61, 527 (2006). 7. K. P. de Jong, J. W. Geus, Catal. Rev., Sci. Eng. 42, 481 (2000). 8. B. G. Baker, N. J. Clark, H. MacArthur, E. Summerville, U.S. Patent (1986). 9. D. B. Bukur et al., Ind. Eng. Chem. Res. 29, 1588 (1990). 10. L. Xu, Q. Wang, Y. Xu, J. Huang, Catal. Lett. 31, 253 (1995). 11. M. L. Cubeiro et al., Appl. Catal. A 167, 183 (1998). 12. V. K. Jones, L. R. Neubauer, C. H. Bartholomew, J. Phys. Chem. 90, 4832 (1986). 13. A. P. B. Sommen, F. Stoop, K. van der Wiele, Appl. Catal. 14, 277 (1985). 14. Supported Iron Nanoparticles as Catalysts for Sustainable Production of Lower Olefins Hirsa M. Torres Galvis, Johannes H. Bitter, Chaitanya B. Khare, Matthijs Ruitenbeek, A. Iulian Dugulan, and Krijn P. de Jong. Science. 17 February 2012: 335 (6070),

 Supported Iron Nanoparticles as Catalysts for Sustainable Production of Lower Olefins  Group 12  Mark Lucas  Trent Benefield  Robert Stroud