Abstract
Supercritical fluids possess unique properties that make them attractive as media for chemical reactions. Densities of supercritical fluids are comparable to those of liquids and therefore their dissolving power is high. On the other side diffusion coefficients of components in supercritical fluids are much higher than in liquids. Therefore processes that are mass transfer limited in the liquid phase, like the majority of heterogeneous catalysed reactions on microporous materials, become faster at supercritical conditions. Supercritical fluids have the potential to replace toxic organic solvents and make reaction processes environmentally friendly. This paper discusses some environmental applications of catalytic reaction processes at supercritical conditions.
The enhanced maintenance of catalytic activity of zeolites and other microporous catalysts, that could enable them to overcome the obstacle of strong deactivation and replace liquid acids, that are used now and are very toxic, corrosive and pose high safety risk. A second example is the Fischer-Tropsch synthesis of liquid hydrocarbons, a process that would enable the production of liquid fuels from huge reserves of natural gas. That would make more economical and environmentally friendly use of natural gas than now. Hydrogenation over microporous catalysts containing precious metals is another only recently studied process. Hydrogenation in supercritical CO2 enhances dramatically the process safety, reduces the reactor size and increases the reaction rate too, due to enhanced solubility of H2 in supercritical CO2 compared to conventional solvents. Finally a novel wastewater treatment, catalytic supercritical water oxidation, takes advantage of the dramatic change of supercritical water properties compared to liquid water.
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References
Eckert, C.A., Knutson B. and Debenedetti P.G., Supercritical fluids as solvents for chemical and materials processing, Nature 383, 313–318 (1996).
Savage P.E., Gopalan S., Mizan T.I., Martino C.J. and Brock E.E., Reactions at supercritical conditions: Applications and fundamentals, AICHE J. 41, 1723–1778 (1995).
Subramaniam B. and McHugh M.A., Reactions in supercritical fluids-A review, Ind. Eng. Chem. Process Des. Dev. 25, 1–12 (1986).
Clifford A., “Reactions in supercritical fluids”, in E. Kiran (Ed.), Supercritical Fluids. Fundamentals for Applications, Kluwer, Dordrecht, pp. 449–479 (1994).
Clifford A. and Bartle K., Chemical reactions in supercritical fluids, Chemistry & Industry 449–452 (1996).
Boock L., Wu B., LaMarca C., Klein M. and Paspek S., Reactions in supercritical fluids, Chemtech 719–723 (1992).
McHugh M.A. and Krukonis V.J., Supercritical Fluid Extraction. Principles and Practice, Butterworths(1986).
Tiltscher H., Wolf H. and Schelchshorn J., A mild and effective method for the reactivation or maintenance of the activity of heterogeneous catalysts, Angewandte Chemie-Intern. Edition 20, 892–894 (1981).
Tiltscher H. and Hofmann H., Trends in high pressure chemical engineering, Chem. Eng. Sci. 42, 959–977 (1987).
Manos G. and Hofmann H., Coke removal from a zeolite catalyst by supercritical fluids, Chem. Eng. Technol. 14,73–78(1991).
Manos G. and Hofmann H., Disproportionation of ethylbenzene on ultrastable Y-Zeolite. Studies on coking mechanism in an integral reactor, Chemiker Zeitung 114, 183–190 (1990).
Ginosar D.M. and Subramaniam B., Olefinic oligomers and cosolvent effects on the coking and activity of a reforming catalyst in supercritical reaction mixtures, J. Catalysis 152, 31–41 (1995).
McCoy B.J. and Subramaniam B., Continuous-mixture kinetics of coke formation from olefinic oligomers, AIChE J. 41, 317–323 (1995).
Ginosar D.M. and Subramaniam B., “Coking and activity of a reforming catalyst in near-critical and dense supercritical reaction mixtures”, in B. Delmon and G.F. Froment (Eds), Catalyst Deactivation 1994 (Studies in Surface Science and Catalysis, Vol. 88), Elsevier, pp. 327–334 (1994).
Jooma A. and Subramaniam B., “In situ mitigation of coke buildup in porous catalysts with supercritical reaction media: Effects of feed peroxides”, in E. Kiran (Ed.), Innovations in Supercritical Fluids (ACS Symposium Series Vol. 608), ACS, pp. 246–256 (1995).
Clark M. and Subramaniam B., 1-Hexene isomerization on a Pt/gamma-Al2O3 catalyst: The dramatic effect of feed peroxides on catalyst activity, Chem. Eng. Sci. 51, 2369–2377 (1996).
Dardas Z., Suer M.G., Ma Y.H. and Moser W.R., A kinetic study of N-heptane catalytic cracking over a commercial Y-type zeolite under supercritical and subcritical conditions, J. Catalysis 162, 327–338 (1996).
Suer M.G., Dardas Z., Ma Y.H. and Moser W.R., An in situ CIR-FTIR study of N-heptane cracking over a commercial Y-type zeolite under subcritical and supercritical conditions, J. Catalysis 162, 327–338 (1996).
Niu F.H. and Hofmann H., Investigation of coke extraction from zeolite HY under supercritical and near critical conditions, Canadian Journal of Chemical Engineering 75, 346–352 (1997).
Niu F.H. and Hofmann H., Studies on deactivation kinetics of a heterogeneous catalyst using a concentration controlled recycle reactor under supercritical conditions, Applied Catalysis A: General 158, 273–285 (1997).
Gao Y., Shi Y.-F., Zhu Z.-N. and Yuan W.-K., “Coking mechanism of zeolite for supercritical fluid alkylation of benzene”, in P.R. von Rohr and C. Trepp (Eds.), High Pressure Chemical Engineering (Process Technology Proceedings Vol. 12), Elsevier, pp. 151–156 (1996).
Dinjus E., Fornika R. and Scholz M., “Organic chemistry in supercritical fluids”, in R. van Eldik and C.D. Hubbard (Eds.), Chemistry Under Extreme or Non-Classical Conditions, J. Wiley, pp. 219–272 (1997).
Bochniak D.J. and Subramaniam B., Fischer-Tropsch synthesis in near-critical N-hexane: Pressure-tuning effects, AIChE J. 44, 1889–1896 (1998).
Hitzler M.G., Smail F.R., Ross S.K. and Poliakoff M., Selective catalytic hydrogenation of organic compounds in supercritical fluids as a continuous process, Organic Process Research & Development 2, 137–146 (1998).
Bertucco A., Canu P., Devetta L. and Zwahlen A.G., Catalytic hydrogenation in supercritical CO2: Kinetic measurements in a gradientless internal-recycle reactor, Ind. Eng. Chem. Res. 36, 2626–2633 (1997).
Ding Z.-Y., Aki S.N.V. and Abraham M.A., “Catalytic supercritical water oxidation. an approach for complete destruction of aromatic compounds”, in E. Kiran (Ed.), Innovations in Supercritical Fluids (ACS Symposium Series Vol. 608), ACS, pp. 232–256 (1995).
Ding Z.-Y., Frisch M.A., Li L. and Gloyna E.F., Catalytic oxidation in supercritical water, Ind. Eng. Chem. Res. 35, 3257–3279 (1996).
Prausnitz J.M., Lichtentaler R.N. and de Azevedo E.G., Molecular Thermodynamics of Fluid Phase Equilibria, Prentice Hall, 2nd Ed., pp. 171–183 (1986).
Luesby J., Chemicals: Smaller, cheaper and safer, Financial Times, 8th Sept. (1998).
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Manos, G. (1999). Heterogeneous Catalysis at Supercritical Conditions Using Microporous Materials. Environmental Advantages. In: Misaelides, P., Macášek, F., Pinnavaia, T.J., Colella, C. (eds) Natural Microporous Materials in Environmental Technology. NATO Science Series, vol 362. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-4499-5_19
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DOI: https://doi.org/10.1007/978-94-011-4499-5_19
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