The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Etherification of Some C8-Alkenes to Fuel Ethers

Reetta Karinen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Komppa Auditorium at Helsinki University of Technology (Espoo, Finland) on the 17th of May, 2002, at 12 noon.

Overview in PDF format (ISBN 951-22-5905-2)   [166 KB]
Dissertation is also available in print (ISBN 951-22-5926-5)

Abstract

Tertiary ethers are formed in a reaction between alcohols and alkenes. They are used in gasoline to enhance its burning and to reduce harmful exhaust emissions. They also have high octane rating, which is beneficial for gasoline blending. Regulations in regard to fuel composition and exhaust emissions are tightening and new, cleaner burning high octane gasoline components are of wide interest.

This work concerns the etherification of C8-alkenes. Several C8-alkenes were screened for their reactivity. Study of the properties of the resulting ethers showed that some of them are potential for gasoline blending. 2,4,4-Trimethyl pentenes were chosen for more detailed study in view of the availability of the feed stock in industrial scale and the promising properties of the resulting ether.

The reactivity of 2,4,4-trimethyl pentenes was tested with various alcohols. The marked effect of the alcohol on the reaction rate was attributed primarily to the polarity of the alcohol, which affects the adsorption of the components and the catalyst.

Compared with the ethers currently in commercial production, the C8-alkenes are etherified rather slowly. A new catalyst was sought to enhance the reaction rate. Traditionally, etherification is catalysed by strong cation exchange resin beads, such as Amberlyst resins, but a novel fibrous Smopex-101 catalyst was found to be more active in the etherification of 2,4,4-trimethyl pentenes with methanol, evidently because diffusional limitations were less.

A kinetic model was developed for the etherification of 2,4,4-trimethyl pentenes with methanol for purposes of reactor design. Kinetic experiments were performed with Smopex-101 as catalyst. Before the kinetic studies, thermodynamic parameters were derived for the etherification reactions and for the isomerisation reaction between 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene.

The results of the kinetic modelling indicated that the adsorption of the alkenes was minor. The best models to describe the data were the Langmuir-Hinshelwood type model where the adsorption of alkenes is assumed to be negligible compared to other reactive components and the Eley-Rideal type model where alkenes are not adsorbed. Adsorption behaviour was different on the fibrous catalyst than on the ion exchange resins: ether was better adsorbed than alcohol on the fibrous catalyst, whereas alcohol is known to better adsorb than ether on the traditional ion exchange resin catalyst. The better adsorption of ether on the fibrous catalyst was attributed to the greater hydrophobicity of this catalyst.

This thesis consists of an overview and of the following 7 publications:

  1. R. S. Karinen, A. O. I. Krause, Reactivity of some C8-olefins in etherification with methanol, Appl. Catal. A 188 (1999) 249-256.
  2. R. S. Karinen, A. O. I. Krause, E. Y. O. Tikkanen, T. T. Pakkanen, Catalytic synthesis of a novel tertiary ether, 3-methoxy-3-methyl heptane from 1-butene, J. Mol. Catal. A. 152 (2000) No 1-2, 253-255.
  3. R. S. Karinen, A. O. I. Krause, A novel tertiary ether. Synthesis of 3-methoxy-3-methyl heptane from 2-ethyl-1-hexene and methanol, Catal. Lett. 67 (2000) 73-79.
  4. R. S. Karinen, A. O. I. Krause, K. Ekman, M. Sundell, R. Peltonen, Etherification over a novel acid catalyst, Stud. Surf. Sci. Catal. 130 (2000) 3411-3416.
  5. R. S. Karinen, M. S. Lylykangas, A. O. I. Krause, Reaction equilibrium of the isomerisation of 2,4,4-trimethyl pentenes, Ind. Eng. Chem. Res. 40 (2001) 1011-1015. © 2001 American Chemical Society. By permission.
  6. R. S. Karinen, J. A. Linnekoski, A. O. I. Krause, Etherification of C5- and C8-alkenes with C1- to C4-alcohols, Catal. Lett. 76 (2001) 81-87.
  7. R. S. Karinen, A. O. I. Krause, Kinetic model for the etherification of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene with methanol, Ind. Eng. Chem. Res. 40 (2001) 6073-6080. © 2001 American Chemical Society. By permission.

Keywords: etherification, 2,4,4-trimethyl pentenes, C8-alkenes, 2-methoxy-2,4,4-trimethyl pentane

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© 2002 Helsinki University of Technology

Last update 2011-05-26