Heterpolyacid catalysts for etherification of isoolefins

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2003

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Obalı, Zeynep

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Due to the water pollution problems created by MTBE, significant research was focused on the production of alternative oxygenates, such as ethyl tert-butyl ether (ETBE), tert-amyl-methyl-ether (TAME) and tert-amyl-ethyl-ether (TAEE) as octane enhancing gasoline blending components. These oxygenates are expected to improve the burning characteristics of gasoline and reduce exhaust emissions of CO and hydrocarbons. Generally, macroreticular acidic resin catalysts (Amberlyst-15) are used for the etherification reactions between C5 iso-olefins (2M1B/2M2B) and alcohols (ethanol/methanol). But in recent years, heteropoly acid compounds are being used in the production of tert-ethers to replace those macroreticular acidic resin catalysts. HPAs are known to be active catalysts for many of homogeneous and heterogeneous acid catalyzed reactions.These compounds have high acidity, high catalytic activity but they are highly soluble in polar solvents such as water,alcohol when they are used in bulk form. In this research, applicability of bulk heteropoly acid (HPA) and its supported form, to the gas-phase etherification reaction of iso-olefin (2-methyl- 2-butene) with ethyl alcohol in a continuous differential reactor was investigated. The heteropoly acid (H3PW12O40.xH2O) was supported on activated carbon, at two different loading levels, by aqueous impregnation technique. After catalyst characterization, kinetic experiments were done in a temperature range between 80°C-97°C with a feed concentration of 30 vol.%2M2B+70 vol.% ethanol. Supported HPA catalysts yielded lower conversion and rate of reaction than the bulk HPA. After that, to make a comparison, same experiments have been carried out with Amberlyst-15 and a different HPA (H3PMo12O40.xH2O) at 90oC. The results showed that, at this temperature, bulk tungstophosphoric acid (H3PW12O40.xH2O) was highly active among the other

Subject Keywords

Octane enhancer, 2M2B, Ethanol, TAEE, Catalyst, Heteropoly acid, Activated carbon, Impregnation technique, Supported heteropoly acid

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http://etd.lib.metu.edu.tr/upload/1134923/index.pdf
https://hdl.handle.net/11511/13511

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

Z. Obalı, “Heterpolyacid catalysts for etherification of isoolefins,” M.S. - Master of Science, Middle East Technical University, 2003.