Mechanisms in the reaction between olefins and alcohols catalyzed by ion exchange resins

Graphical abstract Highlights Model averaging provides the kinetic model taking into account model uncertainty  ETBE is formed faster than TAEE in the simultaneous etherification  Reactions mechanism is deduced from the proposed kinetic model  Active sites are mainly occupied by adsorbed ethanol, ETBE and TAEE  Two active sites participate in etherification reactions, and one in isomerization AbstractA kinetic study on the simultaneous liquid-phase etherification of ethanol with isobutene (IB), 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B) catalyzed by Amberlyst™ 35 to form ethyl tert-butyl ether (ETBE) and tert-amyl ethyl ether (TAEE) is presented. Isothermal experimental runs were carried out in a stirred tank batch reactor in the temperature range 323-353 K at 2.0 MPa, starting from different initial concentrations. Obtained reaction rates were free of catalyst load, internal, and external mass transfer effects. Mathematical fitting of a series 2 of systematically originated models, model selection, and model averaging procedures were applied to find the best model and to draw conclusions about the reaction mechanism. The selected model involves a saturated catalytic surface with the participation of two active sites in etherification reactions and one active site in isoamylenes isomerization. Apparent activation energies for ETBE formation from IB and EtOH, TAEE formation from 2M1B and EtOH, TAEE formation from 2M2B and EtOH, and double bond isomerization between 2M1B and 2M2B were 72.8±1.4, 74.9±2.8, 81.2±2.2 and, 76.5±7.2 kJ/mol, respectively. The alkenes with the double bond in terminal position were more reactive towards EtOH than 2M2B, with the double bond in internal position.

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“…As it can be seen, the lower the temperature, the lower the etherification rates obtained, as expected [29,30]. …”

Section: Experimental Reaction Ratessupporting

confidence: 76%

Kinetic modeling of the simultaneous etherification of ethanol with C4 and C5 olefins over Amberlyst™ 35 using model averaging

Fité

Ramírez

Bringué

et al. 2017

Chemical Engineering Journal

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“…At a fixed concentration of isobutene, the rate of MTBE production rose with the methanol concentration, but, after this concentration reached that of the isobutene, the rate became constant (Figure 4b). This behavior is distinctly different from that observed for Amberlyst 15 resin (Ancillotti et al, 1978;Gicquel and Torck, 1983), where the rate increased rapidly until the methanol concentration was about one tenth of that of the isobutene. At higher methanol concentrations, the rate decreased rapidly until, with an excess of methanol, it became independent of methanol concentration (Ancillotti et al, 1978).…”

Section: Reactions In Sealed Vessels (Meoh + Isobutene)mentioning

confidence: 44%

“…This behavior is distinctly different from that observed for Amberlyst 15 resin (Ancillotti et al, 1978;Gicquel and Torck, 1983), where the rate increased rapidly until the methanol concentration was about one tenth of that of the isobutene. At higher methanol concentrations, the rate decreased rapidly until, with an excess of methanol, it became independent of methanol concentration (Ancillotti et al, 1978). In the present work, it was Effect on the rate of reaction of variation in concentration of methanol at 70"C. 0.1 g of AP § catalyst was used with 2.5 mmole isobutene and 0.5-10 mmole methanol Total volume was kept constant; ~ 3 cm 3 of 1,4-dioxan was used as solvent.…”

Section: Reactions In Sealed Vessels (Meoh + Isobutene)mentioning

confidence: 44%

“…With excess methanol, the rate was directly proportional to the isobutene concentration (Figure 4a) as has been found for resin-catalyzed reactions (Ancillotti et al, 1978;Gicquel and Torck, 1983). At a fixed concentration of isobutene, the rate of MTBE production rose with the methanol concentration, but, after this concentration reached that of the isobutene, the rate became constant (Figure 4b).…”

Section: Reactions In Sealed Vessels (Meoh + Isobutene)mentioning

confidence: 60%

“…Ancillotti et al (1977Ancillotti et al ( , 1978 and Gicquel and Torck (1983) showed that at methanol:isobutene ratios reasonably close to unity the pore spaces of Ambeflyst 15 resin are filled with methanol, which acts as the solvent at the reaction site in the formation of MTBE. The methanol molecules pick up protons from the resin and become the catalytic agents.…”

Section: Meoh + Ch2=c(c[--i3)2 --* Me-o--(2(ch3)3mentioning

confidence: 99%

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Methyl t-Butyl Ether (MTBE) Production: A Comparison of Montmorillonite-Derived Catalysts with an Ion-Exchange Resin

Adams

1986

Clays and clay miner.

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Abstract--Montmorillonite-based catalysts were compared with an acidic ion-exchange resin of the type used industrially for the production of methyl t-butyl ether (MTBE) from methanol and isobutene or t-butanol. When 1,4-dioxan was used as solvent, Al3+-exchanged montmorillonites had about half the efficiency of the resin Arnberlyst 15 at 60~ they were, however, about twice as efficient at this temperature at Ti3+-montmorillonite or K10, a commercially available acid-treated bentonite. Montmorillonite exchanged with Chlorhydrol solutions to give interlayer [AI1304(OH)2(H20)12] 7+ ions and pillared clays derived from such materials were poor catalysts, as was K306, a more drastically acid-treated bentonitebased commercial catalyst. Freeze-drying of the AP+-day before reaction to produce a more open, porous structure had no effect on its catalytic efficiency. The activation energy for the reaction of isobutene and methanol in dioxan was 44 El/mole for an AP+-clay catalyst compared with 25 kJ/mole for reactions catalyzed by Ambedyst 15. With no solvent (as in industrial processes), the rates of reaction were considerably slower for both the clay-and resin-catalyzed reactions. As has been found previously for resin-catalyzed reactions using stoichiometric amounts or an excess of methanol, the rate was proportional to the isobutene concentration, and the rate-determining step appeared to be protonation of the alkene. The performance of the AP+-clay catalyst was increased by reducing the water content of the clay. In most reactions the clay catalysts were equilibrated at 12% relative humidity. Exposure of the clay to a low vacuum (10-1 ton-) before use increased its catalytic activity from 50 to 60% of that of Amberlyst 15.

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Etherification rates of 2-methyl-2-butene and 2-methyl-1-butene with ethanol for environmentally clean gasoline production

Oktar

Mürtezaoğlu

Doğu

et al. 1999

J. Chem. Technol. Biotechnol.

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: Etheriücation of reactive oleüns available in light ýuidized catalytic cracking (FCC) gas-C 5 oline is an attractive way to decrease the oleüns and to increase the octane number. The reactivities of 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B) in the etheriücation reaction with ethanol catalysed by a strongly acidic macroreticular resin catalyst were investigated in a temperature range of 333-360 K using a liquid phase diþ erential ýow reactor. In the presence of excess alcohol, the apparent reaction orders of etheriücation reactions of isoamylenes were found to be 0.93 and 0.69 with respect to 2M1B and 2M2B concentrations, respectively. 2M1B was shown to be more reactive than 2M2B and its activation energy is also lower in the etheriücation reaction. It was also shown that diþ usion resistances, especially in the macropores of the catalyst, may play an important role on the observed rates.

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Mechanisms in the reaction between olefins and alcohols catalyzed by ion exchange resins

Cited by 106 publications

References 8 publications

Kinetic modeling of the simultaneous etherification of ethanol with C4 and C5 olefins over Amberlyst™ 35 using model averaging

Kinetic modeling of the simultaneous etherification of ethanol with C4 and C5 olefins over Amberlyst™ 35 using model averaging

Methyl t-Butyl Ether (MTBE) Production: A Comparison of Montmorillonite-Derived Catalysts with an Ion-Exchange Resin

Etherification rates of 2-methyl-2-butene and 2-methyl-1-butene with ethanol for environmentally clean gasoline production

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