SYNTHESIS OF METHYL TERT-BUTYL ETHER CATALYZED BY ACIDIC ION-EXCHANGERESINS - INFLUENCE OF THE PROTON ACTIVITY

The catalytic activity of various strong acid ion-exchange resins on t he synthesis of methyl tert-butyl ether (MtBE) from methanol and isobu tene has been investigated. Relative to Amberlyst 15, Kastel CS 381 an d Amberlyst CSP have similar rate constants, whereas Duolite ES 276 an d Amberlyst XE 307 have significantly higher and Duolite C26 and Duoli te C16P substantially lower rate constants. All resins show a great de crease in catalytic activity if part of the protons is exchanged by so dium ions. At 10% proton capacity the rate constants per equivalent ac id are reduced by a factor of 9 (for Amberlyst XE 307 and Kastel CS 38 1) to more than a factor 20 for Amberlyst 15 and Duolite ES 276, resul ting in 100-200 times lower MtBE production rates. Depending on the ca talyst applied, mass transfer limitations start to occur between 50 an d 80 degrees C. Values of the effective diffusion coefficient of isobu tene varied between 0.4 x 10(-9) and 4.1 x 10(-9) m(2) s(-1) at 80 deg rees C.