Tert‐Butyl Ethers ‐ A Comparison of Properties, Synthesis Techniques and Operating Conditions for High Conversions

Abstract

Methyl tert‐butyl ether (MTBE) is currently the industrially dominant ether oxygenate although ethyl tert‐butyl ether (ETBE) is growing in importance as an alternative. ETBE has superior oxygenate properties (lower RVP and higher octane) and can be made from renewable ethanol. The ETBE reaction system is thermodynamically more restrictive than MTBE and the increased relative volatility of the ethanol‐isobutylene system compared with the methanol‐isobutylene system makes operation of a reactive distillation column more difficult. In this paper, the advantages of reactive distillation for tertiary ether production are discussed. Twenty different reactive distillation column configurations are identified with different designs being preferred for ETBE and MTBE. The effects of eight key operating criteria in reactive distillation systems are briefly discussed. Finally, reactive distillation systems producing MTBE and ETBE are simulated using Pro/II ver 4.0 to demonstrate that high conversions are possible for both products with relatively simple equipment.