Armando T. Quitain, Shunsaku Katoh and Motonobu Goto

Additional information is available at the end of the chapter http://dx. doi. org/10.5772/52539

1. Introduction

Recent concerns about climate change and problems associated with the use of fossil-de­rived fuels and nuclear energy have inspired researchers to seriously explore environmen­tally benign and economically viable renewable energy and fuels. As potential solution to reduce fossil-derived carbon dioxide (CO2) emissions from gasoline-run automobiles, addi­tion of biomass-derived oxygenates was proposed. Bioethanol has been considered, howev­er, ether oxygenates such as ethyl tert-butyl ether (hereby referred to as ETBE), has gained popularity over ethanol (EtOH) due to its superior properties which blend well with gaso­line [1]. ETBE also outranks MTBE as an octane enhancer due to its low blending Reid vapor pressure. Moreover, ETBE is a better option because it is derived from EtOH which can be obtained from biomass. ETBE is produced from the reaction of isobutene (IB) and EtOH, however, the current supply of IB, which is mostly derived from non-renewable crude oil, may not be sufficient to cope up with the expected high demand in the future. For this rea­son, alternative routes for its synthesis are also currently being explored. tert-Butyl alcohol (TBA), which can also be derived from biomass can be employed instead of IB [2]. Research for the development of efficient and energy-saving methods for the production of these gas­oline oxygenates had gained significant momentum over the past few years. The application of microwave technology was proposed for the synthesis of the above mentioned gasoline oxygenate.

Microwave technology relies on the use of electromagnetic waves to generate heat by the os­cillation of molecules upon microwave absorption. Unlike the conventional heating, the heat is generated within the material, thus rapid heating occurs. Other than the advantages of rapid heating, microwave effects on reaction likely occur, thus obtaining dramatic increase

in the yield even at low temperatures. The benefits of using microwave irradiation to the synthesis of the abovementioned biofuels include energy efficiency, development of a com­pact process, rapid heating and instant on-off process (instant heating-cooling process), among others.

In this chapter, syntheses of ether oxygenates by microwave irradiation will be discussed and summarized, focusing on our recent studies on microwave-assisted heterogeneously catalyzed processes.