tert-Butyl Ethers of Renewable Diols as Oxygenated Additives for Motor Gasoline. Part I: Glycerol and Propylene Glycol Ethers

The study investigates tert- butoxy alkanols (otherwise defined as polyol tert- butyl ethers) that have vicinal tert- butoxy and hydroxy groups in their molecules from the perspective of their usability as oxygenated additives for motor gasoline. A series of propylene glycol mono- tert- butyl ether (PTBE) and glycerol di- tert- butyl ether (di-GTBE) samples were prepared: PTBE by direct acid-catalytic alkylation of diols with tert- butanol, and di-GTBE by alkylation of epichlorohydrin. Adding PTBE and di-GTBE to base motor gasoline was found to improve its antiknock performance: the average blending research octane number to blending motor octane number ratios (bRON/bMON) equaled 120/111 and 124/104 for PTBE and di-GTBE, respectively. Furthermore, the effects of the ether additives on the properties of ethanol-blended base gasoline were characterized. Finally, the study describes the effect of polyol tert- butyl ether additives on the cloud point depression of ethanol-blended gasoline (low-temperature phase stabilization) and demonstrates a positive synergistic effect of adding the ethers mixed with ethanol.