Energy efficiency is a global priority. As fuel oxygenates, ethers (MTBE, ETBE) improve fuel combustion, minimizing the amount of energy that is wasted as unburned hydrocarbons and, hence, maximize efficiency.
Fuel oxygenates are an excellent source of clean octane–significantly higher than reformate, alkylate or toluene. As an octane source, ethers have the added benefit of avoiding the regulatory hurdles that other components (such as toluene and ethanol) face due to higher blend Reid vapor pressure (BRVP), higher aromatics content, higher water solubility and higher oxygen content. In other words, they maximize octane content subject to regulatory limits.
The nuanced view of octane, as detailed below, explains why ethers are the globally preferred oxygenate. It clarifies why ethers demand is expected to grow significantly, at roughly double the rate at which gasoline demand is expected to grow, over the following years. The following table below summarizes key blending properties of high octane components.
Ethers are a significantly better source of octane than reformates and alkylates. They are also a better source of octane than toluene, which is also facing increasingly strict regulatory hurdles through limits on aromatic content.
Compared to alcohols, ethers offer similar octane content. Ethanol, however, has a significantly higher blend Reid Vapor Pressure (BRVP) and significantly higher oxygen content than ethers. BRVP and oxygen content are typically regulated through maximum limits, which mean additional constraints for ethanol use. In addition, ethanol use entails water solubility concerns. In practical terms, this means that, unlike ethers and other fuel components, ethanol can only be blended into fuels in the final distribution phase. This translates into additional logistic hurdles, risks and costs for ethanol, when ethers and ethanol are compared as sources of octane.