For remote small-/medium-sized natural gas fields, transport via pipeline or liquefied natural gas is often not possible. Instead of flaring such natural gas (NG) and, thus, causing unwanted emissions, alternative technologies, which avoid the costly transformation to synthesis gas, could convert NG into valuable, easy-to-transport liquids.

One approach to this issue is the conversion of methane, the main component of NG, via dehydroaromatization to benzene, which subsequently can be converted with the residual components of NG, ethane and propane, to alkylaromatics via dehydroalkylation (Scheme 1). The use of alkanes as alkylating agents for aromatic alkylation has been studied before, hereby using either ethane or propane to alkylate benzene or toluene.

In contrast, this contribution focuses on the dehydroalkylation of benzene with mixtures of ethane and propane for the production of superior fuel components, i.e., with the aim to maximize octane numbers (Scheme 2).

—Hussin and Traa

The dehydroalkylation reaction was conducted over a Pt−H-MFI catalyst at temperatures between 300 and 400 °C and a pressure of 6 bar. Three reaction cycles were conducted with intermittent regeneration with hydrogen to remove coke deposits.

The research octane number of the received liquid fraction was calculated as a measure of quality of the produced alkylaromatic fuel components. The research octane number of the liquid fraction could be increased from 99 to at least 103 via dehydroalkylation with a mixture of cheap and abundant alkanes from natural gas, they found.

Resources

• Dennis Wan Hussin and Yvonne Traa (2014) “Production of High-Octane Fuel Components by Dehydroalkylation of Benzene with Mixtures of Ethane and Propane,” Energy & Fuels 28 (5), 3352-3356 doi: 10.1021/ef500333b