Ethane to Aromatic Hydrocarbons: Past, Present, Future

Ranking high in the current challenges of catalysis, direct transformations of lower saturated hydrocarbons (alkanes) have been investigated for a long time. However, unsaturated hydrocarbons (e.g., aromatics and olefins) have always been the more important feedstocks to produce basic and intermediate chemicals because of their wide variety of possible reaction pathways. This article focuses on the conversion of one representative of lower alkanes—ethane, which is an important constituent of natural gas, accompanying gases and waste effluents of petrochemical processes—to aromatic compounds. Following general considerations on the aromatization of ethane, efficient modification methods of MFI-type zeolites to obtain active and selective catalysts will be presented. The nature of active sites, including the promoting effects of zinc, gallium, or noble metals, will be discussed. Single pathways in the reaction network from ethane toward aromatic hydrocarbons are explored based on experiments under steady-state and transient-state conditions. Finally, an outlook for possible transformations of the fundamental knowledge to full-scale industrial application will be given. A meandering ethane river flows beneath a line of bluffs on Titan. Methane fog blankets the lowlands beyond to the horizon. Attempts to glimpse Titan's surface from Earth-bound observatories and interplanetary probes have been thwarted by the thick hydrocarbon haze that covers the moon at all times. [1]