High-Temperature Synthesis of Aromatic Hydrocarbons from Methane

Arenes of 1, 2, 3, 4 and more rings have been synthesized in a flow system by passing methane through silica gel at 1000°C. Yields of 4.8 to 7.2 percent have been obtained per single pass. As determined by combined gas chromatography-mass spectrometry, the major compound synthesized that are of less than S rings are benzene, naphthalene, acenaphthylene, phenanthrene, fluoranthene, and pyrene. Under certain conditions ( presence of ammonia and water), small amounts of aliphatic hydrocarbons are also synthesized. Even-carbon-numbered hydrocarbons (aromatic as well as aliphatic) predominate, to the extent that about 97 percent of the total weight of the analyzed arenes have even numbers of carbon atoms.