Science. 1991 Apr 5;252(5002):109-12. doi: 10.1126/science.252.5002.109.
The carbon in ancient carbonaceous chondritic meteorites is mainly in a hydrocarbon composite similar to terrestrial kerogen, a cross-linked structure of aliphatic and aromatic hydrocarbons. Until recently, the composite has been commonly thought to have been produced in the early solar nebula by a Fischer-Tropsch-type process, involving the catalytic synthesis of hydrocarbons from carbon monoxide and hydrogen on grain surfaces. Instead, the aromatic hydrocarbons may form in gas-phase pyrolysis of simple aliphatics like acetylene and methane by a mechanism developed recently to explain formation of soot in combustion and of aromatic molecules in circumstellar envelopes. Nonequilibrium chemical kinetic calculations indicate that this mechanism can produce meteoritic aromatics if the initial concentration of simple hydrocarbons in the solar nebula was sufficiently but not unreasonably high.
古碳质球粒陨石中的碳主要以类似于陆地干酪根的烃类复合物形式存在，这是一种脂肪族和芳香族烃的交联结构。直到最近，人们普遍认为这种复合物是通过费歇尔-托普希型（Fischer-Tropsch-type）过程在早期太阳星云中产生的，涉及到在颗粒表面上催化合成一氧化碳和氢气的碳氢化合物。相反，芳香族烃可能是通过最近提出的一种机制在简单脂肪族如乙炔和甲烷的气相热解中形成的，这种机制用于解释燃烧过程中烟灰的形成和星际包层中芳香分子的形成。非平衡化学动力学计算表明，如果太阳星云中简单碳氢化合物的初始浓度足够高但并非高得离谱，那么这种机制可以产生陨石中的芳香族化合物。
