The origin of light hydrocarbons

The light hydrocarbons (LHs) are probably intermediates in the catalytic decomposition of oil to gas: Oil --> LHs --> Gas Two lines of evidence support this possibility. First, the reaction was duplicated experimentally under moderate conditions. Second, natural LHs exhibit the characteristics of catalytic products, in particular a proportionality between isomers: (xy(i))/(x(i)y) = alpha (where x and x(i) are isomers; y and y(i) are isomers that are structurally similar to x and x(i); and a is a constant). All oils exhibit this relationship with coefficients of correlation reaching 0.99. Isomer ratios change systematically with concentrations, some approaching thermodynamic equilibrium, others not. The correlations reported are the strongest yet disclosed for the LHs. Isomers are related in triads (e.g., n-hexane <----> 2-methylpentane <----> 3-methylpentane), consistent with cyclopropane precursors. The LHs obtained experimentally are indistinguishable from natural LHs in (xy(i))/(x(i)y). These relationships are not explained by physical fractionations, equilibrium control, or noncatalytic modes of origin. A catalytic origin, on the other hand, has precedence, economy and experimental support. Copyright (C) 2000 Elsevier Science Ltd.