Raman spectroscopic characterization of cracking and hydrolysis of n-pentane and n-octadecane at 300–375℃ with geological implications

Abstract

Hydrous and anhydrous isothermal experiments on n-pentane and n-octadecane were conducted at 300-375 C for durations up to 1094 h to evaluate the cracking and hydrolysis of hydrocarbons, using fused silica capillary capsules as micro-reactors. The chemical compositions of the gaseous products during cracking of n-octadecane at 350 and 375 C were methane, ethane, propane, and n-butane. The aqueous product in the hydrolysis of n-pentane and n-octadecane at 300-375 C was alcohol. Alkenes and hydrogen were not detected throughout all the isothermal experiments. Results showed that the gaseous yields were characterized by higher contents of wet gas than those in natural gas accumulations. Mechanisms regulating the enrichment of methane in reservoirs should be further studied. The hydrolysis and oxidation of hydrocarbon were relatively limited in the absence of iron-bearing mineral buffers, suggesting that hydrocarbons might be more stable in iron-poor reservoirs (e.g. carbonate and quartz arenite) than in iron-bearing-mineral-rich ones (e.g. mudstone and arkose) under deep burial conditions. The absence of hydrogen was ascribed to its high diffusion rate in fused silica than in gold tube; any hydrogen produced in the reaction tends to diffuse out of the fused silica capsule with no or limited hydrogen accumulation, similar to those in geological environment.

A Series of Primary Alkylamine Borane Adducts CxH2x+1NH2BH3: Synthesis and Properties

“…The gas released over this temperature range for C8AB was analyzed by μGC/MS. The MS results are not reported, but we can mention that, like for alkanes, [49][50][51][52] a number of cracking products (saturated and unsaturated C 1 to C 7 hydrocarbons) were detected above 250°C.…”

Carbon and hydrogen isotope fractionation for methane from non-isothermal pyrolysis of oil in anhydrous and hydrothermal conditions

“…The increase in the yields of H 2 and CO 2 in hydrothermal conditions should be attributed to the water–hydrocarbon reactions (Lewan, 1997; Seewald, 2003). These results demonstrate that water should provide O and H for gas generation in our pyrolysis (He et al., 2018a; Leif and Simoneit, 2000; Seewald, 2003; Wang et al., 2017).…”

“…Water was suggested to affect and even participate in the petroleum generation from organic matters (Helgeson et al, 1993;Lewan et al, 1979;Lewan, 1997;Seewald, 2003, Seewald et al, 2000. Till now, numerous hydrous or hydrothermal experiments have been conducted to understand the effects of water on oil and gas generation (Behar et al, 2003;Gao et al, 2014;He et al, 2018a;Lewan et al, 1979;Lewan, 1997;Lewan and Roy, 2011;Pan et al, 2009;Wang et al, 2017). These works observed that water can provide hydrogen and oxygen for hydrocarbon generation, and alter the features of individual products as well as acting as a medium for petroleum expulsion from source rocks (Hoering, 1984;Lewan, 1997;Schimmelmann et al, 2001).…”

Special Issue: Advances of petroleum exploration and geology research in West China's petroliferous basins

“…Therefore, with increasing burial depth, gypsum-bearing rocks and limestone are preserved, whereas dolomite is more rapidly dissolved. Wang et al (2018) conduct hydrous and anhydrous isothermal experiments on n-pentanes and n-octadecanes to evaluate the cracking and hydrolysis of hydrocarbons. Gases produced during cracking of n-octadecane at 350 C and 375 C contain methane, ethane, propane, and n-butane.…”