This study conducted a comparative analysis of extractable hopanoid hydrocarbons and those released via stepwise pyrolysis of typical Eocene immature oil shales in China,namely the Huadian,Maoming,and Fushun shales.Bo...This study conducted a comparative analysis of extractable hopanoid hydrocarbons and those released via stepwise pyrolysis of typical Eocene immature oil shales in China,namely the Huadian,Maoming,and Fushun shales.Both the Huadian and Maoming shales exhibit immature indicators in extractable and kerogen-bound hopanoids(notably,high abundance of C_(29)to C_(32)17β,21β-hopanes and unsaturated hopenes).In contrast,the Fushun oil shale's hopanoids from extracts and pyrolyzates suggest a higher maturity level.The absence of neohopenes in the pyrolyzates of the shales underpins that the kerogenbound hopanoid skeletons resist rearrangement.However,the Huadian oil shale's asymmetric distribution of C_(29)and C_(30)hopenes and neohopenes hints at the presence of an additional source.Novel unsaturated hopenes,such as hop-20(21)-enes,identified in pyrolyzates of the three kerogens at various pyrolysis temperatures,reveal the occurrence of double bonds in kerogen-bound hopanoid skeletons without methyl rearrangements.The absence of hop-20-(21)-ene in extracts suggests that it might act as an intermediate of these novel hopenes during the epimerization of hopanoid skeletons within kerogen.The extractable and pyrolytic hopanoids'stereochemical alignment indicates that epimerization may occur in both ring systems and alkyl side chains of kerogen-bound hopanoid skeletons.Sequential stepwise pyrolysis proves to be a quick screening method for geological hopanoids without causing any significant alteration to the original skeletons even when cracking multiple covalent bonds is necessary.展开更多
In this study,alkali/acid treatment and ion exchange post-synthesis modification methods to modify the pore diameter and structure of molecular sieve 13X(MS13X)were applied to obtain products,which could then be imple...In this study,alkali/acid treatment and ion exchange post-synthesis modification methods to modify the pore diameter and structure of molecular sieve 13X(MS13X)were applied to obtain products,which could then be implemented to improve the enrichment recovery of hopanoids in petroleum.The modification products were analyzed by SEM with EDS,XRD and nitrogen physisorption.The results indicated that the product which had been prepared in the oxalic acid ethanol solution formed some mesopores,and also retained the initial framework of crystal.It was revealed that this product was able to remarkably increase the recovery rate of hopanoids in petroleum without leading to a significant isotope fractionation phenomenon.It is thus shown that this modification method of non-aqueous oxalic acid solution for MS13X can be used as an effective pretreatment tool in the application of compoundspecific isotope analysis of hopanes with low concentration.展开更多
基金funded by the Natural Science Foundation of China(No.42373028,No.42072154).
文摘This study conducted a comparative analysis of extractable hopanoid hydrocarbons and those released via stepwise pyrolysis of typical Eocene immature oil shales in China,namely the Huadian,Maoming,and Fushun shales.Both the Huadian and Maoming shales exhibit immature indicators in extractable and kerogen-bound hopanoids(notably,high abundance of C_(29)to C_(32)17β,21β-hopanes and unsaturated hopenes).In contrast,the Fushun oil shale's hopanoids from extracts and pyrolyzates suggest a higher maturity level.The absence of neohopenes in the pyrolyzates of the shales underpins that the kerogenbound hopanoid skeletons resist rearrangement.However,the Huadian oil shale's asymmetric distribution of C_(29)and C_(30)hopenes and neohopenes hints at the presence of an additional source.Novel unsaturated hopenes,such as hop-20(21)-enes,identified in pyrolyzates of the three kerogens at various pyrolysis temperatures,reveal the occurrence of double bonds in kerogen-bound hopanoid skeletons without methyl rearrangements.The absence of hop-20-(21)-ene in extracts suggests that it might act as an intermediate of these novel hopenes during the epimerization of hopanoid skeletons within kerogen.The extractable and pyrolytic hopanoids'stereochemical alignment indicates that epimerization may occur in both ring systems and alkyl side chains of kerogen-bound hopanoid skeletons.Sequential stepwise pyrolysis proves to be a quick screening method for geological hopanoids without causing any significant alteration to the original skeletons even when cracking multiple covalent bonds is necessary.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA14010101)the National Natural Science Foundation of China(NNSFC,Project No.41473020)PetroChina Science and Technology Projects(Grants 2019A-0208)for supporting this research project.
文摘In this study,alkali/acid treatment and ion exchange post-synthesis modification methods to modify the pore diameter and structure of molecular sieve 13X(MS13X)were applied to obtain products,which could then be implemented to improve the enrichment recovery of hopanoids in petroleum.The modification products were analyzed by SEM with EDS,XRD and nitrogen physisorption.The results indicated that the product which had been prepared in the oxalic acid ethanol solution formed some mesopores,and also retained the initial framework of crystal.It was revealed that this product was able to remarkably increase the recovery rate of hopanoids in petroleum without leading to a significant isotope fractionation phenomenon.It is thus shown that this modification method of non-aqueous oxalic acid solution for MS13X can be used as an effective pretreatment tool in the application of compoundspecific isotope analysis of hopanes with low concentration.
