Kerogen Chemistry 2. Low-Temperature Anhydride Formation in Kerogens
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- 作者：John W. Larsen ; Carlos Islas-Flores ; Michael T. Aida ; Pakorn Opaprakasit ; and Paul Painter
- 刊名：Energy & Fuels
- 出版年：2005
- 出版时间：January 2005
- 年：2005
- 卷：19
- 期：1
- 页码：145 - 151
- 全文大小：167K
- 年卷期：v.19,no.1(January 2005)
- ISSN：1520-5029
文摘
Bakken kerogens react rapidly when heated at temperatures of 40-180 
C to form carboxylicacid anhydrides and water from carboxylic acids. Differential scanning calorimetry (DSC) showsa pronounced irreversible endotherm over this temperature range, demonstrating the occurrenceof an endothermic chemical reaction. The fact that this reaction is the formation of an acidanhydride was demonstrated using Fourier transform infrared (FTIR) spectroscopy. The amountof anhydride formed can be estimated by measuring the enthalpy of the process using DSC.Approximately 20% of the anhydride is hydrolyzed when the reacted kerogen has been allowedto stand in air at room temperature for three weeks, demonstrating that water has accesspredominantly to the kerogen surface during this time. Exposure of the kerogen to water vaporat 150 C for 48 h results in complete anhydride hydrolysis. Swelling the kerogen with 95 vol%tetrahydrofuran (THF)-5 vol% water also results in only partial hydrolysis of the anhydride;however, exposure to 50% aqueous THF results in complete anhydride hydrolysis. The extent ofanhydride formation decreases as maturation increases. Anhydride formation has been observedwith 13 of 14 kerogens that have been studied and is widespread. It occurs when either theisolated kerogen or the source rock are heated. The carboxylic acid groups must be adjacent toeach other to enable such a fast reaction to occur in a glassy solid where diffusion is stronglylimited. This suggests the existence of molecular-level heterogeneity in kerogens.
C to form carboxylicacid anhydrides and water from carboxylic acids. Differential scanning calorimetry (DSC) showsa pronounced irreversible endotherm over this temperature range, demonstrating the occurrenceof an endothermic chemical reaction. The fact that this reaction is the formation of an acidanhydride was demonstrated using Fourier transform infrared (FTIR) spectroscopy. The amountof anhydride formed can be estimated by measuring the enthalpy of the process using DSC.Approximately 20% of the anhydride is hydrolyzed when the reacted kerogen has been allowedto stand in air at room temperature for three weeks, demonstrating that water has accesspredominantly to the kerogen surface during this time. Exposure of the kerogen to water vaporat 150 C for 48 h results in complete anhydride hydrolysis. Swelling the kerogen with 95 vol%tetrahydrofuran (THF)-5 vol% water also results in only partial hydrolysis of the anhydride;however, exposure to 50% aqueous THF results in complete anhydride hydrolysis. The extent ofanhydride formation decreases as maturation increases. Anhydride formation has been observedwith 13 of 14 kerogens that have been studied and is widespread. It occurs when either theisolated kerogen or the source rock are heated. The carboxylic acid groups must be adjacent toeach other to enable such a fast reaction to occur in a glassy solid where diffusion is stronglylimited. This suggests the existence of molecular-level heterogeneity in kerogens.