Chemical Speciation of Calcium and Sodium Naphthenate Deposits by Electrospray Ionization FT-ICR Mass Spectrometry

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• 作者：Mmilili M. Mapolelo ; Lateefah A. Stanford ; Ryan P. Rodgers ; Andrew T. Yen ; Justin D. Debord ; Sam Asomaning ; Alan G. Marshall
• 刊名：Energy & Fuels
• 出版年：2009
• 出版时间：January 22, 2009
• 年：2009
• 卷：23
• 期：1
• 页码：349-355
• 全文大小：305K
• 年卷期：v.23,no.1(January 22, 2009)
• ISSN：1520-5029

文摘

Calcium and sodium naphthenates are solid deposits and emulsions formed by the interaction of naphthenic acids with divalent (Ca²⁺, Mg²⁺) or monovalent (Na⁺, K⁺) ions in produced waters. Calcium naphthenate formation, an interfacial phenomenon, is thought to depend largely on tetraprotic naphthenic acids known as “ARN” acids (∼C₈₀) in the crude oil, whereas sodium naphthenates originate from lower molecular weight (C₁₅ to C₃₅) monoprotic naphthenic acids. Here we present detailed chemical heteroatom class composition analyses of calcium and sodium naphthenates from the field based on high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In all cases, calcium naphthenate deposits consist predominately of tetraprotic acids with a C₈₀ hydrocarbon skeleton whereas sodium naphthenate emulsions consist mainly of specific monoprotic saturated carboxylic acids. Furthermore, low molecular weight tetraprotic (ARN) acids with C₆₀₋₇₇ hydrocarbon skeletons were identified in the calcium naphthenate deposit. The high resolution and mass accuracy of FT-ICR MS provide detailed acidic speciation for the analyzed deposits and emulsions.