TG/DTG, FT-ICR Mass Spectrometry, and NMR Spectroscopy Study of Heavy Fuel Oil

详细信息    查看全文

• 作者：A. M. Elbaz ; Abdul Gani ; Nadim Hourani ; Abdul-Hamid Emwas ; S. Mani Sarathy ; W. L. Roberts
• 刊名：Energy & Fuels
• 出版年：2015
• 出版时间：December 17, 2015
• 年：2015
• 卷：29
• 期：12
• 页码：7825-7835
• 全文大小：567K
• ISSN：1520-5029

文摘

There is an increasing interest in the comprehensive study of heavy fuel oil (HFO) due to its growing use in furnaces, boilers, marines, and recently in gas turbines. In this work, the thermal combustion characteristics and chemical composition of HFO were investigated using a range of techniques. Thermogravimetric analysis (TGA) was conducted to study the nonisothermal HFO combustion behavior. Chemical characterization of HFO was accomplished using various standard methods in addition to direct infusion atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (APCI-FTICR MS), high resolution ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and two-dimensional heteronuclear multiple bond correlation (HMBC) spectroscopy. By analyzing thermogravimetry and differential thermogravimetry (TG/DTG) results, three different reaction regions were identified in the combustion of HFO with air, specifically, low temperature oxidation region (LTO), fuel deposition (FD), and high temperature oxidation (HTO) region. At the high end of the LTO region, a mass transfer resistance (skin effect) was evident. Kinetic analysis in LTO and HTO regions was conducted using two different kinetic models to calculate the apparent activation energy. In both models, HTO activation energies are higher than those for LTO. The FT-ICR MS technique resolved thousands of aromatic and sulfur containing compounds in the HFO sample and provided compositional details for individual molecules of three major class species. The major classes of compounds included species with one sulfur atom (S₁), with two sulfur atoms (S₂), and purely hydrocarbons (HC). The DBE (double bond equivalent) abundance plots established for S₁ and HC provided additional information on their distributions in the HFO sample. The ¹H NMR and ¹³C NMR results revealed that nearly 59% of the ¹H nuclei were distributed as paraffinic CH₂ and 5% were in aromatic groups. Nearly 21% of ¹³C nuclei were distributed in aromatic groups, indicating that most paraffinic CH₂ groups are attached to aromatic rings. A negligible amount of olefins was present, and an appreciable quantity of monoaromatic and polyaromatic content was observed. Molecular connectivity between the hydrogen and carbon atoms using HMBC spectra was utilized to propose several plausible skeletal structures in HFO.