2 research outputs found
Proton Nuclear Magnetic Resonance (1H-NMR) Methodology for Monolefin Analysis:Application to Aquaprocessing-Upgraded Bitumen
Olefins are problematic components of petroleum products responsible for gum formation, polymers, and solid deposition in oil facilities. This work presents a methodology developed for monolefin analysis of whole oils, diluted bitumen, and partially upgraded heavy oils. A proton nuclear magnetic resonance (1H-NMR) technique calibrated with naphtha fractions of known monolefin contents is proposed. Internal standard addition (IS, dioxane) makes the method independent of the sample C/H atomic ratios (i.e., paraffin/aromatic hydrocarbon ratios). The developed method was applied for monolefin determination of partially upgraded whole bitumen processed under mild catalytic steam cracking (CSC) conditions and is also identified as aquaprocessing (AQP). Large viscosity reductions for AQP-upgraded products (up to 99%) were determined with associated monolefin contents <1.2 wt %
Characterization of Acid-Soluble Oxidized Asphaltenes by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Insights on Oxycracking Processes and Asphaltene Structural Features
The dissolution of organic matter
into water via oxidative processes,
named oxycracking, has been practiced for a long time for the removal
of organic pollutants, in which oxygen induces breakage and functionalization
of organic molecules. Recently, oxycracking has been explored as an
alternative approach to handling the increased amount of solid residues
produced in oil sands upgrading activities that involve carbon rejection
in solvent deasphalting units. This study uses an asphaltene-rich
feedstock, operationally known as petroleum pitch, isolated from an
Athabasca bitumen vacuum residue, which was submitted to oxycracking
reactions at 200 and 220 Ā°C. The feed and water-soluble fractions
isolated at pH 1, termed acid-soluble oxidized asphaltenes (ASOA),
were analyzed by ultrahigh-resolution mass spectrometry [Fourier transform
ion cyclotron resonance mass spectrometry (FTICR-MS)] using electrospray
and atmospheric pressure photoionization ion sources. FTICR-MS analysis
revealed extensive oxidation of all compound classes originally present
in the asphaltene-rich feed. Double bond equivalent (DBE) distribution
plots show that sequential carboxylation (formation of a carboxyl
group) occurs progressively with an increasing reaction temperature,
leading to the incorporation of up to 15 oxygen atoms per molecule,
whereas simultaneous decarboxylation reactions produce a CO<sub>2</sub>-rich gas phase. ASOA samples also show lower overall carbon number
distributions than the asphaltene feed, which is direct evidence of
CāC bond cleavage during the oxycracking process. In addition,
molecular fragments detected in ASOA after carbonācarbon bond
cleavages showed not only lower carbon numbers but also lower DBEs
per molecule, consistent with a more dominant archipelago architecture
for the parent asphaltene molecules