NMR characterization of hydrocarbon adsorption on calcite surfaces: A first principles study

Journal Article · Fri Nov 28 00:00:00 EST 2014 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4902251· OSTI ID:22413251

Bevilaqua, Rochele C. A.; Miranda, Caetano R. ^[1]; Rigo, Vagner A. ^[1]; Veríssimo-Alves, Marcos ^[1]

---

1. Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil)

The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca{sup 2+}. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO{sub 3} (101{sup ¯}4)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for {sup 43}Ca, {sup 13}C, and {sup 17}O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.

• OSTI ID: 22413251
• Journal Information: Journal of Chemical Physics, Vol. 141, Issue 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
BENZENE
CALCITE
CALCIUM CARBONATES
CALCIUM IONS
CARBON 13
CHEMICAL SHIFT
DENSITY FUNCTIONAL METHOD
HEXANE
INTERACTIONS
MOLECULES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
OXYGEN 17
SEDIMENTARY ROCKS
SIGNALS
SIMULATION
SOLIDS
SPECTROSCOPY
SURFACES