DCO Project Summary

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Project Title
Structure, Dynamics, and Reactivity of C-H-O fluids at mineral interfaces
Start DateEnd Date
2011-04-01
NameRoleInstitutionDCO ID
Related GrantsDCO ID
11121/3515-2688-3796-9573-CC
Description
Fluids containing C-H-O species in solution occupy pores and fractures in rocks, but the interactions between fluids and mineral interfaces have been difficult. We are undertaking the construction of a high pressure and temperature interface cell for synchrotron X-ray reflectivity measurements in order to study these interactions. We are also conducting high pressure and temperature experiments to study the adsorption, desportion, and dynamics of hydrocarbon fluids in nanoporous materials, as well as modeling the atomic/molecular level of fluid-solid interfacial behavior.
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Reporting Year 2012 Click to expand


  • RY2012-1 - submitted on Mar 01, 2012

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    [2012-03-01] HPT-MFIC cell fabricated.
  • RY2012-2 - submitted on Jun 01, 2012

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    [2012-06-01] Preliminary test experiments with HTP-MFIC cell performed.
  • RY2012-3 - submitted on Jul 01, 2012

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    [2012-07-01] Awarded with Project User Proposal beamtime at APS for 2 years.
  • RY2012-4 - submitted on Jul 02, 2012

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    [2012-07-02] Converting the high pressure/high temperature adsorption lab to use flammable gases.
  • RY2012-5 - submitted on Jul 03, 2012

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    [2012-07-03] NMR studies involving hydrocarbon behavior in various nanopure solids underway.
  • RY2012-6 - submitted on Jul 04, 2012

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    [2012-07-04] Backscattering experiments underway to determine the mobility of C-H-O fluids under nanoconfinement as a function of pressure at ambient temperature.
  • RY2012-7 - submitted on Jul 05, 2012

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    [2012-07-05] Molecular dynamics simulations for ethanol on sapphire conducted.

Reporting Year 2014 Click to expand


  • RY2014-1 - submitted on Oct 01, 2013

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    10-1-2013

     

    HPCAT, Advanced Photon Source/CIW (Changyong Park, Lead)

         Olivine surface undergoes serpentinization in contacting with water, forming serpentine, brucite, magnetite and molecular hydrogen. The surface hydration is the primary process of the reaction and of ultimate importance to understand the molecular processes. The high reactivity, however, made it difficult to observe the pristine surface interacting with water in-situ, thus the previous studies were mainly based on the ex-situ characterization of the altered surface after reactions. In the present study, we re-challenged the in-situ observation, established a reproducible sample preparation procedure, and successfully determined the termination and hydration structure of single crystal olivine (010) surface with high-resolution x-ray reflectivity technique. The surface termination as reconstructed based on the derived electron density profile in the surface normal direction is qualitatively consistent with that obtained from a computational modeling (de Leeuw et al., 2000. Phys Chem Minerals 27: 332-341). The surface magnesium, however, is likely depleted more than anticipated from its crystallographic termination and the void space seems filled with adsorbed water species. The silicate skeleton on the other hand remains intact and forms a terminal oxygen layer, which is slightly higher than the depleted magnesium layer. The terminal oxygen is linked to another layer of adsorbed water, perhaps, through hydrogen bonding, which results in rather complicated total electron density profile at the interfacial region before it connects to the featureless bulk water structure. The successful determination of in-situ hydration structure at the olivine (010)-water interface provides rigorous constraints to the computational modeling and promises similar approaches to other pristine surface hydration of olivine. 

     

    Oklahoma Univ.  (Alberto Striolo, Lead)

         Funds from the Deep Carbon Observatory have been used to support, in part, Mr. Tuan Ho, Ms. Anh Phan, and now Ms. Thu Le. These students have also been supported by the DOE BES Geosciences program, and by the DOE EPSCOR program. Mr. Tuan Ho has also been supported, for a very short time, by the US National Science Foundation (only Mr. Ho). The goal of this project is to employ molecular dynamics simulations to visualize the equilibrium and transport behavior of fluid mixtures confined in sub-surface formations. We seek to provide interpretation for experimental results, sometimes surprising, obtained from our collaborators. Striolo’s group has conducted significant research for quantifying aqueous solutions at solid-liquid interfaces. Because of the DCO’s emphasis on carbon-bearing molecules, we have been adapting our capabilities to study such systems.

         Our first publication was highlighted in the cover of the Journal of Physical Chemistry C. In this publication we quantified how three metal oxide surfaces determine structure and dynamics of liquid water. This publication concluded our investigation on pure water. Aqueous mixtures will be the interest for subsequent work. The results described in this paper were not unexpected, but they provided quantification for how the properties of a solid surface might affect how interfacial water behaves and how the hydrogen bonds form.

         The first non-water molecule of interest was ethanol. We studied ethanol adsorbed an aluminum oxide surfaces. We quantified hydrogen bonding networks, structure, orientation of interfacial molecules, and mobility. The results are in strikingly good agreement with sum frequency vibrational spectroscopy experimental data available in the literature, and have been published in the open literature.

    Our third publication, by Cole et al., 2013, has compiled our initial experimental and modeling efforts towards understanding mixed fluids under confinement. In our review article, published in the Reviews in Mineralogy and Geochemistry, we have summarized the state of the art. This helped us focusing our efforts towards topics of interest to the geochemistry community.

          Recent progress is being accomplished for understanding water-ethanol mixtures confined in alumina pores (work primarily supported by the DOE), by quantifying the solubility of methane in water under confinement, and by reproducing the experimental adsorption isotherms for propane in silica-based pores reported by Cole and coworkers in a recent article.

         At the present time, our students are writing up papers to describe our results for methane solubility in water under confinement and propane adsorption in silica. For the scopes of the DCO, as well as for the recent interest on hydraulic fracturing, the most important, unexpected result is that our simulations suggest that methane solubility in water within narrow pores can be 1 order of magnitude higher than that observed in bulk water, at equal P and T conditions. This observation might have consequences in our understanding of the carbon cycle. Experimental verification is clearly desirable.

     

    Ohio State University (David Cole, Lead)

    The scientific objective of this effort is to obtain a fundamental atomic- to macro-scale understanding of the sorptivity, structure and dynamics of simple and complex C-O-H fluids (e.g., hydrocarbons, CO2) at mineral surfaces or within nanoporous matrices over temperatures, pressures and compositions encountered in near-surface and shallow crustal environments.  To achieve this goal, in this first year of the project we focused on three synergistic research activities: (1) adsorption-desorption of fluids in nanoporous materials; (2) dynamics of hydrocarbons and related fluids in nanoporous materials; and (3) atomistic and molecular level modeling of fluid-solid interfacial behavior.

       Mr. Patankar and Ms. Liu have been addressing a number of key issues in making the high temperature-high pressure adsorption lab suitable for handling of inflammable gases such as propane. They are currently in the process of acquiring additional equipment to set up the recently acquired Teledyne/ISCO HL (Hazardous Location) 500 syringe pump to function with the balance. Another issue that was discussed was use of mixtures in their sorption studies. In order to make mixtures of CO2 and hydrocarbons, two pumps have to be used simultaneously with a check valve in between. A number of upgrades of existing equipment and installation of new equipment are currently in progress.

        In order to better understand the interfacial and nanopore confinement behavior of hydrocarbon fluids as a function of pore size and chemistry, we are exploring the use of engineered proxies such as mesoporous silica, alumina, titania, zirconia, as well as natural zeolite minerals (e.g., stilbite, mordenite natrolite and heulandite), clays, and serpentine minerals (chrysotile, lizardite). Ms. Liu is focusing on the lighter element oxides whereas Mr. Patankar is addressing hydrocarbon behavior on the transition metal oxides. NMR experiments that probe the dynamical behavior (diffusion and molecular relaxation) of hydrocarbons and their non-aqueous equivalents have been initiated by Dr. Ok using facilities in the OSU Chemistry department.

         We recently conducted SNS/BASIS quasielastic backscattering experiments at Oak Ridge to explore the mobility of methane, propane and CO2 under nanoconfinement as a function of pressure at ambient temperature. A base-catalyzed silica aerogel with a density of 0.3 g/cm3 corresponding to ~90% porosity was synthesized in a mold with the dimensions of the sapphire pressure cell available at SNS – 5 mm diameter and 50 mm in length.  The results have been cast in terms of a jump diffusion model. Propane mobility stays essentially constant or decreases slightly with increasing CO2 loading, however, the residence times and jump distances do decrease appreciably with increase CO2 content – e.g., 11.0  to 1.3 to 0.7 ps with associated jump distances of 8.3, 2.9 and 1.9 A, respectively, for pure CO2, low loading of CO2 (620 pis), and high loading of CO2 (1100 psi). Thus CO2, which is itself fast, greatly enhances (by an order of magnitude) what one might more correctly call ‘jump attempt rate” of propane molecules, even though the overall diffusion coefficient does not increase at all or even gets a bit slower, since the jump distances become much smaller.

     

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