Application of SAXS and SANS in evaluation of porosity, pore size distribution and surface area of coal

Radlinski, A.P.; Mastalerz, María; Hinde, Alan L.; Hainbuchner, M.; Rauch, H.; Baron, M.; Lin, J. S.; Fan, Lifeng; Thiyagarajan, P.

doi:10.1016/j.coal.2004.03.002

Cited by 397 publications

(249 citation statements)

References 29 publications

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“…Although anthracites contain a network of closed micropores (Fryer, 1981;Mahajan, 1984;Daulan et al, 1998;Radlinski et al, 2004) that may originally contain some nitrogen gas, Boudou and Espitalié (1995) showed that elemental nitrogen is removed from micropores by crushing and evacuation. The mean relative peak areas of N-Q2 and N-X are ~9% to 10% and ~6% to 7% of the total N 1s XPS area, respectively.…”

Section: Sub-peaks N-q2 and N-x: Uncertain N Org Assignmentsmentioning

confidence: 99%

Organic nitrogen chemistry during low-grade metamorphism

Boudou

Schimmelmann

Ader

et al. 2008

Geochimica et Cosmochimica Acta

136

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-Most of the organic nitrogen (N org ) on Earth is disseminated in crustal sediments and rocks in the form of fossil nitrogen-containing organic matter. The chemical speciation of fossil N org within the overall molecular structure of organic matter changes with time and heating during burial. Progressive thermal evolution of organic matter involves phases of enhanced elimination of N org and ultimately produces graphite containing only traces of nitrogen. Long-term chemical and thermal instability makes the chemical speciation of N org a valuable tracer to constrain the history of sub-surface metamorphism and to shed light on the subsurface biogeochemical nitrogen cycle and its participating organic and inorganic nitrogen pools. This study documents the evolutionary path of N org speciation, transformation and elimination before and during metamorphism and advocates the use of XRay Photoelectron Spectroscopy (XPS) to monitor changes in N org speciation as a diagnostic tool for organic metamorphism. Our multidisciplinary evidence from XPS, stable isotopes, traditional quantitative coal analyses, and other analytical approaches shows that at the metamorphic onset N org is dominantly present as pyrrolic and pyridinic nitrogen. The relative abundance of nitrogen substituting for carbon in condensed, partially aromatic systems (where N is covalently bonded to three C atoms) increases exponentially with increasing metamorphic grade, at the expense of pyridinic and pyrrolic nitrogen. At the same time, much N org is eliminated without significant nitrogen isotope fractionation. The apparent absence of Rayleigh-type nitrogen isotopic fractionation suggests that direct thermal loss of nitrogen from an organic matrix does not serve as a major pathway for N org elimination. Instead, we propose that hot H, O-containing fluids or some of their components gradually penetrate into the carbonaceous matrix and eliminate N org along a progressing reaction front, without causing nitrogen isotope fractionation in the residual N org in the unreacted core of the carbonaceous matrix. Before the reaction front can reach the core, an increasing part of core N org chemically stabilizes in the form of nitrogen atoms substituting for carbon in condensed, partially aromatic systems forming graphite-like structural domains with delocalized π-electron systems (nitrogen atoms substituting for "graphitic" carbon in natural metamorphic organic matter). Thus, this nitrogen species with a conservative isotopic composition is the dominant form of residual nitrogen at higher metamorphic grade.

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Section: Sub-peaks N-q2 and N-x: Uncertain N Org Assignmentsmentioning

confidence: 99%

Organic nitrogen chemistry during low-grade metamorphism

Boudou

Schimmelmann

Ader

et al. 2008

Geochimica et Cosmochimica Acta

136

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“…Pores can be defined as open pores if they communicate with the external surface and are accessible to molecules or ions from the surroundings. By contrast, closed pores are closed as individual voids in the mineral matrix which is not interconnected to the external surface (Radlinski et al, 2004). The N 2 -gas adsorption method has been widely used to measure the specific surface area (SSA) and characterize the open porosity of airdried soil particles, especially the mesoporosity (pore width between 2-50 nm) and microporosity (pore width not exceeding 2 nm) (Mayer et al, 2004;Pronk et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

et al. 2014

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Abstract:The surface area and pore structure of easily dispersed soil particles < 2 µm in size (water-dispersible colloids, WDCs) are important for carbon sequestration and transport in soil. Two processes are essential for the terrestrial carbon cycling. In this work, we determine the effects of dithionite-citrate-bicarbonate (DCB) extractable metal oxides, and oxalate extractable metal oxides on the specific surface area (SSA) and pore structure of WDCs from silt loam topsoils of three TERENO test sites with a similar clay content (20%) in Germany (arable (Selhausen), grassland (Rollesbroich) and forest (Wuestebach) soils). The N 2 gasadsorption (−196°C), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and microelectrophoretic (ME) methods were used and compared. Results show that 1) the SSA of the WDCs from Selhausen, Rollesbroich, and Wuestebach decreased more after DCB treatment (27%, 35%, and 44%) than after oxalate treatment (5%, 14%, and 22%). DCB removed metal oxide nanoparticles from WDCs were found to have diameters (d p ) ranging from 4 nm to 8 nm and the surface loading ratios on the surface of aluminosilicate residues in WDCs were estimated to be 11% to 22% for three soils where the highest value was found in the acidic forest soil. 2) Pore sizes in the mesopore range (2 nm to 50 nm) were analyzed in the WDC fractions. The results were discussed in terms of accessible open pores for the pristine WDCs and WDC samples from which metal oxide nanoparticles and organic carbon (OC) had been removed. The lower average pore radius (R p ) measured by the N 2 gasadsorption method based on the total volume (V t ) to SSA ratio variations in WDCs without metal oxides compared to WDC with metal oxides indicated a contraction of the porous structure of WDCs due to the presence of metal oxide nanoparticles. The pore size distribution (PSD) analysis showed a sensitive contribution of metal oxide nanoparticles in the low range of pore sizes (< 25 nm) of WDCs. In SAXS measurements, higher surface fractal dimensions (D s ) were observed in WDCs before the metal oxides removal, which supports a roughness increase of the interfaces in the presence of nanoparticles. The colloidal characterization of WDCs by the DLS and ME methods shows, at a µm scale, the role of positively charged metal oxide nanoparticles in forming WDCs with a more compact structure by decreasing the particle size (d z ) and the negative zeta potential (ζ).3) The comparison of R p , k, d z and d p results between different soils also indicates the dependence on the clay mineralogy of WDCs so that the heterocoagulation between kaolinite and illite (clay minerals of different aspect ratios) increases the size of soil mesopores (Rollesbroich). In conclusion, the results of this study clearly show that the combination of the N 2 gas-adsorption, SAXS, DLS and ME methods allows the characterization of soil porosity in the nanometer range where metal oxide nanoparticles contribute to a more compact structure of WDC.

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“…However, a proper, detailed analysis of scales in geology, mineralogy or hydrocarbon recovery. Examples of such studies are provided in diagenesis (change of a sedimentary rock into a different rock) [21,22], pore structure in coals [23] and in nuclear graphite [24], hydrocarbon generation [25], tight gas reservoirs [26] or gas shales [27]. These results are often complemented by other studies, which extend the structural information over length scales larger than 1 µm, like neutron imaging [24] The V s (δ SE ) calculated for the chalk sample and for a maximum δ SE of 100 µm is shown in Fig.…”

Section: Calculation Of Semsans Signal and Sample Transmissionmentioning

confidence: 99%

Feasibility and applications of the spin-echo modulation option for a small angle neutron scattering instrument at the European Spallation Source

Kusmin

Bouwman

Well

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

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We describe theoretical and practical aspects of spin-echo modulated small-angle neutron scattering (SEMSANS) as well as the potential combination with SANS. Based on the preliminary technical designs of SKADI (a SANS instrument proposed for the European Spallation Source) and a SEMSANS add-on, we assess the practicability, feasibility and scientific merit of a combined SANS and SEMSANS setup by calculating tentative SANS and SEMSANS results for soft matter, geology and advanced material samples that have been previously studied by scattering methods. We conclude that lengths from 1 nm up to 0.01 mm can be observed simultaneously in a single measurement. Thus, the combination of SANS and SEMSANS instrument is suited for the simultaneous observation of a wide range of length scales, e.g. for time-resolved studies of kinetic processes in complex multiscale systems.

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Application of SAXS and SANS in evaluation of porosity, pore size distribution and surface area of coal

Cited by 397 publications

References 29 publications

Organic nitrogen chemistry during low-grade metamorphism

Organic nitrogen chemistry during low-grade metamorphism

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

Feasibility and applications of the spin-echo modulation option for a small angle neutron scattering instrument at the European Spallation Source

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