Application of Differential Scanning Calorimetry to Study Solvent Swelling of Kukersite Oil Shale Macromolecular Organic Matter: A Comparison with the Fine-Grained Sample Volumetric Swelling Method

Abstract

A comparison of results of Estonian kukersite oil shale kerogen (i.e., the cross-linked macromolecular organic matter of oil shale) solvent swelling from two different methods is shown. Solvent uptakes calculated from differential scanning calorimetry (DSC) experiments are higher than those obtained by a widely used test-tube-type volumetric solvent swelling technique of fine-grained samples with swollen sample centrifugation. Solvent swelling of the kerogen sample was performed in a test tube in accordance with the common volumetric technique. Then, the swollen sample was introduced into a DSC apparatus, cooled to −120 °C, and heated at a rate of 10 °C/min. The energy of fusion of the freezable part of the solvent was used to calculate the amount of nonfreezable bound solvent that is present inside the kerogen particles and that causes swelling. The data suggest that caution should be exercised in applying the test tube volumetric method because of a possible swollen sample compaction effect.

Application of DSC to study the promoting effect of a small amount of high donor number solvent on the solvent swelling of kerogen with non-covalent cross-links in non-polar solvents

“…The swollen kerogen sample was prepared according to a two stage swelling procedure: the sample was first swollen to equilibrium in a non-polar solvent (base solvent) and then a polar, specifically interacting solvent (swelling promoting solvent) was added. The technical details of the general volumetric swelling experimental procedure are described in our previous papers [15,16]. Briefly, a kerogen sample of 0.25 g was placed into a test tube and mixed with the first solvent.…”

“…As a result, swellability of highly polar kerogen in non-specifically interacting solvents is determined by apparent cross-link density (covalent and non-covalent cross-links), while in the case of specifically interacting (hydrogen-bonding) solvents it is determined by the real (covalent) cross-link density because of the ability of such solvents to disrupt the kerogen's intramolecular hydrogen bonds. Consequently, solvent swelling experiments on these kerogens show increased swelling in hydrogen-bonding solvents with high electron donor numbers, such as pyridine, N-methyl-2-pyrrolidinone or propylamine [15][16][17].…”

“…The aim of the study is to extend application of the DSC-based method presented in our previous paper [16] to quantitatively study the swelling behavior of Kukersite kerogen in three non-specifically interacting solvents in the presence of small amounts of a specifically interacting swelling promoting solvent. The cross-link density reduction and network relaxation effects caused by addition of a small amount of H-bonding solvent were previously shown by Larsen et al for coal [7,8].…”

“…These non-polar solvents have different molar volumes. N-methyl-2-pyrrolidinone (NMP) was selected as a specifically interacting solvent because it is a strong H-bonding solvent with a high Gutmann electron donor number (DN) that is known to be one of the best swelling agents for Kukersite kerogen [16].…”

Methane adsorption on the surface of a model of shale: A density functional theory study

“…Regarding the complexity [34][35][36][37][38] of the kerogen, many researchers have devoted to model simplification. Junfeng Li and coworkers [39] characterized the configurations of kerogen based on the analysis of pyrolysis-gas chromatography -mass spectroscopy data.…”