The extraction of bitumen from the oilsands using solvents has the potential to avoid the environmental problems with wet tailings associated with water-based extraction technology. One of the key performance parameters for this technology is the concentration of fine solids in the recovered bitumen. In this study, the concentration and properties of the fine solids in cyclohexane-extracted bitumen were examined as a function of the water content of the ore. Total water contents from 3.4–13.4 wt % gave the lowest concentrations of fine solids in the bitumen, ca. 0.2 wt % of the initial mass of a low-fines content ore. Higher fine solids contents in the bitumen were observed with water concentrations outside this range and with higher concentrations of fine solids in the initial oilsands ore. The fine solids exhibited a distribution of surface properties, and the most hydrophobic, carbon rich solids were carried into the bitumen even under the most favorable conditions. When the bitumen was more contaminated with fine solids, due to higher fines in the ore or lack of water to bind the fines to the sand, the carbon content of the fine solids decreased. The majority of the carbon in the fine solids was organic material due to bitumen and surface adsorbed components. Despite carbon contents over 20 wt %, XPS analysis showed significant surface silicon and aluminum, and contact angles were in the range of 80–88°, consistent with partial organic coating of the mineral particles. Characterization of the fine solids by SEM, particle size, and mineralogy suggested that the migration of the fine solids into the bitumen, versus remaining with the coarse sand, was significantly affected by the organic surface deposits on the particles.
Power-to-gas is a heavily discussed option to store surplus electricity from renewable sources. Part of the generated hydrogen could be fed into the gas grid and lead to fluctuations in the composition of the fuel gas. Consequently, both operators of transmission networks and end users would need to frequently monitor the gas to ensure safety as well as optimal and stable operation. Currently, gas chromatography-based analysis methods are the state of the art. However, these methods have several downsides for time-resolved and distributed application and Raman gas spectroscopy is favorable for future point-of-use monitoring. Here, we demonstrate that fiber-enhanced Raman gas spectroscopy (FERS) enables the simultaneous detection of all relevant gases, from major (methane, CH 4 ; hydrogen, H 2 ) to minor (C2−C6 alkanes) fuel gas components. The characteristic peaks of H 2 (585 cm −1 ), CH 4 (2917 cm −1 ), isopentane (765 cm −1 ), i-butane (798 cm −1 ), n-butane (830 cm −1 ), n-pentane (840 cm −1 ), propane (869 cm −1 ), ethane (993 cm −1 ), and nhexane (1038 cm −1 ) are well resolved in the broadband spectra acquired with a compact spectrometer. The fiber enhancement achieved in a hollow-core antiresonant fiber enables highly sensitive measurements with limits of detection between 90 and 180 ppm for different hydrocarbons. Both methane and hydrogen were quantified with high accuracy with average relative errors of 1.1% for CH 4 and 1.5% for H 2 over a wide concentration range. These results show that FERS is ideally suited for comprehensive fuel gas analysis in a future, where regenerative sources lead to fluctuations in the composition of gas.
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