Raman and IR Spectroscopy Studies on Propane at Pressures of Up to 40 GPa

Abstract

Raman and IR spectroscopy studies on propane were performed at pressures of up to 40 GPa at ambient temperatures using the diamond anvil cell technique. Propane undergoes three phase transitions at 6.4(5), 14.5(5), and 26.5(5) GPa in Raman spectroscopy and at 7.0(5), 14.0(5), and 27.0(5) GPa in IR spectroscopy. The phase transitions were identified using the Raman and IR splitting modes and the appearance or disappearance of peaks, which clearly corresponded to the changes in the frequencies of the modes as the pressure changed. Our results demonstrate the complex high-pressure behavior of solid propane.

Opening up a Radical Cross-Coupling Etherification Path by a Defect-Rich Cu/ZrO2 Catalyst for a High-Value Transformation of HMF

“…Simultaneously, the vibration peak of ν­(CH 3 ) at 2980 cm –1 gradually shifted to 2936 cm –1 , with two vibration peaks appearing at 2922 and 2848 cm –1 . These bands corresponded well to the vibrational peaks of antisymmetric CH 3 , antisymmetric CH 2 , and symmetric CH 3 in propane, , respectively, which further confirms the dehydroxylation of isopropanol. To reveal the active site for isopropanol activation, we also performed in situ pyridine-IR for the CZ-va10%H 2 catalyst with and without isopropanol preadsorption.…”

Raman Spectroscopy Study on Chemical Transformations of Propane at High Temperatures and High Pressures

“…The signals of the graphite and soot are hard to distinguish, however, there is evidence that the soot itself has broader peaks 27,28 . The spectra of propane under pressure of 3 GPa and at an ambient temperature of 900 K (±100 K) show no major changes in the display of any of the bands that are typical for propane 16 . The stability of propane at a temperature of ~900 K is in good correspondence with the earlier experiments of Kolesnikov et al 12 on methane and ethane, showing the same behavior of propane.…”

“…Then the the acquisition of the spectra was made via the use of a LabRam spectrometer with a 2 cm −1 spectral resolution. If possible, the pressure was determined by a calibration of propane high-pressure behavior 16 , or else the pressure was determined by the first-order peak of the diamond. The uncertainties in the Raman peak positions were ±1 cm −1 .…”

“…The behavior of other hydrocarbons, both unsaturated 10,11 and saturated 12,13 , have been less widely investigated with the use of various high-pressure techniques.The focus on the significance of methane's high-pressure high-temperature behavior implies that the fate of higher hydrocarbons has been ignored. Though the high-pressure, high-temperature (HPHT) behavior of ethane has been investigated several times 12,14 , propane has only been studied at ambient temperatures 15,16 . Propane is the third most abundant hydrocarbon on Earth after methane and ethane.…”

B–O Oligomers or Ring Species in AlB2: Which is More Selective for Propane Oxidative Dehydrogenation?

“…As shown in Figures 4a and S12, after the adsorption of propane on R-AlB 2 and O-AlB 2 , the characteristic vibration peaks of propane appeared in the IR spectra for both samples, including the symmetrical and asymmetrical stretching vibrations of C−H in propane (signals at 3040−2850 cm −1 ), and scissoring vibrations of the −CH 2 group (at 1500−1420 cm −1 ). 26,27 Under R-AlB 2 catalysis (Figure 4a), the peaks of C−H vibration in propane at 3040− 2850 and 1500−1420 cm −1 diminished with increasing temperature, indicating the consumption of C 3 H 8 . Similar variation trends were observed in the in situ FT-IR spectrum of O-AlB 2 (Figure S12).…”