Institutional Repository of Dalian Institute of Chemical Physics, CAS
Not a member yet
45557 research outputs found
Sort by
Single photon ionization time-of-flight mass spectrometry with a windowless RF-discharge lamp for high temporal resolution monitoring of the initial stage of methanol-to-olefins reaction
No full textMethanol-to-olefins (MTO) is a very important industrial catalysis technique for the production of light olefins, which is of great economic value and strategic significance. However, it is a great challenge for the traditional analytical methods to obtain the real-time information of product variation during MTO reaction process, which is vital for the conversion process research and mechanism explanation. In this study, a single photon ionization time-of-flight mass spectrometry (SPI-TOFMS) based on a windowless RF-discharge (WLRF) lamp was developed for real-time measurement of catalytic product during the initial stage of MTO reaction. The vacuum ultraviolet (VUV) photon energy was easily adjusted by changing the discharge gas. Argon (Ar) gas was eventually adopted as the discharge gas, since it produces photons with appropriate energy of 11.6 eV and 11.8 eV for ionization of light olefin molecules. The detection sensitivities of ethylene and propylene were largely improved to a substantially similar level with limits of detection (LODs) down to 16.98 and 9.64 ppbv, respectively. The initial stage of MTO reaction was real-time monitored with a high temporal resolution of 0.5 s, revealing that ethylene was the first olefin product followed by propylene. The successful application of WLRF-SPI-TOFMS in the monitoring of MTO catalytic process indicated broad application prospects of this instrument in the industrial reaction process monitoring
Key Scientific Research Project of Colleges and Universities of Henan Province of China[16B140002]
No full text
Reversible Hydrogen Uptake/Release over a Sodium Phenoxide-Cyclohexanolate Pair
No full textHydrogen uptake and release in arene-cycloalkane pairs provide an attractive opportunity for on-board and off-board hydrogen storage. However, the efficiency of arene-cycloalkane pairs currently is limited by unfavorable thermodynamics for hydrogen release. It is shown here that the thermodynamics can be optimized by replacement of H in the -OH group of cyclohexanol and phenol with alkali or alkaline earth metals. The enthalpy change upon dehydrogenation decreases substantially, which correlates with the delocalization of the oxygen electron to the benzene ring in phenoxides. Theoretical calculations reveal that replacement of H with a metal leads to a reduction of the HOMO-LUMO energy gap and elongation of the C-H bond in the alpha site in cyclohexanolate, which indicates that the cyclohexanol is activated upon metal substitution. The experimental results demonstrate that sodium phenoxide-cyclohexanolate, an air- and water-stable pair, can desorb hydrogen at ca. 413 K and 373 K in the solid form and in an aqueous solution, respectively. Hydrogenation, on the other hand, is accomplished at temperatures as low as 303 K
