Qingqing Guan

Rapid determination of products of phenol hydrogenation in a supercritical water system using headspace gas chromatography

This paper reports a headspace analysis technique for the determination of products, i.e., cyclohexanone (CE) and cyclohexanol (CL), of phenol hydrogenation in a supercritical water reaction system (SWRS) with water removal by hydrate formation. An addition of anhydrous calcium chloride leads to water absorption resulting in crystal water; thus, the samples can be quantitatively measured without the influence of water. After achieving equilibrium at 150°C and maintaining it for 5 min, the obtained results showed a relative standard deviation of less than 5.3% and the recovery ranged from 93% to 104%. The presented method is simple and accurate for the analysis of CL, CE and phenol in samples from phenol conversion in SWRS.

In-situ Analysis of the Adsorption behaviors of CO2 on the Surface of MIL-91(Al)

To prevent global warming caused by the burning of fossil fuels, the formation of metal organic framework materials (i.e., MOFs) is a promising approach for efficient and scalable CO2 adsorption from air. In this study, a novel stable layered bis-phosphonate MOF, i.e., MIL-91(Al), has been synthesized for adsorption of CO2 under ambient conditions. XRD, N2 adsorption–desorption isotherms, FTIR and HRTEM were employed to characterize the synthesized MIL-91(Al). The results show that MIL-91(Al) demonstrates an excellent adsorption performance for CO2 (i.e., the maximum adsorption can reach up to 2.4 mmol g−1) and a relatively high selectivity for CO2vs. other gases (e.g., N2 or CH4). Moreover, the adsorption behavior of CO2 onto the surface of MIL-91(Al) has also been investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The DRIFTS results show that CO2 can be adsorbed by both the free polar groups (N⋯H–OP) and the Al–OH–Al bond. The special adsorption behavior is caused by the layered structure of MIL-91(Al) which leads to the exposure of Al on the surface.

Catalytic gasification of phenol in supercritical water over bimetallic Co–Ni/AC catalyst

ABSTRACT Solid-solution bimetallic alloy catalysts containing no noble metals were developed via both simultaneous and sequential deposition in supercritical water (SCW). These bimetallic nano-catalysts were analyzed by Brunauer–Emmett–Teller, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. Obvious downward shifts are observed in diffraction peaks, situated between the peak (1 1 1) for Co and the peak (1 1 1) for Ni. The shifts indicate the formation of NiCo solid-solution bimetallic alloy(s). The bimetallic nanoparticles show high activity for supercritical water gasification of phenol to produce gaseous fuels. The carbon gasification efficiency (CGE) of phenol in SCW can reach 95% on the Co–Ni/AC catalyst at conditions of 500°C and 30 min, showing nearly the same CGE as the commercial noble-metal-based catalyst, such as Ru/C (5 wt% Ru) from Sigma-Aldrich. The Co–Ni/AC catalyst also shows high stability. Therefore, deposition in SCW provides an effective way to create noble-metal-free solid-solution bimetallic alloy catalysts. GRAPHICAL ABSTRACT