Huiping Zhang

Stability and deactivation of Fe-ZSM-5 zeolite catalyst for catalytic wet peroxide oxidation of phenol in a membrane reactor

Stability and deactivation of Fe-ZSM-5 zeolite catalyst for catalytic wet peroxide oxidation (CWPO) of phenol were studied in a membrane reactor. Firstly, the Fe-ZSM-5 zeolite membrane catalyst was prepared by a paper-making/sintering process, secondary growth process and incipient wetness impregnation method. And the influence of residence time on the CWPO of phenol was evaluated by modifying the catalyst bed height. Then, stability of the Fe-ZSM-5 zeolite membrane catalyst was studied by the long-term experiment (40 hours). Finally, the deactivation mechanisms of the Fe-ZSM-5 zeolite membrane catalyst were investigated by N2 adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermal gravimetric (TG) analysis, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, respectively. The results of CWPO of phenol showed that complete phenol conversion with a high TOC conversion (about 60%) was obtained at the catalyst bed height of 4 cm. Meanwhile, good stability with low Fe leaching concentration (about 0.5 mg L−1) and high phenol conversion (above 85%) were obtained after continuously running for 40 hours. Furthermore, the loss of active component, the partial phase change of Fe2O3, the crystallinity change of the ZSM-5 zeolite membrane and the coke formation on the surface of the catalyst were found to be responsible for the deactivation of the catalyst.

Catalytic oxidation of carbon monoxide in a fixed bed reactor

A fixed bed reactor is used to study the catalytic oxidation of carbon monoxide (CO) using activated carbon impregnated with poly-metals (copper, chromium and silver) as the catalyst. The conversion factor of carbon monoxide was measured under different operation conditions such as reactor bed height, catalyst particle diameter, and temperature. The conditions for which the mass transfer resistance could be eliminated are studied. With such conditions satisfied the surface reaction on the catalyst will be the rate controlling step, and the oxidation of CO was found to follow a first-order catalytic reaction. The reaction activation energy of CO in the copper impregnated carbon bed is found to be 107.2 kJ/ml.

Catalytic wet oxidation of phenol with Fe–ZSM-5 catalysts

Fe–ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared and tested for catalytic wet oxidation of phenol. First, Fe–ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared by the hydrothermal synthetic and incipient wetness impregnation method and characterized to determine the framework and extra-framework Fe3+ species. Second, the catalytic properties of Fe–ZSM-5 in the oxidation of phenol were systematically studied to determine the optimum technological parameters by investigating the effects of reaction temperature, pH, catalyst concentration and stirring rate on the conversion of phenol. In addition to the phenol conversion, selectivity to CO2 and concentration of aromatic intermediates in the oxidation of phenol with the two catalysts were analyzed under the same optimum conditions. Leaching of iron from the catalysts, as well as the catalytic stability of Fe–ZSM-5, was also tested. Finally, the kinetics of catalytic wet oxidation of phenol with Fe–ZSM-5 was studied. The experimental results showed that both the framework and extra-framework Fe3+ species were present in Fe–ZSM-5. The oxidation reaction with Fe–ZSM-5 was performed well at a temperature of 70 °C, pH of 4, catalyst concentration of 2.5 g L−1, stirring rate of 400 rpm and reaction time of 180 min. The conversion of phenol reached 94.1%. From the catalytic results of the two catalysts, it can be concluded that the framework Fe3+ species may be more efficient in phenol oxidation than the extra-framework Fe3+ species, the stability of Fe–ZSM-5 was better and a relatively low decrease in activity could be found after three consecutive runs. The activation energy of 27.42 kJ mol−1 was obtained for phenol oxidation with Fe–ZSM-5.

Preparation and characterization of novel porous zeolite beta coating/PSSF composite in fluoride media

A novel porous zeolite beta coating/PSSF composite was prepared by secondary growth method in fluoride media. The morphology of zeolite beta coating/PSSF composite was characterized by SEM and the structural and textual properties of composite were characterized by XRD and N2 adsorption/desorption isotherms on ASAP 2020, respectively. The thermal stability of composite was analyzed by thermogravimetry (TG) and differential scanning calorimetry (DSC). The results indicated that well-intergrown and continuous zeolite beta coating with highly crystallinity were successfully synthesized on the surface of paper-like stainless steel fibers support. The structures of zeolite beta coating/PSSF composite were three-dimensional network with large void volume and majority of microporous structure. The thickness of zeolite beta coating on stainless steel fibers is approximate 2 μm. The specific surface area (SBET) and the total pore volume of composite were 118 m2 g−1 and 0.067 cm3 g−1, respectively. The composite was stable at temperature up to 650 °C.

Chemical vapor deposition of CuO on ZSM-5 membrane for catalytic wet peroxide oxidation of phenol in a fixed bed reactor

CuO over ZSM-5 zeolite membrane was prepared by chemical vapor deposition (CVD) for catalytic wet peroxide oxidation (CWPO) of phenol in a fixed bed reactor. Firstly, Cu-ZSM-5/PSSFs catalysts with Cu loading of 2 wt%, 4 wt% and 6 wt% were prepared and characterized by XRD, XPS, SEM, EDS, N2 adsorption–desorption and TPR (H2), respectively. Compared with CuO deposited directly onto PSSFs, the CuO supported on ZSM-5/PSSFs tended to be more regular with smaller crystal size. Then, several parameters affecting H2O2 consumption and phenol oxidation such as reaction temperature, Cu loading, and different supports were investigated in the CWPO of phenol with a high concentration (1 g L−1 phenol and 5.1 g L−1 H2O2). Experimental results revealed that Cu-ZSM-5/PSSFs (6%) showed better activity for the oxidation of phenol than Cu-ZSM-5/PSSFs catalysts with lower Cu loading and CuO/PSSFs with same theoretical loading. A complete reduction of phenol and a high TOC removal around 60% had been achieved over Cu-ZSM-5/PSSFs (6%) at the temperature of 80 °C, feed flow rate of 2 mL min−1 and catalyst bed height of 2 cm. Finally, the possible oxidation pathway of phenol was studied based on the by-products detected by high-performance liquid chromatography (HPLC).

Preparation of Cu-ZSM-5 catalysts by chemical vapour deposition for catalytic wet peroxide oxidation of phenol in a fixed bed reactor

Cu-ZSM-5 catalysts were prepared by chemical vapour deposition for catalytic wet peroxide oxidation (CWPO) of phenol in a fixed bed reactor. Firstly, Cu-ZSM-5 catalysts with Cu loading of 0.5, 2, and 6 wt% were prepared and characterized by X-ray diffraction (XRD), N2 adsorption–desorption and X-ray photoelectron spectra (XPS). The characterization results demonstrated that CuO was uniformly dispersed on ZSM-5 with slight effect on the structure properties of the support. Then, several variables, such as the copper loading, reaction temperature, catalyst bed height and feed flow rate were investigated in the CWPO of phenol in aqueous solution at high concentration (1000 ppm). Compared with the catalyst prepared by the impregnation method, the Cu-ZSM-5 prepared by chemical vapour deposition has a better capacity of further oxidizing the intermediate organic products into carbon dioxide and water with less metal loading. Based on the Cu-ZSM-5 catalyst with Cu loading of 6 wt%, complete removal of phenol and a high TOC reduction (around 70%) have been achieved at the temperature of 80°C feed flow rate of 2 ml min−1 and catalyst bed height of 3 cm. Moreover, this catalyst maintained high catalytic activity after three runs with high phenol conversion (94%) under this optimum operating condition. Finally, the reaction mechanism was studied based on the intermediates detected by high-performance liquid chromatography (HPLC).

Increasing Gas Bubble Escape Rate for Water Splitting with Nonwoven Stainless Steel Fabrics

Water electrolysis has been considered as one of the most efficient approaches to produce renewable energy, although efficient removal of gas bubbles during the process is still challenging, which has been proved to be critical and can further promote electrocatalytic water splitting. Herein, a novel strategy is developed to increase gas bubble escape rate for water splitting by using nonwoven stainless steel fabrics (NWSSFs) as the conductive substrate decorated with flakelike iron nickel-layered double hydroxide (FeNi LDH) nanostructures. The as-prepared FeNi LDH@NWSSF electrode shows a much faster escape rate of gas bubbles as compared to that of other commonly used three-dimensional porous catalytic electrodes, and the maximum dragging force for a bubble releasing between NWSSF channels is only one-seventh of the dragging force within nickel foam channels. As a result, it exhibits excellent electrocatalytic performance for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with low overpotentials of 210 and 110 mV at the current density of 10 mA cm-2 in 1 M KOH for OER and HER, respectively. There is almost no current drop after a long-time durability test. In addition, its performance for full water splitting is superior to that of the previously reported catalysts, with a voltage of 1.56 V at current density of 10 mA cm-2.

17)O NMR and Raman Spectroscopies of Green Tea Infusion with Nanomaterial to Investigate Their Properties.

(17)O NMR and Raman spectrograms of green tea infusions with nanomaterial were investigated. Different green tea infusions were prepared by steeping tea powder with different concentrations of nanomaterial aqueous solution. The tea infusions were tested with (17)O NMR and Raman spectroscopies. The (17)O NMR results showed that line width increased to 90 in the tea infusions after nanomaterial was added as a result of the effects of the self-association of Ca(2+) and tea polyphenol. The results of Raman spectroscopy showed that, in tea infusions, the enhancement of C─C and C─O stretching vibrations suggest an increase in the number of effective components in water.