Shufeng Zuo

High-temperature synthesis of strong acidic ionic liquids functionalized, ordered and stable mesoporous polymers with excellent catalytic activities

Strong acidic ionic liquids functionalized, ordered and stable mesoporous phenol–formaldehyde resins (OMR-ILs) monoliths have been successfully synthesized from the treatment of ordered mesoporous resins (OMR-[HMTA]) using 1,3-propanesultone, followed by ion exchanged using various strong acids. The OMR-[HMTA] samples could be synthesized by the assembly of block copolymer template of F127 with preformed resol, which could be obtained from heating a mixture of phenol and formaldehyde at 70 °C; during curing processes, certain contents of the hexamethyltetramine (HMTA) cross linker were also introduced, after hydrothermal treatment at 200 °C for 20 h, calcination at 360 °C under nitrogen, OMR-[HMTA] samples with opened mesopores were obtained. Characterizations suggest that OMR-ILs have ordered and stable mesospores, high BET surface areas, and strong acid strength. Interestingly, OMR-ILs show much higher catalytic activities and recyclability in the esterification of acetic acid with cyclohexanol, hydration of propylene oxide, Peckmann reaction of resorcinol with ethyl acetoacetate and transesterification of tripalmitin with methanol than those of Amberlyst 15, sulfonic group functional ordered mesoporous silicas and acidic zeolites, which were even comparable with that of H2SO4. The unique features of OMR-ILs such as superior thermal stability, excellent catalytic activities and recyclability, will be potentially important for their applications in industry.

An efficient and recyclable heterogeneous palladium catalyst utilizing naturally abundant pearl shell waste

An efficient and recyclable ligand-free heterogeneous catalyst has been prepared by the immobilization of palladium onto ground pearl shell powders (Pd/shell powders, Pd/SP). The catalytic activity and recyclability of the prepared Pd/SP along with the charcoal and calcium carbonate supported palladium (Pd/C and Pd/CaCO3) catalysts have been evaluated using the reductive homocoupling of aromatic halides. Pd/SP not only has higher catalytic activity, but also exhibits much stronger stability than Pd/C and Pd/CaCO3. The remarkable Pd/SP stability has been attributed to the chelation of palladium species with the surface chitin and protein molecules of the supported pearl shell powders. The X-ray photoelectron spectroscopy (XPS) studies show that the reductive Pd0 species can be regenerated in situ from the oxidative Pd2+ species for the Pd/SP catalyzed reductive homocoupling of aromatic halides in ethanol/DMSO solution, suggesting that the heterogeneous and homogeneous palladium catalysis proceeds through a similar Pd0/Pd2+ cycle catalytic mechanism.

Generalized and high temperature synthesis of a series of crystalline mesoporous metal oxides based nanocomposites with enhanced catalytic activities for benzene combustion

We report here a generalized synthesis of various crystalline mesoporous metal oxides including CeO2, Cr2O3, Fe2O3, SnO2, Ce0.5Zr0.5O2, TiO2, Al2O3 and ZrO2 from the self-assembly of a basic poly 4-vinylpyridine (P4VP) template with various metal precursors based on their strong acid–base interaction under high temperature (180 °C) hydrothermal conditions. Using the typically crystalline mesoporous metal oxide of CeO2, after removing the template by calcination at 550 °C and loading with various transition metal oxides such as MnOx, various transition metal oxide functionalized crystalline mesoporous CeO2 (MnOx/P4VP–CeO2) were obtained. X-ray diffraction (XRD) patterns show that the resulting mesoporous metal oxides exhibit a high degree of crystallinity, and the transition metal oxides active sites have been successfully loaded into these samples. N2 sorption–desorption isotherms, SEM images show that the resulting crystalline mesoporous metal oxides, such as CeO2, have a large BET surface area (94 m2 g−1) and abundant mesopores, which exhibit monolithic morphology with crystal sizes ranging from 5 to 15 μm, giving a uniform pore size centered at 5 nm. XPS spectra show that the active sites such as MnOx exhibit the phases of MnO2 and Mn2O3 in P4VP–CeO2. H2-TPR curves show that MnOx/P4VP–CeO2 exhibits decreased reductive temperatures of both active sites of the MnOx and P4VP–CeO2 supporter when compared with the samples reported previously. More importantly, MnOx/P4VP–CeO2 exhibits much better catalytic activities and good recyclability for catalyzing the oxidation of benzene than that of MnOx loaded commercially crystalline CeO2, which will be very important for their wide applications for VOCs removal in industry.

Study of CeO2 Modified AlNi Mixed Pillared Clays Supported Palladium Catalysts for Benzene Adsorption/Desorption-Catalytic Combustion

A new functional AlNi-pillared clays (AlNi-PILC) with a large surface area and pore volume was synthesized. The performance of adsorption/desorption-catalytic combustion over CeO2-modified Pd/AlNi-PILC catalysts was also studied. The results showed that the d001-value and specific surface area (SBET) of AlNi-PILC reached 2.11 nm and 374.8 m2/g, respectively. The large SBET and the d001-value improved the high capacity for benzene adsorption. Also, the strong interaction between PdCe mixed oxides and AlNi-PILC led to the high dispersion of PdO and CeO2 on the support, which was responsible for the high catalytic performance. Especially, 0.2% Pd/12.5% Ce/AlNi-PILC presented high performance for benzene combustion at 240 °C and high CO2 selectivity. Also, the combustion temperatures were lower compared to the desorption temperatures, which demonstrated that it could accomplish benzene combustion during the desorption process. Furthermore, its activity did not decrease after continuous reaction for 1000 h in dry air, and it also displayed good resistance to water and the chlorinated compound, making it a promising catalytic material for the elimination of volatile organic compounds.