CuO/CeO2 mesoporous nanosheets exhibited superior soot oxidation activity owing to the synergistic effects.

No abstract

A urea-functionalized ordered mesoporous polymeric nanoparticle for removing the perrhenate anion ReO as the surrogate of the particularly intractable anion radioactive pollutant TcO was demonstrated in the present study. This nanomaterial (denoted as urea-MPN) was produced for the first time by a surfactant-directed urea-phenol-formaldehyde resol oligomers self-assembly protocol under hydrothermal condition. The obtained urea-MPN possessed the uniform nanosized spherical morphology with a 3D interconnected ordered cubic mesoporous structure. Also, the urea functional groups were succefully embedded in the polymer framework without the alteration of the molecular configuration. Meanwhile, it exhibited excellent β radiation resistance up to 200 kGy dose. We employed the perrhenate anion ReO to test its potential for the removal of anionic radioactive pollutant TcO from water. Interestingly, the optimized urea-MPN nanocomposite achieved the high removal efficiency at a low concentration of 0.25 mM within a short contact time of 30 min. The control experimental results revealed that the short nanoscale pore channels and the hydrophobic mesopore surface facilitated the hydrogen-bonding interaction between the charge-diffuse ReO tetrahedral oxoanion and the urea moieties in the framework of urea-MPN, accounting for the rapid and effective removal performance in pure water. Importantly, it can selectively capture ReO in the presence of different competitive anions including NO, CO, SO, and PO. This attractive capability of this unique nanosized mesoporous polymeric sorbent will pave the way for the diverse applications in the decontamination of nuclear wastes in a more economical and sustainable manner.

A series of Pd/Ph-SBA-15 catalysts with ordered mesoporous structure are designed by using the phenyl-functionalized SBA-15 (Ph-SBA-15) as supports. These catalysts exhibit higher activity and selectivity toward biphenyl than Pd/SiO 2 , Pd/MCM-41, Pd/Ph-MCM-41 and Pd/SBA-15 in a water-medium iodobenzene Ullmann coupling reaction. The promoting effects on the activity and selectivity could be mainly attributed to the high dispersion of Pd active sites, the ordered mesoporous channels and the strong surface hydrophobocity which facilitate the diffusion and/or adsorption of organic reactant molecules, especially in aqueous media. Meanwhile, the relatively large pore channels are favorable for the coupling of iodobenzene to form biphenyl, which is much bigger than the byproduct benzene resulting from the dehalogenation of iodobenzene. The Pd/Ph-SBA-15 catalyst could be separated easily from reaction products and used repetitively several times, showing the superiority over the homogeneous catalysts for industrial applications.

A mesoporous Pd(II) organometallic catalyst is synthesized by coordinating the Pd(II) with the amine-ligand anchored on ethyl-bridged PMOs. During Barbier reaction in water as an environmentally friendly medium, the as-prepared Pd(II)-PMOs (Et) exhibits matchable catalytic activity and selectivity with the corresponding homogeneous Pd(II) catalyst and could be used repetitively for more than 5 times, which could reduce the cost and even diminish the environmental pollution from heavy metallic ions, showing a good potential in industrial applications. On one hand, the excellent catalytic performance could be attributed to the high surface area and ordered mesporous structure of the PMOs support, which ensures the higher dispersion of Pd(II) active sites and also facilitates the diffusion of reactant molecules. On the other hand, the ethyl fragments embedded in the pore walls could enlarge mesopores and also enhance surface hydrophobility of the PMOs support, which further promotes the diffusion and adsorption of organic molecules, especially in aqueous medium, leading to higher activity and selectivity.

Multifunctional mesoporous material (NH 2 &Ph-SBA-15) was synthesized by co-condensation of tetraethyl orthosilicate, amine-silane and phenyl-silane in the presence of triblock copolymer P123. The Pd nanoparticles immobilized on the NH 2 &Ph-SBA-15 support were fabricated by the impregnation and subsequent reduction method. The XRD, TEM, N 2 sorption, IR and solid NMR measurements revealed that this novel mesoporous Pd catalyst (Pd/NH 2 &Ph-SBA-15) not only maintained ordered hexagonal mesopores, but also possessed characteristics of the two organic functional groups on the mesopore surface. Compared with Pd nanoparticles supported on the parent SBA-15 or monofunctionalized mesoporous materials, it displayed much higher catalytic reactivity and selectivity in the water-medium Ullmann reaction. This could be attributed to the synergic promoting effect derived from binary organic functional groups since the NH 2 -groups led to the uniform dispersion of Pd nanoparticles inside the pore channels while the Ph-groups decreased the diffusion limitation of organic molecules in water. Furthermore, it could be conveniently recovered and recycled six times without significant loss of activity and selectivity.

A Si--H functionalized phenyl-bridged periodic mesoporous organosilica [H-PMO(Ph)] is synthesized via a surfactant-directed assembly approach. Pd nanoparticles are then immobilized onto the PMO catalyst [Pd/H-PMO(Ph)] by a Si--H in situ reduction method. The Ullmann reaction, in water as medium, is used to investigate the catalytic performance of Pd/H-PMO(Ph). The results show that the Pd/H-PMO(Ph) catalyst has excellent catalytic activity and selectivity, which can be attributed to synergetic effects derived from the highly dispersed catalytic species and the hydrophobic microenvironments. Furthermore, the catalyst could be conveniently recovered and recycled five times without significant loss of activity and selectivity.

The gas–water interface plays an important role in the photocatalytic degradation of volatile organic compounds (VOCs). Herein, a novel photocatalytic reactor with a tunable gas–water interface was designed and utilized to investigate the performance of photocatalytic degradation of VOCs. The relationship between the key operating parameters of the reactor and VOCs mineralization was investigated in detail with toluene as a model pollutant. The results showed that a tunable gas–water interface was formed in the process of atomized spray photocatalytic oxidation. Furthermore, the photocatalyst was easily excited by light, generating more free radicals, which was conducive to improving the mineralization performance of toluene and the durability of the catalyst. The intermediates of the toluene reaction were analyzed by photoacoustic spectroscopy (PAS), total organic carbon (TOC), and electrospray ionization–ion trap mass spectrometry (ESI–MS). The results show that abundant hydroxyl radicals are formed at the gas–water interface, which is beneficial to the opening of the benzene ring and greatly reduces the formation of toxicity and byproducts. Simultaneously, we investigated the degradation performance of acetone, formaldehyde, and n-hexane in the reactor. This provides a new strategy for using photocatalytic technology to purify industrial flue gas and indoor air.