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Monolithic catalysts with high catalytic activity bring about increasing interest in practical environmental purification field for volatile organic compounds (VOCs) degradation with low pressure drops. Monolithic CoMnAlO catalysts with varied Co/Mn molar ratio derived from in situ supported layered double hydroxides (LDH) film are prepared through ammonia hydrothermal growing on Al substrate following calcinations. The textural properties for CoMnAlO catalysts with low temperature reducibility, surface element species are controlled by tuning the initial Co/Mn molar ratio verified through H2-TPR and XPS spectra. CoMn2AlO film sample shows best activity with the temperature for 90% benzene decomposition (T90) around 238 °C with space velocity 300,000 ml gcat−1 h−1. The reaction rate of CoMn2AlO film is about 1.32 mmol gcat−1 h−1 at 260 °C with T99, which is nearly two times to that of Co3AlO film catalyst with 0.73 mmol gcat−1 h−1, because of the higher Mn4+/Mn3+ and Co3+/Co2+ atomic ratios and reducibility inducing by the synergistic effect of Co and Mn. The value is five times higher than CoMn2AlO powder catalyst with 0.26 mmol gcat−1 h−1, which is due to the great exposure active sites.

High reactivity and sintering resistance are key factors to design outstanding CH4 oxidation noble metal-based supported catalysts. Herein, we prepared and screened 0.5 wt% Pd/Al2O3 (among 0.3–3 wt% Pd loading) samples prepared by wet impregnation with very high CH4 catalytic activity. The hydrophobic modification of γ-Al2O3 support by triethoxyoctylsilane (TEOOS) exhibits further enhanced activity for CH4 oxidation, ca. T90 decrease from 375 °C to 350 °C with enhanced concentration of surface Pd0 sites. Besides, after Al2O3 protection layer deposition over the 0.5 wt% Pd/Al2O3 by atomic layer deposition (ALD), distinct higher temperature stability due to reduced agglomeration was demonstrated.

Herein, we reported the synthesis of well-defined Co3O4 nanoarrays (NAs) supported on a monolithic three-dimensional macroporous nickel (Ni) foam substrate for use in high-efficiency CO oxidation. The monolithic Co3O4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time, solvent polarity and deposition agent, these Co3O4 NAs catalysts exhibited various novel morphologies (single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co3O4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity (GHSV) 10,000 hr− 1 and 150°C with long-term stability. Compared with the other Co3O4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites (Co3 +/Co2 + = 1.26).

A series of V2O5/TiO2 catalysts with high vanadium loading (6.0 ∼ 43.9 wt%) were prepared by wet impregnation over metal–organic framework (MOF) MIL-125(Ti) support following calcination, and were tested for catalytic combustion of 100 ppm chlorobenzene. Taking advantage of MIL-125(Ti) with high surface area, copious catalytically active VOx species generated in the case of high vanadium loading, among which 0.4VTi, 0.6VTi and 0.8VTi showed 100% chlorobenzene conversion at 250 °C. The effect of vanadium loading on the catalysts have been characterized by means of XRD, SEM, TEM, ICP-OES, N2 adsorption–desorption at 77 K, Raman, NH3-TPD and H2-TPR. The reaction mechanism of chlorobenzene over the as-prepared catalysts was also proposed by in situ DRIFTS.

As an emerging p-conjugated materials, graphitic carbon nitride (g-C3N4) has captured worldwide attention due to impending energy crisis and increasingly serious environmental contamination. In this work, the two-dimensional (2D) MgFe mixed metal oxide (MMO) derived from the layered double hydroxides precursor was employed to construct 2D/2D nanosheet heterojunction with g-C3N4. The formed CN/MgFe-30 nanosheet heterojunctions exhibited the optimal photocatalytic hydrogen production about 6.64 times (1.26 mmol/g−1·h−1) than that of pure g-C3N4 under the visible light irradiation, which were attributed to unique inter-plane 2D/2D structure and excellent synergistic effect between g-C3N4 and MgFe MMO. The experiment characterization proved that MgFe MMO nanosheet not only suppressed the overgrowth of g-C3N4, resulting in the formation of nanoscale g-C3N4, but also facilitated the photoinduced carrier separation and transfer based on 2D/2D CN/MgFe-X nanosheet heterojunctions. This proposed synthesis strategy pave a way to realize the large-scale production of nano-g-C3N4 based 2D/2D nanosheet heterojunctions photocatalysts for hydrogen production.

The synthesis of effective and recyclable Fenton-like catalyst is still a key factor for advanced oxidation processes. Herein, magnetic porous Fe3O4/carbon octahedra were constructed by a two-step controlled calcination of iron-based metal organic framework. The porous octahedra were assembled by interpenetrated Fe3O4 nanoparticles coated with graphitic carbon layer, offering abundant mesoporous channels for the solid-liquid contact. Moreover, the oxygen-containing functional groups on the surface of graphitic carbon endow the catalysts with hydrophilic nature and well-dispersion into water. The porous Fe3O4/carbon octahedra show efficiently heterogeneous Fenton-like reactions for decomposing the organic dye methylene blue (MB) with the help of H2O2, and nearly 100% removal efficiency within 60 min. Furthermore, the magnetic catalyst retains the activity after ten cycles and can be easily separated by external magnetic field, indicating the long-term catalytic durability and recyclability. The good Fenton-like catalytic performance of the as-synthesized Fe3O4/carbon octahedra is ascribed to the unique mesoporous structure derived from MOF-framework, as well as the sacrificial role and stabilizing effect of graphitic carbon layer. This work provides a facile strategy for the controllable synthesis of integrated porous octahedral structure with graphitic carbon layer, and thereby the catalyst holds significant potential for wastewater treatment.

Ceria zirconia solid solution with high oxygen storage capacity (OSC) and thermal stability under 1000 ​°C is quite important for support materials in three-way catalysts (TWCs). In this work, Ce1-xZrxO2 with different Zr dopants (x ​= ​0, 0.125, 0.250 and 0.375) have been prepared by flame spray pyrolysis (FSP) with carboxylic acid or ethanol and carboxylic acid (v:v 1:4) solvents. The influences of Zr content and the addition of ethanol into carboxylic acid on the OSC performance and thermal stability have been systematically characterized by X-ray diffraction (XRD), N2 adsorption-desorption, Raman analysis, field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS), hydrogen-temperature programmed reduction (H2-TPR), and pulse thermal analysis using H2 as reducing agent. The presence of cubic-tetragonal interfaces in the Ce0.750Zr0.250O2 sample can enhance the formation of oxygen vacancies and the mobility of lattice oxygen in ceria-zirconia solutions, which results in the largest OSC (349 ​μmol ​g−1) among the fresh samples. The cubic-tetragonal interfaces in the Ce0.750Zr0.250O2 sample can also promote the thermal stability under 1000 ​°C to preserve better OSC (202 ​μmol ​g−1) than other aged samples. Furthermore, after adding with ethanol into carboxylic acid solvent, the OSC of the sample further increases to 371 ​μmol ​g−1 for the increment of oxygen vacancy concentration. It is worthy to note that the introduction of ethanol can suppress Zr migration from the lattice to the surface of CeO2 at high temperature, further enhancing OSC (240 ​μmol ​g−1) and thermal stability.

Particulate matter (PM) from cooking has caused seriously indoor air pollutant and aroused risk to human health. It is urged to get deep knowledge of their spatial-temporal distribution of source emission characteristics, especially ultrafine particles (UFP

Ce/MnAl and MnAl mixed metal oxides catalysts have been obtained by calcination of layered double hydroxides precursors. The composite oxides catalysts were studied in total oxidation of benzene. Physicochemical properties of all the catalysts were characterized by using a series of specific analytical techniques. The results revealed that the 0.2Ce/MnAl catalyst exhibited the highest catalytic performance with T90 about 210 °C at a high space velocity (SV = 60,000 mL g− 1 h− 1), ascribed to its lower-temperature reducibility, the abundant surface lattice oxygen (Olatt), and synergetic effect between Mn4 + and Ce3 +/Ce.

Metal oxides like MnO2, Co3O4 and NiO were fabricated by controlling decomposition of metal salt precursor in the presence and absence of restrictive nanoreactor. The growth of oxide crystals was inhibited in restrictive space provided by hard template (nanocasting), which made the catalysts possess smaller crystal size, higher surface area and better low-temperature reducibility. Significantly, nanocasting-derived oxides (MnO2, Co3O4 and NiO) performed much better for catalytic total oxidation of benzene with T90% at 289, 253 and 355 degrees C, which are 125,41 and 61 degrees C lower than that over the general oxides prepared by direct calcination. (C) 2015 Elsevier B.V. All rights reserved.

Porous and dispersed CuCo-based mixed metal oxides catalysts (denoted as CuxCo3−xAl-MMO) are obtained via the calcination of ternary CuxCo3−xAl-layered double hydroxide (LDH) precursors, which exhibit excellent catalytic activity towards complete oxidation of benzene. The Cu0.5Co2.5Al-MMO sample shows the maximum activity of 2.41 mmol g cat − 1 h − 1 with 90% benzene conversion at 290 °C at a high space velocity (SV = 60,000 mL g−1 h−1), comparable to that of only 8% conversion for Cu3Al-MMO sample. The significantly enhanced activity is correlated with higher surface area, narrower pore size, low-temperature reducibility and rich oxygen vacancies and lattice oxygen derived from the synergistic effect over porous and dispersive CuxCo3−xAl-MMO catalysts containing CuO and Co3O4 spinel mixed oxides verified by XRD, BET, H2-TPR, TEM and XPS measurements. Stability with prolonged time on benzene stream and the resistance to water vapor are further investigated. In addition, a monolithic CuCoAl-MMO film catalyst is fabricated by an in situ growth-calcination method, which displays comparable catalytic activity with CuxCo3−xAl-MMO powder. Therefore, this work provides a facile method for the preparation of CuCo-based catalysts with excellent characters responsible for better catalytic activities, which can be used as promising candidates for practical VOCs oxidation.

Mesoporous Cu-Mn oxides with high surface area (similar to 221 m(2) g(-1)) were successfully obtained through a simple co-nanocasting approach using siliceous SBA-15 mesoporous material as a hard template. Their catalytic performances for deep oxidation of benzene were tested and physicochemical properties were characterized in detail by means of N-2-physisorption, XRD, XPS, H-2-TPR, SEM-EDX and TEM. The asprepared mesoporous Cu-Mn oxides display superior catalytic activity and the temperature required for achieving a benzene conversion of 90% has been obtained at about 234 degrees C over sample Cu0.6Mn, which is 131 degrees C lower than that on the Cu-Mn oxide prepared by co-precipitation method using NaOH. The apparent activation energy over nanocasted catalyst was low to 45.0 kJ mol(-1.) Nanocasting process provides a limited nanoreactor for the formation of Cu-Mn composite oxide which makes the Cu-Mn oxides owing small particle size, high surface area, rich surface adsorbed oxygen species, low temperature reducibility and promoting interaction of Cu-Mn species. These characters generated by nanocasting method are responsible for its better catalytic activity. (C) 2014 Elsevier B.V. All rights reserved.

Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipitation/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs (benzene, toluene and ethyl acetate) were examined. The Mn-Ce oxalate precursor was obtained from metal salt and oxalic acid without any additives. The resulting materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), hydrogen temperature programmed reduction (H-2-TPR) and X-ray photoelectron spectroscopy (XPS). Compared with Mn-Ce composite oxide synthesized through a traditional method (Na2CO3 route), the hierarchical layer-stacking Mn-Ce composite oxide exhibited higher catalytic activity in the complete oxidation of volatile organic compounds (VOCs). By means of testing, the data revealed that the hierarchical layer-stacking Mn-Ce composite oxide possessed superior physiochemical properties such as good low-temperature reducibility, high manganese oxidation state and rich adsorbed surface oxygen species which resulted in the enhancement of catalytic abilities.

Mn-Co mixed oxide nanorod with porous structure and high surface area was fabricated by an oxalate route and further used for deep oxidation of VOCs. Compared to the single MnOx or Co3O4, the Mn-Co mixed oxide showed an enhanced activity for ethyl acetate and n-hexane oxidation with T-90% was low to 194 and 210 degrees C at a high space velocity, respectively. The formation of solid solution with spinel structure inhibits the growth of nanoparticles which leads to its higher surface area, and the strong synergistic effect of Mn-Co species in the oxide makes a great contribution to its low temperature reducibility which plays a key role in VOCs' oxidation. (C) 2014 Elsevier B.V. All rights reserved.

A low-temperature sol-gel process associated with different surfactants in ethanol solvent was applied to prepare ultrafine MnO2 nanowires and nanorods. The surfactants used in the synthesis procedure are crucial for the structure of products. Highly dispersed MnO2 nanowires was formed by assistance of cetyltrimethyl ammonium bromide while hierarchical particles assembled with nanowires were synthesized by usage of pluronic P123 triblock copolymer or Polyvinyl pyrrolidone. The free-standing sheet like structure aggregated with nanorods was obtained by using sodium dodecyl sulfate as a surfactant. All samples were characterized by SEM, TEM, XRD and the results indicated these MnO2 ultrafine nanostructures could be expediently produced by this facile method. (C) 2014 Elsevier B.V. All rights reserved.

2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonate) dye (ABTS) and dodecanesulfonate anion (SDS) have been co-intercalated into the ZnAl-layered double hydroxide (ZnAl LDH) matrix by a hydrothermal co-precipitation method, with obtained samples denoted as ABTS–SDS( x )/LDH ( x stands for the molar percentage content of ABTS with respect to total intercalated content). The structure and chemical composition of the as-prepared compounds were characterized by X-ray diffraction (XRD), FT-IR spectra and elemental analysis. Fluorescence spectra demonstrated that the sample with 60% ABTS molar percentage, exhibited the optimal luminescent intensity. The fluorescence lifetime of ABTS in the gallery of LDH was enhanced significantly compared with that of pristine ABTS powder. As well, the ABTS–SDS/LDH thin film fabricated by the solvent evaporation method exhibited a well-defined c -orientation, which can be confirmed by XRD and scanning electron microscopy (SEM). Moreover, the ABTS–SDS(60%)/LDH film showed polarized luminescence (anisotropy: 0.35) and electrochemical response to aqueous solution containing Pb 2+ ion. These results demonstrate that the ABTS–SDS/LDH system can serve as a good candidate for the solid-sate luminescence and electrochemical sensor materials.