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[Display omitted] • Pd@K-Silicalite-1 is prepared by the encapsulation strategy with K modification. • Pd@K-Silicalite-1 can completely remove HCHO at room temperature. • The addition of K induces the formation of Si-O-K-Pd and increases alkali sites. • Pd@K-Silicalite-1 possesses high dispersion and small size of Pd nanoparticles. • Pd@K-Silicalite-1 exhibits strong HCHO adsorption capacity. The Silicalite-1-encapsulated Pd catalyst with alkali metal K modification (Pd@K-Silicalite-1) was prepared via the hydrothermal method with ethylenediamine as ligand and KOH as precursor of K promoter. The introduction of K partially replaced H of silanol in Silicalite-1 and induced the formation of Si-O-K-Pd species, which were beneficial for the improvement of Pd dispersion. The Pd nanoparticles with a size of ca. 1.9 nm were uniformly encapsulated in the matrix of Silicalite-1 zeolite. The catalytic activity of Pd@K-Silicalite-1 was much better than those of Pd/Silicalite-1 and Pd@Silicalite-1 for HCHO oxidation, HCHO conversion could reach 100 % over Pd@K-Silicalite-1 (Pd content = 0.15 wt%) at room temperature under space velocity (SV) of 120,000 mL/(g × h) and relative humidity (RH) of 35 %. Based on the results of various characterization techniques, one can conclude that the improvement in catalytic activity of Pd@K-Silicalite-1 was attributable to high dispersion and small size of Pd NPs and enhanced HCHO adsorption capacities. In addition, we investigated the reaction mechanism of HCHO oxidation over the Pd@K-Silicalite-1 catalyst by in situ DRIFTS spectra. This work provides some guidance on developing high-performance catalysts for HCHO elimination via in situ encapsulation and alkali metal modification. [ABSTRACT FROM AUTHOR]

Developing novel photocatalysts for green synthesis of important organic intermediates under mild conditions is of great significance in industry. In this work, we synthesized the oxygen‐deficient three‐dimensionally ordered macroporous (3DOM) BiVO4‐supported nanosized Ru (xRu/3DOM BiVO4, x=0.24–2.16 wt %) catalysts by the polymethyl methacrylate‐templating, ethylene glycol reduction, and post‐thermal treatment methods. Physicochemical properties of the materials were characterized using the various techniques, and their catalytic activities for the visible‐light‐driven selective oxidation of benzyl alcohol to benzaldehyde were measured. It is found that the Ru nanoparticles (NPs) with a size of 1.2–1.5 nm were uniformly dispersed on the surface of 3DOM BiVO4, which gave rise to a significant enhancement in photocatalytic activity. Benzyl alcohol conversion first went up and then dropped down with the rise in loading of Ru NPs. The 0.95Ru/3DOM BiVO4−Ar‐300 sample was thermally treated in an Ar flow at 300 °C for 4 h showed the highest benzyl alcohol conversion (78 %) with a benzaldehyde selectivity of 100 % (benzaldehyde formation rate was 1380 μmol/(g h) after 6 h of illumination) and good photocatalytic stability. The high dispersion of Ru NPs and formation of oxygen vacancies in 3DOM BiVO4 improved separation and transfer efficiency of the photogenerated electrons/holes and increased the superoxide radical concentration. In addition, the possible mechanism of benzyl alcohol oxidation over 0.95Ru/3DOM BiVO4−Ar‐300 was also discussed. The oxygen‐deficient 3DOM BiVO4‐supported Ru NPs have promising applications for selective oxidation of organics. [ABSTRACT FROM AUTHOR]

[Display omitted] • 0.1Ru1Mn/ZSM-5 possesses strong acidity and redox ability due to highly dispersed Ru-Mn bimetallic nanoparticles. • 0.1Ru1Mn/ZSM-5 shows the best catalytic activity for 1,2-dichloroethane oxidation. • The double synergies of Ru-Mn bimetal and redox ability-acidity promote chlorine resistance ability. • Vinyl alcohol was the vital intermediates for 1,2-DCE oxidation to CO 2 and H 2 O. Ru-Mn bimetallic catalyst supported on HZSM-5 was prepared by impregnation method for catalytic oxidation of 1, 2-dichloroethane (1, 2-DCE). The 0.1Ru1Mn/ZSM-5 catalyst exhibited the lowest T 90 of 241 °C and the highest yields of HCl (75%) and CO 2 (57%). The products contained a small amount of dichloroethylene, trichloroethylene, and tetrachloroethylene, with a total yield of <5%. By the characterizations of various instruments, it was found that 0.1Ru1Mn/ZSM-5 exhibited the best catalytic activity because of its rich acidity, high redox property, and highly dispersed Ru and Mn nanoparticles on the surface of HZSM-5. Furthermore, due to the synergies of Ru-Mn bimetal and redox ability-acidity, 0.1Ru1Mn/ZSM-5 exhibited excellent chlorine resistance ability and good catalytic activity during long-term test. The reaction mechanism of catalytic oxidation of 1, 2-DCE was investigated using in situ DRIFTS and GC–MS techniques. Vinyl alcohol was the vital intermediate s for 1, 2-DCE oxidation to CO 2 and H 2 O. The double synergistic strategy can provide a reference for designing catalysts to remove chlorinated volatile organic compounds. [ABSTRACT FROM AUTHOR]

x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 (x = 0.56–1.98 wt%, z = 1.9–2.1, and y = 4.80–24.36 wt%) samples are prepared using PMMA-templating, incipient wetness impregnation, and PVA-protected reduction methods. The good performance for methane combustion of 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 is related to its high O ads species concentration, good low-temperature reducibility, and strong interaction between Co 3 O 4 or AuPd 2.1 NPs and 3DOM MnCo 2 O 4. [Display omitted] • 3DOM MnCo 2 O 4 is fabricated using the PMMA-templating method. • 18.20Co 3 O 4 /3DOM MnCo 2 O 4 is obtained by the incipient wetness impregnation method. • 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 is prepared via the PVA-protected reduction route. • 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 perform the best for methane combustion. • O ads concentration, reducibility, and AuPd 2.1 or Co 3 O 4 and MnCo 2 O 4 interaction govern activity. Three-dimensionally ordered macroporous (3DOM) MnCo 2 O 4 -supported Co 3 O 4 and AuPd (x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 ; x = 0.56–1.98 wt%, z = 1.9–2.1, and y = 4.80–24.36 wt%) catalysts were prepared using polymethyl methacrylate (PMMA) microsphere-templating, incipient wetness impregnation, and polyvinyl alcohol (PVA)-protected reduction methods. Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for methane combustion. It is found that the x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 samples with a surface area of 26.5–53.1 m2/g possessed a high-quality 3DOM architecture, in which the AuPd nanoparticles (NPs) with a size of 4.6–5.8 nm were highly dispersed on the surface of the macropore framework. Among all of the samples, 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 exhibited the highest catalytic activity: the T 10% , T 50% , and T 90% (temperatures required for achieving methane conversions of 10, 50, and 90 %, respectively) were 262, 340, and 408 °C at a space velocity of 40,000 mL/(g h). Partial deactivation of the 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 sample due to introduction of water vapor or carbon dioxide was reversible. It is concluded that the good catalytic performance of 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Co 3 O 4 or AuPd 2.1 NPs and 3DOM MnCo 2 O 4. [ABSTRACT FROM AUTHOR]

The PtRu NPs partially embedded in the skeleton of 3DOM Ce 0.7 Zr 0.3 O 2 (CZO) are prepared using the PMMA-templating and EG reduction methods. The embedded structure facilitates formation of a more amount of Pt O Ce-like bonds via the strong interaction between PtRu NPs and 3DOM CZO, hence contributing to the good thermal stability in toluene combustion. • 1.98PtRu@3DOM CZO is prepared via the PMMA-templating and EG reduction routes. • PtRu nanoparticles (NPs) are partially embedded in the skeleton of 3DOM CZO. • Ru promotes enhancement in low-temperature reducibility and oxygen adsorption ability. • Good toluene and oxygen adsorption ability contribute to high activity of 1.98PtRu@3DOM CZO. • Formation of PtRu NPs–3DOM CZO interfaces and Pt O Ce-like bonds is responsible for good stability. We successfully prepared 1.98 wt% PtRu nanoparticles (NPs) partially embedded in the skeleton of three-dimensionally ordered macroporous Ce 0.7 Zr 0.3 O 2 (denoted as 1.98PtRu@3DOM CZO) using the polymethyl methacrylate-templating and ethylene glycol reduction methods. For comparison purposes, we also synthesized a 3DOM CZO-supported 2.03 wt% PtRu catalyst (denoted as 2.03PtRu/3DOM CZO) via a colloidal adsorption route. The 1.98PtRu@3DOM CZO sample exhibited better performance than the Pt or Ru NPs partially embedded in the skeleton of 3DOM CZO. Ru played an important role in promoting the low-temperature reducibility and oxygen adsorption ability of the sample. The catalytic activity of 2.03PtRu/3DOM CZO was better than that of 1.98PtRu@3DOM CZO (Δ T 90% = 23 °C) for toluene combustion, and the former showed lower apparent activation energy (45 kJ/mol). However, 1.98PtRu@3DOM CZO possessed excellent thermal stability, over which the activity did not change obviously, while that over 2.03PtRu/3DOM CZO decreased greatly; furthermore, the catalytic activity of the former was superior to that of the latter after calcination at 800 °C for 5 h. After high-temperature treatment, the average particle size of PtRu NPs in 1.98PtRu@3DOM CZO increased slightly from 4.2 to 6.7 nm, whereas that of PtRu NPs in 2.03PtRu/3DOM CZO increased significantly from 5.1 to 17.3 nm. It is concluded that the good performance of 1.98PtRu@3DOM CZO is associated with its highly dispersed partially embedded PtRu NPs and good toluene and oxygen adsorption ability, since the embedded structure facilitated formation of a larger amount of Pt O Ce-like bonds that possessed strong interaction between PtRu NPs and 3DOM CZO and hence contributed to its better thermal stability. [ABSTRACT FROM AUTHOR]

The 3DOM x Cr 2 O 3 −CeO 2 (x is the Cr 2 O 3 weight percentage (wt%)) samples are prepared using the polymethyl methacrylate-templating method. The good catalytic stability and Cl−-resistant ability of 3DOM 5.5Cr 2 O 3 −CeO 2 is associated with the strong interaction between Cr 2 O 3 and CeO 2. • 3DOM x Cr 2 O 3 −CeO 2 is prepared via the polymethyl methacrylate-templating route. • 3DOM 5.5Cr 2 O 3 −CeO 2 shows the best catalytic activity for trichloroethylene oxidation. • 3DOM 5.5Cr 2 O 3 −CeO 2 exhibits good catalytic stability and Cl−-resistant ability. • The strong Cr 2 O 3 −CeO 2 interaction is responsible for the good stability. Three-dimensionally ordered macroporous (3DOM) CeO 2 , 3DOM Cr 2 O 3 , 3DOM x Cr 2 O 3 −CeO 2 (x (the weight percentage of Cr 2 O 3) = 3.5, 5.5, and 8.0 wt%), and 5.5 wt% Cr 2 O 3 /3DOM CeO 2 samples were prepared using the polymethyl methacrylate (PMMA)-templating and incipient wetness impregnation methods, respectively. A number of techniques were used to characterize physicochemical properties of the materials, and their catalytic activities were evaluated for the oxidation of trichloroethylene (TCE). These samples possessed a good-quality 3DOM structure and a surface area of 35−47 m2/g. The 3DOM 5.5Cr 2 O 3 −CeO 2 sample performed the best (the temperature at TCE conversion = 90% = 255 °C at a space velocity of 20,000 mL/(g h)). Effects of water vapor and carbon dioxide on activity of the 5.5Cr 2 O 3 −CeO 2 sample were also examined. It is observed that partial deactivation induced by H 2 O introduction of the 5.5Cr 2 O 3 −CeO 2 sample was reversible, while that induced by CO 2 addition was irreversible. Based on the activity data and characterization results, it is concluded that the good catalytic activity and thermal stability of 3DOM 5.5Cr 2 O 3 −CeO 2 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Cr 2 O 3 and CeO 2. We believe that the 3DOM 5.5Cr 2 O 3 −CeO 2 catalyst is promising in the application for oxidative removal of chlorinated volatile organic compounds. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • One-pot synthesis allows generation of Ni catalysts supported on MgO. • Effect of group VIB metal addition to Ni/MgO on catalytic activity is examined. • The Ni−Cr/MgO catalysts exhibit high catalytic activity and stability. Abstract Mesoporous 55 wt.% Ni/MgO and group VIB metal (Cr, Mo or W)-doped catalysts were prepared using the facile "one-pot" evaporation-induced self-assembly in ethanol and wetness impregnation methods, respectively. Physicochemical properties of the as-prepared catalysts were characterized by means of the BET, XRD, SEM, TEM, HAADF, XPS, H 2 -TPR, TPO, and Raman techniques. The doping of Cr to 55 wt% Ni/MgO improved catalytic activity and stability for the decomposition of methane under harsh reaction conditions. The maximal initial methane conversions of 80, 87, and 75% were achieved over the 55 wt.% Ni− x Cr/MgO (denoted as 55Ni− x Cr/MgO; x = 5, 10, and 15 wt.%) at 675 oC and GHSV = 48,000 mL/(g h), respectively. It is concluded that the high catalytic efficiency of the Cr-doped sample in methane decomposition was associated with its high surface area, high oxygen adspecies concentration, and good low-temperature reducibility. In addition, multi-walled carbon filaments with metal-encapsulated carbon particles were deposited on the Cr-doped catalysts, and the ordered carbon filaments with different diameters and good crystallinity were produced on the surface of the 55Ni−10Cr/MgO catalyst. [ABSTRACT FROM AUTHOR]

Abstract The concurrent production of CO x -free hydrogen and multi-walled carbon filaments by thermocatalytic decomposition of methane is advantageous in the environmental and energy catalysis. In the present work, a facile "one-pot" evaporation-induced self-assembly strategy was effectively adopted to fabricate the nickel catalysts supported on mesoporous Al 2 O 3 , SiO 2 , TiO 2 , and MgO, and their catalytic activities for methane decomposition were evaluated for the first time. The structural, textural, and redox properties of the as-obtained materials were characterized using a number of analytical techniques. The nitrogen sorption analysis indicated the presence of a mesoporous structure due to homogeneous aggregation of the catalyst particles with a high specific surface area of 32–236 m2/g. Among all of the catalysts, Ni/MgO exhibited the best catalytic activity for methane decomposition (65% methane conversion at 600 °C and GHSV of 48,000 mL/(g h)). The activity increased when Ni loading increased from 25 to 55 wt%. The investigation on the correlation between catalytic performance and promoter doping effect suggests that incorporating copper into the MgO support considerably enhanced the catalytic activity and stability at high temperatures. The XPS results reveal that doping of Cu to Ni/MgO enhanced the adsorption and activation of oxygen molecules. In addition, the disordered crystalline carbon filaments with different diameters and good crystallinity were generated on the surface of the Cu-doped Ni/MgO catalysts. Graphical abstract Unlabelled Image Highlights • The work is focused on pure hydrogen production via catalytic CH 4 decomposition. • One-pot synthesis allows to prepare Ni catalysts supported on various metal oxide. • The catalysts were characterized for their physicochemical properties and activity. • The Ni supported on MgO shows a higher activity than that supported on other metal oxides. • Effect of Ni content and Cu addition in Ni/MgO were investigated in detail. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporous (3DOM) CoFe 2 O 4 , z MnO x /3DOM CoFe 2 O 4 ( z = 4.99–12.30 wt%), and y Pd–Pt/6.70 wt% MnO x /3DOM CoFe 2 O 4 ( y = 0.44–1.81 wt%; Pd/Pt molar ratio = 2.1–2.2) have been prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and bubble-assisted polyvinyl alcohol-protected reduction strategies, respectively. All of the samples were characterized by means of various techniques. Catalytic performance of the samples was measured for methane combustion. It is shown that the as-prepared samples exhibited a high-quality 3DOM structure (103 ± 20 nm in pore size) and a surface area of 19–28 m 2 /g, and the noble metal or alloy nanoparticles (NPs) with a size of 2.2–3.0 nm were uniformly dispersed on the macropore wall surface of 3DOM CoFe 2 O 4 . The loading of MnO x on CoFe 2 O 4 gave rise to a slight increase in activity, however, the dispersion of Pd–Pt NPs on 6.70MnO x /3DOM CoFe 2 O 4 significantly enhanced the catalytic performance, with the 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 sample showing the highest activity ( T 10% = 255 °C, T 50% = 301 °C, and T 90% = 372 °C at a space velocity of 20,000 mL/(g h)). We believe that the excellent catalytic activity of 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 was related to its well-dispersed Pd–Pt alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between MnO x or Pd–Pt NPs and 3DOM CoFe 2 O 4 . [ABSTRACT FROM AUTHOR]