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To solve serious energy and environmental crises caused by rapid industrial development, the formation of heterostructured photocatalysts is a promising approach for efficient and scalable H2 produ...

PtSnNa/γ-Al2O3 catalyst is widely used in the dehydrogenation of light alkane. This paper reports a new fabrication method of the catalyst. In the work, γ-Al2O3, SnCl4 and NaCl were ball milled to upload Sn and Na+ onto the support instead of the conventionally used immersion method. The subsequent baking procedures frimly fixed Sn onto the support, which could disperse Pt introduced by immersion. The effects of Sn and Na+ additives on the catalytic performance of PtSnNa/γ-Al2O3 catalyst were investigated. It was found that the appropriate molar ratio of Sn/Pt was 6:1 while the favorable weight percentage of Na+ was 0.90%. Compared with the reaction catalyzed by the industrially employed PtSnNa/γ-Al2O3 catalyst, the conversion of propane and the selectivity of propylene had been greatly improved, which were 26.97% and 99.18% respectively after 12 h reaction.

A novel dual bed reactor packed with a combination of a zeolite (H-modernite or H-ferrierite) catalyst and a CuZnAl catalyst was proposed to realize direct ethanol (EtOH) synthesis from dimethyl ether (DME) and syngas (CO + H2). DME and CO were firstly introduced into the upper zeolite bed to commence the carbonylation reaction, and then H2 was directly introduced into the CuZnAl catalyst bed below to accomplish the hydrogenation of methyl acetate (MA) produced at the first catalyst bed. In this novel dual bed process, DME and CO were introduced into the reactor at the top of the first catalyst bed layer, but H2 was introduced into the second catalyst bed layer directly through an inner stainless steel tube equipped with evenly distributed holes. Benefitting from the precise control of the distribution of the reactants on the surface of different catalysts, an enhanced catalytic performance was obtained compared with the conventional dual bed reactor which introduced DME and syngas into the reactor simultaneously. The synergistic effects offered by this novel dual bed reactor were further confirmed by numerous comparative tests. Our results show that the excellent catalytic performance in this novel dual bed reactor was ascribed to the improved CO partial pressure in the upper zeolite catalyst bed. Compared with the conventional dual bed reactor, both DME conversion and EtOH yield were almost doubled in this novel dual bed reactor packed with the combination of the H-ferrierite and CuZnAl catalysts.

The covalent triazine frameworks (CTFs) have recently become a new generation of organic semiconductor for photocatalytic hydrogen production from water splitting because of their great application potentials. However, the CTFs need to be combined with noble-metal-cocatalysts to achieve photocatalytic water splitting. Herein, we reported the noble-metal-free Ni2P/CTF composites as an efficient catalyst for photocatalytic hydrogen evolution. With increasing the Ni2P alloy loading on the surface of CTF, the photocatalytic activity increases obviously and then decreases gradually, and the highest photocatalytic H2 evolution rate is achieved for 2.8%Ni2P/CTF, which is almost the same as that of 3.0%Pt/CTF photocatalyst. It has been revealed that the Ni2P alloy act as a cocatalyst for effectively suppressing the recombination of photogenerated electrons and holes, promoting the separation and migration of the charge carriers, thereby improving the efficiency of photocatalytic H2 evolution. This work provides a promising strategy for preparation of cheap and stable photocatalytic system based on CTF for efficient photocatalytic hydrogen evolution under visible-light irradiation.

A novel honeycomb-shaped PtSnNa/γ-Al2O3/cordierite monolithic catalyst (Pt 0.5%, Sn 0.9%, Na 1.0%, relative to Al2O3 weight) was developed and its catalytic performances in propane dehydrogenation were tested and compared with the classical granule catalyst with same Pt, Sn and Na contents under the conditions of 0.1 MPa, 590 °C, C3H8/H2 at 3/1 (molar ratio) and gas hourly space velocity (GHSV) at 155 h−1. Interestingly, despite the generated coke amount and exposed Pt fraction, the honey comb-shaped structure of monolithic catalyst exerted important influences on its catalytic activities and led to the advanced catalytic performances over the granule catalyst.

MnOx/TiO2 (anatase) nanosheets (NS) with a preferentially exposed {001} facet was found to be a better catalyst for selective catalytic reduction (SCR) of NO than conventionally employed MnOx/TiO2 nanoparticles (NP) with the {101} facet preferentially exposed, affording both high NO conversion and high N2 selectivity at 80–280 °C. Further investigations indicated that Mn3+ as the major species on TiO2 (NS) was incorporated into octahedral vacancies with a lower polymerization degree, resulting in high catalytic activity for SCR and low activity for NH3 oxidation, thus restraining the undesirable N2O generation. In comparison, on the surface of TiO2 (NP), Mn4+ as the major species was incorporated into tetrahedral vacancies in a highly polymerized state, leading to lower NO conversion and lower N2 selectivity. The results indicate that it is possible to enhance the low-temperature SCR activity of the catalysts by tailoring the preferentially exposed facet of TiO2.

BiOI/ZnSn(OH)6 composite photocatalysts with different weight percents of BiOI were successfully synthesized by a facile and economical deposition method at 80 °C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and Brunauer–Emmett–Teller (BET) surface area measurements. Photocatalytic reforming of ethanol for H2 production and photocatalytic degradation of phenol over BiOI/ZnSn(OH)6 samples were investigated. The results showed that the BiOI/ZnSn(OH)6 photocatalysts exhibited a coexistence of both tetragonal BiOI and cubic perovskite ZnSn(OH)6 phases. With increasing BiOI content, the absorption intensity of BiOI/ZnSn(OH)6 increased in the 280–550 nm region and the absorption edge shifted significantly to longer wavelengths compared with that of pure ZnSn(OH)6. The 19.7% BiOI/ZnSn(OH)6 catalyst exhibited obviously higher photocatalytic activity as compared to either pure ZnSn(OH)6 or BiOI, which could be primarily attributed to the presence of intimate contacts between ZnSn(OH)6 and BiOI resulted in easier charge transfer and more efficient separation of electron–hole pairs. The photocatalytic mechanism of BiOI/ZnSn(OH)6 was discussed.

The mixed-phase TiO 2 photocatalysts with different anatase/rutile/brookite ratios and high specific surface area (157–218 m 2 /g) were prepared by hydrothermal method at 100 °C and the effect of rutile content in TiO 2 on the BET surface area, light absorption and separation efficiency of photogenerated charge carriers was studied and correlated to the photocatalytic activity of TiO 2 . Rutile content increased from 0% to 100% by increasing the amount of TiCl 4 in aqueous phase and the initial pH value of reaction solution played an important role in the phase composition of TiO 2 . The photocatalytic mechanism of mixed-phase TiO 2 was discussed.

The Cu 2+ –MCM-41 mesoporous materials with different loadings of copper species in the framework have been prepared by hydrothermal method and characterized by using various physico-chemical methods combined with the selective catalytic reduction of NO by NH 3 . It has been shown that the particle size of metallic copper formed after hydrogen reduction is much smaller than that in the supported catalysts prepared by impregnation method, and that the SCR activity of catalyst increases obviously with the increase of Cu content to 10 wt.% because of its higher dispersion of copper metal in the mesoporous catalyst even at higher Cu loading.

CSC (Chinese Scholar Council) [2009631048]; NSFC [20921120405, 21021002]; NSF [CHE-0923910]; DOE [DE-FG02-07ER15895]

The structure and catalytic properties of the supported Ni/γ-Al 2 O 3 catalyst prepared with different nickel salt precursors for hydrogenation of a-pinene have been studied using X-ray diffraction, UV–VIS diffuse reflectance spectroscopy, temperature-programmed reduction, CO chemisorption, and microreactor tests. It has been shown that the catalytic hydrogenation activity of the Ni/γ-Al 2 O 3 catalyst increases with increasing Ni loading, and the catalytic activity of the nickel acetate-derived Ni/γ-Al 2 O 3 catalyst is much higher than that of the nickel nitrate-derived catalyst. The catalyst characterization results indicate that the different catalytic hydrogenation activity of Ni/γ-Al 2 O 3 prepared with different nickel salt precursors is correlated to the different ratio of Ni 2+ ions in the tetrahedral and octahedral vacancies of γ-Al 2 O 3 and the different reduction degree of the NiO/γ-Al 2 O 3 precursors. When the nickel ion loading is far below the dispersion capacity, the supported nickel ions preferentially incorporate into the tetrahedral vacancies of γ-Al 2 O 3 . With increasing nickel loading, the ratio of Ni 2+ ions that incorporate into the octahedral vacancies of γ-Al 2 O 3 increases. The dispersion capacity of nickel ions on γ-Al 2 O 3 derived from nickel acetate is lower than that of the sample derived from nickel nitrate due to the greater shielding effect of acetate anions than nitrate anions. Moreover, the ratio of octahedral Ni 2+ to tetrahedral Ni 2+ on the nickel acetate-derived sample is higher than that on the nickel nitrate-derived sample because of the lower density of octahedral vacancies on γ-Al 2 O 3 . As octahedral Ni 2+ ions are easier to be reduced to the metallic state than tetrahedral Ni 2+ ions, the catalytic activity of the Ni/γ-Al 2 O 3 catalyst prepared with the nickel acetate precursor is much higher than that of the catalyst prepared with the nickel nitrate precursor with the same nickel loading.

We theoretically demonstrate that the two-dimensional porous C2N sheet exhibits an extremely high selectivity and large permeance in favour of H2 among other atmospheric gases. This experimentally available porous C2N is superior to traditional membranes, such as polymers and silica, and could have great potential for hydrogen separation.

In situ EPR investigation by using CO as probe molecules shows that even pre-reduced by H 2 at lower temperature results in SMSI for anatase titania supported palladium catalyst, but not for rutile titania supported palladium catalyst. The reason of the different behavior between rutile and anatase titania supported palladium catalyst is discussed. The very different catalytic properties between anatase and rutile titania supported palladium catalyst pre-reduced at lower temperature, and the rapid change of conversion and selectivity of titania supported palladium catalyst with the elevation of pre-reduction temperature further confirm the above-mentioned results.

A large electrocaloric effect (ECE) near room temperature is reported in Sn doped BaTiO3 ceramics. By tuning Ba(Ti1−xSnx)O3 compositions which also exhibit relaxor ferroelectric response to near the invariant critical point, the Ba(Ti1−xSnx)O3 bulk ceramics at x ∼ 0.12 exhibit a large EC coefficient (ΔT/ΔE =0.27*10−6K⋅mV−1) over a 50 K temperature range. In addition to that, the diffuse phase transition is successfully applied to broaden the EC peaks under low electric field. These properties added together indicate a general solution of the electrocaloric materials with high performance for practical cooling applications.