The direct redox reaction (galvanic displacement) between Pd2+ and substrate Si was used to deposit Pd on Si, and the Pd–Si catalysts enabled a chemoselective hydrogenation of para-chloronitrobenzene with the selectivity for para-chloroaniline higher than 99.9% at complete conversion of para-chloronitrobenzene.

Mesoporous tantalum phosphates (TaOPO4-m) with varying P/Ta molar ratios (m = 0.41–0.89) were prepared, comprehensively characterized by ICP-AES, N2 physisorption, small-angle XRD, TEM, Raman, FT-IR, NH3-TPD and IR of pyridine adsorption and employed to catalyze the dehydration of xylose to produce furfural in a biphasic batch reactor. The physicochemical properties of these TaOPO4-m samples were affected significantly by variation of m. More ordered mesopores were formed in the sample with a higher m. On the other hand, the density of acidity decreased but the ratio of Brønsted acidity to Lewis acidity (B/L) increased with the increase in m. TaOPO4-0.84, which showed adequate mesoporosity and a high B/L ratio, was identified as the best performing catalyst among these TaOPO4-m catalysts in terms of high furfural selectivity (ca. 72 mol%). Correlating the catalyst performance with its acid property showed that the xylose consumption rate decreased with the increasing B/L ratio, while furfural selectivity showed a volcano-type dependence on the B/L ratio. Besides, the huge decrease in the furfural selectivity after poisoning the Brønsted acid sites by adding 2,6-dimethyl pyridine revealed a kind of Brønsted acid catalysis for selective furfural production.

Effects of the crystalline structure and surface property of the Al2O3 support on the NOx storage and reduction (NSR) performance of Pt–BaO/Al2O3 catalysts were studied using catalysts prepared from a series of Al2O3 samples obtained by varying the calcination temperature of an Al(OH)3 hydrogel in the range of 450–1000 °C (referred to as the pre-calcination temperature, PCT). The texture, crystalline structure and surface acidity of the Al2O3(PCT) supports were measured employing nitrogen adsorption–desorption, XRD, NH3-TPD and IR spectroscopy of adsorbed pyridine, respectively. The Al2O3(PCT) samples showed a gradual ordering of the γ-Al2O3 phase when increasing the PCT from 450 to 800 °C, and a phase transition from the γ- to θ-Al2O3 phase upon further increasing the PCT to 1000 °C. The surface density of Lewis acid sites of the Al2O3(PCT) samples exhibited a maximum at PCT in the range of 800–900 °C. The NSR performance of Pt–BaO/Al2O3 catalysts derived from the Al2O3(PCT) samples was studied under cyclic lean/rich conditions. The numbers of NOx stored and reduced on the Pt–BaO/Al2O3(PCT) catalysts showed similar volcano-type dependencies on PCT, peaking at PCT = 800 °C. The origins of the support PCT effect were discussed in the light of Pt particle size, the nature of BaO sites and Pt–BaO synergy. It was found that the increase in the crystallinity of the γ-Al2O3 phase and the surface acid site density of the supporting Al2O3 samples would result in improved proximity and synergy between Pt and BaO sites, leading to much more efficient NSR Pt–BaO/Al2O3 catalysts.

•Ni–Co/Si3N4 catalysts are prepared via reactions between metal halides and Si3N4.•Bimetallic Ni–Co nanoparticles encapsulated by a SiNx layer structures are formed.•The 4.0Ni–3.6Co/Si3N4 catalyst enables stable and coke-free CO2 reforming of CH4.A series of Ni–Co/Si3N4 catalysts with different Ni/Co ratios were prepared via reactions between commercial silicon nitride (Si3N4) and metal halides (i.e., NiCl2 and CoF3) at high temperature (930 °C). By using X-ray diffraction and electron microscopy, it was shown that this method of catalyst preparation leads to formation of bimetallic Ni–Co nanoparticles encapsulated by a SiNx layer (Ni–Co@SiNx) on supporting Si3N4 material. The 4.0Ni–3.6Co/Si3N4 catalyst was highlighted by showing highly stable catalysis for stoichiometric CO2 reforming of methane under widely varied reaction conditions, and was found completely free of coke formation after CRM reaction for 100 h.

The direct redox reaction (galvanic displacement) between Pd2+ and substrate Si was used to deposit Pd on Si, and the Pd–Si catalysts enabled a chemoselective hydrogenation of para-chloronitrobenzene with the selectivity for para-chloroaniline higher than 99.9% at complete conversion of para-chloronitrobenzene.

Effects of the crystalline structure and surface property of the Al2O3 support on the NOx storage and reduction (NSR) performance of Pt–BaO/Al2O3 catalysts were studied using catalysts prepared from a series of Al2O3 samples obtained by varying the calcination temperature of an Al(OH)3 hydrogel in the range of 450–1000 °C (referred to as the pre-calcination temperature, PCT). The texture, crystalline structure and surface acidity of the Al2O3(PCT) supports were measured employing nitrogen adsorption–desorption, XRD, NH3-TPD and IR spectroscopy of adsorbed pyridine, respectively. The Al2O3(PCT) samples showed a gradual ordering of the γ-Al2O3 phase when increasing the PCT from 450 to 800 °C, and a phase transition from the γ- to θ-Al2O3 phase upon further increasing the PCT to 1000 °C. The surface density of Lewis acid sites of the Al2O3(PCT) samples exhibited a maximum at PCT in the range of 800–900 °C. The NSR performance of Pt–BaO/Al2O3 catalysts derived from the Al2O3(PCT) samples was studied under cyclic lean/rich conditions. The numbers of NOx stored and reduced on the Pt–BaO/Al2O3(PCT) catalysts showed similar volcano-type dependencies on PCT, peaking at PCT = 800 °C. The origins of the support PCT effect were discussed in the light of Pt particle size, the nature of BaO sites and Pt–BaO synergy. It was found that the increase in the crystallinity of the γ-Al2O3 phase and the surface acid site density of the supporting Al2O3 samples would result in improved proximity and synergy between Pt and BaO sites, leading to much more efficient NSR Pt–BaO/Al2O3 catalysts.