The hierarchically structured zeolite with high surface area and a large number of mesoporosities has attracted tremendous attention. Particularly, the morphology and structural tailoring of a diverse mesoporous zeolite with a single template is regarded as a crucial step toward the realization of an environmentally friendly synthesis. Herein, crystalline silicoaluminophosphate (SAPO-5) of the AFI framework type with a bimodal pore system was hydrothermally synthesized using di-n-butylamine (DBA) as a single template. The structural and catalytic properties of the hierarchical SAPO-5 were extensively characterized and compared to those of a conventional SAPO-5 using triethylamine (TEA) as a template. After loading Pt nanoparticles by incipient wetness impregnation, due to the promoting effect of hierarchical SAPO-5 in which the reactant and product were rapidly contacted with the acidity sites and metal sites, the 0.5 wt% Pt/SAPO-5-1.0DBA catalyst exhibits an enhanced hydroisomerization performance, with heptane conversion of 76.1% and iso-C7 yields of 48.4%, compared to a conventional 0.5 wt% Pt/SAPO-5-1.0TEA catalyst. The crystallization evolution under a series of hydrothermal times was also studied here. More importantly, this green, sustainable and economical strategy will extend the application of the synthesis of a silicoaluminophosphate-based zeolite.

A simple and solvent-free solid-state method was used to prepare NiMo–Al2O3 hydrodesulfurization (HDS) catalysts using Ni(NO3)2·6H2O, (NH4)6Mo7O24·4H2O, and AlCl3·6H2O as the solid raw materials and polyethylene glycol (PEG) as an additive. The effects of PEG addition on the precursor thermal decomposition, catalyst properties and dibenzothiophene (DBT) HDS activity were investigated. The as-prepared catalysts were characterized by nitrogen adsorption–desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that an increase in PEG addition dramatically increases specific surface area and pore volume of the catalyst, and improves Mo sulfidability and active MoS2 dispersion by blocking the aggregation of metals, and consequently increases the number of HDS active sites. However, excess PEG leads to the decrease in specific surface area and pore volume attributed to the metal sintering caused by the strong heat release during thermal decomposition. As a result, dibenzothiophene HDS activity enhanced with increasing PEG addition and peaked at NiMoAl-15 (15% weight ratio of PEG to alumina), which exhibited a significantly higher activity as compared to the NiMo/Al2O3 catalyst prepared by wetness co-impregnation.

•The addition of La in Ru/Carbon fiber (Ru1La0.5/CF) enhances the catalytic activity, resulting into a maximum reaction rate of (216.1 μmol gcat−1 s−1) at 100 °C.•The increased reactivity was a consequence of the amount of Ru active site and the promoting effect of Ru-La interaction.•The exact nature of the promotional effect of La in the levulinic acid hydrogenation has been clarified.A series of La-modified Ru/carbon fiber (CF) catalysts was designed, and used for the conversion of levulinic acid (LA) into γ-valerolactone (GVL) under batch reactor conditions. The dopant of Lanthanum improved the hydrogenation activity from 37.7 μmol gcat−1 s−1 to 216.1 μmol gcat−1 s−1 when the mole La/Ru was 0.5 on the catalyst. Even in low temperatures, the Ru1La0.5/CF catalyst also showed a high activity in the hydrogenation of LA. Aiming at a detailed understanding the role of Ru-La interactions in the catalyst, the Ru1Lax/CF catalysts was characterized by the H2-TPR, H2-TPD, CO2-TPD, XPS, TEM and CO chemsorption. The electron density of Ru species has been enhanced by La addition to Ru/CF. The hydrogenation activity was a consequence of the amount of Ru active site and the promoting effect of Ru-La interaction.The analyses of characterization show that the Ru-La interaction facilities the levulinic acid hydrogenation and the reaction rate was a consequence of the amount of Ru active site and the promoting effect of Ru-La interaction.Download high-res image (113KB)Download full-size image

A dandelion-like SAPO-11 with multiple branches was fabricated by seed-induced steam-assisted conversion (SISAC), which combined an in situ inoculating seed method (in this case, the initial gel was pre-crystallized at 433 K for 24 h) and steam-assisted conversion (SAC) process. The dandelion-like SAPO-11 was fully crystalline and exhibited more acidity, external surface and mesopore volume compared with conventional hydrothermally crystallized SAPO-11, confirmed by Ar adsorption–desorption, pyridine-adsorbed infrared (Py-IR), 2,6-dimethylpyridine-adsorbed infrared (2,6-DMPy-IR) and NH3 temperature-programmed desorption (NH3-TPD). After loading Pt nanoparticles by incipient wetness impregnation, the morphological modification (benefiting from smaller nanobranches and introducing more external surface active sites) leads to enhanced heptane hydroisomerization activity of the dandelion-like Pt/SAPO-11 as great as 15.4% higher in comparison with a conventional Pt/SAPO-11 catalyst.

Hierarchical SAPO-11 was successfully synthesized without a secondary template by changing the hydrothermal crystallization temperature. SAPO-11 with a larger external surface area, more acidity, and a large number of external active sites was constructed through a novel two-step crystallization strategy. Both precrystallization step and the low-temperature crystallization step were confirmed to be indispensable conditions for constructing hierarchical SAPO-11. After loading Pt nanoparticles by incipient wetness impregnation, the heptane hydroisomerizations based on 0.5 wt% Pt/C-SAPO-11-200 and 0.5 wt% Pt/T-SAPO-11-120 catalysts were carried out in a fixed-bed at a total pressure of 1.5 MPa with a H2/n-heptane volumetric of 400 and WHSV = 10 h−1. A conversion level of 75.7% of 0.5 wt% Pt/T-SAPO-11-120 catalyst was reached, which was higher than that of 0.5 wt% Pt/C-SAPO-11-200 catalyst (64.3%) at 300 °C. The enhanced performance achieved was attributed to the improved effect of the support, in terms of not only better mass transport and higher number of exposure active sites but also improved dispersity and decrease in the size of Pt particles.

•Hierarchical meso-macroporous alumina supports were applied to the hydrodemetallization.•Hierarchically porous nest-like supports were synthesized with template-free methord.•MoNi/nest-like γ-Al2O3 exhibited superior catalytic performance and longer life due to enhanced diffusion of the reactants.The design of hierarchically porous catalytic supports is considered as one of the most efficient strategies to achieve efficient mass transport and thus high catalytic performance in heterogeneous catalysis. As one of the most important catalytic supports, facile synthesis of γ-Al2O3 with hierarchical porosities is of great industrial importance. In this paper, nest-like hollow γ-AlOOH microspheres constructed from numerous hierarchically organized nanowires were synthesized via a template-free simple hydrothermal approach, from which hierarchically porous γ-Al2O3 microspheres with average macropores of 900 nm, mesopores of 20 nm and a pore volume of 0.93 cm3/g were obtained readily. Due to their structural merits, such nest-like γ-Al2O3 microspheres could serve as excellent catalytic support. As a demonstration, a MoNi/γ-Al2O3 supported catalyst was prepared, which was applied for hydrodemetallization (HDM) catalysis. Compared with the catalyst prepared with the commercial γ-Al2O3, our catalyst exhibits superior catalytic performance and longer life due to enhanced diffusion of the reactants.A novel nest-like γ-Al2O3 material is rationally designed and synthesed and exhibit superior catalytic performance and longer life as a support of hydrodemetallization catalysts compared with traditional commercial catalysts.Download high-res image (169KB)Download full-size image

•A controllable copper species (Cu0 and Cu+) supported on LaFeO3 was synthesized.•Hydrogen-treatment was used to control copper species and content on the surface.•Photocatalyst with optimized copper showed hydrogen evolution of 343 μmol h−1 g−1.•The high activity was attributed to better charge separation on the surface.LaFeO3 has been reported to have excellent optoelectronic properties and a narrow bandgap, which make it a promising candidate for photocatalytic reactions. In this work, to further improve the photocatalytic water-splitting performance by enhancing the separation of photo-excited carriers and providing active sites for H2 production, cocatalysts (copper species) supported on the perovskite-type oxide LaFeO3 was obtained by a citrate complexation and reduction treatment. Copper ions in the perovskite lattice are easily reduced and LaFeO3 possesses good stability in reducing atmospheres; thus, a series of stable LaFeO3 with a controllable copper species were synthesized and characterized by XRD, DRS, XPS and PL. The results showed that copper species (Cu0 and Cu+) supported on the LaFeO3 surface brought about a significant enhancement of photocatalytic activity. The LaFe0.8 + LaCu0.2 treated at 300 °C exhibited the highest photocatalytic activity, with a H2 evolution rate of 343 μmol g−1 h−1, which was attributed to the fact that a proper Cu0 to Cu+ ratio (Cu0/Cu+ = 1.34) could serve as a cocatalyst for photocatalytic hydrogen evolution, providing accelerated electron–hole separation and proton-reduction sites.

•Ni–CsxH3−xPW12O40/SiO2 catalysts for hydrocracking were prepared by direct synthesis.•The addition of Cs enhances the resistance to the sulfur and nitrogen compounds.•The direct synthesized catalyst had better dispersion than impregnated catalyst.•The catalysts achieve the good balance between acidity and hydrogenation function.A series of Ni–CsxH3−xPW12O40/SiO2 catalysts were prepared by direct synthesis method and characterized by BET, XRD, in situ XRD, FT-IR, NH3-TPD, H2-TPR, and H2-TPD. The catalytic performance of the catalysts for the hydrocracking of n-decane with various concentrations of thiophene and pyridine was studied. The best result was obtained on direct synthesized 8%Ni–50%Cs1.5H1.5PW/SiO2 catalyst which has shown the highest activity for the hydrocracking of n-decane and excellent tolerance to the sulfur and nitrogen compounds in the feedstock, superior to the impregnated catalyst and the industrial catalyst. The highest catalytic performance of the catalyst may be due to that the direct synthesized catalysts had better dispersion, higher numbers of acid sites and stronger hydrogenation-dehydrogenation function than that of the impregnated catalyst.

The effect of Cs content in CsxH3-xPW12O40 on the catalytic performance of the reduced Ni-CsxH3-xPW12O40/Al2O3 catalysts for hydrocracking of n-decane with the presence of thiophene and pyridine is studied. The catalysts were characterized by BET, XRD, in situ XRD, Raman, H2-TPR, H2-TPD, NH3-TPD and FT-IR of pyridine adsorption. The best result was obtained on 8%Ni-50%CsH2PW12O40/Al2O3 catalyst which shows the highest catalytic activity and with tolerance to 525 ppm of thiophene and 170 ppm of pyridine (the reaction conditions: 2.0 MPa, LHSV = 2.92 h− 1, H2/n-decane 1500 vol/vol at 300 °C). The high catalytic performance of the catalyst may be due to the proper balance between metal and acid functions by adding a certain proportion of Cs to the system.Highlights►Effect of Cs in Ni-CsxH3-xPW12O40/Al2O3 for hydrocracking of n-decane is studied. ►Proper balance between metal and acid functions is established by adding Cs. ►The highest catalytic activity is obtained on 8% Ni-50% CsH2PW12O40/Al2O3.

In this work, a series of NiMo/γ-Al2O3 catalysts is prepared by one-pot method with controlled precipitation of AlCl3·6H2O, (NH4)6Mo7O24·4H2O and NiCO3·2Ni(OH)2·4H2O using urea and ammonium carbonate as additives. The molar ratio of urea to Al varied from 4.1 to 17.2 and the influence of this parameter on the surface and structural properties of the catalysts and HDM activity was studied. HDM of Ni-TPP was carried out in a batch reactor. The catalysts were characterized by BET, XRD, H2-TPR, DRS, XPS, EDS, FT-IR, TG–DTA and NH3-TPD. The results show that urea employed as additive not only improves the solubility of Mo and Ni salt, but also adjusts the hydroxyl concentration and facilitates the formation of molybdate and polymolybdate. The existence of residual chlorine may improve the dispersion of the particles containing Ni and Mo on the surface of porous Al2O3, enhance hydrogen spillover and the acidity of the catalyst. HDM activity varied with the amount of urea to a maximum at urea/Al of 12.3 with activity of 98%. The highest activity occurred at this ratio is mainly due to better porosity, well dispersed active particles, increased octahedral molybdenum/nickel oxides and proper acidity.Highlights► NiMo/Al2O3 catalysts were prepared by one-pot method using urea as additive. ► NiMo/Al2O3 possessed better porosity and well dispersed active particles. ► The effect of urea concentrations on HDM activity of NiMo/Al2O3 is investigated. ► The HDM activity varied with the amount of urea to maximum at urea/Al of 12.3.

Nano Ni–W catalysts with different tungsten contents prepared by mixing alkaline nickel carbonate with ammonium tungstate show high activity and good sulfur tolerance for hydrogenation of thiophene-containing ethylbenzene. The catalysts were characterized by XRD, TPR, SEM, Raman and BET. The results show that the activity of the catalysts for ethylbenzene hydrogenation is affected profoundly by W loading and the best result was obtained on catalyst with W/Ni ratio equal to 0.16. The increase of activity of the catalyst can be attributed to the interaction between Ni and W doped and the increase of the surface area of the catalyst.

Different nickel precursors, i.e., nickel nitrate, nickel acetate and nickel acetate plus citric acid, were used to prepare supported Ni/γ-Al2O3 catalysts for naphthalene hydrogenation to decalin. The catalysts thus prepared were reduced without calcination and after calcination, respectively. The physicochemical characterization and activity testing results show that the catalyst prepared with nickel acetate as precursor and reduced without calcination possesses modest reduction character, higher adsorption and desorption abilities of H2, and exhibits most excellent catalytic performance for the reaction with 99.1% selectivity of decalin at the naphthalene conversion of 100%.

•NiMo–Al2O3 catalysts were prepared by combustion synthesis using starch as fuel.•The textural properties of the catalysts depended strongly on the starch addition.•Starch addition markedly improved the sulfidity and generated Ni–Mo–S Type II phase.•TOF increased with increasing starch addition.•A starch addition ratio of 2.5 exhibited the best hydrodesulfurization performance.The effect of starch addition on the precursor combustion reaction, physicochemical properties, active phase, and intrinsic hydrodesulfurization activity of Al2O3-supported Ni–Mo catalysts prepared by combustion synthesis in a one-pot process has been studied. The results show that the increase in starch addition markedly enhances the molar enthalpy of the combustion reaction, develops the porosity of the catalysts, and improves the reducibility and sulfidability by reducing the interaction of Mo and Ni with the Al2O3 support. Thus, the total number of Ni–Mo–S active sites increases, and substantial amounts of the Ni–Mo–S Type II phase forms, leading to an increase in the turnover frequency (TOF) for the catalysts. However, excess starch will lead to a large agglomeration of Mo particles, resulting in high MoS2 stacking and low MoS2 dispersion. As a result, the specific activities of hydrodesulfurization over NiMoAl-x catalysts peak at a starch addition ratio (x) of 2.5 ((C6H10O5):2Al).Graphical abstractDownload high-res image (70KB)Download full-size image

A series of bifunctional Ni-H3PW12O40/SiO2 catalysts for the hydrocracking of n-decane were designed and prepared. The evaluation results of the catalysts show that Ni-H3PW12O40/SiO2 catalysts possess a high activity for hydrocracking of n-decane and an excellent tolerance to the sulfur and nitrogen compounds in the feedstock. Under the reaction conditions: reaction temperature 300 °C; H2/n-decane volume ratio of 1500; total pressure of 2 Mpa and the LHSV 2 h−1, the conversion of n-decane over reduced 5%Ni-50%H3PW12O40/SiO2 catalysts is as high as 90%, the C5+ selectivity equal to 70%. In order to reveal the structure and nature of the catalysts, a number of characterizations including XRD, Raman, H2-TPD, NH3-TPD, XPS and FT-IR of pyridine adsorption were carried out. The characteristic results show that the high activity of the catalysts and high C5+ selectivity can be related to the unique structure of the H3PW12O40 and its suitable acidity.