Catalytic performances of large pore Ti-SBA15 supported Pt nanocomposites for the citral hydrogenation reaction

Hybrid Nanostructure Catalyst with Low Loading of Pt for the High-Efficiency Catalytic Hydrogenation of Chloronitrobenzene

Fabrication of low-loading, noble-metal, stable, and high-performance metal catalysts remains a thorny issue. Herein, we demonstrate the successful formation of a hybrid nanostructure Pt/TiO₂/SBA-15 catalyst (denoted as HNSC-P/T/S; Pt, 0.09%; TiO₂, 10%) with satisfactory activity in the hydrogenation of para-chloronitrobenzene (p-CNB). The HNSC-P/T/S showed >99% conversion and a high selectivity of >98%, and the turnover frequency number (TOF) reached 66 766 h^-1, which was impossible to achieve with Pt/TiO₂ (denoted as P/T) or Pt/SBA-15 (denoted as P/S). The success of the catalytic activity of the HNSC-P/T/S mainly relies on its synergistic effect and special structure, which can fully develop the catalytic ability of Pt, thereby reducing the Pt loading in the noble-based catalyst. Furthermore, the HNSC-P/T/S could also achieve an excellent catalytic activity in the hydrogenation of other nitroarenes. Hence, this work proposes a direction to prepare a noble-based catalyst with a low loading of noble metals for diverse applications.

Heterogeneous iron-containing nanocatalysts – promising systems for selective hydrogenation and hydrogenolysis

Bimetallic catalytic systems Fe–Me (Pt, Pd, Cu) demonstrate synergy in the activity/selectivity pattern in reactions involving hydrogen: selective hydrogenation of CC bonds, NO₂ and carbonyl groups and hydrogenolysis of C–O bonds.

Continuous Flow Preferential Hydrogenation of an Octanal/Octene Mixture Using Cu/Al2O3 Catalysts

γ-Alumina-supported catalysts with varying copper loadings (5-25 wt %) were prepared by incipient wet impregnation and characterized by various characterization techniques. These catalysts were tested for the selective hydrogenation of octanal in a mixture containing 10 wt % octanal and 2 wt % octene diluted in octanol. The reactions were carried out in a continuous flow fixed-bed reactor in a down flow mode with varying pressures, liquid hourly space velocities, and hydrogen (H₂)-to-aldehyde molar ratios. The catalyst activities were assessed over a temperature range between 100 and 180 °C using hydrogen gas as the hydrogen source. The results obtained showed that under these experimental conditions, copper preferentially hydrogenates the aldehyde and the copper content exhibited no significant influence on the catalyst activity or product selectivity. Kinetic modeling revealed that both octanal and octene hydrogenation were first-order reactions, although octene conversion was very low until octanal conversion had reached a significant level. The activation energy for octanal hydrogenation is higher than the octene hydrogenation. A maximum octanal conversion of >99% was obtained at 160 °C, and the best selectivity toward octanol of 99% was achieved at 100 °C (53% conversion). The pressure played a small role with regards to octanal conversion and selectivity toward octanol, whereas it exhibited a significant influence on the octene conversion. Increasing the hydrogen-to-aldehyde ratio was found to have a direct influence on both octanal and octene conversion.

Study of the structure and characteristics of mesoporous TiO2 photocatalyst, and evaluation of its factors on gaseous formaldehyde removal by the analysis of ANOVA and S/N ratio

This study differs from previous studies of TiO₂/SiO₂ in that 0.5–10 μm microsized TiO₂-rutile based catalysts (TR catalysts) with varying proportions of titanium and silicon were synthesized using a one-step modified hydrothermal method. At Ti/Si = 1/9, a two-dimensional channel-structured catalyst with a morphology resembling that of SBA-15 was obtained. In contrast, at Ti/Si = 3/7 or 5/5, a three-dimensional porous structure was formed, and Ti–O–Si–C bonds appeared. The structure of the TR catalyst transformed due to the decrease in C–Si bond content and the increase in C–C bond content with increasing Ti/Si ratio. The results indicated that the rutile phase was the main crystal phase of the TR catalyst. The small crystal size and large rutile phase content of the mesoporous TR catalyst contributed to the low band gap energy below 3.0 eV. Under 2 × 10 W lamp irradiation with either UVA or visible light, the three TR catalysts showed better formaldehyde (HCHO) removal efficiency than P25. Furthermore, the Taguchi method was employed to evaluate the catalytic factors by analysis of variance (ANOVA) and S/N ratio. The results revealed the contributions of each of the three factors to HCHO removal efficiency over TR catalysts to be as follows: space velocity (62%), Ti ratio (32%), and time on stream (5%). The TR catalyst with Ti/Si = 1/9 showed good HCHO removal efficiency with a high S_BET (787.1 m² g⁻¹) and large pore volume (0.95 cm³ g⁻¹) for a residence time of over 2.29 × 10⁻¹ s under visible light irradiation. Microwave-assisted EG reduction was successfully applied to dope a TR catalyst with nanosized Pt particles in a short synthesis time. After Pt doping, the removal efficiency in the stream improved and stabilized. The Pt particles were Pt⁰ and proved effective for improving the photocatalytic removal of HCHO over the TR catalyst by prolonging the separation time of the electron–hole pairs. Overall, the Pt/TR catalyst is a potential material for pollutant removal and can be easily separated from the pollutant removal system since the catalysts are microsized.

This study differs from previous studies of TiO₂/SiO₂ in that 0.5–10 μm microsized TiO₂-rutile based catalysts (TR catalysts) with varying proportions of titanium and silicon were synthesized using a one-step modified hydrothermal method.

Efficient Pt–FeOx/TiO2@SBA-15 catalysts for selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

Pt–FeO_x/TiO₂@SBA-15 serves as an efficient and recyclable catalyst for liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol under mild conditions.