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In this study, 1 wt% platinum (Pt) nanoparticles were incorporated into five types of zeolites (HY, Beta, mordenite, ZSM-5, and ferrierite) with an impregnation technique. The synthesis strategy included the use of water as a solvent for the applied Pt source. Moreover, the incorporation process was performed at ambient conditions followed by calcination at 450 °C. The five prepared materials were characterized by different physical and chemical characterization techniques and the obtained results confirmed the formation of Pt nanoparticles with an average size of 5–10 nm. The catalytic performance of the prepared materials was evaluated in the hydrogenation of cyclohexene under a solvent-free system at room temperature. Pt nanoparticles supported on ZSM-5 zeolite exhibited the best catalytic performance. Moreover, the optimization of operational conditions such as temperature, pressure, and catalyst amount was investigated and the obtained results showed the possibility to convert 100% of cyclohexene within 35 min over Pt-ZSM-5. Finally, the reusability of the Pt-ZSM-5 catalyst was investigated in four consecutive runs without treatment and the obtained results showed a negligible activity loss. [ABSTRACT FROM AUTHOR]

Palladium (Pd) was incorporated into TUD-1 mesoporous siliceous material by using one-pot synthesis procedure. The catalytic activity of the prepared samples was evaluated in the selective hydrogenation of 1,5-cyclooctadiene (COD) at 80 °C in a solvent-free condition. Pd-TUD-1 showed > 95% conversion of COD with a selectivity > 90% towards cyclooctene (COE). [ABSTRACT FROM AUTHOR]

Rhodium (Rh) nanoparticles were embedded in the mesopores of TUD-1 siliceous material and denoted as Rh-TUD-1. Five samples of Rh-TUD-1 were prepared with different loadings of Rh that ranged from 0.1 to 2 wt% using the sol-gel technique. The prepared samples were characterized by means of several chemical and physical techniques. The obtained characterization results show the formation of highly distributed Rh0 nanoparticles with an average size ranging from 3 to 5 nm throughout the three-dimensional silica matrix of TUD-1. The catalytic activity of the prepared catalysts was evaluated in the solvent-free hydrogenation of cyclohexene to cyclohexane at room temperature using 1atm of hydrogen gas. The obtained catalytic results confirm the high activity of Rh-TUD-1, in which a turn over frequency (TOF) ranging from 4.94 to 0.54 s−1 was obtained. Moreover, the change in reaction temperature during the reaction was monitored, and it showed an obvious increase in the reaction temperature as an indication of the spontaneous and exothermic nature of the reactions. Other optimization parameters, such as the substrate/catalyst ratio, and performing the reaction under non-ambient conditions (temperature = 60 °C and hydrogen pressure = 5 atm) were also investigated. Rh-TUD-1 exhibited a high stability in a consecutive reaction of five runs under either ambient or non-ambient conditions. [ABSTRACT FROM AUTHOR]

Four different metal nanoparticles (metal = Ag, Ru, Pt, or Rh) were impregnated on the acidic cesium salt of tungstophosphoric acid Cs2.5H0.5PW12O40 (CsPW) with a loading amount of 2 wt%. The prepared catalysts were characterized by using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), N2 sorption measurements, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Results confirmed the formation of highly distributed metallic nanoparticle centres over the acidic CsPW. The catalytic activity of the prepared catalysts were evaluated in the liquid phase hydrogenation of methyl isobutyl ketone (MIBK) to 2-methylpentane (2-MP) at 453 K. Pd-CsPW showed the highest activity compared to other catalysts, where 10% conversion was obtained with 91% selectivity after 4 h's reaction time. [ABSTRACT FROM AUTHOR]

Abstract Here, different loading of palladium (Pd), ranged from 0.5 to 5 wt%, was incorporated into the three dimensional siliceous mesoporous material; TUD-1. The synthesis procedure was carried out without the use of solvents, surfactants, and/or copolymers. Only triethanolamine and water with the precursors of Si and Pd were applied in one-pot synthesis procedure to prepare Pd-TUD-1 materials. The prepared materials were characterized by means of elemental analysis, XRD, Raman spectroscopy, N 2 sorption measurements, SEM and TEM. Characterization data confirmed the formation of PdO particles inside the pores of TUD-1 matrix, moreover bulky PdO particles were also detected as an extra-framework separated phase in the high loading samples. The prepared samples were divided into two batches, the first was activated by hydrogenation at 300 °C for 3 h, and the second batch did not activated. The catalytic activity of the two batches was examined in the selective hydrogenation of 1,5-cyclooctadiene (COD) at 80 °C under solvent-free condition to produce cyclooctene (COE). The obtained results showed that the samples of the two batches were able to catalyze the reaction with a very comparable activity. The non-hydrogenated sample with a 0.5% Pd gave 98.5% COD conversion with a COE selectivity of 92.8%, while the same sample which pre-hydrogenated gave 96.8% of COD conversion and 93.5% selectivity towards COE. The characterization of the used catalysts confirmed that PdO was in-situ reduced to Pd nanoparticles during the reaction. Graphical abstract Image 1 Highlights • PdO nanoparticles were incorporated with different loading in TUD-1 mesoporous material. • Pre-activation of PdO nanoparticles was performed by hydrogenation to generate Pd0 active sites. • The reduction of 1,5-cyclooctaniene was used to evaluate the catalytic activity of the pre-activated catalysts and the as-synthesized ones. • The activity data shows that the pre-activation (hydrogenation) step is not necessary at low Pd loading. [ABSTRACT FROM AUTHOR]

A new heterogeneous catalyst contains two different catalytic sites is introduced. Pt-Al-TUD-1, which contains acidic and metallic active sites incorporated in a three dimensional mesoporous siliceous TUD-1 material, was prepared by one-pot synthesis procedure. Characterization data confirm the formation of metallic nanoparticles of Pt (5–10 nm) incorporated on acidic Al-TUD-1 matrix. The catalytic performance of Pt-Al-TUD-1 was evaluated in the liquid phase hydrogenation of methyl isobutyl ketone (MIBK) at 453 K. 13% conversion of MIBK was obtained after 4 h with 99% selectivity towards 2-methylpentane (2-MP). The catalytic activity of the prepared catalyst outperformed the other metal incorporated Al-TUD-1 catalysts (metal = Pd, Ru, or Ag). [ABSTRACT FROM AUTHOR]

[Display omitted] • Well-defined Pt0 nanoparticles were incorporated into TUD-1 by one-step procedure. • The size of Pt0 nanoparticles was in the range of 5–10 nm. • Pt-TUD-1 catalyzed the solvent-free hydrogenation of four different cycloalkenes at room temperature. • Pt-TUD-1 exhibited higher activity than Pt incorporated mordenite, ferrite, or SBA-15. Well-defined Pt nanoparticles were integrated into the mesoporous material TUD-1 by applying one-pot sol–gel methodology and denoted as Pt-TUD-1. The characterization data of Pt-TUD-1 confirmed the presence of highly dispersed nanoparticles of zero-valent platinum (Pt0) of 5–10 nm average size incorporated into the three-dimensional silica framework. Pt-TUD-1 was used to catalyze the liquid-phase hydrogenation of four cycloalkenes; cyclopentene (CPE), cyclohexene (CXE), cyclooctene (COE), and cyclooctadiene (COD) without the use of any solvents in room temperature. The obtained results showed that cyclopentene is the fastest to be hydrogenated where 57.7% was converted within one hour's reaction. The activity of Pt-TUD-1 benchmarked not only the commercial Pt nanopowder but also the Pt supported SiO 2 and SBA-15. Moreover, Pt-TUD-1 showed high stability and it was recycled successfully for four consecutive runs without activity loss. [ABSTRACT FROM AUTHOR]