Consecutive hydrogenation of benzaldehyde over Pd catalysts

Pinna, Francesco; Menegazzo, Federica; Signoretto, Michela; Canton, Patrizia; Fagherazzi, G.; Pernicone, N.

doi:10.1016/s0926-860x(01)00685-8

Cited by 114 publications

(95 citation statements)

References 10 publications

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“…Other authors suggest that the hydrogen consumption at these temperatures is due to the reduction of Pd x O y Cl z oxychlorinated species or the reduction of Pd 2? ions stabilized by adjacent Cl -remaining after the calcination process [27][28][29]. The difference in reduction pattern depending on the kind of metal precursor and on whether this precursor is chlorinated or not has been pointed out by many authors studying the Pt catalysts.…”

Section: Catalytic Reaction Testsmentioning

confidence: 99%

Resistance to Sulfur and Oxygenated Compounds of Supported Pd, Pt, Rh, Ru Catalysts

et al. 2010

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The poisoning resistance to sulfided and oxygenated compounds of some VIII Group PYGAS selective hydrogenation catalysts based on metals was assessed. Low content alumina supported Rh, Pd, Ru and Pt catalysts (0.35 wt%) were prepared from chlorided precursors. In the case of the palladium catalysts a nitrogenated precursor was also used. The catalysts were mainly assessed in the catalytic test of selective styrene hydrogenation in the presence or absence of known poisons. Model feedstocks spiked with thiophene, thiophane and tetrahydrofuran were used. The catalysts were further characterized by means of chemical analysis, XPS, TPR and chemisorption. The results indicate that chlorided precursors yield more sulfur resistant catalysts. The effect was attributed in part to the formation of oxychlorinated species, refractory to reduction, that leave the metal in an electron deficient state, thus inhibiting the formation of strong poison-metal bonds, the chloride species could also be a steric factor that can contribute to the sulfur resistance of the catalyst. Pd based catalyts had the highest activity and resistance to poisons of all the metals tested. This superior performance was attributed in part to the total occupancy of the 4d electronic levels of the Pd metal that was supposed to promote the rupture of the H 2 bond during the hydrogenation reaction. Keywords Low metal loading catalysts Á Selective hydrogenation Á Sulfided and oxygenated poisons List of Symbols PF Poison free condition TE Thiophene TA Thiophane THF Tetrahydrofuran D Metal dispersion S Metal specific surface (m 2 g met -1 ) d Average metal particle size (Å ) V HAds (CNPT) Volume of hydrogen chemisorbed at normal conditions (cm 3 ) PA Atomic weight of the metal (g mol -1 ) w Metal content per unit gram of catalyst M Mass of sample (g) m Stoichiometry of chemisorption of the gas on the surface metal atoms V m CNPT Volume of the chemisorbed monolayer of the adsorbate at normal conditions (cm 3 g -1 ) N Avogadro's number (6.023 9 10 23 ) V N Molar volume of the adsorbate at normal conditions r Number of metal atoms per square meter (atoms m -2 ) xAdsorption stoichiometry (number of hydrogen atoms adsorbed per unit of metal atom) qDensity of the metal (g m -3 ) M Red /M Tot Reduced metal amount and total metal amount ratio wt M% Nobel metal content (weight percentage) T Red Reduction temperature (K) r°E S Initial styrene hydrogenation rate in poison free condition (mol g cat -1 min -1 ) DESRelative deactivation per concentration of poison (ppm -1 )

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Section: Catalytic Reaction Testsmentioning

confidence: 99%

Resistance to Sulfur and Oxygenated Compounds of Supported Pd, Pt, Rh, Ru Catalysts

et al. 2010

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“…Other authors suggest that the consumption of hydrogen near these temperatures is due to the reduction of Pd η+ Cl x O y (0 < η < 2) species or to the reduction of Pd +2 ions stabilized by neighbouring Cl -, that were not eliminated during calcination and remain on the alumina surface. [26][27][28] Figure 3 shows that above 503 K multiple hydrogen consumption peaks appear due to the reduction of NiO species that interact with the support. The first peaks at 520-620 can be assigned to the reduction of NiO x with weak or null interaction with the support (bulk NiO).…”

Section: Catalysts Characterizationmentioning

confidence: 99%

MORE ACTIVE AND SULFUR RESISTANT BIMETALLIC Pd-NI CATALYSTS

Betti¹,

Carrara²,

Badano³

et al. 2017

Quim. Nova

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The influence of the kind of metal precursor and the sequence of impregnation on the properties of Pd-Ni catalysts was evaluated during the test reaction of selective hydrogenation of styrene to ethylbenzene by means of physicochemical characterization. The focus was put on the final hydrogenating activity and the resistance to deactivation by sulfided compounds (thiophene). The used techniques of characterization were ICP, XPS, XDR, TPR, CO chemisorption and TEM. XPS results indicated the presence of different Pd species: Pd δ-, Pd 0 and Pd δ+ . In the case of the Ni containing catalysts, Ni 0 and NiO species were also detected. These palladium and nickel species would be responsables of the variation of activity and sulfurresistance of the catalysts. NiClPd catalysts had a higher resistance to deactivation by sulfur poisoning. This was associated to a higher concentration of Pd η+ Cl x O y species that would prevent the adsorption of thiophene by both steric and electronic effects. It could also be due to the lower concentration of Pd 0 and Ni 0 on these catalysts, as compared to those shown by the PdNiCl catalysts. Both the Pd 0 and Ni 0 species are more prone to poisoning because of their higher electronic availability.

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“…The reaction data at the initial stage fit well with a one order reaction. The reaction can be described with Langmuir-Hinshelwood mechanism [13]. Thus, for benzaldehyde hydrogenation assuming one order reaction,…”

Section: Hydrogenation Of Benzaldehyde On Pd/cnts Catalystsmentioning

confidence: 99%