Local Structure of Pd1 Single Sites on the Surface of PdIn Intermetallic Nanoparticles: A Combined DFT and CO-DRIFTS Study

Local structure of Pd1 single sites on the surface of Pd1In1 intermetallic nanoparticles supported on α-Al2O3 was investigated by the combination of CO-DRIFTS spectroscopy and DFT. CO-DRIFTS spectra of PdIn/Al2O3 catalyst exhibit only one asymmetric absorption band of linearly adsorbed CO comprising two peaks at 2065 and 2055 cm−1 attributable to CO molecules coordinated to Pd1 sites located at (110) and (111) facets of PdIn nanoparticles. The absence of bridged or hollow-bonded CO bands indicates that multipoint adsorption on PdIn nanoparticles is significantly hindered or impossible. DFT results show that on (110) facet multipoint CO adsorption is hindered due to large distance between neighboring Pd atoms (3.35 Å). On (111) facet multipoint CO adsorption on surface palladium atoms is impossible, since adjacent Pd atoms are located below the surface plane.

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DRIFTS study of Fe promoter effect on Rh/Al2O3 catalyst for C2 oxygenates synthesis from syngas

Applied Petrochemical Research ◽

10.1007/s13203-019-00238-3 ◽

2019 ◽

Vol 9 (3-4) ◽

pp. 211-219

Author(s):

Fang Li ◽

Weixing Qian

Keyword(s):

Co Adsorption ◽

Catalytic Performance ◽

Desorption Rate ◽

Hydrogenation Activity ◽

Promoter Effect ◽

Fe Content ◽

Adsorbed Co ◽

Key Steps ◽

Performance Results ◽

Al2o3 Catalyst

Abstract DRIFTS experiments such as CO adsorption, CO-TPSR and CO+H2 were designated to study the effect of Fe promoter on the key steps of C2 oxygenates formation from syngas. The CO adsorption results demonstrated that Fe weakened CO adsorption and especially the bridging adsorption. It was found in CO-TPSR experiments that the catalyst with lower Fe loading is more easily dissociated while the ones with higher Fe loading own stronger hydrogenation activity. Moreover, it was observed by CO+H2 experiments that Fe plays a role in stabilizing the lineally adsorbed CO species and decreasing the CO desorption rate. The catalytic performance results indicated that when Fe content is 4wt. %, the selectivity of total C2 oxygenates is the highest, which was in accordance with the DRIFTS results.

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Formation of supported intermetallic nanoparticles in the Pd–Zn/α-Al2O3 catalyst

Kinetics and Catalysis ◽

10.1134/s0023158417040127 ◽

2017 ◽

Vol 58 (4) ◽

pp. 471-479 ◽

Cited By ~ 13

Author(s):

I. S. Mashkovsky ◽

P. V. Markov ◽

G. O. Bragina ◽

G. N. Baeva ◽

A. V. Bukhtiyarov ◽

...

Keyword(s):

Α Al2o3 ◽

Al2o3 Catalyst ◽

Intermetallic Nanoparticles

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Adsorption of Carbon Monoxide on Pd/SiO2/Si(111) Studied by Core-Level Photoemission

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19981793 ◽

1998 ◽

Vol 63 (11) ◽

pp. 1793-1802 ◽

Cited By ~ 1

Author(s):

Zdeněk Bastl ◽

Tomáš Šarapatka

Keyword(s):

Carbon Monoxide ◽

Photoelectron Spectroscopy ◽

Co Adsorption ◽

Charge Balance ◽

Adsorption Activity ◽

Chemical States ◽

Adsorbed Co ◽

Pd Clusters ◽

Almost All ◽

P Type

X-Ray photoelectron spectroscopy (XPS) has been used to study the adsorption of carbon monoxide on Pd dispersed on oxidized Si(111) surface. A fraction of the deposited Pd diffusing at room temperature to the SiO2/Si interface increases with decreasing SiO2 thickness. For oxide layers thinner than ≈1 nm, almost all deposited Pd diffuses to SiO2/Si interface forming there Si silicide. Consequently, the amount of adsorbed CO is dependent on the thickness of the thermally grown SiO2 layer. Two different chemical states of adsorbed carbon atoms, the population of which depends on the amount of the Pd deposited, are observed in the C (1s) spectra of adsorbed CO. Adsorption activity of Pd clusters does not depend on whether n- or p-type Si is used. Comparison of the experimental Pd/CO concentration ratios with those calculated assuming several different modes of the Pd growth on SiO2/Si points to the pseudo-Stranski-Krastanow mode (flat clusters with incomplete condensation of the first layer) at 300 K. Changes in charge balance across the Pd/SiO2/Si interface caused by CO adsorption are discussed in terms of the surface photovoltage effect and work function variation.

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Role of chlorohydrocarbon in increasing selectivity of propylene oxide over Ag–Y2O3–K2O/α-Al2O3 catalyst for epoxidation of propylene by molecular oxygen

Journal of Molecular Catalysis A Chemical ◽

10.1016/j.molcata.2011.04.006 ◽

2011 ◽

Vol 342-343 ◽

pp. 30-34 ◽

Cited By ~ 16

Author(s):

Wei Yao ◽

Xiang Zheng ◽

Yanglong Guo ◽

Wangcheng Zhan ◽

Yun Guo ◽

...

Keyword(s):

Molecular Oxygen ◽

Propylene Oxide ◽

Epoxidation Of Propylene ◽

Α Al2o3 ◽

Al2o3 Catalyst

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Optimization of K–Ni/α-Al2O3 catalyst for high-pressure oxidative reforming of methane by radial basis function network and multivariate analysis

Applied Catalysis A General ◽

10.1016/j.apcata.2009.12.041 ◽

2010 ◽

Vol 377 (1-2) ◽

pp. 9-15 ◽

Cited By ~ 4

Author(s):

Junpei Horiguchi ◽

Seishiro Kobayashi ◽

Yuichiro Yamazaki ◽

Takayuki Nakanishi ◽

Daisuke Itabashi ◽

...

Keyword(s):

High Pressure ◽

Multivariate Analysis ◽

Radial Basis Function ◽

Basis Function ◽

Radial Basis Function Network ◽

Radial Basis ◽

Oxidative Reforming ◽

Α Al2o3 ◽

Al2o3 Catalyst ◽

Function Network

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An Experimental Approach on Industrial Pd-Ag Supported α-Al2O3 Catalyst Used in Acetylene Hydrogenation Process: Mechanism, Kinetic and Catalyst Decay

Processes ◽

10.3390/pr7030136 ◽

2019 ◽

Vol 7 (3) ◽

pp. 136

Author(s):

Ourmazd Dehghani ◽

Mohammad Rahimpour ◽

Alireza Shariati

Keyword(s):

Kinetic Model ◽

Experimental Approach ◽

Catalyst Deactivation ◽

Catalyst Activity ◽

Hydrogenation Process ◽

Support Surface ◽

Acetylene Hydrogenation ◽

Wide Range ◽

Α Al2o3 ◽

Al2o3 Catalyst

The current research presents an experimental approach on the mechanism, kinetic and decay of industrial Pd-Ag supported α-Al2O3 catalyst used in the acetylene hydrogenation process. In the first step, the fresh and deactivated hydrogenation catalysts are characterized by XRD, BET (Brunauer–Emmett–Teller), SEM, TEM, and DTG analyses. The XRD results show that the dispersed palladium particles on the support surface experience an agglomeration during the reaction run time and mean particle size approaches from 6.2 nm to 11.5 nm. In the second step, the performance of Pd-Ag supported α-Al2O3 catalyst is investigated in a differential reactor in a wide range of hydrogen to acetylene ratio, temperature, gas hourly space velocity and pressure. The full factorial design method is used to determine the experiments. Based on the experimental results ethylene, ethane, butene, and 1,3-butadiene are produced through the acetylene hydrogenation. In the third step, a detailed reaction network is proposed based on the measured compounds in the product and the corresponding kinetic model is developed, based on the Langmuir-Hinshelwood-Hougen-Watson approach. The coefficients of the proposed kinetic model are calculated based on experimental data. Finally, based on the developed kinetic model and plant data, a decay model is proposed to predict catalyst activity and the parameters of the activity model are calculated. The results show that the coke build-up and condensation of heavy compounds on the surface cause catalyst deactivation at low temperature.

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