Oxy-chlorination as an effective treatment of aged Pd/CeO2-Al2O3 catalysts for Pd redispersion

Lambrou, P.S.; Polychronopoulou, Kyriaki; Petallidou, Klito C.; Efstathiou, Angelos M.

doi:10.1016/j.apcatb.2011.10.018

Cited by 22 publications

(15 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This re-dispersion has been widely reported in the literature, which can take place in chlorine environment at moderate temperatures, depending on the nature of the support, the metallic phase and chlorine concentration [55][56][57] . In former hydrodechlorination studies, small particle sizes were found to prevent deactivation of metallic catalysts avoiding the oligomerization of carbonaceous species and subsequent poisoning of active centres 46,58 .…”

Section: Resultssupporting

confidence: 54%

“…Mean particle sizes of 10.0 and 2.7 nm were measured for the fresh reduced and used catalysts, respectively. This redispersion has been widely reported in the literature, which can take place in a chlorine environment at moderate temperatures, depending on the nature of the support, metallic phase, and chlorine concentration. − In former hydrodechlorination studies, small particle sizes were found to prevent deactivation of metallic catalysts avoiding the oligomerization of carbonaceous species and subsequent poisoning of active centers. , The excellent stability of the ZnCPd catalyst appears to be a consequence of the combination of an optimum surface chemistry and metal particle size. A mean particle size of 3 nm was measured in the used PCPd catalyst.…”

Section: Results and Discussionmentioning

confidence: 80%

See 1 more Smart Citation

Selectivity to Olefins in the Hydrodechlorination of Chloroform with Activated Carbon-Supported Palladium Catalysts

Fernandez-Ruiz

Bedia

Andreoli

et al. 2019

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

This study analyzes the selectivity of Pd (1 wt%) catalysts supported on different activated carbons to produce olefins from hydrodechlorination of chloroform. It was found that selectivity to olefins was favoured by a higher zero-valent to electrodeficient Pd ratio (Pd 0 /Pd n+) and by a lower amount of oxygen-containing surface functional groups on the activated carbon supports. Thus, the highest selectivity to olefins was obtained by catalysts supported on FeCl 3 and ZnCl 2-activated carbons. Conversely, the catalysts supported on KOH-, NaOH-, and H 3 PO 4-activated carbons gave the lowest selectivity to olefins. These catalysts showed higher surface concentrations of electro-deficient Pd as well as high concentrations of oxygen functional groups that enhance the adsorption of reactants and intermediates. This leads to complete hydrogenation of reaction intermediates and poisoning of active sites by the adsorption of chlorocarbon compounds. ZnCl 2-derived catalysts with the highest selectivity to olefins also showed an outstanding

show abstract

Section: Resultssupporting

confidence: 54%

Section: Results and Discussionmentioning

confidence: 80%

Selectivity to Olefins in the Hydrodechlorination of Chloroform with Activated Carbon-Supported Palladium Catalysts

Fernandez-Ruiz

Bedia

Andreoli

et al. 2019

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…Figure 2 shows the temperature programmed reduction (TPR) profiles of the non-reduced catalysts. The evolution of Pd species upon H 2 -TPR is well-described in the literature [38,39]. Bulk PdO reduces in H 2 atmosphere at room temperature (around 25 • C or even lower) and forms palladium hydrides, β-PdHx [40].…”

Section: Introductionmentioning

confidence: 88%

Promoting Light Hydrocarbons Yield by Catalytic Hydrodechlorination of Residual Chloromethanes Using Palladium Supported on Zeolite Catalysts

et al. 2020

View full text Add to dashboard Cite

Gas catalytic hydrodechlorination (HDC) of trichloromethane (TCM) and dichloromethane (DCM) was analyzed using Pd (1 wt.%) on different zeolites as catalysts. The aim of this study was to know the surface properties of the catalysts and reaction conditions that promote the yield to light hydrocarbons in this reaction. Five different zeolite supports were used from three commercial zeolites (KL, L-type; NaY, Faujasite; H-MOR, Mordenite). KL and NaY were submitted to ionic exchange treatments in order to increase their acidity and analyze the effect of the acidity in the activity and selectivity of the HDC reaction. Exchanged zeolites (HL and HY) showed the highest Pd dispersion due to their higher surface acidity. The best TCM/DCM conversion and selectivity to light hydrocarbons was obtained using the two non-exchanged zeolite-catalysts, KL and NaY. Low surface acidity seems to be the key aspect to promote the formation of light hydrocarbons. The formation of these products is favored at high reaction temperatures and low H2: chloromethane ratios. KL showed the highest selectivity to olefins (60%), although with a lower dechlorination degree. Non-exchanged NaY catalyst showed high selectivity to paraffins (70% and 95% for the HDC of DCM and TCM, respectively).

show abstract

“…Generally, the larger the metal NPs are, the more difficult it is for these materials to disintegrate, and more energy is needed to prevent smaller particles from reaggregating, , according to Monte Carlo models. ,, Ding et al reported that Rh NPs with a size of approximately 5 nm can be dispersed into isolated Rh mononuclear complexes on an active carbon support, while Ir NPs larger than approximately 6 nm are difficult to disperse due to strong Ir–Ir bonds and the resulting kinetic stability of Ir NPs . Au particles larger than 10 nm were also very difficult to disperse. ,, In addition, some molecules with lone-pair electrons such as CO, O 2 , and NO could coordinate with the surface metal ions of NPs, reducing their specific energy and weakening their interaction with the parent matrix during the atomic dispersion of NPs. , Furthermore, chlorination, oxychlorination, − and halogenated hydrocarbon treatment ,− for the redispersion of metal NPs have been discussed previously. However, urgent issues remain, including high energy consumption, particle size limitation, and subsequent recoalescence of exfoliated metal atoms, especially after removing the dispersants or induced species.…”

Section: Introductionmentioning

confidence: 99%

Iodide-Coordinated Single-Site Pd Catalysts for Alkyne Dialkoxycarbonylation

Feng

Hemberger

et al. 2021

ACS Catal.

View full text Add to dashboard Cite

Heterogeneous single-metal-site catalysts (HSMSCs) have attracted considerable interest, but most studies have focused on the metal atoms in the active site while ignoring the key role of ligands. The unique coordination environment of a single-site catalyst is crucial for realizing its potential. Constructing this kind of catalyst via a feasible and practical fabrication method is challenging. Herein, a single-site Pd catalyst with iodide ligands supported on activated carbon (Pd1/AC) was successfully fabricated by atomic dispersion of large Pd nanoparticles (NPs). Intermediate I• radicals were detected during the atomic dispersion process of Pd NPs by in situ imaging photoelectron photoion coincidence spectroscopy (in situ iPEPICO) with vacuum ultraviolet synchrotron radiation. The molecular structure of single-site Pd was established as [Pd(CO)I4(OAC)]2– through combined characterization. Alkyne dialkoxycarbonylation with high selectivity toward 1,4-dicarboxylic acid esters (>94%) and high acetylene conversion (>99%) was achieved. A sulfonic promoter on the Pd1/AC catalyst for alkyne dialkoxycarbonylation was avoided because of the iodide ligand. Good durability and a broad substrate scope were successfully achieved.

show abstract

Oxy-chlorination as an effective treatment of aged Pd/CeO2-Al2O3 catalysts for Pd redispersion

Cited by 22 publications

References 71 publications

Selectivity to Olefins in the Hydrodechlorination of Chloroform with Activated Carbon-Supported Palladium Catalysts

Selectivity to Olefins in the Hydrodechlorination of Chloroform with Activated Carbon-Supported Palladium Catalysts

Promoting Light Hydrocarbons Yield by Catalytic Hydrodechlorination of Residual Chloromethanes Using Palladium Supported on Zeolite Catalysts

Iodide-Coordinated Single-Site Pd Catalysts for Alkyne Dialkoxycarbonylation

Contact Info

Product

Resources

About