Gas-phase hydrodechlorination of mixtures of chloromethanes with activated carbon-supported platinum catalysts

Arevalo-Bastante, A.; Álvarez-Montero, M.A.; Bedia, Jorge; Gómez-Sainero, L.M.; Rodrı́guez, Juan J.

doi:10.1016/j.apcatb.2015.05.058

Cited by 26 publications

(14 citation statements)

References 29 publications

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“…The XRD patterns of the fresh-reduced catalysts did not show any remarkable peak associated with zero-valent metal, the main line located at 2θ value of 39.9º, 40.1 o , 41.1º and 40.0º for Pt/CM, Pd/CM, Rh/CM and Ru/CM respectively [33]. This suggests that the catalysts are well dispersed as it was found in previous works for similar catalysts [22,31]. Figures 4-7 show the conversion of DCM and TCM at different reaction temperatures for all the catalysts, as well as the selectivity to the different reaction products.…”

Section: Characterization Of the Catalystssupporting

confidence: 76%

“…The metallic catalysts were prepared by incipient wetness impregnation of a commercial activated carbon (Merck), whose characteristics have been reported elsewhere [31], using acid aqueous solutions (1M) of PtCl4, PdCl2, RhCl3 and RuCl3 (supplied by Sigma-Aldrich) of the required concentrations to obtain 1 wt.% active phase (Pt, Pd, Rh or Ru) nominal loadings. The catalysts were dried overnight at room temperature and heated under air atmosphere to 100 C at 20 C h -1 , the final temperature being maintained for 2 h. The resulted catalysts were called Pt/CM, Pd/CM, Rh/CM and Ru/CM.…”

Section: Catalysts Preparationmentioning

confidence: 99%

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Valorization of chloromethanes by hydrodechlorination with metallic catalysts

et al. 2018

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The performance of Pd, Pt, Rh and Ru based catalysts in the hydrodechlorination of chloromethanes to obtain ethane and ethylene was evaluated by means of computational analysis and hydrodechlorination experiments. A computational analysis using density functional theory (DFT) was developed to obtain preliminary insight on the potential catalytic mechanisms for the reactions involved using palladium, platinum, rhodium and ruthenium metallic clusters. Stable catalytic intermediates were obtained by quantum-chemical calculations in the hydrodechlorination of dichloromethane on Pd6 and Rh6 clusters, presenting ••CH2 and •CH3 radicals and C2H4, C2H6 and CH4 products. On the contrary, it was not possible to obtain all these stable intermediates using Pt6 and Ru6 clusters. Theoretical analysis revealed lower desorption energies for ethane and ethylene products in Pd6 than in Rh6 clusters, what indicates a favorable selectivity of Pd-based catalyst for desired C2 products. Then, carbon supported catalysts containing these four metals were prepared and experimentally evaluated in the hydrodechlorination of dichloromethane (DCM) and trichloromethane (TCM) at low H2 excess and a reaction temperature range of 150-400 ºC. In agreement with computational results, in experimental tests, the Pd based catalyst showed the best performance for the hydrodechlorination of chloromethanes to obtain C2 products, followed by Rh. Ru and Pt have a poor performance, in special Pt based catalyst, which shows almost no selectivity to C2 products. This computational and experimental study emphasizes, for the first time, the good performance (high activity and selectivity) of Pd carbon supported catalysts in the valorization of chloromethane compounds to obtain C2 hydrocarbon products.

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Section: Characterization Of the Catalystssupporting

confidence: 76%

Section: Catalysts Preparationmentioning

confidence: 99%

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

et al. 2018

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“…Other authors have reported similar behavior in carbon-supported Pd catalysts [30]. With regard to Pt/C, the mean particle size after reduction at the highest temperature is 2.5 nm, also higher than the 1.6 and 1.7 nm previously obtained for the catalyst reduced at 250 °C [23,38]. Therefore, it can be concluded that sintering of metallic particles takes place during reduction at increasing temperatures, although to different extents, in the cases of Pt and Pd catalysts.…”

Section: Characterization Of the Catalystssupporting

confidence: 69%

“…Among the publications related to the HDC with activated carbon-based catalysts, metals like Pd, Pt, Rh, Ru or Ni are the most frequent active phases found, with Pd being by far the most preferred one, due to its high capacity for the hydrogenolysis of C-Cl bonds [11][12][13]. This metal, as well as Pt and Rh, have demonstrated high activity and dechlorination capacity [12,[14][15][16][17][18][19][20][21][22][23]. Several authors have reported relationships between the catalyst performance and different properties, like metal particles structure, catalyst porosity or surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

Properties of Carbon-supported Precious Metals Catalysts under Reductive Treatment and Their Influence in the Hydrodechlorination of Dichloromethane

et al. 2018

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This study analyzes the effect of the reduction temperature on the properties of Rh, Pt and Pd catalysts supported on activated carbon and their performance in the hydrodechlorination (HDC) of dichloromethane (DCM). The reduction temperature plays an important role in the oxidation state, size and dispersion of the metallic phase. Pd is more prone to sintering, followed by Pt, while Rh is more resistant. The ratio of zero-valent to electro-deficient metal increases with the reduction temperature, with that effect being more remarkable for Pd and Pt. The higher resistance to sintering of Rh and the higher stability of electro-deficient species under thermal reductive treatment can be attributed to a stronger interaction with surface oxygen functionalities. Dechlorination activity and a TOF increase with reduction temperature (250–450 °C) occurred in the case of Pt/C catalyst, while a great decrease of both was observed for Pd/C, and no significant effect was found for Rh/C. Pt0 represents the main active species for HDC reaction in Pt/C. Therefore, increasing the relative amount of these species increased the TOF value, compensating for the loss of dispersion. In contrast, Pdn+ appears as the main active species in Pd/C and their relatively decreasing occurrence together with the significant decrease of metallic area reduces the HDC activity. Rh/C catalyst suffered only small changes in dispersion and metal oxidation state with the reduction temperature and thus this variable barely affected its HDC activity.

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“…Catalytic hydrodechlorination (HDC) can be one of the alternatives considered to transform chlorinated compounds into more valuable light hydrocarbons. HDC has been extensively studied for the removal of chloromethanes due to the mild required conditions of pressure and temperature [7]. However, only a few works have reported high selectivity to olefins in the HDC reaction, using different types of supports and metallic active phases [8][9][10][11][12].…”

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confidence: 99%

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

et al. 2020

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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).

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Gas-phase hydrodechlorination of mixtures of chloromethanes with activated carbon-supported platinum catalysts

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Cited by 26 publications

References 29 publications

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

Properties of Carbon-supported Precious Metals Catalysts under Reductive Treatment and Their Influence in the Hydrodechlorination of Dichloromethane

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

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