Kinetic Study of the Hydrodechlorination of Chloromethanes with Activated-Carbon-Supported Metallic Catalysts

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

doi:10.1021/ie5042484

Cited by 12 publications

(12 citation statements)

References 23 publications

(97 reference statements)

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“…A similar behavior follow Rh/CM and Ru/CM when DCM is used as the reactant, however the selectivity to chlorinated products considerably increases for the HDC of TCM with these catalysts, specially for Ru/CM. This is in agreement with kinetics results obtained with similar catalyst [35]. In a previous work where a kinetic study of the HDC of DCM and TCM to obtain methane with carbon supported Pd, Pt, Rh and Ru catalysts was performed it was found that Pd/C and Pt/C followed a LHHW model controlled by adsorption.…”

Section: Catalytic Activitysupporting

confidence: 91%

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: Catalytic Activitysupporting

confidence: 91%

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

et al. 2018

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“…In In the literature, the HDC technology has been used for the removal of the chlorinated pollutant or the production of valuable products from chlorinated compounds. Complete conversion and almost complete dechlorination have been achieved for DCM [1,18,20,21,23,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], TCM [1,18,20,21,23,27,[31][32][33][34]43,[47][48][49][50] and TTCM [27,. Additionally, the upgrading of residual chloromethanes for the production of valuable hydrocarbons, such as light olefins or paraffins, which could be used as feedstock in chemical and petrochemical industries, has also been explored in recent years [32][33][34]48].…”

Section: Synthesis Of Catalysts For Hydrodechlorination Active Phase ...mentioning

confidence: 99%

Understanding Hydrodechlorination of Chloromethanes. Past and Future of the Technology

et al. 2020

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Chloromethanes are a group of volatile organic compounds that are harmful to the environment and human health. Abundant studies have verified that hydrodechlorination might be an effective treatment to remove these chlorinated pollutants. The most outstanding advantages of this technique are the moderate operating conditions used and the possibility of obtaining less hazardous valuable products. This review presents a global analysis of experimental and theoretical studies regarding the hydrodechlorination of chloromethanes. The catalysts used and their synthesis methods are summarized. Their physicochemical properties are analyzed in order to deeply understand their influence on the catalytic performance. Moreover, the main causes of the catalyst deactivation are explained, and prevention and regeneration methods are suggested. The reaction systems used and the effect of the operating conditions on the catalytic activity are also analyzed. Besides, the mechanisms and kinetics of the process at the atomic level are reviewed. Finally, a new perspective for the upgrading of chloromethanes, via hydrodechlorination, to valuable hydrocarbons for industry, such as light olefins, is discussed.

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“…For the two different studies, the common experiments' conditions are: operation at atmospheric pressure; employing a total flow rate of 100 N cm 3 min −1 ; a reagents molar ratio of 100 (H 2 /DCM); a reaction temperature of 250 • C. The inlet DCM concentration for both studies was 1000 ppmv, which was prepared by mixing a DCM/N 2 commercial mixture and N 2 in the appropriate ratios (both gases supplied by Praxair, Madrid, Spain). According to a previous study, under these conditions, transfer limitations might be discarded [39]. The catalysts were reduced in situ under continuous H 2 flow at 300 • C for 90 minutes prior to the HDC experiments.…”

Section: Catalytic Activity Experimentsmentioning

confidence: 99%

Recycling of Gas Phase Residual Dichloromethane by Hydrodechlorination: Regeneration of Deactivated Pd/C Catalysts

et al. 2019

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Dichloromethane (DCM) is an important pollutant with very harmful effects on human health and the environment. Catalytic hydrodechlorination (HDC) is an environmentally friendly technology for its removal from gas streams; it avoids the formation of hazardous pollutants like dioxins and phosgene (produced by other techniques), and the products obtained can be reused in other industries. When compared to other precious metals, Pd/C catalyst exhibited a better catalytic activity. However, the catalyst showed a significant deactivation during the reaction. In this study, the oxidation state and particle size of Pd was monitored with time on stream in order to elucidate the transformations that the catalyst undergoes during HDC. The deactivation can be ascribed to the formation of a new PdC x phase during the first hour of reaction. Carbon atoms incorporated to Pd lattice come from (chloro)-hydrocarbons adsorbed in the metallic species, whose transformation is promoted by the HCl originating in the reaction. Nevertheless, the catalyst was regenerated by air flow treatment at 250 • C, recovering the catalyst more than 80% of initial DCM conversion.

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Kinetic Study of the Hydrodechlorination of Chloromethanes with Activated-Carbon-Supported Metallic Catalysts

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Cited by 12 publications

References 23 publications

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

Understanding Hydrodechlorination of Chloromethanes. Past and Future of the Technology

Recycling of Gas Phase Residual Dichloromethane by Hydrodechlorination: Regeneration of Deactivated Pd/C Catalysts

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