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

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

doi:10.3390/catal9090733

Cited by 9 publications

(5 citation statements)

References 39 publications

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“…However, unlike in the case of KCPd, now peaks associated with metallic Pd can be seen with a shift to higher scattering angle after reaction. This may indicate the formation of Pd carbide species 42,46 , in agreement with the XPS results. The formation of these species was found to cause the deactivation of Pd catalysts in previous studies 46,47 .…”

Section: Resultssupporting

confidence: 90%

“…The analysis of the catalysts after the reaction shows a decrease of zerovalent Pd for KCPd, NaCPd, and FeCPd, while for ZnCPd this proportion increases, contributing to the reactivation of the catalyst at the highest time on stream tested 42 (Figure 4). On the other hand, an increase in organic chlorine on the surface of the catalysts was observed after reaction (Table 4), more pronounced in KCPd and NaCPd.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

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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.

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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

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Section: Resultssupporting

confidence: 90%

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

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.

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“…At 90 to 105 h, the conversion continued to drop, indicating that the catalyst was gradually deactivated and needs to be replaced or reactivated. According to previous studies, there are three common methods that can be used to reactivate Pd/C catalysts: washing the catalyst with hot water or ethanol, 33 blowing the catalyst with hydrogen or air flow at high temperatures, 34 or treating the catalyst with microwave and ultrasonic sprays. 35 Kinetic Study of Hydrogenolysis of HFA•3H 2 O.…”

Section: Effects Of External Andmentioning

confidence: 99%

Heterogeneous Continuous Flow Hydrogenation of Hexafluoroacetone Trihydrate and Its Kinetic Modeling

Xue

et al. 2023

Ind. Eng. Chem. Res.

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Hexafluoroisopropanol (HFIP) is an important intermediate of sevoflurane, an inhalation anesthetic for pediatric anesthesia, and it is produced industrially mainly by the catalytic hydrogenation reduction of hexafluoroacetone (HFA). In previous studies, the hydrogenation of HFA was usually performed in batch reactors with the disadvantages of harsh reaction conditions and low conversion rates. On the other hand, continuous flow technology is increasingly being used for intrinsically safe hydrogenation processes to avoid safety issues caused by the accumulation of hydrogen gas in high-pressure reactors. In this study, a continuous flow system was developed in a micropackedbed reactor, and the intrinsic kinetics of the reaction were studied. This continuous flow process minimized mass and heat transfer problems and achieved higher productivity in terms of time and space yield than traditional process methods. Under kinetically controlled conditions, the operating conditions were varied with temperature between 363 and 393 K, hydrogen pressure of 10 bar, and catalyst loading between 0.1 and 0.5 g. In the end, we achieved conversion and selectivity of up to 99% and a space−time yield of about 9 times that of the batch reactor. To further investigate the long-term stability of the reaction system, the flow system was successfully operated for 90 h at a liquid flow rate of 0.5 mL/min. In addition, residence time distribution curves at different flow rates were determined, and possible mechanistic pathways of the reaction were explored based on the Langmuir−Hinshelwood method. The reaction was found to be an adsorption−desorption type with a mechanism of competitive adsorption by H 2 dissociation, and the thermodynamic properties associated with the rate constants were estimated.

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“…The supported noble metals (Pt, Pd, Rh, and Ru) and their alloys are recognized as the most effective catalysts for the hydrodechlorination due to their high reactivity in the target reaction and very high resistance to the deactivation caused by the chlorination [2,3,8,[10][11][12][13][14][15][16]. However, high prices and limited availability of the precious metals render their industrial applications unreasonable.…”

Section: Introductionmentioning

confidence: 99%

Two Scenarios of Dechlorination of the Chlorinated Hydrocarbons over Nickel-Alumina Catalyst

et al. 2020

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Dechlorination processes attract great interest since they are involved in environmental protection and waste disposal technologies. In this paper, the process of gas-phase dechlorination of 1,2-dichloroethane, chloroform, and chlorobenzene over Ni/Al2O3 catalyst (90 wt% Ni) prepared by a coprecipitation technique was investigated. The reduction behavior of the oxide precursor NiO/Al2O3 was studied by thermogravimetric analysis in a hydrogen medium. A thermodynamic assessment of the conditions under which metallic nickel undergoes deactivation due to the formation of nickel chloride was performed. The dechlorination of chlorinated substrates was studied using a gravimetric flow-through system equipped with McBain balances in a wide range of temperatures (350–650 °C) and hydrogen concentrations (0–98 vol%). The impact of these parameters on selectivity towards the products of hydrodechlorination (C2H4, C2H6, and C6H6) and catalytic pyrolysis (carbon nanomaterial and CH4) was explored. The relationship between the mechanisms of the catalytic hydrodechlorination and the carbide cycle was discussed, and the specific reaction conditions for the implementation of both scenarios were revealed. According to the electron microscopy data, the carbonaceous products deposited on nickel particles during catalytic pyrolysis are represented by nanofibers with a disordered structure formed due to the peculiarity of the process including the side carbon methanation reaction.

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

Cited by 9 publications

References 39 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

Heterogeneous Continuous Flow Hydrogenation of Hexafluoroacetone Trihydrate and Its Kinetic Modeling

Two Scenarios of Dechlorination of the Chlorinated Hydrocarbons over Nickel-Alumina Catalyst

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