Dehydrochlorination of Intermediates in the Production of Vinyl Chloride over Lanthanum Oxide-Based Catalysts

Heijden, Alwies W. A. M. van der; Mens, A.J.M.; Bogerd, René; Weckhuysen, Bert M.

doi:10.1007/s10562-008-9436-2

Cited by 25 publications

(12 citation statements)

References 36 publications

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“…The chemistry of gas‐phase β‐elimination over solid catalysts has been well established on alkyl halides (RX) with different α‐leaving groups and/or β‐substituents . However, there were few academic articles on the selective dehydrohalogenation of haloalkanes with more than one halogen leaving groups on the same C α atom.…”

Section: Introductionmentioning

confidence: 99%

Highly Selective Dehydrochlorination of 1,1,1,2‐Tetrafluoro‐2‐chloropropane to 2,3,3,3‐Tetrafluoropropene over Alkali Metal Fluoride Modified MgO Catalysts

et al. 2017

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Gas‐phase selective dehydrochlorination of 1,1,1,2‐tetrafluoro‐2‐chloropropane (HCFC‐244bb) to 2,3,3,3‐tetrafluoropropene was investigated over various K and Cs halides modified MgO catalysts. The reaction proceeded in the absence of additives such as air and HF. High dehydrochlorination selectivity (>97 %) with moderate activity (>14 μmol h−1 m−2) was achieved on KF and CsF modified MgO catalysts, in which the dehydrofluorination process was inhibited. Compared with alkali metal modified MgO, the dehydrofluorination product, 2‐chloro‐3,3,3‐trifluoropropene increased over Zr and Al modified MgO and fluorinated MgO catalysts (sel. of 20–76 %). XRD and energy‐dispersive‐spectrometry results revealed that surface chlorination and fluorination occurred on the MgO‐based catalysts during the reaction. Introducing alkali metal fluorides into the catalyst can reduce the fluorination of MgO and the deposition of chlorine species, thus improving the dehydrochlorination activity and stability of MgO. The NH3 temperature‐programmed desorption (TPD) results show that decreasing the surface acidity of catalyst benefits the dehydrochlorination of HCFC‐244bb, whereas the relationship between the basicity of the catalyst and its dehydrohalogenation behavior is complicated as shown by the CO2 TPD results. According to the hard–soft acid–base principle, the dehydrohalogenation selectivity can be correlated with the surface chemical hardness of the catalyst.

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Section: Introductionmentioning

confidence: 99%

Highly Selective Dehydrochlorination of 1,1,1,2‐Tetrafluoro‐2‐chloropropane to 2,3,3,3‐Tetrafluoropropene over Alkali Metal Fluoride Modified MgO Catalysts

et al. 2017

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“…However, the oxychlorination cycle can be skipped, once terminal lattice oxygen is formed via condensation via the hydrolysis of surface hydroxyl groups (arrow 5). 37 The catalytic destruction of CMs over terminal lattice oxygen of La is well described, 38 and it is hypothesized that a similar mechanism plays a role for the lanthanide-based catalysts tested in this study. When the CM catalytically destructs (arrows 6−7), surface chlorination is again obtained, where it crosses paths with the oxychlorination cycle again.…”

Section: Experimental Methodsmentioning

confidence: 74%

Mechanistic Insights into the Lanthanide-Catalyzed Oxychlorination of Methane as Revealed by Operando Spectroscopy

Terlingen

Oord

Ahr³

et al. 2021

ACS Catal.

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Commercialization of CH 4 valorization processes is currently hampered by the lack of suitable catalysts, which should be active, selective, and stable. CH 4 oxychlorination is one of the promising routes to directly functionalize CH 4 , and lanthanidebased catalysts show great potential for this reaction, although relatively little is known about their functioning. In this work, a set of lanthanide oxychlorides (i.e., LnOCl with Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) and Er-and Yb-based catalysts were synthesized, characterized, and tested. All lanthanide-based catalysts can directly activate CH 4 into chloromethanes, but their catalytic properties differ significantly. EuOCl shows the most promising catalytic activity and selectivity, as very high conversion levels (>30%) and chloromethane selectivity values (>50%) can be reached at moderate reaction temperatures (∼425 °C). Operando Raman spectroscopy revealed that the chlorination of the EuOCl catalyst surface is rate-limiting; hence, increasing the HCl concentration improves the catalytic performance. The CO selectivity could be suppressed from 30 to 15%, while the CH 4 conversion more than doubled from 11 to 24%, solely by increasing the HCl concentration from 10 to 60% at 450 °C. Even though more catalysts reported in this study and in the literature show a negative correlation between the S CO and HCl concentration, this effect was never as substantial as observed for EuOCl. EuOCl has promising properties to bring the oxychlorination one step closer to an economically viable CH 4 valorization process.

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“…Various catalysts for DCE conversion to VCM have been studied, e.g., metal oxides and chlorides, and molecular sieves, to enable DCE pyrolysis at 300-400 • C, but the catalysts were rapidly deactivated and unsuitable for industry [5][6][7][8][9][10][11][12]. Yozo and co-workers first reported that a polyacrylonitrile-based active carbon fiber could catalyze dehydrochlorination of DCE into VCM over 300 • C, but catalytic activity fast decreased [13].…”

Section: Introductionmentioning

confidence: 99%

Understanding Surface Basic Sites of Catalysts: Kinetics and Mechanism of Dehydrochlorination of 1,2-Dichloroethane over N-Doped Carbon Catalysts

et al. 2020

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The production of vinyl chloride (VCM) by pyrolysis of 1,2-dichloroethane (DCE) is an important process in the ethylene-based poly(vinyl chloride) industry. The pyrolysis is performed at temperatures above 500 °C, gives low conversions, and has high energy consumption. We have shown that N-doped carbon catalysts give excellent performances in DCE dehydrochlorination at 280 °C. The current understanding of the active sites, mechanism, and kinetics of DCE dehydrochlorination over N-doped carbon catalysts is limited. Here, we showed that pyridinic-N on a N-doped carbon catalyst is the active site for catalytic production of vinyl chloride monomer from DCE. The results of CO2 and DCE temperature-programmed desorption experiments showed that the pyridinic-N catalytic sites are basic, and the mechanism of dehydrochlorination on a N-doped carbon catalyst involves a carbanion. A kinetic study of dehydrochlorination showed that the surface reaction rate on the N-doped carbon catalyst was the limiting step in the catalytic dehydrochlorination of DCE. This result enabled clarification of the dehydrochlorination mechanism and optimization of the reaction process. These findings will stimulate further studies to increase our understanding of the relationship between the base strength and catalytic performance. The results of this study provide a method for catalyst optimization, namely modification of the amount of pyridinic-N and the base strength of the catalyst, to increase the surface reaction rate of DCE dehydrochlorination on N-doped carbon catalysts.

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Dehydrochlorination of Intermediates in the Production of Vinyl Chloride over Lanthanum Oxide-Based Catalysts

Cited by 25 publications

References 36 publications

Highly Selective Dehydrochlorination of 1,1,1,2‐Tetrafluoro‐2‐chloropropane to 2,3,3,3‐Tetrafluoropropene over Alkali Metal Fluoride Modified MgO Catalysts

Highly Selective Dehydrochlorination of 1,1,1,2‐Tetrafluoro‐2‐chloropropane to 2,3,3,3‐Tetrafluoropropene over Alkali Metal Fluoride Modified MgO Catalysts

Mechanistic Insights into the Lanthanide-Catalyzed Oxychlorination of Methane as Revealed by Operando Spectroscopy

Understanding Surface Basic Sites of Catalysts: Kinetics and Mechanism of Dehydrochlorination of 1,2-Dichloroethane over N-Doped Carbon Catalysts

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