Alumina-Supported Copper Chloride

Leofanti, G.; Marsella, A.; Cremaschi, B.; Garilli, M.; Zecchina, A.; Spoto, G.; Bordiga, Silvia; Fisicaro, P.; Prestipino, Carmelo; Villain, F.; Lamberti, Carlo

doi:10.1006/jcat.2001.3460

Cited by 66 publications

(46 citation statements)

References 20 publications

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“…In the same set of works by Leofanti et al it has been shown that the surface Cu-aluminate phase is totally inactive 23 and that the overall ethylene oxychlorination reaction (3) is catalyzed only by the CuCl 2 phase following a three steps redox mechanism: chlorination of ethylene by reduction of CuCl 2 to CuCl (4); oxidation of CuCl to an oxychloride (5) and re-chlorination with HCl (6), closure of the catalytic cycle: 24,25 2CuCl 2 + C 2 H 4 → C 2 H 4 Cl 2 + 2CuCl (4) 2CuCl + 1/2O 2 → Cu 2 OCl 2 (5)…”

Section: Introductionmentioning

confidence: 96%

Quantification of copper phases, their reducibility and dispersion in doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination

Muddada

Olsbye

Leofanti³

et al. 2010

Dalton Trans.

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The comprehensive understanding of the composition, behaviour and reactivity of a catalyst used inside industrial plants is an extremely hard task that is rarely achieved. It requires the use of different spectroscopic techniques, applied under in situ or in operando conditions, and combined with the investigation of the catalyst activity. Often the operating experimental conditions are different from technique to technique and the different results must be compared with care. In the present contribution, we combined in situ XANES/EXAFS, IR spectroscopy of adsorbed CO, CO chemisorption and catalytic tests performed using a pulse reactor in depletive mode. This multitechnical approach resulted in the understanding of the role that dopants (LiCl, KCl, CsCl, MgCl(2) LaCl(3)) have in the nature, relative fraction, reducibility and dispersion of Cu-phases on CuCl(2)/gamma-Al(2)O(3) catalysts for oxychlorination reaction, a key step of the PVC chemistry. In the undoped catalyst two Cu phases coexist: Cu-aluminate and supported CuCl(2), being the latter the only active one [J. Catal., 2000, 189, 91]. EXAFS and XANES highlighted that all dopants contribute more or less efficiently in increasing the fraction of the active copper species, that reaches a value of almost 100% in the case of MgCl(2) or LaCl(3). EXAFS directly, and IR indirectly, proved that the addition of KCl or CsCl (and less efficiently of LiCl) results in the formation of mixed CuK(x)Cl(2+x) or CuCs(x)Cl(2+x) phases, so altering the chemical nature of the active phase. XANES spectroscopy indicates that addition of MgCl(2) or LaCl(3) does not affect the reducibility by ethylene (under static conditions) of the active CuCl(2) phase and that the reducibilility of the new copper-dopant mixed chloride are in the order CuCl(2)> CuLi(x)Cl(2+x) > CuK(x)Cl(2+x) > CuCs(x)Cl(2+x). However, when reduction is done inside a pulse reactor, a more informative picture comes out. The last technique is able to differentiate all samples, and their ability to be reduced by ethylene resulted in the order: La- > Mg- > Li-doped > undoped > K- > Cs-doped catalyst. To understand this apparent discrepancy the dispersion of the active phase, measured by CO chemisorption, was needed: it has been found that addition of LiCl increases enormously the dispersion of the active phase, LaCl(3) significantly and MgCl(2) barely, while addition of both KCl and CsCl results in a decrease of the surface area of the active phase. The mechanism of the enhancing effect of La and Mg on catalytic activity is still not clear, but it could be associated to the modification that they induce to the support surface: the Cu is so highly dispersed that almost all is in direct contact with support surface. It is finally worth noticing that the previous EXAFS and XANES study allowed us to refer the chemisorption data to the active phase only, while the IR study allowed us to fix the Cu(+)/CO surface stoichiometry. Summarizing the use of a multidisciplinary approach has been the conditio sine qua non (mandator...

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Section: Introductionmentioning

confidence: 96%

Quantification of copper phases, their reducibility and dispersion in doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination

Muddada

Olsbye

Leofanti³

et al. 2010

Dalton Trans.

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“…Other chlorides (mainly alkali or alkaline earth metal chlorides) in variable concentration are also added to make the catalyst more suitable for industrial reactors 1–3. In spite of an abundant literature on the subject,1–8 a significantly improved knowledge of the system—limited to the basic catalyst (containing only CuCl 2 without additives)—has been achieved only recently 4, 6–8. In particular, it has been shown by feeding separately the three reagents that the oxychlorination reaction (1) is catalyzed by a highly dispersed CuCl 2 phase4, 6 and follows a three‐step redox mechanism: a) chlorination of ethylene by reduction of CuCl 2 to CuCl [Eq.…”

mentioning

confidence: 99%

“…(2)], b) oxidation of CuCl to an oxychloride [Eq. (3)], and c) re‐chlorination of this oxychloride with HCl [closure of the catalytic cycle,7, 8 Eq. (4)]…”

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confidence: 99%

The Chemistry of the Oxychlorination Catalyst: an In Situ, Time-Resolved XANES Study

Lamberti,

Prestipino,

Bonino

et al. 2002

Angew. Chem. Int. Ed.

125

154

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Almost all of the world production of vinyl chloride today is based on cracking of 1,2-dichloroethane. For many decades, this compound has been produced by catalytic oxychlorination of ethylene with hydrochloric acid and oxygen [Eq. (1)]. The reaction is performed at 490 ± 530 K and 5 ± 6 atm (1 atm % 1.01 Â 10 5 Pa) using both air and oxygen in fluid-or fixed-bed reactors. [1] C 2 H 4 2 HCl 1 ³2O 2 3 C 2 H 4 Cl 2 H 2 O(1) 24 h, then cooled to 0 8C, and quenched with aqueous hydrochloric acid (3 m, 5 mL). The resulting mixture was warmed to 23 8C and stirred for 30 min, at which point aqueous sodium hydroxide (3 m, 10 mL) was added. The mixture was stirred at 23 8C for 30 min and extracted with diethyl ether (3 Â 20 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Column chromatography on silica gel eluting with 30 % diethyl ether in pentane afforded (R)-2-ethyl-2-methyl-2,3-dihydrocinnamyl alcohol 5 a (239 mg, 1.34 mmol, 96 %) as a colorless oil. 1 H NMR (CDCl 3 ): d 7.19 ± 7.31 (m, 5 H), 3.33 (s, 2 H), 2.61 (AB, 2 H, J 24.6 Hz), 1.58 (bs, 1 H), 1.27 ± 1.40 (m, 2 H), 0.93 (t, 3 H, J 7.5 Hz), 0.82 ppm (s, 3 H); 13 C NMR (CDCl 3 ): d 139.0, 130.8, 128.1, 126.2, 68.4, 42.8, 39.1, 29.1, 21.0, 8.3 ppm. High-resolution FAB-MS: m/z (MH): 179.14359 (C 12 H 19 O requires 179.14359).[a] 25 D À 5.9 (c 14.2, CH 2 Cl 2 ). The product was determined to have 94 % ee by HPLC (Chiralcel OD column, eluting with 1 % 2-propanol in hexanes at 0.7 mL min À1 ; R t 20.5 min (major enantiomer), 22.8 min (minor enantiomer)).[21] Greater than two equivalents of electrophile must be added, as the Sand C-alkylations occur at similar rates.[22] The reasons for this dichotomous behavior are unclear. We have been unable to detect significant E/Z isomerization under the reaction conditions. Other effects such as aggregation state and/or different reactive conformations of the E and Z enolates cannot be ruled out.[23] Alkylation of amide enolates with unactivated electrophiles often requires the addition of HMPA or LiCl for useful reaction rates to be observed. For examples see ref.[19] and a

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“…The first commercial Deacon catalysts were based on CuCl 2 supported on pumice 2–5. These catalysts were improved in the 1960s by Shell and were used in fluidized‐bed reactors with a capacity of 30 kt per year for the production of chlorine 1, 6.…”

Section: Introductionmentioning

confidence: 99%

Corrosion‐Resistant Parallel Fixed‐Bed Reactors for High‐Throughput Screening of New Deacon Reaction Catalysts

et al. 2014

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Two ten‐channel fixed‐bed reactor systems were developed for high‐throughput screening of new Deacon catalysts. The sequential ten‐channel reactor allows the determination of the activity of up to ten catalysts per day. With a ten‐channel ageing reactor the long‐time stability of catalytic activity can be tested in parallel. Both systems are robust, quite resistant against corrosion, and use the identical reaction tubes which enable the direct transfer of a catalyst from one to the other system. A mass‐spectrometric pulse method has been developed and applied successfully for the analysis of the corrosive product gas mixture of the Deacon reaction.

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Alumina-Supported Copper Chloride

Cited by 66 publications

References 20 publications

Quantification of copper phases, their reducibility and dispersion in doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination

Quantification of copper phases, their reducibility and dispersion in doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination

The Chemistry of the Oxychlorination Catalyst: an In Situ, Time-Resolved XANES Study

Corrosion‐Resistant Parallel Fixed‐Bed Reactors for High‐Throughput Screening of New Deacon Reaction Catalysts

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