?Ethane oxychlorination? over ?-Al2O3 supported CuCl2?KCl?LaCl3

Xueju, L.; Liu, Jie; Guang-hong, Zhou; Zhen, Kaiji; Li, Wen‐Xing; Cheng, Tiexin

doi:10.1007/s10562-004-3448-3

Cited by 25 publications

(19 citation statements)

References 12 publications

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“…The latter was confirmed by the sharp weight loss accompanied with a exothermic peak from TGA/DTA profiles (Figure 14b). 174 To date, the highest yield of VCM (88% at 823 K) was obtained over CuLiPtClx-K3PO4/α-Al2O3 catalysts reported by the researchers in Monsanto Company. 184 The catalysts were prepared by sequential impregnation of first a mixture of metal chlorides and then K3PO4, and tested in a fluidized-bed reactor.…”

Section: Ethane Oxychlorination For Vcm Productionmentioning

confidence: 98%

“…713 K for 90% alkane conversion) owing to the difficulty of activating the strong C-H bond in ethane molecule. [174][175][176][177] At these temperatures, the formation of undesired over-chlorinated compounds (both saturated and unsaturated) and carbon oxides is observed.…”

Section: Ethane Oxychlorination For Vcm Productionmentioning

confidence: 98%

“…174,176,184,189,190 These systems are not suitable in the case of ethane, because the operating temperature of alkane oxychlorination is much higher than that of alkene oxychlorination and thus compromises the stability of copper catalysts. 174,191 45…”

Section: Ethane Oxychlorination For Vcm Productionmentioning

confidence: 99%

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Halogen-Mediated Conversion of Hydrocarbons to Commodities

2017

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Halogen chemistry plays a central role in the industrial manufacture of various important chemicals, pharmaceuticals, and polymers. It involves the reaction of halogens or halides with hydrocarbons, leading to intermediate compounds which are readily converted to valuable commodities. These transformations, predominantly mediated by heterogeneous catalysts, have long been successfully applied in the production of polymers. Recent discoveries of abundant conventional and unconventional natural gas reserves have revitalized strong interest in these processes as the most cost-effective gas-to-liquid technologies. This review provides an in-depth analysis of the fundamental understanding and applied relevance of halogen chemistry in polymer industries (polyvinyl chloride, polyurethanes, and polycarbonates) and in the activation of light hydrocarbons. The reactions of particular interest include halogenation and oxyhalogenation of alkanes and alkenes, dehydrogenation of alkanes, conversion of alkyl halides, and oxidation of hydrogen halides, with emphasis on the catalyst, reactor, and process design. Perspectives on the challenges and directions for future development in this exciting field are provided.

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Section: Ethane Oxychlorination For Vcm Productionmentioning

confidence: 98%

Section: Ethane Oxychlorination For Vcm Productionmentioning

confidence: 98%

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Halogen-Mediated Conversion of Hydrocarbons to Commodities

2017

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“…CuCl 2 is a highly volatile species at the reaction temperature, so other chlorides (dopants or promoters), (mainly alkaline or alkaline earth chlorides) in a variable concentration, are also incorporated in order to improve the catalytic performances making the catalyst more suitable for use in industrial reactors. [1][2][3][6][7][8][9] In particular, KCl is always present in the catalysts used in fixed bed technologies, sometimes together with other alkali-metal chlorides such as CsCl, NaCl or LiCl. [10][11][12][13] Rare-earth-metal chlorides such as LaCl 3 , added to CuCl 2 and KCl, are also claimed in the patent literature.…”

Section: Introductionmentioning

confidence: 99%

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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“…This alternative route comprises chlorination of ethene, which is performed over FeCl 3 catalysts and yields the intermediate product ethylene dichloride (EDC, C 2 H 4 Cl 2 ), which is thermally dehydrochlorinated in a second step to VCM [2,3]. The hydrogen chloride (HCl) released as a stoichiometric byproduct of the overall process is recycled by ethene oxychlorination to EDC over promoted alumina-supported CuCl 2 catalysts [2,3,[5][6][7][8][9][10][11][12][13][14][15][16][17]. Nevertheless, the instability of the copper chloride system, resulting in its volatilization due to hot spot formation or particle stickiness in fixed-bed or fluidized-bed reactors, constitutes a persisting challenge [18].…”

Section: Introductionmentioning

confidence: 99%