Active carbonsupported nickel–palladium catalysts

Authors: I I Kamińska A Śrębowata

Publish Date: 2015/03/07

Volume: 41, Issue: 12, Pages: 9267-9280

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Abstract

Norit active carbonsupported Ni–Pd catalysts were prepared by incipient wetness impregnation from the metal chlorides NiCl2·6H2O and PdCl2 The catalysts were characterized by temperatureprogrammed reduction Xray diffraction and scanning electron microscopy and by temperatureprogrammed hydrogenation TPH of the catalysts after use When the catalysts were used for gasphase hydrodechlorination HDC of 12dichloroethane 12DCA and 112trichloroethene TCE very high activity and stability at a relatively low reaction temperature 503 K were observed Hydrodechlorination of TCE led to formation of hydrocarbons as the main products Use of Ni and Ni–Pd catalysts for hydrodechlorination of 12DCA resulted in very high ~100  selectivity for ethene TPH of the catalysts after use for HDC of 12DCA and TCE revealed the presence of carbon and chlorinecontaining deposits on the surfaces of the catalysts Formation of the NiC x fcc phase and the Ni3C hcp carbide phase were detected for the monometallic nickel and Ni95Pd05 catalystsThe continuous development of industry results in large amounts of harmful substances in the atmosphere water and soil Particular attention should be focused on the chlorinated hydrocarbons eg 12dichloroethane 12DCA and 112trichloroethene TCE—substances commonly used in industry as solvents extractants and degreasing agents Because of their potential carcinogenic mutagenic and teratogenic effects on living organisms the danger is very serious 1 2 3 Therefore finding effective and inexpensive methods for removal of these compounds is extremely important One such method is hydrodechlorination HDC Noble metals for example palladium and platinum are effective catalysts of HDC 4 5 6 but their high cost limits practical application Nickel an inexpensive metal with very good catalytic properties in the transformation of chlorinated compounds into value added products can be an attractive alternative for Pd and Pt 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Depending on the type of the support different product distributions are obtained Application of supports with acidic properties for example the acidic form of BEA zeolite or γAl2O3 usually leads to formation of vinyl chloride as the main product of HDC of 12DCA 15 16 TCE conversion usually leads to hydrocarbons 20The purpose of this study was to investigate the effect of addition of small amounts of palladium on the catalytic behavior of Norit CNR 115 carbonsupported nickel in HDC of 12DCA and TCE and the effect of nickel carbiding and of fcc NiC x phase and hcp Ni3C phase formation on the properties of Ni–Pd systems Use of carbon obtained from a renewable raw material by use of a patented version of the phosphoric acid process also has environmental advantagesA commercial activated carbon CNR115 produced from a renewable raw material by use of a patented version of the phosphoric acid process 22 and supplied by Norit was used as support Before preparation of the catalysts the carbon was washed with redistilled water only and dried in an air at 393 K

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