Preparation, characterization, and performance of HMS-supported Ni catalysts for hydrodechlorination of chorobenzene / Jixiang Chen in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3802–3811 Titre : Preparation, characterization, and performance of HMS-supported Ni catalysts for hydrodechlorination of chorobenzene Type de document : texte imprimé Auteurs : Jixiang Chen, Auteur ; Jianjun Zhou, Auteur ; Rijie Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 3802–3811 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : HMS-supported Ni catalysts Hydrodechlorination N2 adsorption X-ray diffraction Résumé : HMS-supported Ni catalysts were prepared by the direct synthesis and the impregnation method. In the direct synthesis, the effect of nickel content and pH value of the preparation system on the catalyst structure and hydrodechlorination performance was systematically investigated. The physicochemical properties of the catalysts were characterized by means of N2 adsorption, hydrogen temperature-programmed reduction, low- and wide-angle X-ray diffraction, hydrogen chemisorption, hydrogen temperature-programmed desorption, transmission electron microscope, and atomic absorption spectroscopy. The catalyst activity in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. For the n%Ni(m%)-HMS samples prepared by the direct synthesis method, BET surface area, pore volume, and the pore (2∼5 nm) diameter decrease with increasing Ni content, and the mesostructures becomes worse. When the nickel content exceeds 7.0 wt%, the sample with mesostructures cannot be prepared. This is attributed to the decrease of pH value in the preparation system and the embedment of Ni2+ in the SiO2 matrix. Ni2+ ions highly disperse in the n%Ni(m%)-HMS samples and mainly exist as nickel silicate. After reduction at 450∼650 °C, the metallic nickel particles in n%Ni(m%)-HMS uniformly distribute at about 3 nm. However, for the im−4.1%Ni/HMS sample prepared by the impregnation method, the metallic nickel particles are much larger than those of n%Ni(m%)-HMS. In the hydrodechlorination of chlorobenzene, the n%Ni(m%)-HMS samples show higher activities than im−4.1%Ni/HMS, which can be attributed to the strong interaction between small metallic nickel particles and the support, a greater amount of spilt-over hydrogen, and the acidity of nickel silicate. When the nickel content exceeds 5.9 wt % and the reduction temperature is above 450 °C, there is no remarkable difference in chlorobenzene conversion for n%Ni(m%)-HMS samples. This is perhaps related to the intraparticle mass transfer limitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801792h [article] Preparation, characterization, and performance of HMS-supported Ni catalysts for hydrodechlorination of chorobenzene [texte imprimé] / Jixiang Chen, Auteur ; Jianjun Zhou, Auteur ; Rijie Wang, Auteur . - 2009 . - pp. 3802–3811. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3802–3811 Mots-clés : HMS-supported Ni catalysts Hydrodechlorination N2 adsorption X-ray diffraction Résumé : HMS-supported Ni catalysts were prepared by the direct synthesis and the impregnation method. In the direct synthesis, the effect of nickel content and pH value of the preparation system on the catalyst structure and hydrodechlorination performance was systematically investigated. The physicochemical properties of the catalysts were characterized by means of N2 adsorption, hydrogen temperature-programmed reduction, low- and wide-angle X-ray diffraction, hydrogen chemisorption, hydrogen temperature-programmed desorption, transmission electron microscope, and atomic absorption spectroscopy. The catalyst activity in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. For the n%Ni(m%)-HMS samples prepared by the direct synthesis method, BET surface area, pore volume, and the pore (2∼5 nm) diameter decrease with increasing Ni content, and the mesostructures becomes worse. When the nickel content exceeds 7.0 wt%, the sample with mesostructures cannot be prepared. This is attributed to the decrease of pH value in the preparation system and the embedment of Ni2+ in the SiO2 matrix. Ni2+ ions highly disperse in the n%Ni(m%)-HMS samples and mainly exist as nickel silicate. After reduction at 450∼650 °C, the metallic nickel particles in n%Ni(m%)-HMS uniformly distribute at about 3 nm. However, for the im−4.1%Ni/HMS sample prepared by the impregnation method, the metallic nickel particles are much larger than those of n%Ni(m%)-HMS. In the hydrodechlorination of chlorobenzene, the n%Ni(m%)-HMS samples show higher activities than im−4.1%Ni/HMS, which can be attributed to the strong interaction between small metallic nickel particles and the support, a greater amount of spilt-over hydrogen, and the acidity of nickel silicate. When the nickel content exceeds 5.9 wt % and the reduction temperature is above 450 °C, there is no remarkable difference in chlorobenzene conversion for n%Ni(m%)-HMS samples. This is perhaps related to the intraparticle mass transfer limitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801792h

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