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Alumina-boron catalysts for oxidative dehydrogenation of ethylbenzene to styrene: Influence of alumina-boron composition and method of preparation on catalysts properties

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Chinese Journal of Catalysis 2019年第11期40卷 1758-1765页

作者： Nagaraju Pasupulety Muhammad A.Daous Abdulrahim A.Al-Zahrani hafedh driss Lachezar A.Petrov Chemical and Materials Engineering Department Faculty of Engineering King Abdulaziz University P.O. Box 80204 Jeddah 21589 Saudi Arabia

Different mole ratio Al-B catalysts (Al-10B to Al-35B) were synthesized by using sol-gel (SG) method. Ethyl benzene (EB) dehydrogenation in the presence of oxygen and water steam was carried out on these catalysts at 450–500℃ with EB contact time of 0.54 ***^–3. Acidity of Al-B catalysts was estimated by using NH3-TPD-mass spectral analysis studies. SEM-mapping images revealed fine distribution of boron up to 15% of its loading in alumina (Al-15B), whereas, boron aggregation was observed in higher boron content (Al-25B and Al-35B) catalysts. Essentially, acid sites of very weak strength (Tmax ≤ 125℃) were observed for Al and Al-10B catalysts and resulted in low EB conversion and styrene yield. On the other hand, acid sites of weak strength (Tmax ≤ 180℃) were observed for Al-25B and Al-35B catalysts and resulted in high EB conversion. However, greater styrene yield (43.2%) with reasonable EB conversion (46%) was obtained on acid sites of weak moderate strength in Al-15B catalyst. Further, Al-15B catalyst was synthesized by using co-precipitation (COP) and impregnation (IMP) methods. Acid sites related to NOx formation during the NH3-TPD-mass analysis on IMP and COP catalyst essentially improved the EB conversion to 66% and 63% respectively at 500℃. However, these acid sites were diminished in Al-B SG catalyst and resulted in 50% of EB conversion at 500 ℃. At 50% of EB conversion level, styrene selectivity of 73%, 82.5% and 84% were observed on Al-B IMP, Al-B COP and Al-SG catalysts, respectively. Hence, different method of preparation of Al-B catalyst generated acid sites of different strength and density and thereby influenced the styrene formation.

关键词： Alumina-boron Oxidative dehydrogenation Ethyl benzene Styrene Co-precipitation

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Catalytic performances of Ni/mesoporous SiO_2 catalysts for dry reforming of methane to hydrogen

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Journal of Energy Chemistry 2016年第4期25卷 709-719页

作者： Fei Huang Rui Wang Chao Yang hafedh driss Wei Chu Hui Zhang College of Chemistry and Chemical Engineering Southwest Petroleum University Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province Drilling & Production Engineering Technology Research Institute CNPC Chuanqing Drilling Engineering Co.Ltd. SABIC Chair in Catalysis King Abudulaziz University Department of Chemical Engineering Sichuan University

Several mesoporous silicas with different morphologies were controllably prepared by sol-gel method with adjustable ratio of dual template, and they were further impregnated with aqueous solution of nickel nitrate, followed by calcination in air. The synthesized silica supports and supported nickel samples were characterized using N2-adsorption/desorption, X-ray diffraction (XRD), H2temperature-programmed reduction (H2-TPR), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and thermo-gravimetric analysis (TGA-DTG) techniques. The Ni nanoparticles supported on shell-like silica are highly dispersed and yielded much narrower nickel particle-size than those on other mesoporous silica. The methane reforming with dioxide carbon reaction results showed that Ni nanoparticles supported on shell-like silica carrier exhibited the better catalytic performance and catalytic stability than those of nickel catalyst supported on other silica carrier. The thermo-gravimetric analysis on used nickel catalysts uncovered that catalyst deactivation depends on the type and nature of the coke deposited. The heterogeneous nature of the deposited coke was observed on nickel nanoparticles supported on spherical and peanut-like silica. Much narrower and lower TGA derivative peak was founded on Ni catalyst supported on the shell-like silica. © 2016 Science Press

关键词： Carbon Catalyst activity Catalyst deactivation Catalysts Catalytic reforming Coke Gravimetric analysis Hydrogen Methane Nanoparticles Nickel Particle size Scanning electron microscopy Silica Sol gel process Sol gels Solutions Thermogravimetric analysis Transmission electron microscopy X ray diffraction

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