Reaction Engineering, Kinetics and Catalysts,
Abdullah Irankhah; Sepideh Ghafoori; atieh ranjbar
Abstract
In the present work, the effect of synthesis method (simultaneous impregnation and coprecipitation) and copper to nickel active phases loading were investigated in Ni-Cu-Al catalysts. The water/ethanol molar ratio of 6 and gas hourly space velocity (GHSV) of 20000 hr-1 were used in all the experiments. ...
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In the present work, the effect of synthesis method (simultaneous impregnation and coprecipitation) and copper to nickel active phases loading were investigated in Ni-Cu-Al catalysts. The water/ethanol molar ratio of 6 and gas hourly space velocity (GHSV) of 20000 hr-1 were used in all the experiments. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) techniques. The catalytic activity results revealed that 13Ni-6Cu/γ-Al2O3 impregnated catalyst was more active than co-precipitated one (13NiO-6CuO-81Al2O3) in the same amount of compositions of active metals and Al2O3, but by increasing the active phases (Cu and Ni) loading in co-precipitated catalysts (24NiO-31CuO-45Al2O3, 31NiO-24CuO-45Al2O3, 40NiO-15CuO-45 Al2O3 and 47NiO-8CuO-45Al2O3), they achieved a better performance than 13NiO-6CuO-81Al2O3 catalyst. The 40NiO-15CuO-45Al2O3 catalyst showed 99% ethanol conversion, as well as 303 hydrogen yield and 4% CO selectivity at 470oC. SEM images revealed agglomerated particles for the samples with high Al2O3 content and with increasing the active phase content in the catalyst the particle sizes decreased. The 40NiO-15CuO-45Al2O3 showed smallest particle size among the catalysts.
Reaction Engineering, Kinetics and Catalysts,
M. Takht Ravanchi; S. Sahebdelfar; M. Rahimi Fard; H. Moosavi
Abstract
The impregnation of the alumina support with the PdCl2 solution was investigated in batch and semi-batch operation modes using a recycle packed-bed reactor. The UV-visible analysis was used to evaluate the kinetics of the adsorption of Pd on the alumina support. The adsorption data related to transient ...
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The impregnation of the alumina support with the PdCl2 solution was investigated in batch and semi-batch operation modes using a recycle packed-bed reactor. The UV-visible analysis was used to evaluate the kinetics of the adsorption of Pd on the alumina support. The adsorption data related to transient palladium showed that the adsorption of Pd was very rapid and completed within few minutes. Bi-metallic Pd-Ag/Al2O3 catalysts were synthesized by the sequential impregnation method. CO-chemisorption, CO-TPD and FE-SEM tests were used to characterize the synthesized bi-metallic samples. The catalytic performance of the samples was evaluated for the tail-end acetylene selective hydrogenation process in a fixed-bed reactor. Moreover, the deactivation of the catalysts was evaluated mathematically by the integral method of analysis, considering reaction kinetics as power laws in terms of nth orders in H2 and C2H2 partial pressures. It was observed that by the batch-wise addition of the Pd precursor solution, a sample, with the lowest amount of Pd dimmers that had the highest ethylene selectivity and lowest hydrogenation reaction rate, was obtained.
Reaction Engineering, Kinetics and Catalysts,
F. Tahriri zangeneh; S. sahebdelfar; A. Taeb
Abstract
The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates, that is, 5, 10 and 15 °C/min were applied after incipient wetness impregnation of the support (1.6–1.8 mm in diameter) with KNO3. The obtained ...
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The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates, that is, 5, 10 and 15 °C/min were applied after incipient wetness impregnation of the support (1.6–1.8 mm in diameter) with KNO3. The obtained catalysts were characterized by N2 physisorption, SEM-EDAX analysis and XRF for textural and chemical properties. Catalytic performance tests were performed in a fixed-bed quartz reactor under kinetically controlled conditions for proper catalyst screening. The EDAX measurement results illustrated that the potassium concentration profile changed with drying rate with the catalyst prepared by lower drying rate exhibited highest K concentration at the center as well as highest propylene yield. These were attributed to the retraction of impregnation solution during drying at slow rates which results in lower concentration of acidic sites in catalyst center, thereby reducing the contact time of the propylene product with strong acid sites during reaction.
Reaction Engineering, Kinetics and Catalysts,
M. Ghashghaee; S. Shirvani; V. Farzaneh
Volume 15, Issue 2 , May 2018, , Pages 38-51
Abstract
Furfural is one of the most promising chemical platforms with bright perspective with respect to the production of biobased chemicals and fuels from lignocellulosic material. Globally, the majority of this biomass derived chemical is converted into furfuryl alcohol, a building block in polymers industry. ...
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Furfural is one of the most promising chemical platforms with bright perspective with respect to the production of biobased chemicals and fuels from lignocellulosic material. Globally, the majority of this biomass derived chemical is converted into furfuryl alcohol, a building block in polymers industry. The vapor-phase hydrogenation of furfural over copper species dispersed on two types of silica (bulk-type and nano-sized) supports with or without chromium as a promoter was studied for the first time. The catalysts were synthesized via impregnation method and operated under mild hydrogenation reaction conditions. The results represented that the catalytic performance of the nano-sized silica-supported catalyst was better in terms of furfural conversion, furfuryl alcohol yield and selectivity than that of the bulk-type silica after 4 hours of operation. However, by incorporation of chromium as a promoter, the bulk-type silica-supported catalyst exhibited an improved performance during the whole run length (higher than 82% and 96% of furfural conversion and furfuryl alcohol selectivity, respectively).