The effect of preparation factors on the structural and catalytic properties of mesoporous nanocrystalline iron-based catalysts for high temperature water gas shift reaction

Fereshteh Meshkani,Mehran Rezaei 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7

A systematic study was done on the effect of preparation factors on the structural and catalytic properties of mesoporous nanocrystalline iron-based catalysts in high temperature water gas shift reaction. The catalysts were prepared by coprecipitation method, and the effect of the main preparation factors (pH, refluxing temperature, refluxing time, concentration of the precursors solution) was studied. The catalysts were characterized by powder X-ray diffraction (XRD), N2 adsorption (BET), Temperature programmed reduction (TPR), transmission and scanning electron microscopies (TEM, SEM) techniques. The results revealed that the preparation factors affected the textural and catalytic properties of the Fe-Cr-Cu catalyst. The results showed that the prepared catalyst with the highest activity showed higher specific surface area compared to commercial catalyst and consequently exhibited higher activity in high temperature water gas shift reaction. The TEM analysis showed a nanostructure for this sample with crystallite size less than 20 nm.

A facile method for preparation of iron based catalysts for high temperature water gas shift reaction

Fereshteh Meshkani,Mehran Rezaei 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Nanocrystalline Fe3O4 based catalysts with theoretical particle size of 31–78 nm were synthesized by a facile direct pyrolysis method and employed in high temperature water gas shift reaction. XRD analysis showed that this method led to obtaining the catalysts directly in the active phase with chromium and copper incorporated into magnetite lattice. The results showed that the addition of chromium significantly increases the BET surface area of the pure iron oxide from 14.87 to 35.42 m2 g-1. Among the catalysts evaluated, Fe–Cr–Cu catalyst revealed higher activity compared to commercial catalyst and showed high stability during 10 h time on stream.

Investigation of the catalytic performance of Ni/MgO catalysts in partial oxidation, dry reforming and combined reforming of methane

Fereshteh Meshkani,Mehran Rezaei,Mahmood Andache 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

Dry reforming, partial oxidation and combined reforming of methane (combination of partial oxidation and dry reforming) to synthesis gas over nickel catalysts supported on nanocrystalline magnesium oxide with various nickel loadings have been studied. Among the catalysts evaluated, catalyst with 15 wt.% nickel content revealed the most active catalytic performance toward dry reforming, partial oxidation and combined reforming reactions. In addition, catalyst with 5 wt.% nickel loading was employed in long term stability test and has shown stable catalytic performance up to 50 h time on stream without any decrease in methane conversion in these three processes.

High-temperature water-gas shift reaction over nanostructured Cr-free Fe2O3–Al2O3–CuO–MO (M: Ba, Ca, Mg and Sr) catalysts for hydrogen production

Fereshteh Meshkani,Mehran Rezaei 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.30 No.-

In this paper the promotion of Fe2O3–Al2O3–CuO chromium free catalyst with Ba, Ca, Mg and Sr forhydrogen production via high temperature water gas shift reaction was studied. The catalysts weresynthesized by coprecipitation method and characterization of the prepared catalysts were performedusing X-ray diffraction (XRD), N2 adsorption (BET), temperature-programmed reduction (TPR) andtransmission electron microscopy (TEM) techniques. The results revealed that addition of alkaline earthpromoters decreased the BET surface area while improved CO conversion. Among the promotedcatalysts, 9 wt% Ba promoted Fe2O3–Al2O3–CuOcatalyst exhibited higher BET surface area and catalyticactivity.

Carbon dioxide reforming of methane for syngas production over Co–MgO mixed oxide nanocatalysts

Fateme Mirzaei,Mehran Rezaei,Fereshteh Meshkani,Zohreh Fattah 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

Carbon dioxide reforming of methane (CH4 + CO2$2CO + 2H2) was studied over nanostructure Co–MgO mixed oxide catalysts with different cobalt contents. The catalysts were prepared by coprecipitationmethod and characterized using XRD, BET, TEM, TPR, SEM and TPO techniques. The BETanalysis showed a high specific surface area and mesoporous structure (pore sizes < 15 nm) and the TEManalysis indicated a nanostructure with crystallite sizes smaller than 10 nm for the prepared catalysts. The obtained results revealed that the catalyst with cobalt content of 10 wt.% had the highest activity andstability in dry reforming reaction.

Dry reforming over CeO2-promoted Ni/MgO nano-catalyst: Effect of Ni loading and CH4/CO2 molar ratio

Masoud Khajenoori,Mehran Rezaei,Fereshteh Meshkani 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

Ceria promoted nickel catalysts supported on nanocrystalline MgO were prepared and employed inmethane reforming with carbon dioxide. The prepared catalysts were characterized by XRD, BET, SEM,TPO and TPR techniques. The effect of nickel loading on the catalytic performance of catalysts wasinvestigated and the results showed that 10%Ni–7%CeO2/MgO catalyst possessed the highest catalyticactivity. The results also showed that increasing in CO2/CH4 molar ratio decreased the amount ofdeposited carbon and increased the methane conversion.

Preparation of highly active nickel catalysts supported on mesoporous nanocrystalline γ-Al2O3 for CO2 methanation

Soudabeh Rahmani,Mehran Rezaei,Fereshteh Meshkani 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

In this study, a group of Ni catalysts supported on mesoporous nanocrystalline γ-Al2O3 with high surface area and with different Ni contents was prepared and employed in carbon dioxide methanation reaction. The obtained results showed increasing in nickel content from 10 to 25 wt.% decreased the specific surface area of catalysts from 177 to 130 m2/g and increased the nickel crystallite size from 12 to 24 nm. In addition, increasing in nickel content increased the reducibility of catalyst. The catalytic results revealed that the catalyst with 20 wt.% of Ni possessed high activity and stability in CO2 methanation reaction.

Effect of alkaline earth promoters (MgO, CaO, and BaO) on the activity and coke formation of Ni catalysts supported on nanocrystalline Al2O3 in dry reforming of methane

Zahra Alipour,Mehran Rezaei,Fereshteh Meshkani 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Ni/Al2O3 promoted catalysts with alkaline earth metal oxides (MgO, CaO, and BaO) were prepared and employed in dry reforming of methane (DRM). The catalysts were prepared by impregnation method and characterized by XRD, BET, TPR, TPO, and SEM techniques. The obtained results showed that the addition of MgO, CaO, and BaO as promoter decreased the surface area of catalysts (SBET). The catalysis results exhibited that adding alkaline earth promoters (MgO, CaO, and BaO) enhanced the catalytic activity and the highest activity was observed for the MgO promoted catalyst. TPR analysis showed that addition of MgO increased the reducibility of nickel catalyst and decreased the reduction temperature of NiO species. The TPO analysis revealed that addition of promoters decreased the amount of deposited coke; and among the studied promoters, MgO has the most promotional effect for suppressing the carbon formation. SEM analysis confirmed the formation of whisker type carbon over the spent catalysts.

COx-free hydrogen and carbon nanofibers production by methane decomposition over nickel-alumina catalysts

Mehran Rezaei,Nima Bayat,Fereshteh Meshkani 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.2

Nickel catalysts supported on mesoporous nanocrystalline gamma alumina with various nickel loadings were prepared and employed for thermocatalytic decomposition of methane into COx-free hydrogen and carbon nanofibers. The prepared catalysts with different nickel contents exhibited mesoporous structure with high surface area in the range of 121.3 to 66.2m2g−1. Increasing in nickel content decreased the pore volume and increased the crystallite size. The catalytic results revealed that the nickel content and operating temperature both play important roles on the catalytic performance of the prepared catalysts. The results showed that increasing in reaction temperature increased the initial conversion of catalysts and significantly decreased the catalyst lifetime. Scanning electron microscopy (SEM) analysis of the spent catalysts evaluated at different temperatures revealed the formation of intertwined carbon filaments. The results showed that increasing in reaction temperature decreased the diameters of nanofibers and increased the formation of encapsulating carbon.

Preparation of promoted nickel catalysts supported on mesoporous nanocrystalline gamma alumina for carbon dioxide methanation reaction

Soudabeh Rahmani,Mehran Rezaei,Fereshteh Meshkani 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

Nickel-based catalysts supported on mesoporous nanocrystalline gamma Al2O3 promoted with variouspromoters (CeO2, MnO2, ZrO2, La2O3) were prepared and employed in the carbon dioxide methanationreaction. It was found that the addition of promoters to the catalyst varied the specific surface area from139.4 to 147.4 m2/g and CeO2 and MnO2 improved the reducibility of catalyst. The catalytic resultsshowed that the catalyst with 2 wt% of cerium promoter possessed high activity and stability in CO2methanation reaction and showed a high CO2 conversion of 80.3% at 350 ℃.