OXIDATIVE-REFORMING OF METHANE AND PARTIAL OXIDATION OF METHANE REACTIONS OVER NiO/PrO2/ZrO2 CATALYSTS: EFFECT OF NICKEL CONTENT (original) (raw)
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International Journal of Chemical Engineering, 2018
In this work, the production of Syngas (H2/CO) from oxidative reforming of methane (ORM) and partial oxidation of methane (POM) over NiO/Y2O3/ZrO2 catalysts was studied. The nickel concentration was varied (ranging from 0 to 40 wt.%) aiming to optimize the performance in ORM and POM reactions; these reactions were carried out at 750°C and 1 atm for 6 hours. The catalysts were prepared by the one-step polymerization method (OSP) and characterized by different techniques. This method led to production of materials of smaller crystallite size than others of similar composition prepared under other methods; the catalysts presented good nickel dispersion, well-defined crystalline structure, and well-defined geometrical morphology. Additionally, the OSP method was advantageous because it was carried out in a single calcination step. The catalyst containing 20% wt. of nickel (20Ni20YZ sample) showed the highest methane conversion, high selectivity to H2 and CO, low carbon deposition rates,...
Oxidative transformation of methane over nickel catalysts supported on rare-earth metal oxides
Catalysis Today, 2000
The oxidative transformation of methane over Ni catalysts supported on La, Sm and Ce oxides was investigated at atmospheric pressure, T=723-923 K and CH 4 /O 2 =1-10. The BET surface areas were low (3-22 m 2 g −1 ) and decreased strongly after reaction (down to 0.5 m 2 g −1 ). Carbonate species, Ni 2 O 3 and supported oxides were identified by XRD or IR spectroscopy studies in both the fresh and used catalysts. The Ni • phase was also probably formed as amorphous phase. The oxidative coupling of methane route passed through a minimum as a function of the Ni percentage and was favored by the Ce or Sm oxide support, Li additive and low reaction temperature. High selectivities (60-90%) and good yields (about 15%) in C 2 hydrocarbons with low carbon balance (0-10%) were obtained at 823 K. La supported oxide, Ba additive and high reaction temperature favored the partial oxidation of methane. The obtained results were discussed in the light of the reducibility and acid-base properties of the catalysts.
Applied Catalysis A-general, 1997
The NiO/A1203 catalyst was modified by alkali metal oxide (Li, Na, K) and rare-earth metal oxide (La, Ce, Y, Sm) in order to improve the thermal stability and the carbon-deposition resistance during the partial oxidation of methane to syngas (POM) reaction at high temperature. The reaction performance, thermal stability, structure, dispersity of nickel and carbon-deposition of the modified NiO/A1203 catalyst and unmodified NiO/AlaO3 catalyst were investigated by a series of characterization techniques including flow-reaction, BET, XRD, CO chemisorption and TG analysis. The results indicated that the modification with alkali metal oxide and rare-earth metal oxide improves the dispersion of active component nickel and the activity for the POM reaction over the nickel-based catalysts, and enhances their thermal stability during high temperature reaction and the ability to suppress the carbon-deposition over the nickel-based catalysts during the POM reaction. The nickel-based catalysts modified by alkali metal oxide and rare-earth metal oxide have excellent POM reaction performance (CH4 conversion of 94.8%, CO selectivity of 98.1%, 2.7 x 104 1/kg.h), excellent stability and carbon-deposition resistance.
Catalysts
Dry reforming of methane (DRM) over an Ni-based catalyst is an innovative research area due to the growing environmental awareness about mitigating global warming gases (CH4 and CO2) and creating a greener route of synthesis. Herein, 5% Ni supported on ZrO2 obtained from various sources was prepared by the impregnation method. The catalysts were calcined at 600, 700, and 800 °C. Furthermore, Ni-RC stabilized with MgO, SiO2, TiO2, and Y2O3 were tested. Characterization techniques employed comprise the N2 physisorption, infrared spectroscopy, Raman, thermogravimetric analysis, XRD, and TEM. The results of the present study indicated that the ZrO2 support source had a profound effect on the overall performance of the process. The best catalyst Ni-RC gave an average conversion of CH4 and CO2 of 61.5% and 63.6% and the least deactivation of 10.3%. The calcination pretreatment differently influenced the catalyst performance. When the average methane conversion was higher than 40%, increas...
Promotional effect of magnesium oxide for a stable nickel-based catalyst in dry reforming of methane
Scientific Reports, 2020
The generation of synthesis gas (hydrogen and carbon monoxide mixture) from two global warming gases of carbon dioxide and methane via dry reforming is environmentally crucial and for the chemical industry as well. Herein, magnesium-promoted NiO supported on mesoporous zirconia, 5Ni/xMg-ZrO 2 (x = 0, 3, 5, 7 wt%) were prepared by wet impregnation method and then were tested for syngas production via dry reforming of methane. The reaction temperature at 800 °C was found more catalytically active than that at 700 °C due to the endothermic feature of reaction which promotes efficient CH 4 catalytic decomposition over Ni and Ni-Zr interface as confirmed by CH 4-TSPR experiment. NiO-MgO solid solution interacted with ZrO 2 support was found crucial and the reason for high CH 4 and co 2 conversions. The highest catalyst stability of the 5Ni/3Mg-ZrO 2 catalyst was explained by the ability of CO 2 to partially oxidize the carbon deposit over the surface of the catalyst. A mole ratio of hydrogen to carbon monoxide near unity (H 2 /CO ~ 1) was obtained over 5Ni/ZrO 2 and 5Ni/5Mg-ZrO 2 , implying the important role of basic sites. Our approach opens doors for designing cheap and stable dry reforming catalysts from two potent greenhouse gases which could be of great interest for many industrial applications, including syngas production and other value-added chemicals. The production of syngas (a mixture of H 2 and CO) through dry reforming of methane is an excellent strategy to reduce the global warming effects of carbon dioxide (CO 2) and methane (CH 4). Noble metals such as palladium (Pd), platinum (Pt), and ruthenium (Ru) have been used for this purpose, but costly precursors and instability of catalyst, at high reaction temperature around 800 °C, have limited their application 1. On the other hand, cost-effective nickel (Ni) metal, supported on an appropriate supports such as alumina 2 , mesoporous silicates 3-7 , and zirconia 8-10 , has been found to withstand at this reaction temperature (800 °C). In this context, many researchers have followed the surface modification methodology to optimise the catalyst performance because Ni-based catalyst is also prone to deactivation. The first series of modifications were carried out over alumina supports. Due to the extended pore network (from micro to meso) and easy pore tunable synthetic methodology of silicates, silica support is preferable over alumina support 28. Therefore, the second series of modifications were carried out over mesoporous silicates supports with Li alumina nor silica supports can utilize their lattice oxygen during carbon deposit oxidation at the surface, but zirconia support does and is thus are used as oxygen carrier materials. Zirconia support is characterized by its thermal stability, an expanded network, and the ability to utilize its mobile oxygen during the surface reaction 45. The third series of modifications were carried out over open
Partial Oxidation of Bio-methane over Nickel Supported on MgO–ZrO2 Solid Solutions
Topics in Catalysis, 2023
Syngas can be produced from biomethane via Partial Oxidation of Methane (POM), being an attractive route since it is ecofriendly and sustainable. In this work, catalysts of Ni supported on MgO-ZrO 2 solid solutions, prepared by a one-step polymerization method, were characterized by HRTEM/EDX, XRD, XPS, H 2-TPR, and in situ XRD. All catalysts, including Ni/ZrO 2 and Ni/MgO as reference, were tested for POM (CH 4 :O 2 molar ratio 2, 750 ºC, 1 atm). NiO/MgO/ZrO 2 contained two solid-solutions, MgO-ZrO 2 and NiO-MgO, as revealed by XRD and XPS. Ni (30 wt%) supported on MgO-ZrO 2 solid solution exhibited high methane conversion and hydrogen selectivity. However, depending on the MgO amount (0, 4, 20, 40, 100 molar percent) major differences in NiO reducibility, growth of Ni 0 crystallite size during H 2 reduction and POM, and in carbon deposition rates were observed. Interestingly, catalysts with lower MgO content achieved the highest CH 4 conversion (~ 95%), high selectivity to H 2 (1.7) and CO (0.8), and low carbon deposition rates (0.024 g carbon .g cat −1 h −1) with Ni4MgZr (4 mol% MgO) turning out to be the best catalyst. In situ XRD during POM indicated metallic Ni nanoparticles (average crystallite size of 31 nm), supported by MgO-ZrO 2 solid solution, with small amounts of NiO-MgO being present as well. The presence of MgO also influenced the morphology of the carbon deposits, leading to filaments instead of amorphous carbon. A combustion-reforming mechanism is suggested and using a MgO-ZrO 2 solid solution support strongly improves catalytic performance, which is attributed to effective O 2 , CO 2 and H 2 O activation at the Ni/MgO-ZrO 2 interface.
Support Effect in Supported Ni Catalysts on Their Performance for Methane Partial Oxidation
Catalysis Letters, 2003
Supported nickel catalysts were prepared by impregnation of La2O3, MgO and ZrO2 substrates and tested in the partial oxidation of methane to synthesis gas at atmospheric pressure. Nickel interacted strongly with La2O3 forming a deficient LaNiO3-δ perovskite structure upon calcination. Upon reduction at 973 K, the Ni/La2O3 catalysts that resulted were highly active and selective for syngas production. By contrast, a separate and readily reducible NiO phase was formed on the ZrO2 support. Because the interaction of metallic nickel particles on ZrO2 is weak, the catalysts underwent deactivation by sintering of metal particles during on-stream operation as confirmed by photoelectron spectroscopy. The relatively high activity of the Ni/MgO systems was associated with the formation of a highly stable cubic Ni-Mg-O solid solution, in which nickel remains highly dispersed during the methane partial oxidation reaction.
Syngas Production via CO2 Reforming of Methane over Sm2O3−La2O3-Supported Ni Catalyst
Industrial & Engineering Chemistry Research, 2009
Ni-Co/Al 2 O 3-ZrO 2 nanocatalysts with 5, 10 and 15 wt.% nominal Ni content have been prepared by impregnation followed by a non-thermal plasma treatment, characterized and tested for dry reforming of methane. For nanocatalysts characterization the following techniques have been used: XRD, FESEM, TEM, EDX dot-mapping, BET, FTIR and XPS. The dry reforming of methane was carried out at different temperatures (550-850°C) using a feed mixture of CH 4 :CO 2 (1:1). Among the nanocatalysts studied, the catalyst with the medium Ni content (10 wt.%) was the most active in dry reforming of methane. This higher activity exhibited by Ni-Co/Al 2 O 3-ZrO 2 catalyst with medium Ni content (10 wt.%) can be attributed to small and well dispersed particles of Ni within the catalyst. Apart from the narrow surface particle size distribution in the case of Ni(10 wt.%)-Co/Al 2 O 3-ZrO 2 , the presence of small active components with average size of 7.5 nm is proposed to be the reason for the superior performance of the catalyst. Ni(10 wt.%)-Co/Al 2 O 3-ZrO 2 nanocatalyst had maximum surface area and the lower surface area was observed in the case of Ni(5 wt.%)-Co/Al 2 O 3-ZrO 2 and Ni (15 wt.%)-Co/Al 2 O 3-ZrO 2 due to the formation of the larger agglomeration and higher mean particle size of nickel particles, respectively. Although, GHSV enhancment had inverse effect on product yield but yield reduction for Ni-Co/Al 2 O 3-ZrO 2 catalyst with 10 wt.% Ni was less drastic at high GHSVs. According to XRD and XPS, existence of NiAl 2 O 4 confirms strong interaction between Ni and support but higher loadings of Ni resulted in less NiAl 2 O 4 ; loser interaction between support and active phase. Small particles of active components and well-defined dispersion of them in Ni (10 wt.%)-Co/Al 2 O 3-ZrO 2 nanocatalyst resulted in stability of the catalyst for either feed conversion or H 2 /CO molar ratio.
E3S Web of Conferences, 2019
Positive environmental and technological contexts make dry methane reforming (DMR) an extensively studied reaction. During this process two main greenhouse gases CH4and CO2can be simultaneously converted into syngas – a mixture of CO and H2. Supported-nickel is one of the most frequently applied DMR catalysts. Their activity depends mainly on Ni concentration, kind of its precursor and a deposition method. As DMR is a demanding high-temperature reaction, it requires not only an active but first a very stable catalyst. Structural, textural and functional properties of such support remain thus of crucial efficiency. Main aim of this work was to elucidate how the synthesis of CeO2-ZrO2support obtained by supercritical fluid method (i.e.at temperature of 400°C under a pressure of 25 MPa), can influence the properties of Ni-based DMR catalysts. The supports of various compositions (CeO2content from 100 to 0 %), subsequently calcined at 800°C for 6h in air have been analyzed. Nickel was d...