“…This nucleation is related in similar materials to the formation of binary intermetallic compounds. 26 Figure 1.Electron micrograph (100 K) for selected Ni5%/MgO and Ni1%/Al 2 O 3 catalysts series. (A) Ni5%/MgO, (B) Ni5%Sn0.3%/MgO, (C) Ni5%Sn1%/MgO, (D) Ni1%/γ-Al 2 O 3 (dark field), (E) Ni1%Sn0.3%/γ-Al 2 O 3 , (F) Ni1%Sn0.5%/γ-Al 2 O 3 .…”
Section: Resultsmentioning
confidence: 99%
“…This nucleation is related in similar materials to the formation of binary intermetallic compounds. 26 In Figure 2 is presented the selected area electron diffraction patterns of the mono and bi-metallic Ni5.0% catalysts series in MgO and γ-Al 2 O 3 . The formation of intermetallic compounds of nickel and tin was found in bimetallic catalysts in both supports.…”
Section: Transmission Electron Microscopy and Selected Area Electron ...mentioning
Monometallic and bimetallic Ni and Sn catalysts were prepared in different ratios by the Solvated Metal Atom Dispersed (SMAD) method for the catalytic hydrogenation of acetophenone to 1-phenylethanol. The preparation of the catalysts was carried out by evaporation of Ni and Sn metal atoms and subsequent co-deposition at 77 K using 2- isopropanol as solvent on alumina and magnesium oxide as supports. X-ray photoelectron spectroscopy (XPS) analysis showed a high percentage of nickel atoms in zero valence, while the tin phases were founded in reduced and oxidized form. The average size of the nanoparticles measured by transmission electron microscopy (TEM) ranged from 8 to 15 nm while the metal dispersion on the surface measured by hydrogen chemisorption ranged from 0.07% for Ni1% Sn0.3%/MgO to 3.2% for Ni5%/MgO. Thermogravimetric analysis shows that γ-Al2O3 catalysts exhibit higher thermal stability than MgO catalysts. The catalysis results showed that the best support is MgO reaching 66% conversion in Ni5% Sn0.5%/MgO catalyst.
“…This nucleation is related in similar materials to the formation of binary intermetallic compounds. 26 Figure 1.Electron micrograph (100 K) for selected Ni5%/MgO and Ni1%/Al 2 O 3 catalysts series. (A) Ni5%/MgO, (B) Ni5%Sn0.3%/MgO, (C) Ni5%Sn1%/MgO, (D) Ni1%/γ-Al 2 O 3 (dark field), (E) Ni1%Sn0.3%/γ-Al 2 O 3 , (F) Ni1%Sn0.5%/γ-Al 2 O 3 .…”
Section: Resultsmentioning
confidence: 99%
“…This nucleation is related in similar materials to the formation of binary intermetallic compounds. 26 In Figure 2 is presented the selected area electron diffraction patterns of the mono and bi-metallic Ni5.0% catalysts series in MgO and γ-Al 2 O 3 . The formation of intermetallic compounds of nickel and tin was found in bimetallic catalysts in both supports.…”
Section: Transmission Electron Microscopy and Selected Area Electron ...mentioning
Monometallic and bimetallic Ni and Sn catalysts were prepared in different ratios by the Solvated Metal Atom Dispersed (SMAD) method for the catalytic hydrogenation of acetophenone to 1-phenylethanol. The preparation of the catalysts was carried out by evaporation of Ni and Sn metal atoms and subsequent co-deposition at 77 K using 2- isopropanol as solvent on alumina and magnesium oxide as supports. X-ray photoelectron spectroscopy (XPS) analysis showed a high percentage of nickel atoms in zero valence, while the tin phases were founded in reduced and oxidized form. The average size of the nanoparticles measured by transmission electron microscopy (TEM) ranged from 8 to 15 nm while the metal dispersion on the surface measured by hydrogen chemisorption ranged from 0.07% for Ni1% Sn0.3%/MgO to 3.2% for Ni5%/MgO. Thermogravimetric analysis shows that γ-Al2O3 catalysts exhibit higher thermal stability than MgO catalysts. The catalysis results showed that the best support is MgO reaching 66% conversion in Ni5% Sn0.5%/MgO catalyst.
“…Although the catalyst with the addition of 2 mol% of each promoter Ce, Ba, Cr in Cu/Zn/Al = 6.4:2.6:1.0 and their evaluation with reaction at 50 bar pressure, 240 °C temperature, syngas containing CO 2 /CO/H 2 = 1/1/14.5, GHSV = 12 400 mL h −1 favors excellent methanol selectivity having 99.17 mol% 74 . Although using 2CuO·CeO 2 catalyst on the same reaction condition, the methanol selectivity was reported to be 93%, which is more than CeCu 2 and other f‐block elements 75 . The redox behavior of CeO may enhance the oxidation of Cu with the presence of a small quantity of CO 2 and H 2 O, and the catalytic activity is stabilized by adding a third component 76 .…”
Section: Copper‐based Catalyst System and Effect Of Various Promoters...mentioning
confidence: 96%
“…74 Although using 2CuO•CeO 2 catalyst on the same reaction condition, the methanol selectivity was reported to be 93%, which is more than CeCu 2 and other f-block elements. 75 The redox behavior of CeO may enhance the oxidation of Cu with the presence of a small quantity of CO 2 and H 2 O, and the catalytic activity is stabilized by adding a third component. 76 CeO stabilizes the Cu species in the reductive reaction mixture, while the synthesis of Cu 2+ oxide and partial development of CeO 2 crystallite would subsequently deactivate the catalyst.…”
Section: Copper-based Catalyst System and Effect Of Various Promoters...mentioning
Methanol synthesis from syngas is an effective method for producing fuel additives, oxygenated fuels, and other chemicals. Several promoted catalytic systems have been tested for the synthesis of methanol. Catalysts based on noble metals are extremely active in generating methanol from syngas. However, sintering, poisoning, and related expenses accounted for the switch to Cu-based catalysts. The promotion of Cu-based catalysts, even with small doses of an effective promoter, resulted in a considerable change in product selectivity. A suitable promoter is required for Cu-based catalysts used in the synthesis of methanol because it significantly impacts the electronic, geometric, or acid/base surface properties, which in turn affect the catalyst's activity and selectivity. It also significantly impacts the interactions between the catalyst's active ingredients. However, the interactions between the active component and the promoter can be adjusted or influenced by appropriate support. The present paper primarily focuses on several promoters in the copper-based catalyst for synthesizing methanol from syngas. We briefly deliberated on the need for copper-based catalysts for methanol synthesis, their reaction and mechanism, the reasons for promoter addition concerning their role and influence, the importance of CO 2 addition in feed synthesis gas and their impact on the catalyst. This paper mainly highlights the selectivity and activity of various promoted Cu-based catalysts, although different reaction parameters are the cause of promotion and inhibition in the catalyst. The effects of reaction conditions, including pressure, temperature, gas hourly space velocity (GHSV), and syngas composition, are briefly reported. This paper also comprehensively compares the effects of adding various promoters in small amounts to copper-based catalysts. This review intends to be illustrative rather than exhaustive.
Cobalt-lanthanide bimetallic oxide nanofibers (5Co 3 O 4 .3LnCoO 3 , Ln=La, Pr; 4Co 3 O 4 .Ln 2 O 3 , Ln=Sm, Gd, Dy, Yb and 2Co 3 O 4 .CeO 2 ) were prepared by electrospinning technique and for the first time evaluated as catalysts for the hydrogenation of CO 2 . Depending on the lanthanide, the reaction products are different: lighter lanthanides (La, Pr, Sm and Gd) produce mainly CO and are more active to reverse water gas shift (RWGS), whereas the catalysts with Ce, Dy and Yb are more active and selective to methane. Lanthanide intrinsic properties such as ionic radii and basicity strongly correlate with the nanofibers' catalytic performance: lower lanthanide ionic radii and higher basicity favour the catalysts activity. Moreover, the bimetallic oxide nanofibers catalytic behavior also seems to point to the existence of a synergetic interaction between cobalt and lanthanide. The cobalt-lanthanide bimetallic oxides present a high deactivation resistance for at least 60 h in the gaseous stream, which is an advantage for any catalytic application. Compared with a commercial catalyst (5 wt.% Rh/Al 2 O 3 ) tested in the same conditions, cobalt-ytterbium, dysprosium and cerium bimetallic oxide nanofibers present an activity 5 to 13 times higher at 350 °C.
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