Solution-combustion Synthesized Nano-pellet α-Al₂O₃ and Catalytic Oxidation of Cyclohexane by Its Supported Cobalt Acetate

Abstract

Nano-pellet α-Al₂O₃ was prepared using aluminum nitrate as precursor and urea as fuel by a fast method of solution combustion synthesis. The formation of the nano material was dependent on the molar ratio of fuel/oxidant, calcination temperature, and foreign metallic ions. The prerequisite conditions of the formation were a suitable fuel/oxidant molar ratio larger than two and calcination temperature higher than 673 K. Foreign ions, Ce⁴⁺ or Co²⁺, hindered this formation via promoting the generation of stable penta-coordinated Al³⁺ ions due to strong interaction with alumina, were revealed by ²⁷Al NMR spectra. Such Al³⁺ ions were recognized as a critical intermediate state for the phase transformation of alumina and their presence deterred the transformation. The nano-pellet morphology of the product demonstrated a specific surface area of 69 m²/g, of which the external surface area occupied 59 m²/g. It was found that the supported cobalt acetate on such nanopellets existed as nanoparticles attached to the external surface, evidenced by the TEM characterization. The prepared catalyst could efficiently catalyze the selective oxidation of cyclohexane under the reaction condition of pressure under 0.8 MPa, temperature at 373 K, and time for 4 hours. The conversion of the reaction achieved up to 7.9%; while the cyclohexanone selectivity was 42.7% and the cyclohexanone and cyclohexanol selectivity was 91.6%. This catalytic performance recommends the supported cobalt acetate on the inert nano-pellet α-Al₂O₃ as a promising catalyst for the selective oxidation of cyclohexane.

Keywords

solution combustion synthesis / alumina / cyclohexane / catalytic oxidation

References

[1] Busca G. Structural, Surface, and Catalytic Properties of Aluminas[J]. Advances in Catalysis, 2014, 57: 319-404.

[2] Lei Z, Jiang XQ, Xu TC, et al. Sorption Characteristics and Separation of Rhenium Ions from Aqueous Solutions Using Modified Nano-Al₂O₃[J]. Industrial & Engineering Chemistry Research, 2012, 51(15): 5 577-5 584.

[3] Kiani S, Zadeh MM, Khodabakhshi S, et al. Newly Prepared Nano Gamma Alumina and Its Application in Enhanced Oil Recovery: An Approach to Low-salinity Waterflooding[J]. Energy & Fuels, 2016, 30(5): 3 791-3 797.

[4] Hu JZ, Xu SC, Kwak JH, et al. High Field ²⁷Al MAS NMR and TPD Studies of Active Sites in Ethanol Dehydration Using Thermally Treated Transitional Aluminas as Catalysts[J]. Journal of Catalysis, 2016, 336: 85-93.

[5] Busca G. The Surface of Transitional Aluminas: A Critical Review[J]. Catalysis Today, 2014, 226: 2-13.

[6] Zhang ZR, Pinnavaia TJ. Mesostructured Forms of the Transition Phases η- and χ-Al₂O₃[J]. Angewandte Chemie International Edition, 2008, 47(39): 7 501-7 504.

[7] Lin JF, Degtyareva O, Prewitt CT, et al. Crystal Structure of A High-pressure/High-temperature Phase of Alumina by in situ X-ray Diffraction[J]. Nature Materials, 2004, 3(6): 389-393.

[8] Duvel A, Romanova E, Sharifi M, et al. Mechanically Induced Phase Transformation of γ-Al₂O₃ into α-Al₂O₃. Access to Structurally Disordered γ-Al₂O₃ with A Controllable Amount of Pentacoordinated Al Sites[J]. Journal of Physical Chemistry C, 2011, 115: 22 770-22 780.

[9] Chen SB, Liu XG, Zhang BQ. Preparation and Properties of Porous α-Al₂O₃ Based Ceramic Disk Substrates[J]. Journal of Inorganic Materials, 2013, 28(6): 599-604.

[10] Wang JF, Liu XG, Zhang PP, et al. Synthesis of Continuous and Dense TAPO-5 Molecular Sieve Membranes by Steam-assisted Gel Conversion Method[J]. Journal of Inorganic Materials, 2013, 28(06): 589-593.

[11] Liu XG, Ma X, Liu Y, et al. Preparation of Perfective TAPO-5 Membrane through Tertiary Growth with Amorphous Seed[J]. Journal of Inorganic Materials, 2015, 30(5): 555-560.

[12] Martín J, Martín-González M, Francisco Fernández J, et al. Ordered Three-dimensional Interconnected Nanoarchitectures in Anodic Porous Alumina[J]. Nature Communications, 2014, 5: 5 130.

[13] Lee W, Ji R, Gösele U, et al. Fast Fabrication of Long-range Ordered Porous Alumina Membranes by Hard Anodization[J]. Nature Materials, 2006, 5(9): 741-747.

[14] Zhang Q, Liu Y, Liu XG, et al. Facile Preparation of Bilayer Titanium Silicate (TS-1) Zeolite Membranes by Periodical Secondary Growth[J]. Coatings, 2019, 9(12): 850

[15] Mokoena TP, Linganiso EC, Swart HC, et al. Cooperative Luminescence from Low Temperature Synthesized α-Al₂O₃: Yb³⁺ Phosphor by Using Solution Combustion[J]. Ceramics International, 2017, 43(1): 174-181.

[16] Liu XG, Li ZY, Zhang BQ, et al. Improvement of Hydrodeoxygenation Stability of Nickel Phosphide Based Catalysts by Silica Modification as Structural Promoter[J]. Fuel, 2017, 204: 144-151.

[17] Liu XG, Xu L, Zhang BQ. Essential Elucidation for Preparation of Supported Nickel Phosphide upon Nickel Phosphate Precursor[J]. Journal of Solid-State Chemistry, 2014, 212: 13-22.

[18] Liu XG, Zhang BQ, Xu L. Noble Metal Catalyzed Preparation of Ni₂P/α-Al₂O₃[J]. Physical Chemistry Chemical Physics, 2013, 15(25): 10 510-10 514.

[19] Amrute AP, Łodziana Z, Schreyer H, et al. High-surface-area Corundum by Mechanochemically Induced Phase Transformation of Boehmite[J]. Science, 2019, 366(6464): 485-489.

[20] Galvis HMT, Bitter JH, Khare CB, et al. Supported Iron Nanoparticles as Catalysts for Sustainable Production of Lower Olefins[J]. Science, 2012, 335(6070): 835-838.

[21] Lee J, Jeon H, Oh DG, et al. Morphology-dependent Phase Transformation of γ-Al₂O₃[J]. Applied Catalysis A General, 2015, 500(5): 58-68.

[22] Padilla I, López-Andrés S, López-Delgado A. Effects of Different Raw Materials in the Synthesis of Boehmite and γ- and α-alumina[J]. Journal of Chemistry, 2016, 2016(2–3): 1-6.

[23] Varma A, Mukasyan AS, Rogachev AS, et al. Solution Combustion Synthesis of Nanoscale Materials[J]. Chemical Reviews, 2016, 116: 14 493-14 586.

[24] Liu WQ, Liu XG, Zhang PP, et al. Nano-sized Plate-like Alumina Synthesis via Solution Combustion[J]. Ceramics International, 2019, 45(8): 9 919-9 925.

[25] Zhuravlev VD, Bamburov VG, Beketov AR, et al. Solution Combustion Synthesis of α-Al₂O₃ Using Urea[J]. Ceramics International, 2013, 39(2): 1 379-1 384.

[26] Zhang JS, Guo QJ, Liu YZ, et al. Preparation and Characterization of Fe₂O₃/Al₂O₃ Using the Solution Combustion Approach for Chemical Looping Combustion[J]. Industrial & Engineering Chemistry Research, 2012, 51(39): 12 773-12 781.

[27] Yoo YS, Park KY, Jung KY, et al. Preparation of α-alumina Nanoparticles via Vapor-phase Hydrolysis of AlCl₃[J]. Materials Letters, 2009, 63(21): 1 844-1 846.

[28] Carstens S, Enke D. Investigation of the Formation Process of Highly Porous α-Al₂O₃ via Citric Acid-assisted Sol-gel Synthesis[J]. Journal of the European Ceramic Society, 2019, 39(7): 2 493-2 502.

[29] Pérez LL, Zarubina V, Heeres HJ, et al. Condensation-enhanced Self-assembly as A Route to High Surface Area α-aluminas[J]. Chemistry of Materials, 2013, 25(20): 3 971-3 978.

[30] Zhu LH, Tu RR, Huang QW. Molten Salt Synthesis of α-Al₂O₃ Platelets Using NaAlO₂ as Raw Material[J]. Ceramics International, 2012, 38(2): 901-908.

[31] Gao Y, Meng F, Cheng Y, et al. Influence of Fuel Additives in the Urea-nitrates Solution Combustion Synthesis of Ni-Al₂O₃ Catalyst for Slurry Phase CO Methanation[J]. Applied Catalysis A General, 2017, 534: 12-21.

[32] Gao Y, Meng FH, Li X, et al. Factors Controlling Nanosized Ni-Al₂O₃ Catalysts Synthesized by Solution Combustion for Slurry-phase CO Methanation: the Ratio of Reducing Valences to Oxidizing Valences in Redox Systems[J]. Catalysis Science & Technology, 2016, 6(21): 7 800-7 811.

[33] Liu DC, Zang BQ, Liu XF, et al. Cyclohexane Oxidation over AFI Molecular Sieves: Effects of Cr, Co Incorporation and Crystal Size[J]. Catalysis Science & Technology, 2015, 5(6): 3 394-3 402.

[34] Unnarkat AP, Sridhar T, Wang HT, et al. Cobalt Molybdenum Oxide Catalysts for Selective Oxidation of Cyclohexane[J]. Aiche Journal, 2016, 62(12): 4 384-4 402.

[35] Toniolo JC, Lima MD, Takimi AS, et al. Synthesis of Alumina Powders by the Glycine-nitrate Combustion Process[J]. Materials Research Bulletin, 2005, 40(3): 561-571.

[36] Behra PS, Bhattacharrya S, Sarkar R. Effect of Citrate to Nitrate Ratio on the Sol-gel Synthesis of Nanosized α-Al₂O₃ Powder[J]. Ceramics International, 2017, 43(17): 15 221-15 226.

[37] Shi L, Deng GM, Li WC, et al. Al₂O₃ Nanosheets Rich in Pentacoordinate Al³⁺ Ions Stabilize Pt-Sn Clusters for Propane Dehydrogenation[J]. Angewandte Chemie International Edition, 2015, 54(47): 14200-14204.

[38] Ding J, Liu YT, Zhang J, et al. Synergetic Effect of Cu and Pentacoordinate Al³⁺ Sites: Direct Synthesis of Ethyl Ethoxyacetate via Hydrogenation of Diethyl Oxalate[J]. Catalysis Communications, 2017, 89: 106-110.

[39] Kwak JH, Hu JZ, Mei DH, et al. Coordinatively Unsaturated Al³⁺ Centers as Binding Sites for Active Catalyst Phases of Platinum on g-Al₂O₃[J]. Science, 2009, 325(5948): 1 670-1 673.

[40] Shojaie-Bahaabad M, Taheri-Nassaj E. Economical Synthesis of Nano Alumina Powder Using an Aqueous Sol-gel Method[J]. Materials Letters, 2008, 62(19): 3 364-3 366.

[41] Sasikala R, Sudarsan V, Kulshreshtha SK. ²⁷Al NMR Studies of Ce-Al Mixed Oxides: Origin of 40ppm Peak[J]. Journal of Solid-State Chemistry, 2002, 169(1): 113-117.

[42] Sarou-Kanian V, Gleizes AN, Florian P, et al. Temperature-dependent 4-, 5- and 6-fold Coordination of Aluminum in MOCVD-grown Amorphous Alumina Films: A Very High Field ²⁷Al-NMR Study[J]. Journal of Physical Chemistry C, 2013, 117: 21 965-21 971.

[43] Kwak JH, Hu J, Lukaski A, et al. Role of Pentacoordinated Al³⁺ Ions in the High Temperature Phase Transformation of γ-Al₂O₃[J]. Journal of Physical Chemistry C, 2015, 112(25): 9 486-9 492.

[44] Prakash AS, Shivakumara C, Hegde MS. Single Step Preparation of CeO₂/CeAlO₃/γ-Al₂O₃ by Solution Combustion Method: Phase Evolution, Thermal Stability and Surface Modification[J]. Materials Science and Engineering: B, 2007, 139(1): 55-61.

[45] Wang S, Borisevich AY, Rashkevv SN, et al. Dopants Adsorbed as Single Atoms Prevent Degradation of Catalysts[J]. Nature Materials, 2004, 3(3): 143-146.

[46] Vázouez A, López T, Gómez R, et al. X-ray Diffraction, FTIR, and NMR Characterization of Sol-gel Alumina Doped with Lanthanum and Cerium[J]. Journal of Solid-State Chemistry, 1997, 128(2): 161-168.

[47] Rosenflanz A, Frey M, Endres B, et al. Bulk Glasses and Ultrahard Nanoceramics based on Alumina and Rare-earth Oxides[J]. Nature, 2004, 430(7001): 761-764.

[48] Patel K, Blair V, Douglas J, et al. Structural Effects of Lanthanide Dopants on Alumina[J]. Scientific Reports, 2017, 7: 39 946.

[49] Łodziana Z, Topsøe NY, Nørskov JK, et al. A Negative Surface Energy for Alumina[J]. Nature Materials, 2004, 3(5): 289-293.

[50] Carstens S, Meyer R, Enke D. Towards Macroporous α-Al₂O₃—routes, Possibilities and Limitations[J]. Materials, 2020, 13(7): 1 787

[51] Tan XY, Wang X, Yin YS, et al. Crystal Structure and Valence Electron Structure of α-Al₂O₃[J]. China Journal of Nonferrous Metals, 2002, 12(z1): 18-23.

[52] Yu Q, Qiu XL. The Calculation of The Electronic Structure and Mechanical Properties of α-Al₂O₃l Using the First Principle[J]. Materials Research and Applications, 2009, 3(3): 162-167.

[53] Fu Y, Zhan WC, Guo YL, et al. Highly Efficient Cobalt-doped Carbon Nitride Polymers for Solvent-free Selective Oxidation of Cyclohexane[J]. Green Energy & Environment, 2017, 2(002): 142-150.

[54] Xu LX, He CH, Zhu MQ, et al. A Highly Active Au/Al₂O₃ Catalyst for Cyclohexane Oxidation Using Molecular Oxygen[J]. Catalysis Letters, 2007, 114(3–4): 202-205.

[55] Wu MZ, Zhan WC, Guo YL, et al. An Effective Mn-Co mixed Oxide Catalyst for the Solvent-free Selective Oxidation of Cyclohexane with Molecular Oxygen[J]. Applied Catalysis A General, 2016, 523: 97-106.

[56] Unnarkat AP, Sridhar T, Wang H, et al. Study of Cobalt Molybdenum Oxide Supported on Mesoporous Silica for Liquid Phase Cyclohexane Oxidation[J]. Catalysis Today, 2017, 310: 116-129.

[57] Fu Y, Zhan WC, Guo YL, et al. Effect of Surface Functionalization of Cerium-doped MCM-48 on Its Catalytic Performance for Liquid-phase Free-solvent Oxidation of Cyclohexane with Molecular Oxygen[J]. Microporous and Mesoporous Materials, 2015, 214: 101-107.