Synthesis and characterization of ultra-fine Cr₂O₃ from hydrogen reduction of K₂CrO₄

Abstract

As a part of the green process for manufacturing chromium compounds, two steps are involved in the synthesis of ultra-fine Cr₂O₃ powders: the first is the hydrogen reduction of K₂CrO₄ into intermediate trivalent (Cr³⁺) or tetravalent (Cr⁴⁺) chromium compounds; the second is the decomposing of the intermediate into Cr₂O₃ by heat treating. The intermediate is well characterized by means of SEM, XRD, and XPS. The possible reaction mechanism of the process is analyzed.

Keywords

hydrogen reduction / ultra-fine chromic oxide / potassium chromate / green process

References

[1] Liotta L. F., Venezia A. M., Pantaleo G. Chromia on Silica and Zirconia Oxides as Recyclable Oxidizing System: Structural and Surface Characterization of the Active Chromium Species for Oxidation Reaction[J]. Catal. Today, 2004, 91: 231-236.

[2] Fountzoula C., Matralis H. K., Papadopoulou C. The Influence of the Chromium Content on the Physicochemical Properties and the Catalytic Behavior of CrO_x/TiO₂ Catalysts for the Selective Catalytic Reduction of Nitric Oxide by Ammonia at Relatively High Temperatures[J]. J. Catal., 1997, 172: 391-405.

[3] Trunschke A., Hoang D. L., Radnik J. Influence of Lanthana on the Nature of Surface Chromium Species in La2O3-Modifi ed CrO_x/ZrO₂ Catalysts[J]. J. Catal., 2000, 191: 456-466.

[4] Balachandran U., Siegel R. W., Liao Y. X,. Synthesis, Sintering, and Magnetic Properties of Nanophase Cr₂O₃[J]. Nanostruct. Mater., 1995, 5(5): 505-512.

[5] Vollath D., Szabó D. V., Willis J. O. Magnetic Properties of Nanocrystalline Cr2O3 Synthesized in a Microwave Plasma[J]. Mater. Lett., 1996, 29(4–6): 271-279.

[6] Zhu Y. J., Qian Y. T., Zhang M. W. γ-Radiation Synthesis of Nanometer-size Amorphous Cr₂O₃ Powders at Room Temperature[J]. Mat. Sci. Eng. B, 1996, 41(2): 294-296.

[7] Zhong Z. C., Cheng R. H., Bosley J. Fabrication of Chromium Oxide Nano-Particles by Laser-induced Deposition from Solution[J]. Appl. Surf. Sci., 2001, 181(3–4): 196-200.

[8] Peters G., Jerg K., Schramm B. Characterization of Chromium (III) Oxide Powders Prepared by Laser-induced Pyrolysis of Chromyl Chloride[J]. Mater. Chem. Phy., 1998, 55(3): 197-201.

[9] Nikumbh A. K., Rahman M. M., Aware A. D. A Study of the Thermal Decomposition of Chromium(II) Oxalate Dihydrate Using Direct Current Electrical Conductivity Measurements[J]. Thermochimica Acta, 1990, 159: 109-123.

[10] Tsuzuki T., Mccormick P. G. Synthesis of Cr₂O₃ Nanoparticles by Mechanochemical Processing[J]. Acta. Mater., 2000, 48(11): 2795-2891.

[11] Zhang Y., Li Z. H., Qi T. Green Manufacturing Process of Chromium Compounds[J]. Environm. Prog., 2005, 24(1): 44-50.

[12] Xu H. B., Zheng S. L., Zhang Y. Oxidative Leaching of a Vietnamese Chromite Ore in Highly Concentrated Potassium Hydroxide Aqueous Solution at 300 °C and Atmospheric Pressure[J]. Minerals Engineering, 2005, 18(5): 527-535.

[13] Xu H. B., Zhang Y., Li Z. H,. Development of a New Cleaner Production Process for Producing Chromic Oxide from Chromite Ore[J]. J. Clean. Prod., 2005, 14(2): 211-219.

[14] Xu H B, Bai Y L, Zhang Y, et al. The Method for Preparation of Chromium Oxide by Reducing the Chromate with Hydrogen[P]. CN 200510089010.8, 2005(in Chinese)

[15] Yim S. D., Nam I. S. Characteristics of Chromium Oxides Supported on TiO₂ and Al₂O₃ for the Decomposition of Perchloroethylene[J]. J. Catal., 2004, 221(2): 601-611.

[16] Rao J. M., Sivaprasad A., Rao P. S,. A Comparative Study of Bulk and Supported Chromia Catalysts for the Fluorination of Trichloroethylene[J]. J. Catal., 1999, 184(1): 105-111.

[17] Liu B., Terano M. Investigation of the Physico-Chemical State and Aggregation Mechanism of Surface Cr Species on a Phillips CrO_x/SiO₂ Catalyst by XPS and EPMA[J]. J. Mol. Catal. A-Chem., 2001, 172(1–2): 227-240.

[18] Liu X., Su W., Lu Z. Mixed Valence State and Electrical Conductivity of La_1−xSr_xCrO₃[J]. J. Alloy. Compd., 2000, 305(1–2): 21-23.

[19] Machet A., Galtayries A., Zanna S. XPS and STM Study of the Growth and Structure of Passive Films in High Temperature Water on a Nickel-base Alloy[J]. Electrochimica Acta, 2004, 49(22–23): 3957-3964.

[20] Hoang D. L., Dittmar A., Radnik J. Redox Behaviour of La-Cr Compounds Formed in CrO_x/La₂O₃ Mixed Oxides and CrO_x/La₂O₃/ZrO₂ Catalysts[J]. Appl. Catal. A-Gen., 2003, 239(1–2): 95-110.