Adsorption of NO and NH₃ over CuO/γ-Al₂O₃ catalyst

Abstract

The selective catalytic reduction reaction belongs to the gas-solid multiphase reaction, and the adsorption of NH₃ and NO on CuO/γ-Al₂O₃ catalysts plays an important role in the reaction. Performance of the CuO/γ-Al₂O₃ catalysts was explored in a fixed bed adsorption system. The catalysts maintain nearly 100% NO conversion efficiency at 350 °C. Comprehensive tests were carried out to study the adsorption behavior of NH₃ and NO over the catalysts. The desorption experiments prove that NH₃ and NO are adsorbed on CuO/γ-Al₂O₃ catalysts. The adsorption behaviors of NH₃ and NO were also studied with the in-situ diffusion reflectance infrared Fourier transform spectroscopy methods. The results show that NH₃ could be strongly adsorbed on the catalysts, resulting in coordinated NH₃ and NH₄⁺ NO adsorption leads to the formation of bridging bidentate nitrate, chelating bidentate nitrate, and chelating nitro. The interaction of NH₃ and NO molecules with the Cu²⁺ present on the CuAl₂O₄ (100) surface was investigated by using a periodic density functional theory. The results show that the adsorption of all the molecules on the Cu²⁺ site is energetically favorable, whereas NO bound is stronger than that of NH₃ with the adsorption site, and key information about the structural and energetic properties was also addressed.

Keywords

CuO/γ-Al₂O₃ / NH₃ / NO / adsorption / diffusion reflectance infrared Fourier transform spectroscopy / density functional theory

References

[1] CentiG., PassariniN., PerathonerS., RivaA., StellaG.. Combined DeSO_x/DeNO_x reactions on a copper on alumina sorbent catalyst.3.DeNO_x behavior as a function of the surface coverage with sulfate species [J]. Industrial and Engineering Chemistry Research, 1992, 31(8): 1963-1970

[2] JeongS. M., JungS. H., YooK. S., KimS. D.. Selective catalytic reduction of NO by NH₃ over a bulk sulfated CuO/γ-Al₂O₃ catalyst [J]. Industrial and Engineering Chemistry Research, 1999, 38(6): 2210-2215

[3] XiangJ., ZhaoQ.-s., HuS., SunL.-s., SuS., FuP., ZhangA.-c., QiuJ.-r., ChenH.-p., XuM.-hou.. Experimental research and characteristics analysis of alumina-supported copper oxide sorbent for flue gas desulfurization [J]. Asia-Pacific Journal of Chemical Engineering, 2007, 2(3): 182-189

[4] ZhaoQ.-s., XiangJ., SunL.-s., ShiJ.-m., SuS., HuSong.. Selective catalytic reduction of NO with NH₃ over sol-gel-derived CuO-CeO₂-MnO_x/γ-Al₂O₃ catalysts [J]. Journal of Central South University of Technology, 2009, 16(3): 0513-0519

[5] RamisG., YiL., BuscaG., TurcoM., KoturE., WilleyR. J.. Adsorption, activation and oxidation of ammonia over SCR catalysts [J]. Journal of Catalysis, 1995, 157(2): 523-535

[6] RamisG., LarrubiaM. A.. An FT-IR study of the adsorption and oxidation of N-containing compounds over Fe₂O₃/Al₂O₃ catalyst [J]. Journal of Molecular Catalysis A: Chemical, 2004, 215(1/2): 161-167

[7] LiuQ.-y., LiuZ.-y., LiC.-yue.. Adsorption and activation of NH₃ during selective catalytic reduction of NO by NH₃ [J]. Chinese Journal of Catalysis, 2006, 27(7): 636-646

[8] KimT. W., SongaM. W., KohaH. L., KimaK. L.. Surface properties and reactivity of Cu/γ-Al₂O₃ catalysts for NO reduction by C₃H: Influences of calcination temperatures and additives [J]. Applied Catalysis A: General, 2001, 210(1/2): 35-44

[9] LuG., van GrondelleaJ., AndersonaB. G., van SantenaR. A.. Selective low temperature NH₃ oxidation to N₂ on copper-based catalysts [J]. Journal of Catalysis, 1999, 186(1): 100-109

[10] ShimizuK. I., MaeshimaH., SatsumaA., HattoriT.. Transition metal-aluminate catalysts for NO reduction by C₃H₆ [J]. Applied Catalysis B: Environmental, 1998, 18(1/2): 163-170

[11] ShimizuK. I., KawabataH., MaeshimaH., SatsumaA., HattoriT.. Intermediates in the selective reduction of NO by propene over Cu-Al₂O₃ catalysts: Transient in-situ FTIR study [J]. The Journal of Physical Chemistry B, 2000, 104(13): 2885-2893

[12] LiW., ChengHua.. Synthesis and characterization of Cu-Cr-O nanocomposites [J]. Journal of Central South University of Technology, 2007, 14(3): 291-295

[13] YinX. L., FahmiA., HanH. M., EndouA., AmmalS. S. C., KuboM., TeraishiK., MiyamotoA.. Adsorption of H₂O on the V₂O₅(010) surface studied by periodic density functional calculations [J]. Journal of Physical Chemistry B, 1999, 103(16): 3218-3224

[14] YinX. L., HanH. M., KuboM., MiyamotoA.. Adsorption of NH₃, NO₂ and NO on copper-aluminate catalyst: An ab initio density functional study [J]. Theoretical Chemistry Accounts, 2003, 109(4): 190-194

[15] XieG.-y., LiuZ.-y., ZhuZ.-p., LiuQ.-y., GeJ., HuangZ.-geng.. Simultaneous removal of SO₂ and NO_x from flue gas using a CuO/Al₂O₃ catalyst sorbent: I. Deactivation of SCR activity by SO₂ at low temperatures [J]. Journal of Catalysis, 2004, 224(1): 36-41

[16] LarrubiaA., RamisG., BuscaG.. An FT-IR study of the adsorption and oxidation of N-containing compounds over Fe₂O₃-TiO₂ SCR catalysts [J]. Applied Catalysis B: Environmental, 2001, 30(1/2): 101-110

[17] WuZ.-b., JiangB.-q., LiuY., WangH.-q., JinR.-ben.. DRIFT study of manganese/titania-based catalysts for low-temperature selective catalytic reduction of NO with NH₃ [J]. Environmental Science & Technology, 2007, 41(16): 5812-5817

[18] ChiY. W., StevenS. C.. Infrared study of NO adsorption and reduction with C₃H₆ in the presence of O₂ over CuO/Al₂O₃ [J]. Journal of Catalysis, 2000, 190(1): 75-91

[19] CentiG., PerathonerS.. Nature of active species in copper-based catalysts and their chemistry of transformation of nitrogen oxides [J]. Applied Catalysis A: General, 1995, 132(2): 179-259