NO<sub>x</sub> Storage-Reduction over Pt/Mg-Al-O Catalysts with Different Mg/Al Atomic Ratios

Hao Cheng; Guangwen Chen; Shudong Wang; Diyong Wu; Yin Zhang; Henqiang Li

Korean Journal of Chemical Engineering, Vol.21, No.3, 595-600, May, 2004

DOI10.1007/BF02705493 Export Citation

NO_x Storage-Reduction over Pt/Mg-Al-O Catalysts with Different Mg/Al Atomic Ratios

Hao Cheng, Guangwen Chen^†, Shudong Wang, Diyong Wu, Yin Zhang, and Henqiang Li

Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Korea

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A series of Pt/Mg-Al-O catalysts with different Mg/Al atomic ratios were prepared. The NO_x storage capacities of these catalysts were measured by isothermal storage at 350 ℃. It was found that the NO_x storage capacity increased with increasing Mg/Al atomic ratios. The catalytic behaviors of Pt/Mg-Al-O and Pt/MgO were studied with storage-reduction cycles at 400 ℃. Under oxidizing conditions, NO_x concentration in the outlet gas gradually increased with time, which indicated the catalysts could store NO_x effectively. After a switch from oxidizing conditions to reducing conditions, NO_x desorption peak emerged immediately due to the incomplete reduction of stored NO_x, which lowered the total NO_x conversion. With increasing Mg/Al atomic ratio in the catalysts, NO_x conversion increases. Pt/MgO has the highest NO_x conversion because of its best activity in the reduction of NO_x by C₃H₆. It seems that with an increasing amount of MgO in the catalysts, the self-poisoning of Pt-sites by adsorbed species during the reaction of NO_x with C₃H₆ may be inhibited effectively.

Keywords:Lean-burn;NO_x Storage-reduction;Platinum;Hydrotalcite;MgO

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