| Energy and Chemical Engineering |
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| Quantum chemical study on the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process |
| Zheng-cheng WEN, Zhi-hua WANG, Jun-hu ZHOU, Ke-fa CEN |
| State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China |
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Abstract Quantum chemical simulation was used to investigate the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process. Both NO-char and NO-Na/K reactions were considered as three-step processes in this calculation. Based on geometry optimizations made using the UB3LYP/6-31G(d) method, the activation energies of NO-char and NO-Na/K reactions were calculated using the QCISD(T)/6-311G(d, p) method; Results showed that the activation energy of the NO-Na/K reaction (107.9/82.0 kJ/mol) was much lower than that of the NO-char reaction (245.1 kJ/mol). The reactions of NaO/KO and Na2O/K2O reduced by char were also studied, and their thermodynamics were calculated using the UB3LYP/6-31G(d) method; Results showed that both Na and K can be refreshed easily and rapidly by char at high temperature during the coal reburning process. Based on the calculations and analyses, the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process was clarified.
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Received: 05 May 2008
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