Zhu Lianjie, Frens Gert
Department of Chemical Technology, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands.
J Phys Chem B. 2006 Sep 21;110(37):18307-12. doi: 10.1021/jp063456x.
We explored the surface temperature excess DeltaT = T(r) - T(m) (real reaction temperature T(r), measured catalyst temperature T(m)) on the basis of experimental data, a gradually curved Arrhenius plot for CO oxidation reactions over Pd/gamma-Al(2)O(3) catalysts. Such a plot could be an indication of the surface temperature excess in the 2-dimensional reaction surfaces of catalysts. The positive or negative surface temperature excess could be developed to be a general explanation for a gradually curved Arrhenius plot of a gas-solid catalytic system. This is a new insight into solving the puzzle on such common phenomena in heterogeneous catalysis. By using the reciprocal of the real reaction temperature T(r) in the hypothetical 2-D reaction surface, instead of the experimentally determined catalyst temperature T(m) or the gas temperature T(g), the gradually curved Arrhenius plot becomes linear. We investigated the implications of such a difference among T(r), T(m), and T(g). The surface temperature excess could be the effect of coupling between the fluxes of a chemical reaction and heat transport in the 2-D reaction surface. Its order of magnitude is 10 K for the present model system.(1) The surface temperature excess increases exponentially with the reaction temperature.
我们基于实验数据，对Pd/γ-Al₂O₃催化剂上CO氧化反应的逐渐弯曲的阿累尼乌斯图，探究了表面温度过剩ΔT = T(r) - T(m)（实际反应温度T(r)，测量的催化剂温度T(m)）。这样的图可能表明催化剂二维反应表面存在表面温度过剩。正的或负的表面温度过剩可作为对气固催化体系逐渐弯曲的阿累尼乌斯图的一种普遍解释。这是解决多相催化中此类常见现象谜团的一个新见解。通过在假设的二维反应表面使用实际反应温度T(r)的倒数，而非实验测定的催化剂温度T(m)或气体温度T(g)，逐渐弯曲的阿累尼乌斯图变为线性。我们研究了T(r)、T(m)和T(g)之间这种差异的影响。表面温度过剩可能是二维反应表面化学反应通量与热传输之间耦合的效应。对于当前模型系统，其量级为10 K。(1)表面温度过剩随反应温度呈指数增加。
