Chinese Journal of Catalysis ›› 2015, Vol. 36 ›› Issue (10): 1750-1758.DOI: 10.1016/S1872-2067(15)60899-3

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Effects of pretreatment temperature on bimetallic Ir-Re catalysts for glycerol hydrogenolysis

Chenghao Deng, Li Leng, Jinghong Zhou, Xinggui Zhou, Weikang Yuan   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2015-03-11 Revised:2015-05-16 Online:2015-09-26 Published:2015-09-26
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21106047).

Abstract:

A series of bimetallic Ir-Re/KIT-6 catalysts was prepared by direct activation of impregnated samples at various reduction temperatures to study the effect of pretreatment temperature on catalyst structure and on catalytic performance for glycerol hydrogenolysis. All catalysts were characterized by N2 adsorption-desorption, transmission electron microscopy, CO chemisorption, in-situ CO adsorption diffuse reflectance infrared Fourier transform spectroscopy and temperature-programmed desorption of ammonia (NH3-TPD). The results demonstrated that those catalysts reduced at 400 to 700 ℃ exhibited an Ir-Re alloy structure with similar particle sizes and Ir dispersions. Furthermore, NH3-TPD results indicated that all catalysts had similar acid strengths, though acid density varied with the reduction temperature. Increasing the pretreatment temperature from 400 to 600 ℃ monotonically increased the acid density of the catalysts and also improved the catalytic activity for glycerol hydrogenolysis. Reducing the Ir-Re alloy catalyst at 700 ℃ slightly decreased the activity due to the growth of the metal particles. Moreover, a linear relationship was identified between the acid density of a catalyst and its activity, verifying the vital roles of both Re and surface acidity with regard to optimizing the performance of Ir-Re alloy catalysts.

Key words: Glycerol hydrogenolysis, Iridium-Rhenium alloy, Bifunctional mechanism, Surface acidity, Reduction temperature