Applied Catalysis A: General, Vol.519, 48-55, 2016
Influence of the state of Zn species over Zn-ZSM-5/ZSM-11 on the coupling effects of cofeeding n-butane with methanol
Combination of the exothermic methanol aromatization with the endothermic n-butane aromatization provides a good way to meet the increasing demand for aromatics. Here, a series of Zn-ZSM-5/ZSM-11 catalysts were prepared with different introduction methods. The influence of location and state of Zn species on the coupling effects of cofeeding n-butane with methanol were investigated in detail. UV-vis, H-2-TPR and XPS spectra were applied to reveal the state of the Zn species on different catalysts. Quantitative results of NH3-TPD and Pyridine-FTIR were provided to compare the acidity changes of the catalyst after Zn loading. Physical mixing method led to high portion of bulk ZnO particles outside the channel which could promote the formation of C-2-C-4 light alkane in cofeeding reaction. Ion exchange and impregnation modes were beneficial for the formation of Zn-O-Zn bridging species in the micropore channel. Zn-O-Zn bridging species was found to increase the promoting effect of cofeeding n-butane with methanol on aromatics selectivity. (C) 2016 Published by Elsevier B.V.