Cracking of n-heptane with activation of vanadium oxide based catalyst: effect of support and modification by K or P
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In the present study, n-heptane cracking was comparatively investigated over ZSM-5 equilibrium catalyst with introduction of VOX/Al2O3, VOX/SiO2 and VOX/MgO, as well as the potassium or phosphorous incorporated VOX/Al2O3. The results showed that the conversion varied significantly with introduction of different VOX/support catalysts. The conversion decreased in the order of Base (without introduction) < + VOX/SiO2 < + VOX/MgO < + VOX/Al2O3. The different extent of improvement in conversion could be closely associated with the reducibility of them. The incorporation of potassium or phosphorous modified the acid properties of VOX/Al2O3. But the conversions were barely influenced. There was an increasing trend of selectivity to hydrogen and aromatic products with increasing acidity of the vanadia based catalysts. It was suggested that the improved basicity favored desorption of the active intermediate species from VOX unit, leading to a lower selectivity to hydrogen and aromatics produced.
KeywordsVanadium oxide Support Reducibility Acidity Cracking Selectivity
This work is financially supported by National Natural Science Foundation of China (No. 21506247) and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
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