Regulating the Pt dispersion by increasing the specific surface area of Al2O3 support for perhydro-dibenzyltoluene catalytic dehydrogenation reaction

Perhydro-dibenzyltoluene (18H-DBT) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of its high hydrogen storage, easy transportation, low price and other advantages. The 18HDBT dehydrogenation reaction rate is the key point of the hydrogen storage. In this work, the relationship between the Pt dispersion, the average coordinated number and the total catalyst activity for 18H-DBT dehydrogenation reaction was studied. Al2O3 with the large specific surface area was synthesized by the sol-gel method and Pt/Al2O3 catalysts were prepared by incipient wetness impregnation. Their catalytic performance was tested by 18H-DBT dehydrogenation reaction. It was found that the relationship between the Pt dispersion and the catalytic performance is a volcano curve. The optimal dispersion of Pt for dehydrogenation reaction is 11.16 %. That's because that there exists a balance between the Pt dispersion and the average coordinated number in order to obtain the best total catalyst activity. The experiments and characterization results show that the increasing of Pt dispersion will increase the active site number but the average coordinated number will decrease. DFT calculation results further confirm that the catalytic activity of the single active site would decline with the decreasing average coordinated number.