The influence of the loading position of Pt/HZSM-22 and Pt/HMOR in the catalyst bed on the n-dodecane hydroisomerization performance

Pt/HMOR and Pt/HZSM-22 catalysts were prepared by mechanical grinding pre-prepared Pt/Al 2 O 3 (prepared via excess wetness impregnation using H 2 PtCl 6 ·6H 2 O) with HMOR and HZSM-22 zeolites, respectively, at a 1:1 mass ratio. The influence of the loading position of Pt/HZSM-22 and Pt/HMOR in the catalyst bed on the n -dodecane hydroisomerization performance was systematically investigated using n -dodecane as the model reactant. By adjusting the relative positions of Pt/HZSM-22 and Pt/HMOR in catalyst bed, the isomers selectivity and yield of catalyst Pt/HMOR(U)-Pt/HZSM-22(D) (U and D represent the upstream catalyst bed and downstream catalyst bed, respectively) were higher than Pt/HZSM-22(U)-Pt/HMOR(D) and the difference of yield of mono-branched isomers and multi-branched isomers reached the maximum of 31.31 % and 16.78 % at the reaction temperature of 320 °C and 340 °C, respectively. In order to explore the reaction process of isomers on Pt/HZSM-22 and Pt/HMOR, 2-methylpentane was selected as the probe molecule. The results were shown that 2-methylpentane would undergo isomerization reaction on Pt/HMOR to form 2,3-dimethylbutane, while the ability to produce 2,3-dimethylbutane on Pt/HZSM-22 was weaker.