Article

Journal of Porous Materials

, Volume 13, Issue 3, pp 353-357

H-MCM-22 zeolitic catalysts modified by chemical liquid deposition for shape-selective disproportionation of toluene

  • Xiaoqian RenAffiliated withKey Laboratory of Materials-Oriented Chemical Engineering of Ministry of Education, College of Chemistry and Chemical Engineering, Nanjing University of Technology
  • , Jinhua LiangAffiliated withKey Laboratory of Materials-Oriented Chemical Engineering of Ministry of Education, College of Chemistry and Chemical Engineering, Nanjing University of Technology
  • , Jun WangAffiliated withKey Laboratory of Materials-Oriented Chemical Engineering of Ministry of Education, College of Chemistry and Chemical Engineering, Nanjing University of Technology Email author 

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Abstract

Catalysts were prepared by dealumination of H-MCM-22 zeolite with oxalic acid leaching, followed by shaping and liquid phase modification with siloxane. The catalytic performance was measured with selective disproportionation of toluene in a fixed-bed reactor. The unmodified H-MCM-22 zeolite exhibited much higher initial activity than H-ZSM-5 with a thermodynamic equilibrium distribution of xylene products. The oxalic acid treatment of H-MCM-22 improved the selectivity for para-xylene by 10–18%. The modification by siloxane of the oxalic acid treated H-MCM-22 turned out to be highly selective for para-xylene, however, with the expense of the conversion. It is proposed that the high para-selectivity was closely associated with the contraction of micropore windows and the elimination of acid sites at the external surface by the deposited silica. Therefore, the modified H-MCM-22 is a potential catalyst for the selective disproportionation of toluene with a high para-selectivity.

Keywords

MCM-22 Disproportionation of toluene Para-xylene Dealumination Chemical liquid deposition