キンゾク オヨビ ホウソ タンジ ZSM-5 ショクバイ ノ サンキョウド ブンプ ト トルエン フキンカ ハンノウ カッセイ

The effects of acid strength distribution and micro pore size of the zeolites on the catalytic activity of toluene disproportionation reaction have been studied with metal and boron modified HZSM-5 zeolites. It has been found that the concentration of strong acid sites, toluene conversion and p-xylene selectivity for the metal or boron exchanged ZSM-5 modified by the different methods were dependent only upon the metal content in the zeolites. Since the micro pore size of the modified zeolite decreased with the content, a precursor for o- and m- xylene, whose molecular sizes are larger than that of p-xylene, was not produced in the micro pore. This steric effect results in the improvement of p-xylene selectivity