Thesis (M.Eng.)--Chulalongkorn University, 2008

Light olefins synthesis from butane was investigated on H-ZSM-5 modified with phosphorus or magnesium. The effect of introduction of phosphorus or magnesium was also studied using incipient wetness impregnation and solid state ion exchange. H-ZSM-5 with Si/Al ratios of 40, 70 and 100 were hydro thermally synthesized, and the catalytic performances were examined during 400 – 700℃. The H-ZSM-5 with Si/Al ratio of 70 exhibited the relatively high light olefins yield at 600 ℃. Further modification of the catalyst was made by introduction P or Mg ranging from 0.1 – 3.0 % by weight via incipient wetness impregnation and solid state ion exchange. The introduction method gave significantly indifferent yield of light olefins for each of P and/or Mg. However, H-ZSM-5 modified with P exhibited relatively higher light olefins yield than did Mg. The better dispersion of P-modified ZSM-5 observed from SEM images should be responsible for the good catalytic performance. On the other hand, the adverse effect of Mg may be attributed to the pore blockage as clearly demonstrated by SEM and micro pore results.