Effects of added phosphorus on conversion of ethanol to propylene over ZSM-5 catalysts

We investigated the effects of added phosphorus on the conversion of ethanol to propylene over ZSM-5 zeolite catalysts. We found that the activity of the catalysts was enhanced by the addition of phosphorus, and we suggest that the added phosphorus suppressed oligomerization of propylene and butene by decreasing the acidity of the active sites of the zeolites. Furthermore, the addition of phosphorus greatly enhanced the hydrothermal stability of the zeolites and thus substantially improved the catalyst durability during ethanol conversion. Carbon deposition, which was the main cause of deactivation of the phosphorus-modified zeolites, was suppressed by H2O produced by dehydration of ethanol.

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► The effect of added phosphorus on ethanol conversion over ZSM-5 was investigated.
► Phosphorus maintained the active sites in the presence of H2O.
► Carbon deposition on P-ZSM-5 was suppressed in the presence of H2O.
► Kinetics analysis indicated that the catalyst was deactivated by carbon deposition.