Highly selective formation of benzene upon toluene transformation on CsY zeolite

Abstract

Gas-phase transformation of toluene is carried out on Cs-exchanged NaY zeolite in a fixed-bed tubular reactor and it is observed that toluene can transform through dealkylation, producing benzene and a small amount of hydrogen under the experimental conditions. After a definite activation period, the transformation of toluene can achieve its steady state with the yield of benzene above 25 % for a relatively long continuous time at low space velocity. Combining the results of characterization and catalytic performances, it can be concluded that benzene is the steadiest product except the carbonaceous residues within the CsY zeolite pores. The in situ carbonaceous deposition experiment shows a similar trend of the carbonaceous forming process and the yield of benzene, indicating the important role of carbonaceous species in the formation of benzene, i.e., it is necessary for the accumulation of carbonaceous species in the initial stage of reaction. The discovery in the current work sheds light on new strategies for the transformation of other similar compounds.