Adsorption and reaction properties of SnBEA, ZrBEA and H-BEA for the formation of p-xylene from DMF and ethylene
The adsorption and reaction properties of H-BEA, SnBEA, ZrBEA and siliceous BEA were examined to understand the reaction of 2,5-dimethylfuran (DMF) with ethylene to form p-xylene. Temperature-programmed desorption (TPD) of diethyl ether, DMF, 2,5-hexanedione and p-xylene on each of the zeolites demonstrated that the Brønsted sites in H-BEA are more reactive than the Lewis sites in SnBEA and ZrBEA and tend to promote the oligomerization of DMF and 2,5-hexanedione, even at 295 K; however, the adsorbed 2,5-hexanedione is converted to DMF at both Lewis- and Brønsted-acid sites. H-BEA, SnBEA and ZrBEA all catalyzed the reaction to p-xylene with high selectivity in a continuous-flow reactor, with all three catalysts showing rates that were first order in both DMF and ethylene. H-BEA was found to deactivate rapidly due to coking, while ZrBEA and SnBEA were both stable. The implications of these results for practical applications are discussed.