Orchestrating fluoride effect, secondary growth and microwave irradiation in the synthesis of EU-1/ZSM-48 intergrowth crystals for the conversion of dimethyl ether to olefins

Abstract A great decrease in the crystallization time of EU-1 zeolite to 10 h was achieved by coupling between the microwave-assisted hydrothermal synthesis and the addition of fluoride as crystallization promoter in the presence of 10% EU-1 seeds in alkaline media. Interesting characterization results were obtained by observing an octahedral coordination of Al incorporated with the fluoride presented in the synthesis in the form of AlO 4 F 2 . This finding was confirmed by analyzing the spectra of FTIR and 27 Al MAS NMR which showed additional peak attributed to AlO 4 F 2 . The short crystallization time offered a significant decrease of EU-1 particle size to ∼500 nm as observed on FE-SEM. A pure phase of EU-1 was synthesized in the range of 25–100 Si/Al ratio. An intergrowth phase of EU-1 and ZSM-48 was observed on XRD when 200 Si/Al ratio gel was prepared. Excellent catalytic performance of DME conversion to olefins was achieved over the co-crystalline EU-1 and ZSM-48 sample. The sample showed exceptional stability for 360 min on stream compared with other samples and the highest olefins selectivity which reached to 78%.