One-pot template-free synthesis of metal-doped ETS-10 zeolites for Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate

Abstract

Three types of metal-doped ETS-10 zeolites including Ni-ETS-10, Al-ETS-10, and Ga-ETS-10 were successfully synthesized by one-pot template-free hydrothermal treatments. The effect of doping metals on the crystallinity, morphology, textural property, and basicity of the produced zeolites was systematically studied. It was found that doping with an appropriate amount of Ni could enhance the crystallinity and basicity of ETS-10 zeolites in comparison with Al and Ga, and the Ni species mainly existed in two forms of framework coordination and exchange site connection within Ni-ETS-10. The catalytic evaluation by the liquid Knoevenagel condensation reaction of benzaldehyde with ethyl cyanoacetate confirmed the superiority of ETS-10 and metal-doped ETS-10 in comparison with the contrast base zeolites of NaY and KY. And the 0.4Ni-ETS-10 catalyst exihibted the best performance with 75.6 % yield of ethyl ɑ-cyanocinnamate (ECC) among all the synthesized (metal-doped) ETS-10 zeolites. It is reasonable to expect that the demonstrated work has important implications for the design and facile synthesis of new-type high-performance base zeolite catalysts.

Keywords

• Base zeolite
• ETS-10
• Metal doping
• Lewis basicity
• Knoevenagel condensation