Synthesis of Cr, Cu, Ni, and Y-Doped 3D-Printed ZSM-5 Monoliths and Their Catalytic Performance for n-Hexane Cracking

In this work, chromium, copper, nickel, and yttrium-doped 3D-printed ZSM-5 monoliths were synthesized by doping the ZSM-5 zeolite paste with corresponding metal precursors. The physical and acid properties of the metal-doped 3D-printed ZSM-5 monoliths were systematically characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR), N2 adsorption, temperature programmed reduction of H2(H2-TPR), and temperature-programmed desorption of ammonia (NH3-TPD) techniques. The characterization of bare and metal-doped monoliths confirmed the presence of metal promoters within the zeolite matrix while their MFI frameworks were retained after doping and printing. It was also found that the metal doping significantly affected the ZSM-5 porosity, acidity, and morphology according to the N2 physisorption, NH3-TPD, and SEM, respectively. The dependence of products selectivities on the conversion of n-hexane and the reaction temperature over 3D-printed ZSM-5 monolith catalysts were reported. Catalytic tests showed that the Cr, Cu and Ni-doped 3D-printed ZSM-5 monolith catalysts exhibited high selectivity toward benzene, toluene, and xylene (BTX), while Y-doped ZSM-5 monolith promoted the light olefins selectivity. The effect of reaction temperature on the cracking activity was also investigated. 3D printing offers a facile and rapid approach for preparing various metal-doped 3D-printed zeolite monoliths. The catalytic findings reported in this investigation highlight the potential of metal-doped 3D-printed zeolite monoliths for use in n-hexane cracking.