LAUSR

Abstract Bifunctional catalysts are widely applied to chemical and petrochemical industry. Herein nickel was introduced by ionic exchange in HZSM5 zeolite resulted in a Ni/HZSM5 catalyst that contains both H+ and Ni2+ as compensation cations of the zeolite framework. This catalyst has been characterized by using different in-situ techniques as Dispersive X-ray Absorption (DXAS), X-ray Absorption Fine Structure (XAFS), Diffuse Reflectance Infrared Fourier-Transform (DRIFTS) spectroscopies, Temperature Programmed Reduction experiments (TPR) under both H2 and isobutane atmospheres, and by X-Ray Diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HRTEM) after exposure to H2 or isobutane. The reduction of Ni2+ species under isobutane started at about 120 °C, meanwhile under H2 stream the reduction started at 350 °C. Under isobutane, nickel undergoes a sequential reduction from Ni2+ to Ni+ and then to Ni0 and the number of Bronsted acid sites of the catalyst increased. By increasing the temperature (500 °C), sintering occurs and nickel particles are formed.