Nickel/gallium modified HZSM-5 for ethane aromatization: Influence of metal function on reactivity and stability

Bimetallic catalysts often outperform their monometallic counterparts due to the synergistic effect. Here we reported that the Ni/Ga co-functionalized HZSM-5 catalyst, specifically with Ni-1/Ga-1 stoichiometric ratio, shows significantly improved selectivity (above 80 %) and stability than the Ni/HZSM-5 catalyst and higher activity (with identical selectivity) than the Ga/HZSM-5 catalyst in ethane aromatization. According to the transient experiment, the Ga and Ni1Ga1/HZSM-5 catalysts show an induction period of a few minutes. However, for Ni/ HZSM-5 and Ni1Ga1/3/HZSM-5, the induction period increased to> 10 min and >30 min, respectively, where up to 100 % of ethane was converted into methane and coke through cracking/hydrogenolysis. Based on the generalized power-law equation model, a modified model for deactivation kinetic was proposed. Consequently, the influence of the metal function on the kinetic parameters was discussed. We anticipate the formation of Ni3Ga intermetallic alloy and its synergy with the exchanged Ga delta+ to be responsible for optimal BTX formation.