The Promotional Role of Potassium on InZr/SAPO-34 for Syngas to Light Olefins

Direct synthesis of light olefins from syngas over a bifunctional catalyst containing oxides and zeolites is one of the best choices for clean and efficient utilization of coal resources. InZr/SAPO-34 is considered as a promising Cr-free catalyst for STO reaction; however, the selectivity of paraffin increased obviously at high CO conversion. Hence, the inhibition of paraffin production on oxides is strongly desired to further enhance the catalytic performance. Herein, we attempt to modify the properties of InZr oxides with K to modulate the hydrogenation process. The structures of oxides were investigated thoroughly using multiple techniques such as XRD, SEM, and Raman spectroscopy. The promotional role of K on the reaction pathways were explored by H2-TPD and model reaction, such as C2H4 hydrogenation. Characterization results showed that the introduction of K could weaken the hydrogenation ability by suppressing the H2 adsorption and inhibiting surface hydrogenation process. Additionally, K preferentially inhibited the olefin hydrogenation than CO hydrogenation, which are key to achieving the excellent catalytic performance.