Catalytic hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene over solid base-hydrogenation bifunctional catalysts: Effect of alkali metals on Pd/γ-Al2O3

Abstract Alkali metals doped Pd solid base-hydrogenation bifunctional catalysts were prepared, characterized, and employed in the hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene. The results indicated that the basicity of catalyst endowed by the alkali metals indeed hindered the formation of amino by-products. Among them, K doped catalyst exhibited the best catalytic performance and 84.79% benzotriazole selectivity was obtained. Furthermore, besides the good distribution of palladium particles, it is important for basic sites to distribute around the palladium particles strictly, which is the guarantee of high benzotriazole selectivity.