Influence of [La(EDTA)]− on pore structure of activated alumina carrier at high-temperature

The activated alumina as a catalyst carrier were widely used in automotive exhaust catalysts under high temperature, such as, petroleum refining catalysts, hydrogenation and hydrodesulfurization catalyst carrier in China and abroad. γ-Al2O3 was the catalyst carrier that was the most widely used and the best carrier of improved specific surface area . However, the activation of the coating consisted of γ-Al2O3 were usually transformed into α-Al2O3 at 800 °C, causing increased density, reduced specific surface area, and the collapse result of pore structure. While the temperature reached 1200 °C, activation of coating detached from the carrier, the resistance of flowing gas increased, catalytic activity decreased. Addition of La2O3 stabilized the γ-Al2O3 crystal structure, which would keep the activation stability of coating at a high temperature and inhibit activity loss. The activated alumina carrier treated with the solid-pore-expanding agent containing [La(EDTA)]− that synthesized using solid and solid-hybrid approach with the thermal stabilizer lanthana and EDTA at the high-temperature had a 10-30 μm large pore porous network-like structure, after alumina was calcined at 1200 °C for 1 h. The specific surface area of four specimen were beyond 120 m2/g, while the sample specific surface area of x([La(EDTA)]−)=1% was up to 150.36 m2/g.