Effect of calcination temperature on surface properties and catalytic performance in dehydration ethanol to ethylene of La-modified HZSM-5

A series of La/HZSM-5 catalysts were prepared by impregnating the HZSM-5 zeolite with lanthanum nitrate solution. The effect of calcination temperature between 450 and 600°C was investigated on the surface properties and catalytic performance in dehydration of ethanol to ethylene of these catalysts. According to XRD and N₂ adsorption-desorption measurements, it was shown that calcination temperature had little influence on crystal structure, specific surface area and pore volume of La/HZSM-5. While NH₃-TPD results indicated that the surface acid quantities and strength of La/HZSM-5 were significantly decreased as calcination temperature rose and their catalytic performance and lifetime also reduced. It might be attributed to different existence of La species under different calcination temperatures. The optimized catalyst was 3% La/HZSM-5 calcined at 450°C, whose single pass lifetime could reach 108 d at its optimal reaction conditions.