选择性加氢催化剂载体氧化铝的热稳定性研究

Study on thermal stability of alumina for selective hydrogenation catalysts

采用CO2气体成胶法制备出氧化铝载体,研究了磷、硅改性对载体的晶型、比表面积、孔结构、压碎强度等的影响。结果表明,所制备拟薄水铝石较纯净,不存在其他杂晶型;改性剂的添加有效改善了γ(δ,θ,α)-Al2O3等几种晶型的转变温度,且加入改性剂的载体在1 250℃焙烧后仍存在θ(α,δ)-Al2O3多种晶型;随焙烧温度的升高,载体比表面积、孔容逐渐减小,平均孔径逐渐增大,磷改性载体即使在1 250℃高温焙烧,比表面积和孔容仍可分别保持在27.46 m2/g,0.31 cm3/g;随焙烧温度的升高,载体的堆密度先减小后增大,压碎强度则呈上升趋势,磷的添加对载体的堆密度和强度无明显影响。

Alumina（ Al2O3 ） carrier were prepared by the carbon dioxide gelling process. The influences of phosphorus or/and silicon modification on crystalline form, specific surface area, pore structure and crushing strength of the carrier were studied. The results showed that the prepared pseudo - boehmite was pure. The transition temperature of γ （δ,θ, α） - Al2O3 could be improved effectively by adding modifiers, and there still existed crystalline forms of θ（ α, δ） - Al2O3 in the carrier after calcined at 1 250 ℃. With increasing calcination temperature, the specific surface area and pore volume of the carrier decreased, the average aperture gradually augmented.The surface area and pore volume of phosphorus modified carrier could be kept at 27.46 m2/g and 0.31 cm3/g respectively even if it was calcinated at 1 250 ℃. With increasing the calcination temperature, the bulk density of the carrier decreased first and then increased, and the crushing strength increased too. No significant effect of phosphorus was observed on the bulk density and crushing strength of the carriers.