Condensation Of Acetone To Isophorone On Mg/Al Composite Oxides Catalysts

As an important chemical intermediate, isophorone is widely used in chemical industry for producing polyurethane, medicine, pesticide and coating and so on. Besides, it can be used as a solvent to dissolve high polymer materials. In resent years, the environmental preparation of isophorone became more and more important along with the increading demands of isophorone and the progress of green chemistry.This paper is mainly consist of three parts. In the first part, magnesium-aluminum complex oxides were prepared under different conditions. The influences of precipitants, magnesium-aluminum mole ratio, doped metals and doped contents on the structure and properties of the materials were investigated by XRD, N2physical adsorption, IR, CO2-TPD techniques. The catalytic proformances were tested on a fixed bed reactor. The results showed that, when the precipitant was ammonium hydroxide, the mole ratio of Mg/Al was1.75, doped La contents was2%, the catalyst had the best catalytic performance. With a space velocity of1.6h-1under250℃, the acetone conversion, selectivity of isophorone and yield of isophorone reached41.3%,71.5%and28.5%respectively.In the second part, the KF solution modified catalysts were prepared under different conditions. The conditions including temperature, time, concentration of KF solution and solid-liquid ratio. The structure and properties of the modified materials were characterized by XRD, CO2-TPD, N2physical adsorption and SEM techniques. The catalytic proformances were also tested on a fixed bed reactor. It showed that the layered structure of hydrotalcite precursors had been recovered partially after modified by KF solution. The specific surface area of the modified materials increased slightly. When the temputer was40℃, the concentration of KF solution was0.3mol/L, solid-liquid ratio was6:100, impregnation time was3hours, the modified material performed good catalytic properties. The conversion of acetone reached27.6%, selectivity of isophorone reached80.1%, yield of isophorone reached23.0%with a space velocity of1.6h-1under250℃.In the third part, the hydrotalcite precursors were doped by glucose in the coprecipitation process. After the precursors calcined, a series of magnesium-aluminum complex oxides possessed large specific surface area were synthesized. The results showed that when the ratio between glucose and elemental metals was1, the specific surface area of the magnesium-aluminum complex oxides increased to283m2/g. The basicity of catalyst increased gradually with the increasing glucose contents. The catalytic performance showed that, the convertion of acetone, the selectivity and yield of isophorone were37.9%,66.4%and25.6%respectively.