Study On Vapor-phase Condensation Of Acetone To Isophorone On Cma Solid Base Catalysts

Isophorone is one of three molecular acetone derivatives and has an extensive use. It is commonly used as a quality solvent of resin, coating and other polymer materials. And it is also an important raw material and intermediates of fine chemicals, widely used in resins, polyurethane, coating, medicine, pesticide industries. In recent years, along with the development of green chemistry, the green process route of vapour phase acetone condensation to isophorone is more and more payed attention.In this thesis, a series of Ca-doped hydrotalcites (p-CMA) were prepared by co-precipitation method. After calcined at certain tempereture in air atmosphere, corresponding complex oxides (CMA) were obtained. The characterization of p-CMA and CMA composite oxides were carried out by means of XRD, FT-IR, N2-absorption/desorption and CO2-in-situ IR. Meanwhile, the catalytic activity, selectivity and stability of the CMA samples were evaluated for gas-phase condensation of acetone to isophorone on a fixed-bed reactor.The results show that p-CMA prepared by co-precipitation method under different conditions all have the layered structures, and the CMA composite oxides mainly have two different basic sites according to CO2-in-situ IR,70～200℃weak ones and200℃～500℃moderate ones. CMA samples showed high activity and selectivity. The optimized CMA sample was prepared by the precursor with MgCaAl molar ratio of24:1:20crystallized for12h and calcined under500℃. When the reaction carried out at250℃with space velocity of1.08h-1, the conversion of acetone reached56.13%, the selectivity and yield of IP achieved62.89%and35.30%. Total selectivity of IP and MO was72.81%. In addition, the existence of acid and basic centers on the surface of CMA complex oxides are favorable for the synthesis of IP and it has a relatively good stability. The performance of regeneraged catalyst calcined at500℃for4h can recover more than80%compared with the new.