Acidic Montmorillonite/Cordierite Monolithic Catalysts For Cleavage Of Cumene Hydroperoxide

Both phenol and acetone are important chemicals in the organic chemical industry, which are widely used in the chemical industry. The cumene peroxidation method for the preparation of phenol and acetone is the most important technology in the current world, in which cumene hydroperoxide (CHP) cleavage as the final step of the method has a direct influence on product yield. The commercial acid catalyst most commonly used for CHP cleavage is concentrated sulfuric acid, however, the concentrated sulfuric acid shows intrinsic disadvantages. Solid acid catalysts were extensively studied due to the possibility to avoid the disadvantages of the traditional industrial production process, but only a small number of acidic resin used in domestic industrial production. However, the fragmentation, instability, easy erosion and nonuniform distribution of acidic center are the main disadvantages for these solid acid catalysts, which restrict their wide industrial application. Therefore, it is necessary to develop new and appropriate acidic catalysts to replace solid acid catalysts. In recent years, the monolithic catalyst as a novel kind of catalyst with the internal structure of a regular honeycomb structure exhibits some advantages compared with the conventional particulate catalyst, e.g., low pressure drop, high effectiveness factor, minimum axial dispersion stemming from the uniquely structured multichannel configuration, high catalyst utilization efficiency and good heat and mass transfer performances. This paper studied the acidic montmorillonite/cordierite monolithic catalysts for CHP cleavage reaction using methods of experiments and CFD simulations combination, and the affecting factors of preparation of monolithic catalysts and reaction processes were investigated and optimized. Specific contents are as follows:Firstly, the cordierite samples were pretreated and the montmorillonite powder was activated, then the acidic montmorillonite, silica sol, and deionized water were mixed together at a certain proportion, The one-step coating method was used to prepare a series of acidic montmorillonite/cordierite monolithic catalysts, and then the samples were characterized by X-ray diffraction (XRD), N2adsorption/desorption (BET), scanning electron microscope (SEM), and temperature programmed desorption (NH3-TPD) to characterize the morphology and structure of catalysts. The results showed that under the condition of about acidic montmorillonite content20wt%, calcination temperature550℃, and the coating time5min the acidic montmorillonite/cordierite monolithic catalysts are uniform, highly dispersed, and fewer cracks. Secondly, the catalytic activity of monolithic catalysts and solid acid catalyst (acid resins) were measured using a conventional fixed-bed reactor apparatus. It was found that the conversion of CHP increased substantially with increasing reaction temperature for both monolithic catalysts and acid resins, but the selectivity of phenol shows an inverse trend. However, phenol selectivity using monolithic catalysts is higher than that using acid resins. In addition, the influences of acidic montmorillonite loading, reaction temperature, CHP concentration, and WHSV of CHP on the conversion of CHP and selectivity of phenol were studied, respectively. Finally the optimum operation conditions were obtained, which were acidic montmorillonite loading32.5wt%, the reaction temperature is80℃, a mass ratio of CHP to acetone1:3, WHSV90h-1, CHP conversion rate reached100%, the selectivity to phenol of99.8%.Finally, a reliable and effective three-dimensional (3D) mathematical model was established to identify the geometric configutation performance relation and the characteristics of heat and mass transfer about CHP cleavage process using monolithic catalysts. Furthermore, the different operating parameters (reaction temperature, CHP concentration and inlet velocity) and geometry parameters (coating thickness and pore diameter) were investigated for CHP conversion, which resulted in the reaction and structure performance was optimized.