Molding And Application Of Honeycomb Shaped Monolithic Fe-β Zeolite Catalyst

Honeycomb shaped monolithic Fe-β zeolite catalyst for N2O decomposition prepared by direct extrusion method was investigated. In this paper, we optimized the parameters of the molding process and studied the influence degree of the content of HNO3, SB powder and water in plasticity and mechanical strength of monolithic honeycomb zeolite catalysts. The optimum molding conditions was determined and the catalysts were used for the catalytic N2O decomposition. Construct a three dimensional integral mathematical model of honeycomb shaped monolithic Fe-β zeolite catalyst and reactor, use Fluent software to simulate the reaction process.First of all, the influences of the HNO3, SB powder and water content on the plasticity and mechanical strength were investigated by the method of single factor experiment. Suitable molding material proportion is the key to guarantee the extruded honeycomb monolithic catalysts have good rheological properties. Monolithic materials could be extruded successfully only with the plasticity ranging from0.177to0.473. With increasing content of nitrate and water, the mechanical strength increases to the maximum and then decreases. Although the increasing content of SB powder can make the mechanical strength increase, too much SB powder may cause zeolitic monolith too dry to be extruded.Secondly, the influences of the HNO3, SB powder and water content on the plasticity and mechanical strength were investigated by the orthogonal experimental method. When preferred catalyst mechanical strength, the optimal synthetic conditions for honeycomb shaped monolithic Fe-β zeolite catalyst is60%zeolite powder,40%SB powder,8%nitrate and60%water (mass ratio of raw materials and dry powder).Thirdly, the influences of the space velocity, catalyst aperture and laughing gas concentration on the plasticity and mechanical strength were investigated by the method of single factor experiment. For the same aperture of monolithic catalyst, with the increasing of reaction speed, the reaction conversion rate at the same temperature gradually decreases; For the same aperture of monolithic catalyst, under the same reaction space velocity and temperature, with the increase of N2O concentration, reaction conversion rate is on the rise; Under the same reaction airspeed, laughing gas concentration and reaction temperature, with the increase of catalyst pore diameter, the reaction conversion rate is on the decline.Finally, by using Fluent software, the fluid dynamics and heat transfer characteristics of monolithic catalyst with different aperture were simulated, the flow field and temperature field were calculated which, were compared with rod catalyst performance of fixed bed. With the catalyst pore size decreases, the N2O conversion rises in the same temperature, the temperature at which the N2O completely transformed gradually reduced. In terms of the pressure drop, the rod catalyst performed two orders of magnitude higher than that of monolithic catalyst. Temperature distribution in the monolithic catalyst is rising gradually, in the rod catalyst is rising sharply.