Research On Catalytic Combustion Of Acrylonitrile Off-Gas Over Structured Catalyst

Acrylonitrile is an important chemical raw material, which can be produced during propylene ammoxidation process. However, the harmful gases, such as propylene, propane, carbonic oxide and trace acrylonitrile, can be emitted from the exhaust stream, giving a great threat to the environment, especially for acrylonitrile being lethal at ppm level in air. Nowadays, catalytic combustion technique has been widely used to purify the VOCs (Volatile Organic Compounds), wherein the Cu-ZSM5 constitutes one kind of highly efficient catalysts for above-mentioned exhaust gases catalytic purifications. Present work investigated three kinds of Cu-ZSM-5 monolith catalysts (particle, honeycomb and porous monolith) by employing both experimental (XRD, BET, SEM, H2-TPR, ultrasonic tests, and activity evaluations) and theoretical (CFD, Computational Fluid Dynamics) approaches, mainly focusing on the structure effect imposed on deVOCs reactivity, mass and heat transfer (fluid dynamics) by different configurations of monolith catalysts. The detailed simulation steps and acquired results were briefly stated below.1). Establishing CFD modelsThe three dimensional mathematic models with the same porosity and aperture were established for these monolith samples by FLUENT, wherein the fluid dynamics (mass and heat transfer) during acrylonitrile passing through the porous catalyst as well as the reactivities were compared with each other.2) Confirming the validity of the modelThis validity of the constructed models contains three steps:(i) the independence of the CFD network through mesh quality inspection; (ii) the reliability of the mathematic model can be achieved through the Greiz test of round tube; (iii) the applicability of hydraulic resistance models of different monolith models we verified through cold model experiments.3) Optimizing the CFD simulation parameters(i) Improving the physical parameters of fluids and solids in FLUENT based on experiments; (ii) constructing the kinetic model for C3H8 catalytic combustion by a custom program of C-language;4). Numerical simulationFirstly, we discuss the influence of catalyst structure characteristics of laboratory minitype fixed bed reactor on its response characteristics, hydromechanics and thermodynamics. Secondly, according to experiment condition of Jilin Petrifaction pilot plant test reactor, we discuss catalyst structure and sparger, analyze concentration, temperature and pressure in reactor, and study influence of catalyst structure and sparger on reactor. Finally, the layer distribution influence of Jilin Petrifaction reactor catalytic bed will be discussed.