Reaction Kinetics Study Of Hydrogen Chloride Catalytic Oxidation

HCl catalytic oxidation is the important process of Cl2 recycling,and it has turned into a current research hotspot of chemical engineering.In order to realize Cl2 efficient recycle and industrial reactor optimization,reaction kinetics of HCl catalytic oxidation over Cu-based composite catalyst was studied.First,reactor reliability was evaluated.In the non-gradient reactor,external diffusion can be eliminated while HCl conversion can reach only 50%.In the fixed-bed reactor external diffusion can’t be eliminated while HCl conversion can reach 90%.Device combined with non-gradient reactor and fixed-bed reactor is suitable for reaction kinetics study.Because external diffusion can be eliminated and HCl conversion can reach 1%～90%,reaction can reach stable in a short time and experimental data has good repeatability.Next,influence of T=360～400℃,nHCl/nO2=1～4,FHCl0/W=0.01～60h-1 on HCl conversion and reaction rate was studied.Before chemical equilibrium,HCl conversion and reaction rate increase with the increase of T,or the decrease of nHCl/nO2;With the decrease of FHCl0/W,HCl conversion increases while HCl reaction rate decreases.After chemical equilibrium,HCl conversion decreases with the increase of T and nHCl/nO2,or the decrease of FHCl0/W.Then,kinetics models were proposed by assuming HCl adsorption,O2 adsorption,surface reaction,and Cl2 desorption as rate-controlling steps,respectively.By NLS method parameters fit and statistical test,the kinetics model assuming O2 adsorption as rate-controlling step can suitably describe the reaction behaviour of HCl catalytic oxidation over Cu-based composite catalyst and the kinetics model is established as follow:Finally,concentration distribution,temperature distribution and thermal stability of tubular fixed-bed reactor were analyzed.At point A,reaction temperature can keep in 369～387℃ when Ts=355～360℃&do=0.025～0.032m.At point B,reaction temperature can keep in 365～410℃ when(Ts)min=341～381℃&△Tmax=24～29℃&(do)max=0.015～0.079m.HCl conversion increases along axial distance and the maximum xHCl=69%.Temperature first increases and then decreases along axial distance and hot spot T=664K appears at Z=1.1m.