Reaction Kinetics of HCl Catalytic Oxidation over a Supported Cu-Based Composite Industrial Catalyst

Abstract

The chlorine from HCl can be recycled by catalytic oxidation during the industrial process, but excessive heat will be produced during the HCl catalytic oxidation, which leads to catalyst deactivation. Thus, a study of the reaction kinetics of HCl catalytic oxidation over a Cu-based composite catalyst is necessary. The influence of T values of 360−400 °C, n HCl /n O 2 values of 1−4, and F HCl0 /W values of 0.01−60 h −1 on HCl conversion and reaction rate was studied, and a kinetic model was established by a MATLAB parameter fit and a statistical test. Results show that, before chemical equilibrium, HCl conversion and reaction rate increase with an increase in T or a decrease in n HCl /n O 2 . With a decrease in F HCl0 /W, HCl conversion increases while the HCl reaction rate decreases. After chemical equilibrium, HCl conversion decreases with an increase in T and n HCl /n O 2 or a decrease in F HCl0 /W. The kinetic model that assumes O 2 adsorption is the rate-controlling step can suitably describe the reaction behavior of HCl catalytic oxidation over a Cu-based composite catalyst.

Understanding the Catalytic Oxidation of Hydrogen Chloride to Chlorine from Thermodynamics and Reaction Kinetics

“…The HCl catalytic oxidation is a heterogeneous catalytic reaction in which reactants HCl and O 2 molecules are adsorbed on the surface of the catalyst, and related studies on its reaction mechanism are relatively mature. ,, In this work, a kinetic model was established based on the Langmuir–Hinshelwood mechanism, and the surface reaction is adopted as the rate control step. ,, The elementary reaction steps for HCl catalytic oxidation are formulated as follows And the corresponding reaction rate equations can be derived where * refers to the active site on the catalyst; HCl*, O*, Cl*, and H 2 O* are the adsorption sites of HCl, O 2 , Cl 2 , and H 2 O on the catalyst, respectively; and θ A , θ B , θ C , and θ D are the coverage fraction of the active sites of HCl, O 2 , Cl 2 , and H 2 O on the catalyst, respectively. It is assumed that all catalyst surfaces are monolayer adsorption, each active adsorption site is evenly distributed, and the adsorbed gas molecules are independent of each other …”

“…On the other hand, the large heat effect has strict requirements on the performance of the reactor. A few works focused on improving the performance of the HCl catalytic oxidation process from this perspective, which is the essence of the whole problem. , Therefore, it is necessary to analyze and investigate the thermodynamics and kinetics of the catalytic oxidation of HCl. Herbert Over calculated the HCl equilibrium conversion in the Deacon process as a function of temperature, which is parametrically dependent on the stoichiometric ratio of the reaction feed and the total pressure.…”

The Influence of Copper on Halogenation/Dehalogenation Reactions of Aromatic Compounds and Its Role in the Destruction of Polyhalogenated Aromatic Contaminants

“…The so-called Deacon process, Cu-based oxidation of waste HCl with O2 is one of the intensively studied techniques enabling reuse of chlorine spent during chlorination processes from HCl by-product (Scheme 1) [23][24][25]. Scheme 1.…”

“…The Cu-based recycling of chlorine from waste HCl significantly increases Cl atom efficiency of SEAr chlorination process and is an important part of chlorination technologies [25]. The other disadvantage of SEAr-based synthetic strategies is the low regioselectivity of this halogenation and problems with the formation of more halogenated products (Scheme 2).…”

Can Gold be an Effective Catalyst for the Deacon Reaction?

“…Samples for titration were taken every 20 min and the reaction was continued for 4 h. Reactions in the absence of catalyst showed no conversion and a standard 7 wt% Ru/TiO 2 catalyst under these reaction conditions gave a steady state HCl conversion of 40% which under these reaction conditions is well below the equilibrium level of ca. 83% [18]. For reactions where H 2 was included 0.25% H 2 was added to the reaction gases.…”