Catalyst Development for HCl Oxidation to Cl₂ in the Fluorochemical Industry

Abstract

The catalytic oxidation of gaseous HCl (containing a small amount of HF) to Cl 2 is important and highly desired for chlorine recycling in the fluorochemical industry. In the present work, a series of Al-doped MgF 2 (Al− MgF 2 ) materials were synthesized via a sol−gel method, followed by calcination at different temperatures and then these synthesized Al−MgF 2 materials were used as supports to prepare RuO 2 /Al−MgF 2 catalysts by an incipient impregnation method. These developed catalysts were evaluated in the oxidation of HCl with an upper-bound HF concentration of 400 ppm, as is common in the fluorochemical industry. Specific attention was paid to investigating the effects of calcination temperature for preparing Al−MgF 2 supports on the activity and stability of the resultant catalysts. It is found that at an optimal calcination temperature, Al can be incorporated into the framework of rutile structure MgF 2 , which can further modify the cell parameters of MgF 2 close to those of RuO 2 , modulate the interactions between RuO 2 and the support, and yet affect the chemical environment of RuO 2 to enhance the catalytic activity and stability. The study on the catalytic kinetics reveals that the estimated apparent activation energy is in line with the incorporated amount of Al into the framework of MgF 2 and shows an inverted volcano relationship with the calcination temperature for preparing Al−MgF 2 supports. The lowest apparent activation energy of RuO 2 /Al−MgF 2 can be achieved when the Al−MgF 2 composite is calcined at 400 °C, and the resultant catalyst shows long-term stability with high activity for the oxidation of HCl containing a small amount of HF.

Selective Ru Adsorption on SnO2/CeO2 Mixed Oxides for Efficient Destruction of Multicomponent Volatile Organic Compounds: From Laboratory to Practical Possibility

“…As shown in Figure , both the Ru-decorated samples under pH = 8 and pH = 5.8 exhibited corresponding lattice spacings of 0.313 nm for the (111) plane of CeO 2 nanorods and 0.265 nm for the (101) plane of cassiterite SnO 2 . The Ru/SnCe-(5.8) was shown with significant fine Ru species on the SnO 2 surface (Figure b), with an epitaxial growth of the RuO 2 film on top of SnO 2 originating from their lattice matching (Figure c,d) . In comparison, the Ru/SnCe-(8.0) sample revealed distinct RuO x particles, with the corresponding lattice spacing of 0.320 nm for the (110) plane on CeO 2 nanorods (Figure e,f).…”

“…1b), with an epitaxial growth of the RuO 2 film on top of SnO 2 originating from their lattice matching (Figure 1c,d). 31 In comparison, the Ru/SnCe-(8.0) sample revealed distinct RuO x particles, with the corresponding lattice spacing of 0.320 nm for the (110) plane on CeO 2 nanorods (Figure 1e,f). We assumed that the film form of RuO 2 on SnO 2 could induce superior Ru surficial dispersion on the oxide supports.…”

Insight into the effects of calcination temperature on the structure and performance of RuO2/TiO2 in the Deacon process

“…The H 2 -TPR profile was then recorded from 50 to 800 °C at a heating rate of 10 °C min −1 in 5 vol% H 2 in Ar with a total flow rate of 30 mL min −1 . The adsorption-microcalorimetry measurements on the pulse adsorption of O 2 on the RuO 2 /TiO 2 catalysts at 350 °C were performed using a house-made set-up consisting of an adsorption apparatus (Micromeritics AutoChem II 2920), a microcalorimeter (Setaram Sensys EVO 600), and a mass spectrometer (MS, Hiden HPR-20), 37 similar to those reported in the literature. 38,39 Typically, the sample cell of the microcalorimeter was loaded with 50 mg of the catalyst and then the catalyst was activated in a flowing feed of HCl + O 2 (50 vol% HCl and 50 vol% O 2 ) with a total rate of 80 mL min −1 at 350 °C for 2 h. Afterwards the catalyst was purged with He (40 mL min −1 ) at 350 °C for 45 min.…”

“…[29][30][31][32][33] Very recently, an empirical intrinsic kinetic model, assuming the dissociative adsorption of O 2 as the rate-determining step, has been established, and the model describes the experimental data very well. 37 Here, the adsorption of O 2 on RuO 2 /TiO 2 catalysts at 350 °C was then conducted by the adsorption-microcalorimetry technique. As shown in Fig.…”

Integrated pH Sensors Based on RuO2/GO Nanocomposites Fabricated Using the Aerosol Jet Printing Method

“…RuO 2 has gained considerable attention for numerous electrochemical applications due to its capability of driving reversible multielectron transfer redox reactions, − high electrocatalytic activity, and affinity for hydrogen . RuO 2 -based materials have been used as electrode materials for supercapacitors, active components for chlorine generation from HCl, and as a catalyst for different reductions. , Exploiting the intrinsic properties of RuO 2 , we might consider some other potential applications in Li-ion batteries, aerobic oxidation of alcohols, and sensing materials in chemical sensors. − Previously, we demonstrated that the reversible redox reactions between RuO 2 and hydronium ions (H 3 O + ) could be used for highly sensitive pH monitoring, as pH is at the center of a wide range of health monitoring fields, including pharmaceuticals, food processing, environmental science, and biomedical applications. , …”