Preparation Of RuO₂/SnO₂ And Its Aoolication In The Catalysic Oxidation Of HCl To Cl₂

Chlorine is a very important chemical raw material,and its widespread use is accompanied by the production of a large amount of hydrogen chloride,which is of low purity and oversupply.Its digestion and utilization have become a common problem restricting the development of chlorine-related industries such as chlor-alkali,polyurethane,fluorine/chlorine chemical industry and so on.The catalytic oxidation of hydrogen chloride is an effective method to realize the recycling of chlorine resources.Ruthenium-based catalysts show excellent activity in the catalytic oxidation of hydrogen chloride.However,it is necessary to maintain excellent activity at a high oxygen feed ratio n?HCl/O₂??1:2,which greatly limits the popularization and application of this process.In this paper,SnO₂,with different morphology and crystal planes were prepared by hydrothermal synthesis,and then RuO₂/SnO₂ catalysts were synthesized by using them as supports.Hydrogen chloride oxidation activity of SnO₂carrier morphology effect at low oxygen partial pressure,that is,feed ratio n?HCl/O₂?=4:1 was investigated.The main research contents are as follows:1)The RuO₂/SnO₂ catalyst was prepared by equal volume impregnation method,and its catalytic activity was investigated at different reaction temperature?250-390 ^oC?, mass space velocity(4-35 h^-1)and feed ratio?n?HCl/O₂?=1:1-4:1?.The general rule under the influence of various reaction factors was obtained,and the factors affecting the catalytic activity of RuO₂/SnO₂ were determined.2)2.SnO₂ supports with different morphology and crystal planes were prepared by hydrothermal synthesis,and then RuO₂/SnO₂ catalysts were synthesized by impregnation in the same volume.The catalysts were characterized by X-ray powder diffraction,scanning electron microscope,N₂-adsorption and desorption, hydrogen temperature programmed reduction,UV Raman spectroscopy,X-ray photoelectron spectroscopy and so on.The results show that under the action of morphology inducers such as polyvinylpyrrolidone?PVP K30?and polyethylene glycol 400?PEG 400?,the branch angle length and crystal plane distribution of the synthesized SnO₂ carrier can be effectively adjusted by changing the pH of the hydrothermal synthesis solution,and finally three different branch corner lengths ?0 nm,300-500 nm,1-1.2?m?and four different crystal planes?octahedron,long dodecahedron,rhombohedral dodecahedron,slender dodecahedron?rutile phase SnO₂,was then impregnated with it as carrier to synthesize RuO₂/SnO₂ catalyst.3)The catalytic performance of the prepared RuO₂/SnO₂ catalysts for HCl oxidation was investigated under low oxygen partial pressure.The results show that for SnO₂ carriers with different morphology,with the increase of SnO₂ branch angle length, the conversion of HCl and the space-time yield of Cl₂ also increased.When the branch angle length was 1-1.2?m,the conversion of HCl and the space-time yield of Cl₂ were 36.2%and 27.8 g_Cl2h^-1g^-1_cat,respectively.For SnO₂ carriers with different crystal planes,the catalytic activity of RuO₂/SnO₂ increases with the increase of the proportion of crystal planes.When using the elongated twelve-sided SnO₂ with 82%?110?crystal plane ratio as the carrier,the highest conversion of HCl can reach 53.1%and the space-time yield of Cl₂ can reach 49.2 g_Cl2h^-1g^-1_cat, which is the highest space-time yield of Cl₂ reported under the same conditions.