| Chlorine is an important chemical raw material,mainly used in the chemical industry,electronics industry,pharmaceutical industry,sewage treatment,etc.In the industrial process of producing various chlorine-containing products,the utilization rate of chlorine is less than half,and hydrogen chloride is produced as a by-product.Chlorine production is mainly a method of electrolyzing saturated brine,which produces a large amount of caustic soda,which causes an imbalance in the production capacity of the chlor-alkali industry.If hydrogen chloride can be converted into chlorine gas and the closed loop of chlorine atoms can be realized,the above contradiction can be alleviated to a certain extent.Gas-phase hydrogen chloride catalytic oxidation to produce chlorine has become the most industrialized sustainable development approach due to its high conversion rate and low energy consumption.The catalyst is the core of the production of chlorine by catalytic oxidation,and its performance has a decisive influence on the industrialization of this technology.First of all,this article reviews and summarizes the current methods for preparing chlorine from hydrogen chloride,focusing on the development of catalysts and reactors in the catalytic oxidation method,and the current technological process.Secondly,a fluidized bed was determined as the catalyst evaluation reactor for this experiment,and a catalytic oxidation experimental device was built.The device is divided into five main parts:feed gas delivery system,preheating system,reaction system,reaction gas post-treatment system,and pipe road and circuit system.Secondly,based on the established evaluation device,a certain copper-based catalyst was characterized and evaluated.The morphology of the catalyst before and after use was compared and its catalytic mechanism was analyzed.The details are as follows:In order to understand the microstructure and performance changes of the catalyst before and after the reaction,a variety of experimental methods were used to characterize it.Scanning and transmission electron microscopy showed that the catalyst was solid spherical particles with a particle size of about 20μm.XRD（X-ray diffraction）shows that the catalyst carrier isγ-Al2O3,the active component is mainly Cu Cl2,and the active component coverage is relatively uniform,and the crystal form does not change much before and after use.The BET（specific surface area method）shows that the specific surface area is relatively large,and the specific surface area of the catalyst after use is slightly increased,indicating that there is a small amount of loss of catalyst active components.EDS（X-ray Energy Dispersive Spectroscopy）elemental analysis shows that Mg and K active additives are also added.In addition,the performance of the catalyst was evaluated,and the effects of reaction temperature,material ratio and reaction space velocity on its performance were mainly investigated.The results showed that by controlling the reaction temperature at 380°C～460°C,the conversion rate of hydrogen chloride first increased and then decreased as the temperature increased.When the temperature is low,the activity of the catalyst is low,and when the temperature is too high,the active components are easy to lose.When the molar ratio of oxygen to hydrogen chloride is between 0.75～1.73,gradually increase the amount of hydrogen chloride to reduce the molar ratio,and the conversion rate of hydrogen chloride will increase.Continue to increase the amount of hydrogen chloride.Excess hydrogen chloride will cause the catalyst to stick together and decrease the fluidity of the conversion rate.When the molar ratio is about 1:1,the conversion rate of hydrogen chloride is the highest.The reaction space velocity is controlled at 100h-1～220h-1,the space velocity of hydrogen chloride is large,the residence time is short,the reaction time is short,the conversion rate of hydrogen chloride is low,and the phenomenon of adhesion will also occur.The space velocity is reduced,the residence time of the reactants is long,so the reaction time is long,and the hydrogen chloride conversion rate is improved.Preliminary studies on the catalytic oxidation of hydrogen chloride show that the copper-based composite catalyst can run smoothly in a self-made fluidized bed reactor.At a temperature of 430℃～440℃,the molar ratio of oxygen to hydrogen chloride gas is about 1:1,and the reaction space velocity of hydrogen chloride is 160h-1,the conversion rate of hydrogen chloride is more than 85%,and it can run continuously for more than 300h.In this paper,the structure,performance and reaction behavior of the catalyst were studied by related characterization methods,and the catalyst evaluation experiment was carried out in a fluidized bed reactor.It is verified that the catalyst has catalytic oxidation activity,can be selectively applied to the catalytic oxidation process of hydrogen chloride,and provides reference value for actual industrial applications. |
