Cobalt-Based Catalysts For Catalytically Removing Hydrogen From Tail Chlorine

The chlor-alkali industry plays an important role in the national economy and its products and related products are spread all over our lives.The treatment of liquid chlorine tail gas is still a problem that troubles practitioner in the production of chlor-alkali industry.The liquid chlorine tail gas is a byproduct of chlorine liquefaction in the chlor-alkali industry and it is made up of chlorine,nitrogen,oxygen and hydrogen.It is hard to further compress liquefaction or applied to other chlorine consumption product due to the uncontrollable of hydrogen explosion.With the development of chlor-alkali industry,the reasonable treat of liquid chlorine tail gas has become an urgent problem to solve.Therefore,the study of effectively remove the hydrogen from chlorine gas has attracted the widespread attention of researchers.The reaction gas in this experiment was prepared by the same composition with industrial tail chlorine which contains Cl₂?65%⁸0%?,O₂?8%¹0%?,N₂?6%¹6%?and H₂?1.5%⁴%?.In this experiment,Cobalt,Co₃O₄,Co₃O₄/Al₂O₃and Co₃O₄/ZSM-5 were used as catalysts to catalyze the removal of hydrogen from tail chlorine in a fixed bed reactor.The conclusions of this experiment are as follows:1.Within the scope of the study,the cobalt powder?100-120 mesh?had the best catalytic performance in the reaction of removing hydrogen from tail chlorine at 150°C,and the average hydrogen conversion rate was 95.09%within 120minutes.The optimal temperature for Co₃O₄ as the catalyst to catalyze removing hydrogen from the tail chlorine was 130°C,and the average hydrogen conversion rate was 99.61%within 120 minutes.2.Within the scope of the study,the Co₃O₄/Al₂O₃ which calcinated under450°C has the average conversion rate of hydrogen was 98.81%in 120 minutes when the reaction temperature was 110°C with the loading amount of 1%wt.The conversion rate of hydrogen was 75.18%after 540 minutes of reaction,the catalyst was still activated.3.Within the scope of the experiment,the Co₃O₄/ZSM-5 which calcinated under 300°C has an optimum average conversion rate of hydrogen in 120 minutes was 99.59%when the reaction temperature was at 50°C with the loading amount of 1%wt.And the conversion rate of hydrogen was 87.48%after 540 minutes of reaction,the catalyst was still activated.4.In the above experiments,the selectivity of hydrogen chloride reaction was higher than that of hydrogen and oxygen.Therefore,when cobalt and Co₃O₄were used as active components,hydrogen tend to react with chlorine.After comparing the experimental results,we can conclude that the supported catalyst can appropriately reduce the temperature of the catalytic reaction and the ZSM-5with larger surface area has better catalytic effect and stability.5.According to the XRD characterization analysis,the cobalt catalyst formed cobalt chloride after the reaction,which is consistent with the reduced of catalytic activity.According to the XRD characterization analysis of Co₃O₄ catalyst,a small amount of catalyst was converted into cobalt chloride,which is consistent with the experimental results that the catalytic stability of Co₃O₄ catalyst is slightly higher than that of the cobalt catalyst.The XRD characterization of Co₃O₄/Al₂O₃ and Co₃O₄/ZSM-5 catalysts showed that the catalytic active component was Co₃O₄ in the catalysts,and the diffraction peaks of the catalysts did not change significantly before and after the reaction,which indicate that the catalytic process had not influence the crystal structure of the catalysts;the SEM image and the N₂ adsorption-desorption characterization denotes that the pore size of the catalyst is significantly increased after the reaction,indicating that the chlorine gas had corroded the catalysts during the catalytic reaction,which is consistent with the experimental results of the reduced catalytic activity.