Adsorption Properties And Reaction Mechanism Of Yellow Phosphorus Off-gas Catalytic Oxidation

This thesis aim to research catalytic purification of yellow phosphorus off-gas.The emphases of article is on about adsorption performance of PH₃,H₂S and reaction mechanism of transition metal oxide catalyst and acid-base catalyst.Firstly,experiments were conducted to select carrier of catalyst and active component of catalyst;secondly, single factor adsorption experiments of two different catalyst and orthogonal testing of transition metal oxide catalyst were studied which was basic experiments; thirdly,adsorption isotherm of PH₃ and H₂S was used to acquire heat of adsorption;Fourthly, the adsorption samples of transition metal oxide catalyst was characterized by SEM,BET,XRD and XPS;the adsorption samples of acid-base catalyst was characterized by IR and calorimetry of alkali adsorption;finally,reaction mechanism of catalyst was inferred by basic experiments,heat of adsorption and characterization.This thesis also research the efficiency of catalyst regeneration and investigated practical purifying efficiency of catalyst in onsite experiments.The carrier of transition metal oxide catalyst and acid-base catalyst was ZP-3 virgin activated carbon and 13X zeolite respectively.Transition metal oxide catalyst was prepared by Cu(Ac)₂ impregnants and active component was CuO and Cu₂O.Acid-base catalyst was prepared by Cu(SO)₄ impregnants and active component was Brφnsted acid and Lewis acid on Cu(SO)₄ of dehydration.The optimum experiment parameters of single factor experiment for transition metal oxide adsorbed both PH₃ and H₂S were impregnant concentration 0.05mol/L,drying temperature 120℃,cremating temperature 250℃,reaction temperature 95℃,oxygen content 3%;The optimum experiment parameters of single factor experiment for acid-base catalyst adsorbed both PH₃ and H₂S were impregnant concentration 0.1mol/L,drying temperature 120℃,cremating temperature 300℃,oxygen content 1%;in the condition of anoxie,the optimum experiment parameters of reaction temperature was 20℃;in the condition of aerobic,the optimum experiment parameters of reaction temperature was 95℃.The adsorption isotherm of PH₃ and H₂S showed the adsorption performance of transition metal oxide catalyst,the adsorption on transition metal oxide catalyst were mostly chemisorption of decalescence.Heat of adsorption and adsorption process all showed chemisorption degree.Combining basic experiments,characterization of catalyst and heat of adsorption,the catalytic purification mechanism of transition metal oxide catalyst was inferred.Two-step regeneration method had better efficiency than four-step regeneration method and could avoided second pollution.In the condition of anoxic,heat of adsorption of acid catalyst illustrate that chemisorption was exothermic process and adsorption heat 71.23165kJ/mol,the lower the temperature was the higher rate of polymerization.In the condition of aerobic, chemisorption was decalescence and adsorption heat 105.20229KJ/mol,the higher the temperature was the higher removal efficiency.Characterization identified Brφnsted acid and Lewis acid,strength of catalytic activity and characteristic peaks of PH₃.Combining basic experiments,characterization,molecular structure and heat of adsorption,the reaction mechanism of acid catalyst was inferred.Regeneration method was effective for PH₃ and H₂S and regeneration method could avoid second pollution.Gas composition of yellow phosphorus off-gas was analysis and determination in Jianglin Corporation.Onsite experiments were conducted to investigate the practical purifying efficiency of catalyst on phosphorus off-gas.On same carrier,transition metal oxide catalyst had better purifying efficiency than acid catalyst.