Multiphase Catalytic Oxidize The Off-gas Of Using Phosphorus Sludge To Produce Sodium Hypophosphite

Phosphorus chemical industry takes a very important station in Yunnan province's economy. In yellow phosphorus producing industry, phosphorus sludge which is harmful but containing phosphorus is generated. Using phosphorus sludge react with alkali solution to get sodium hypophosphite is an effective method. Sodium hypophosphite is strong reducing agent and with high economic value, widely used in chemical plating, food processing and other industries. However, about 20% phosphorus in the phosphorus sludge translates into phosphine by using this treatment, it will cause air pollution.In this thesis, the high concentration of phosphine which let by using phosphorus sludge to produce sodium hypophosphite is the object of study. Designed multiphase catalytic oxidation method to deal with this gas. Used hydrogen peroxide as absorbent material; catalyst prepared by using dipping calcination method, joined into the solution as solidstate, accordingly not into other impurities. Under the condition of alkaline and free sodium ions exist in solution, sodium hypophosphite and sodium phosphite are generated by using hydrogen peroxide oxidize phosphine; the recovery efficiency of the phosphorus in the phosphorus sludge will be enhanced.Focuse on the capability and the mechanism of the one-component catalyst and two-component catalyst multiphase catalytic oxidize the high concentrations of phosphine which let by using phosphorus sludge to produce sodium hypophosphite. The carrier of the catalyst is sifted; the the active component of the one-component and two-component catalyst is identified; the single factor experiment of the multiphase catalytic oxidation is done; the capability of catalyst is studied; the stability of the catalyst is reviewed by doing the reusing experiment; the catalyst characterized by SEM and XPS; the mechanism of the catalysis is studied through basic experimental data and characterization results. The results of the experimental and characterization shows the reasons for the catalyst deactivation, and regeneration of the catalyst was investigated.The carrier of the one-component catalyst is 4A zeolite; the impregnant is Ce(NO3)3. The best single factor experiment conditions in catalyst preparation:the pH of the impregnant 7; the impregnant concentration 0.1mol/L; the calcination temperature 500℃. The best condition in the reaction:carrier gas flow rate 20mL/min; pH of reacting solution 13; reacting temperature 20℃; volume fraction of hydrogen peroxide 6%; the amount of catalyst 5g/L. Reuse the catalyst 3 times, the production approach 4A zeolite as catalyst.The carrier of the two-component catalyst is 4A zeolite; the impregnant are Ce(NO3)3 and Fe(NO)3; the active component Ce:Fe is 1:1. The best reaction conditions of multiphase catalytic oxidation:pH of reacting solution 13; volume fraction of hydrogen peroxide 6%; the amount of catalyst 2.5g/L. Reuse the catalyst 5 times, the production approach 4A zeolite as catalyst.One-component catalyst and two-component catalyst are characterized by SEM and XPS. After using SEM, the catalyst's surface characterization changes before and after used is got, and compared with the 4A zeolite; through XPS, the tyes and contents of active comonent are reviewed, and by comparing the active component in the catalyst surface changes before and after reaction to determine the type of catalyst is the transition metal oxides redox catalyst, and ulteriorly determined the mechanism of multiphase catalytic oxidation. Through the characterization, the reason of the catalyst lose active is got, which is the active component dissolved in the hydrogen peroxide solution. The regeneration of the catalyst is studied, shows the catalyst can be effectively regenerated.