Exhaust Gas Purifying Yellow Phosphorus Catalytic Paritial Shift Process Of Synthesis Gas

Highly purified yellow phosphorus exhaust is excellent good source of Cl gas. Based on the high volume fraction of CO (>85%) and the technology of CO catalytic hydrogenation, the yellow phosphorus exhaust would be developed to directly produce methanol synthesis gas with appropriate ratio of H2/CO. It helps reduce air pollution and reuse resources. In order to prepare the synthesis gas for methanol from purified yellow phosphorus exhaust by water gas shift reaction based on previous work. The activity influencing factors including process conditions, intrinsic kinetics and catalyst poisoning of PH3 of B112 industrial catalyst were further studied under the condition that the purified yellow phosphorus exhaust is the material gas. The main conclusions are as follows:(1) Accoding to literature review we selected the catalytic activity factors: temperature, steam to gas ratio and space velocity as the object of study; used single-factor experimentwithtemperature 350～530℃, steam to gas ratio from 0.6 to 3.3 and space velocity 1000～3100 h-1 respectively to investigate the patterns of CO conversion rate. Obtained in high concentrations of CO shift reaction process of reaction rate due to the occurrence of side effects and there is an optimum temperature;due to water vapor will cause a temporary deactivation of the catalyst reasons there is an optimum steam-gas ratio; in changing technological conditions in, space velocity the smaller the reactants in the reactor where the longer the stay, the more favorable reaction to the full. Deactivation of the catalyst before and after the SEM, XPS and XRD characterization analysis resulted in a normal catalyst deactivation by carbon deposition on the catalyst active sites.(2) Study on highly concentrated CO tail gas of purification yellow phosphorus transformation process conditions with B112-type high-temperature shift catalyst based on test results of influnce factors. The results showed that affect its transformation efficiency of the factors in decreasing order as follows:reaction temperature, space velocity, steam to gas ratio, CO2 concentration. The uniform design was applied to optimize reaction conditions, and a regression equation was established to describe the influences of reaction temperature, space velocity, steam to gas ratio, and CO2 content on CO transformation efficiency. The calculation results of the regression equation agree well with the experimental data. Through optimized model and experimental verification, combined with industrial practices, the optimal process conditions for CO transformation efficiency is 88.9 % at 490℃, space velocity 1000h-l,steam to gas ratio and 1% CO2 content by uniform design. It maintains high catalytic activity and logevity requirements, based on which the changing rate can be accurately adjusted.(3)Under the atmospheric pressure, the temperature at (350～450℃), and the inlet gas fractions as CO 0.75～0.95, CO2 0.01～0.10, H2 0.01～0.08.The rest being N2, this research focuses on the intrinsic kinetics features of high concentration CO shift catalyst with the quartz glass tube reactor. By the use of objective function estimated value method, it nonlinear parameter estimated values the experimental data, and the power function model high concentration CO shift catalyst atmospheric pressure intrinsic kinetics is established. Results from parameter estimation showed high confidence level of the kinetic equations.(4)Using thermodynamics software HSC Chemistry 5.0 and its Database Software, based on the principle of Gibbs free energy minimum, we inferred theoretically that the compounds, spontaneity and reaction competitive force may produced during the poisoning process of the active constituent Fe3O4 of high concentration CO shift catalyst in PH3.It is observed that the generated pyrophosphate and carbon deposition will cover the outside of catalyst,so that it will bring about the reversible poisoning of catalyst because the phosphorus and iron compound made the active centers of the catalyst occupied, the structure was irreversibly destroyed poisoning.(5) The poison resistance experiment for high concentration CO shift catalyst in the concentration of PH3 5.12～955.41 mg/m3 and the coerciveness poisoning experiment in the concentration of PH3 955.41 mg/m3 in 2～50 h was conducted. We also present the characterizations of the surface morphology the elemental composition and phase of the enforcement poisoning catalyst by SEM,XPS and XRD, and the mechanism of its poisoning was analyzed. We found that conclude that in the poisoning process of industry high concentration CO shift the maximum allowable concentration of PH3 is 400.05mg/m3. The catalyst activity will be affected below the maximum concentration, but after a while, the catalyst activity will still meet the requirement while reducing the catalyst activity. The mechanism of PH3 poisoning is as following. First, PH3 poisoning will made pyrophosphate and carbon deposition cover the outside of catalyst and the reversible poisoning occurred out of the weakness of chemical bond. Second, the solvable phosphate and iron-based high temperature conversion catalyst will produce some insoluble phase and phosphorus & iron compound, and this made the active centers of the catalyst occupied, the structure destroyed and so that the irreversible poisoning occurred.