Study On Catalytic Hydrolysis Of TBEE-PEG200-H₂O System With Carbonyl Sulfide

In recent years,industrialization and urbanization have aggravated air pollution.The exhaust gas of blast furnace gas,coke oven gas,refinery gas and other industrial gases all contain a certain amount of carbonyl sulfide.At present,national,regional and industrial emission standards for sulfur-containing gases are increasingly strict,and the removal of organic sulfur is a challenge in gas purification.Carbonyl sulfide is the main form of organic sulfur in industrial gas,and the removal of carbonyl sulfide is the key to realize gas desulfurization.Carbonyl sulfide has stable physical and chemical properties.The development of desulfurization solvent with high desulfurization efficiency,low price and green is the priority in the field of carbonyl sulfide removal.As a sterically hindered amine,tert-butylaminoethoxyethanol（TBEE）contains amine groups,hydroxyl groups and ether groups,which can not only increase the physical solubility of carbonyl sulfide but also react with carbonyl sulfide as catalyst.Polyethylene glycol 200（PEG200）,as a carbonyl sulfide absorbent,has the characteristics of low toxicity,easy availability of raw materials,and green.Therefore,TBEE,PEG200 and H₂O as teactant was expected to construct a new desulfurization system with their specific advantages.The influence of the proportion of each component on carbonyl sulfur absorption was investigated,and the optimal content of each component in the desulfurization system was determined as TBEE:PEG200:H₂O=3:3:4（V/V/V）.At 298 K,the absorption effect of carbonyl sulfur can reach 94%with 500 ppm carbonyl sulfur at 30 m L/min while the liquid volume is 30m L.When the temperature is 308 K,the absorption effect of carbonyl sulfide can reach 98%.It is crucial to pay attention to the conversion of carbonyl sulfide in the liquid phase to improve the hydrolysis rate of carbonyl sulfide.Therefore,a methylene blue UV spectrophotometric method is developed in this paper to monitor and analyze the concentration pf S^2-in desulfurization system with increase of carbonyl sulfide function of absorption time.This method can achieve the quantification of methylene blue formation through UV spectroscopy,which has the advantages of high sensitivity,low detection limit and simple operation.The absorbance of methylene blue in 672nm has a good linear relationship with the concentration of S^2-in the desulfurization system（R²≥0.998）,and the minimum detection limit is 3.608×10^-5mg/m L,carbonyl sulfide and a small amount of SO₃^2-and S₂O₃^2-,has little influence on the measurement of S^2-,and the maximum measurement error is 3.64%.In this paper,the hydrolysis reaction model of the reaction of TBEE deslfurization system and carbonyl sulfide was established,and the hydrolysis reaction rate constant and pseudo first-order reaction kinetics in the range of 298K-338K were established.The physicochemical data（density,viscosity,surface tension）,mass transfer reaction characteristics（gas holdup,average diameter of bubble and specific surface area of liquid mass transfer）of the desulfurization system were investigated at different temperatures.According to the two-film theory,the gas-liquid mass transfer reaction model was established and the parameters required by the model were calculated.It was concluded that the absorption rate of the system was mainly affected by chemical intensification.The main factor affecting the mass transfer resistance of liquid film is the physical diffusion of the product from the gas-liquid interface to the liquid phase bulk.In addition,the liquid-phase mass transfer coefficient of the reaction is small,thus the mass transfer resistance of the liquid film is large.There is an active hydrogen in TBEE which is a sterically hindered amine.It can prevent the formation of N-C bond because the steric effect reducing the formation of zwitterionic intermediate state.In this paper,the solution is analyzed by IR,NMR.The results show that the TBEE has a variety of reaction modes when reacting with carbonyl sulfide.