| At present, the production of Yellow phosphorus is really high, for Yunnan province the phosphorus chemical industry a pillar industry. During the production of Yellow phosphorus, it will produce a great deal of off-gas. The main ingredient of off-gas is CO, but because of the existence of impurity gas (eg. COS, CS2, H2S etc.) in off-gas, which bring some difficulties in the using of CO chemical industry material gas. In order to solve this problem, this catalytic hydrolysis method will be applied to remove COS and CS2, under the condition of protecting CO not effected and low energy consumption.The technology of Non-thermal plasma surface modification get more and more attention. The main modification character is to introduce active groups or functional groups on the surface of catalyst to influence the adsorption performance of catalyst. And, at the same time, influence the load components dispersion and active component grain size. So this research will use Non-thermal plasma to modify carbon base catalyst to research its affection to the catalytic hydrolysis of COS and CS2 under different modification condition. Which laid a certain theoretical base to the research of catalytic purification of yellow phosphorus off-gas. This research will be divided into three parts. Firstly, research of the removal of COS by using NTP-modified coconut shell activated carbon base catalyst. Secondly, research of the removal of CS2 by using NTP-modified coconut shell activated carbon base catalyst. Thirdly, research of simultaneous removal of COS and CS2 by using NTP-modified coconut shell activated carbon base catalyst. The main research and conclusions are as follows.Research on the removal of COS by using NTP-modified coconut shell activated carbon base catalyst:Firstly, making nitrogen as modification atmosphere to study the effect of the catalytic hydrolysis of COS alone before and after modification. Secondly, the effect of catalytic hydrolysis of COS under the modification of different NTP reactors was investigated. (coaxial cylinder-type, plate-plate type, and needle-plate type), different input voltages (25V.35V and 45V), and different modification times (5min, 10min,20min,30min and 40min). And analyze the active species dispersion, particle size, metal specific surface area, catalyst surface morphology, pore structure, external surface area, surface element content, changes of surface groups under different voltage, and dispose time through CO-TPD, SEM, BET and XPS characterization. Finally, the reason of the improving of catalyst sulfur capacity after NTP surface modification was analyzed by Gaussian theoretical calculation, using b31yp method and 6-311G (d) basis set. The study shows that plate-plate type modification of Fe/SAC catalyst, has better affection in catalyzing hydrolysis of COS. The characterization found that the Load components dispersity and metal particle specific surface area has an obvious increasing after NTP modification. The improving of these physical properties are good for the bareness of catalyst surface atoms, then improve the sulfur capacity of the catalyst. The external specific surface area of catalyst increased about 4 times after modification, which can decrease the resistance of external diffusion. And this is good for the diffusion of COS from gas phase to solid phase, to adsorb and contact more active sites, improving the catalytic activity of the catalyst. The increasing of K, Fe and other active components, can make COS contact more active sites during Gas-solid mass transfer. After Gaussian simulation calculation it’s found that, with the existence of K, the reaction energy barrier of COS and H2O will obviously decrease, which further proved the result that with the increasing of K contents of catalyst after NTP modification the catalyst sulfur capacity increase.Research on the removal of CS2 by using NTP-modified coconut shell activated carbon base catalyst. Firstly, studying the effection of catalytic hydrolysis of CS2 before and after NTP modification. And then study the effection of catalytic hydrolysis of CS2 through different reactor types (coaxial cylinder-type, plate-plate type and needle-plate type). different modification atmosphere (N2, Air, NH3 and O2). different different modification time (5min.7.5min. 10min,12.5min and 15min), different input voltage (10V,15V,20V,25V and 30V). and different discharge gap (0.5mm,2mm,3.5mm and 4.5mm). Besides, the SEM. XPS and BET characterization method were also used to analyse. It’s mainly analyze the effection of catalytic hydrolysis of CS2 through surface morphology, different modification atmosphere, surface groups and changes of pore structure of catalyst. In the end, analyzing the reason of the improving of catalytic activity after NTP modification by using the Gaussian theoretical calculation by using b31yp method and 6-311G (d) basic set. The research result shows that after the modification of coaxial cylinder-type reactor, the catalyst has the best capability in catalyzing hydrolysis CS2. For different modification atmosphere, the research result shows that the catalyst sulfur capacity is the worst after oxygen modification. The main reason is the increasing of acid groups after oxygen modification, which is bad for the hydrolysis reaction of CS2 However, the catalyst sulfur capacity will be increased significantly after the NH3 modification. From the analysis of XPS characterization, it shows that there is not much oxygen-containing groups generated in catalyst surface after NH3 modification. And there are much atomic percentage content of K in catalyst surface. Besides that, the catalyst surface will adsorb more water molecules if there too much oxygen-containing groups, which will occupy the adsorption sites of CS2, leading to the catalytic activity will be decreased. Through Gaussian simulation calculation, we found that the hydrolysis reaction energy barrier will be lower, with the involvement of K, which further proved the result that the increasing of K in catalyst surface after NTP modification is good for the hydrolysis reaction of CS2.Research on simultaneous removal of COS and CS2 by using NTP-modified coconut shell activated carbon base catalyst. After the studying of the catalytic hydrolysis of COS and CS2 separately, in this part, the effection of catalyst catalytic hydrolysis of COS and CS2 simultaneously under different NTP modification condition was studied. Base on the previous study, we found that modification atmosphere has an obvious effection on the sulfur capacity of the catalyst. So in this part, we mainly talk about the sulfur capacity of the catalyst after NH3 and O2 modification, and analyze the reasons. The changes of catalyst physical structure, surface groups after different modification atmosphere modification were analyzed through BET, XPS and other characterized methods. Through BET characterization method found that the catalyst specific surface area and pore diameter changed obviously after O2 modification, the main reason is due to the strong oxidizing particles of oxygen modification atmosphere. Through the in-situ FTIR characterization method found that, different atmosphere modification has different effection on chemical stability of catalyst surface. After the oxygen modification, the activity species of catalyst surface will be more active which will react with oxygen when expose in the air, generating some acidic oxygen-containing groups, which will inhibit the catalytic hydrolysis of COS and CS2. |
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