| At present, there are a large number of enterprises discharging great amount of benzene organic exhaust gas in the course of production in Guangdong province. These enterprises usually use activated carbon adsorption to treat organic exhaust gas. But now they are crying for some new-style treatments and technology, because a good many matters restrict activated carbon, such as adsorption capacity, regeneration, cost, manipulation, etc. And that many provinces hold great amount of feebleness felt coal in store in our country, though they have not too much oil. People there generally adopt erective kilns to produce coal gas, at the same time produce a great deal of semi-coke. Mass semi-coke piled up look as if mountains, which is serious pollution for environment. Therefore, thinking over environment and clean coal technology, we must seek ask for some new method and production to make use of semi-coke.On the basis of national and international literature summarization, this thesis focus on the preparation methods of activated semi-coke in order to increase adsorption capacity for toluene organic exhaust gas. In this experiment, two kinds of raw semi-coke are selected, that is ShenMu semi-coke from ShanXi province and DaTong semi-coke from ShanXi province. After pre-activation they are modified with HNO3 and H2O2 at the condition of differently concentration and temperature, as well as loaded surface active agent. And about thirty samples of activated semi-cokes are prepared. The fixed-bed reactor is used to test adsorption property and study the influence of temperature and space velocity on toluene adsorption effect. By means of the measurements of physical property and structure, the effect factor of activated semi-coke adsorption is investigated. Furthermore the effects of different acid washing concentration as well as the factors of activation process on the adsorption properties of obtained activated semi-coke were studied.Through evaluation of toluene adsorption properties, it is concluded that: the raw material is the decisive factor of toluene adsorption property. The semi-coke which has larger specific surface area, pore and lower volatility is propitious to be modified as toluene sorbent. The DaTong raw semi-coke samples need to be crushed into 10～20 mesh and then, they are activated by soaking 30% nitric acid and vibration at normal temperature for 24 hours, after washing and drying the sample is a super activated semi-coke with high toluene adsorption capacity and long breakthrough time. Besides the optimal space velocity is 2000h-1.Results of our experiments show:Through soaking at higher temperature, activated semi-coke gain high performance toluene adsorption, so which is considered to be the absolutely necessary step to improve toluene adsorption.The optimum conditions for preparation of activated semi-coke are: 10-20 mesh DaTong semi-coke soaked by 45% nitric acid , temperature 80℃, 24 hours and then washed and drying. The toluene capacity of the adsorbent is 50.29g toluene/100gC. |
