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通过实验讲解氢氧化钾的活化处理

发布来源:http://www.jinhao360.com    更新时间:2022-05-16 点击数:

活化处理是制备活性炭中重要的阶段。活化有两种方式:物理活化和化学活化。物理活化往往先要将原料炭化,然后在一定温度下通入二氧化碳或水蒸汽,这种方式活化时间长,温度高,耗能大。化学活化是将炭化与活化同时进行的一种制备方式,简化了操作,节省时间和能源,是目前应用较多的活化处理方式。
Activation treatment is an important stage in the preparation of activated carbon. There are two ways of activation: physical activation and chemical activation. In physical activation, the raw material is often carbonized first, and then carbon dioxide or steam is introduced at a certain temperature. This method has long activation time, high temperature and high energy consumption. Chemical activation is a preparation method of carbonization and activation at the same time, which simplifies the operation and saves time and energy. It is a widely used activation treatment method at present.
氢氧化钾活化法是从20世纪70年代发展起来的一种活化方法。氢氧化钾作为活化剂,主要有抑制焦油生成,提高反应收率,而且主要是利用氢氧化钾、氧化钾和碳酸钾把原料中的部分碳浸蚀掉,经过洗涤后生成多孔性的炭。
Potassium hydroxide activation method is an activation method developed from the 1970s. As an activator, potassium hydroxide mainly inhibits the formation of tar and improves the reaction yield. In addition, it mainly uses potassium hydroxide, potassium oxide and potassium carbonate to etch part of the carbon in the raw material and generate porous carbon after washing.
接下来通过以无烟煤为原料,KOH为化学活化剂进行活化过程中,通过热分析实验,获得温度与烧失率之间的关系,并探讨KOH作为化学活化剂的活化过程。
Next, through the activation process with anthracite as raw material and KOH as chemical activator, the relationship between temperature and ignition loss rate is obtained through thermal analysis experiment, and the activation process of KOH as chemical activator is discussed.
用颚式破碎机将煤块粗碎后,再用球磨机对颗粒煤进行细磨,将煤粉过200目筛后,得到原料1。称取原料1煤粉145g,加入盐酸(36.5%)10ml,氢氟酸(73%)10ml,高氯酸(37%)20ml,水50ml,搅拌均匀,室温下浸泡24h。
After the coal is roughly crushed by jaw crusher, the granular coal is finely ground by ball mill, and the pulverized coal is sieved through 200 mesh to obtain raw material 1. Weigh 145g of raw material 1 pulverized coal, add 10ml of hydrochloric acid (36.5%), 10ml of hydrofluoric acid (73%), 20ml of perchloric acid (37%) and 50ml of water, stir evenly and soak at room temperature for 24h.
用抽滤装置对上述原料洗涤,洗至pH值为6后,置于电热鼓风千燥箱内烘千水份,此为原料2。
Wash the above raw materials with a suction filtration device until the pH value is 6, and then place them in an electric blast drying box to dry thousands of water. This is raw material 2.
称取烘干后煤粉10g,加入氢氧化钾溶液(10%)10ml,搅拌成糊状,放人表面皿,置于电热鼓风干燥箱中在105C保温30min,此为原料3。
Weigh 10g of dried pulverized coal, add 10ml of potassium hydroxide solution (10%), stir it into a paste, put it in a watch glass, place it in an electric blast drying oven and keep it warm at 105C for 30min. This is raw material 3.
取原料1少许,以惰性气体氮气为保护气,升温速度为15C/min的情况下进行热分析。
Take a little of raw material 1, take inert gas nitrogen as protective gas, and conduct thermal analysis at a heating rate of 15C / min.
取原料2少许,以氮气为保护气,升温速度为15C/min的情况下进行热分析。取原料3少许,以氮气为保护气,升温速度为15C/min的情况下进行热分析。
Take a little of raw material 2, take nitrogen as protective gas, and conduct thermal analysis when the heating rate is 15C / min. Take a small amount of raw material 3, take nitrogen as the protective gas, and conduct thermal analysis when the heating rate is 15C / min.
酸处理过的原料煤粉与未用酸处理过的原料煤粉的烧失率曲线有较大的差异:600C之前,酸处理过的原料煤粉仅有1.2%的烧失率,而酸处理过的原料煤粉烧失率已达28%,这主要原因是高氯酸浸泡煤粉后,已形成下面的分子模型:CooHz2Cho.49(HC104)1.4(H2O)3.8活化过程中,当温度升至200C以上时,高氯酸浸蚀掉部分碳而使之失重。
The loss on ignition curve of acid treated raw coal powder is quite different from that of raw coal powder without acid treatment: before 600C, the loss on ignition rate of acid treated raw coal powder is only 1.2%, while the loss on ignition rate of acid treated raw coal powder has reached 28%, which is mainly due to the formation of the following molecular model after soaking coal powder in perchloric acid: coohz2cho 49 (hc104) 1.4 (H2O) 3.8 in the activation process, when the temperature rises above 200C, perchloric acid erodes part of the carbon and makes it lose weight.
从热分析升温至350~550C之间时,样品质量基本保持不变,从DSC可以看到放热峰。此时活化剂氢氧化钾(熔点:360C)已为熔融状,KOH开始分解:2KOH-K2O+H2O
When the temperature rises from thermal analysis to 350 ~ 550c, the sample quality basically remains unchanged, and the exothermic peak can be seen from DSC. At this time, the activator potassium hydroxide (melting point: 360C) has been molten, and KOH begins to decompose: 2koh-k2o + H2O
上述反应发生的同时,生成的-OK基团取代原料中焦油某些H原子,原料开始脱氢,以氢气的形式释放出来,因此,KOH阻止煤焦油的挥发和促进了微晶层之间交联网状结构的形成。
At the same time, the hydrogen atoms in the coal tar are replaced by KOH atoms to form a network structure, which prevents the formation of cross-linking between the above raw materials.
随着温度的继续上升至600C时,碱金属化合物(如K2O和K2003)开始与碳发生反应,使得碳以氧化物形式释放出来,同时有碱金属钾的形成,而钾在石墨微晶平面之间的穿行,在没有暴露的表面上产生刻蚀,从而增大微孔结构和改变微晶体中芳香平面结构及其电子分布情况,提高活性炭的性能。
As the temperature continues to rise to 600C, alkali metal compounds (such as K2O and k2003) begin to react with carbon, so that carbon is released in the form of oxide, and alkali metal potassium is formed. The passage of potassium between the planes of graphite microcrystals produces etching on the unexposed surface, so as to increase the microporous structure, change the aromatic plane structure and electronic distribution in the microcrystals, and improve the performance of activated carbon.
氢氧化钾
从热流率曲线比较可以看出,在近700C时有一强吸收峰,该处可能为某活化反应进行所吸热而产生的变化,此时的DTG亦达到极值。因此,以KOH为活化剂制作活性炭时,在700C时保温时间可能对活性炭吸附性能及孔径结构产生一定的影响。
From the comparison of heat flux curves, it can be seen that there is a strong absorption peak at nearly 700C, which may be the change caused by the heat absorption of an activation reaction, and the DTG also reaches the extreme value at this time. Therefore, when making activated carbon with KOH as activator, the holding time at 700C may have a certain impact on the adsorption performance and pore structure of activated carbon.
活化剂与原料煤粉混合物的实际烧失率与理论计算所得曲线(假设KOH与原料煤粉之间无作用)有较大的差异:
The actual loss on ignition rate of the mixture of activator and raw pulverized coal is quite different from the curve obtained by theoretical calculation (assuming that KOH has no effect on raw pulverized coal):
600C之后,由于K2O与K20O3与碳之间发生化学反应导致实际重量损失率比计算大得多,其原因是碱金属氧化物(如K2O与K2CO3)开始与碳发生反应,使得碳以氧化物形式释放出来。
After 600C, the actual weight loss rate is much larger than calculated due to the chemical reaction between K2O, k20o3 and carbon. The reason is that alkali metal oxides (such as K2O and K2CO3) begin to react with carbon, so that carbon is released in the form of oxide.
当温度大于800C时,一方面会导致烧失率增大,产品得率低,另-方面可能过多的碳烧失后导致微孔结构坍塌,使得活性炭孔径分布不理想,所以适宜的活化温度在750~800C之间。根据KOH的活化特性,以不同的活化工艺,可以研制出性能优良的活性炭样品。
When the temperature is greater than 800C, on the one hand, it will increase the loss on ignition rate and low product yield. On the other hand, it may lead to the collapse of microporous structure after excessive carbon loss on ignition, resulting in the unsatisfactory pore size distribution of activated carbon. Therefore, the appropriate activation temperature is between 750 ~ 800C. According to the activation characteristics of KOH, activated carbon samples with excellent properties can be developed by different activation processes.
通过实验讲解氢氧化钾的活化处理的相关内容便是这样了,当然在实验过程中还是要做好保护措施,人身安全很重要,更多内容就来网站www.jinhao360.com咨询吧!
This is how to explain the activation treatment of potassium hydroxide through experiments. Of course, protective measures should be taken during the experiment. Personal safety is very important. For more information, please visit www.jinhao360.com Com consultation!

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