Preparation Of Activated Carbon From Wheat Straw In A Fluidized Bed With Inert Particles

Activated carbon(AC)is a biological organic material(such as wood,coke,petroleum coke,all kinds of nuts)prepared with well-developed pore structure and specific surface area of the porous carbon materials use.Activated carbon is widely used in food,chemical,military,environmental protection,pharmaceutical and other fields.With the rapid development of China’s industry,the demand for activated carbon is increasing.The traditional method of preparing activated carbon with wood as raw material has been limited by forestry development,so the use of agricultural and forestry waste resources to prepare activated carbon becomes a realistic choice at present.China is a large agricultural country,the straw resources are very rich,with the preparation of activated carbon,not only makes the use of agricultural waste resources,but also reduce the accumulation of rural straw,burning cause pollution problems.This paper is based on the wheat straw fluidization condition to prepare the activated carbon,the cold state experiment studied the mixed fluidization characteristics of biomass and inert particles.The experimental study found that the inert particles can be very good to the wheat straw particles fluidization,the experimental process will appear significant particle stratification phenomenon.The effect of wheat straw particle size(0.4-2mm)on the process of the wheat straw particle is very limited.In this paper,the activated carbon was prepared by using CO2 and phosphoric acid activation method in the high temperature fluidized bed with wheat straw as raw material.The optimum technological conditions of two kinds of different activation methods were studied.The effects of dipping proportion,activation temperature,activation time and flow pattern on the pore structure of activated carbon products were studied.The morphology of activated carbon prepared by scanning electron microscopy(SEM)was observed.Research results show that:(1)the activation temperature is the most important factor affecting the activated carbon prepared by physical activation.The pore structure of wheat straw activated carbon prepared by CO2 fluidized bed is mainly based on the microporous structure,which belongs to the typical I type adsorption curve.In this paper,the optimum technological conditions of preparing wheat straw by single factor experiment are as follows:the activation temperature 900℃,the addition of quartz sand,the activation time 60min,the specific surface area is 805.01 m2/g,the total pore volume is 0.4378cm3/g.(2)the wheat straw mixed with quartz sand has a good flow,and the particle separation phenomenon occurs in the late stage of the experiment.Fluidization of CO2 activation preparation straw activated carbon influence greatly,with activation temperature elevated fluidization of activated carbon surface area of increasingly significant,in activation temperature 900 ℃,activation time 30min,fluidization of preparation activated carbon specific surface area is about five times more than the Non-fluidized bed,(3)impregnation ratio is the main factor affecting the activation of activated carbon by chemical activation,and the increase of the proportion of impregnation in phosphoric acid activation experiment can greatly promote the development of Mesoporous.When the proportion is 3:1,the wheat straw particles can form a very small ball group,which has lost the original structure form.(4)after adding quartz sand,it can be very good to help the wheat straw particle fluidization of phosphoric acid.However,the fluidization for preparing activated carbon by phosphoric acid method,effect of straw is very small,very little to affect the pore structure.Using CO2-H3PO4 activation method to improve the specific surface area of activated carbon prepared by H3PO4 activation,the increase of the amount of 43%,and to a certain extent,promote the development of the structure of the micro hole and the hole.