Study On Polygeneration Process Of Bamboo Charcoal Activated By Bamboo Vinegar

At present,bamboo is mostly used to make fuel carbon in China,which is characterized by low added value of products and heavy process pollution.Tar,a liquid product of bamboo pyrolysis,is directly discharged,causing serious pollution to the environment.Compared with foreign studies,there are few studies on the joint production of gas,liquid and solid products in bamboo processing in China.In this study,bamboo pyrolysis and activation technology was applied to bamboo polygeneration,and high-quality products such as bamboo charcoal,activated carbon,bamboo vinegar and hydrogen were produced,which greatly improved the utilization rate of bamboo resources and provided a reasonable and effective way to realize efficient and clean utilization of bamboo waste.Firstly,the bamboo pyrolysis experiment was carried out in a fixed-bed experimental device.The distribution characteristics of solid and liquid products of bamboo pyrolysis at different temperatures were investigated,and the pyrolysis reaction mechanism was revealed.The results showed that at 350-550℃,a large amount of cellulose and hemicellulose in bamboo were degraded,the solid yield decreased sharply,and the liquid yield increased,among which the contents of aldehydes,ketones and furans increased continuously When the temperature is higher than 550℃,the liquid yield begins to decrease,and the content of aromatic compounds also begins to decrease,which indicates that the degradation of lignin is nearly complete,while the content of aldehydes,ketones and furans rises again mainly because of the secondary cracking of macromolecular aromatic compounds at high temperature,resulting in a large number of small molecular compounds.At the same time,the study on the calorific value of solid bamboo charcoal shows that when the pyrolysis temperature is higher than 550℃,the calorific value of coke is 2462.19J/g,which exceeds the calorific value of commercial charcoal by 2459.72J/g,making it a highquality fuel carbon.In the process of catalytic pyrolysis,it was found that the furfural content in the liquid product after catalytic pyrolysis of sepiolite increased by 9.1%,which indicated that sepiolite could effectively promote the degradation of bamboo cellulose.Then,in this study,bamboo vinegar produced by pyrolysis was used instead of steam to activate bamboo charcoal produced by pyrolysis to prepare activated carbon.The effects of activation temperature,activation time and mass ratio of bamboo vinegar to bamboo charcoal on activation reaction were investigated,and the optimum process conditions were obtained as follows: activation temperature 850℃,activation time 1.5h,and m(bamboo vinegar)/m(carbonized material)=6 ∶1.The activated carbon obtained by bamboo vinegar activation is mainly mesoporous activated carbon,and its methylene blue adsorption rate exceeds the national first-class wooden activated carbon standard,and the activated carbon yield is increased by 7.45% compared with the traditional steam activation process.At the same time,the study on the composition changes of bamboo vinegar before and after activation showed that after activation,the types of bamboo vinegar decreased from 22 to 4,and the main components changed from phenol compounds(49.83%)to toluene compounds(89.27%),thus achieving the purpose of refining bamboo vinegar and increasing the added value of products.Therefore,this study put forward the idea of bamboo charcoal polygeneration,which can produce high-quality bamboo charcoal,activated carbon,bamboo vinegar and hydrogen and other high-value products.Finally,Aspen Plus software is used to simulate the technological process of activating bamboo charcoal with bamboo vinegar.The hydrogen production and gas calorific value are the research directions,and the hydrogen production process by reforming bamboo vinegar is designed.Using sensitivity analysis software,the optimum process conditions were obtained as follows: activation temperature 850℃,reaction pressure normal pressure,mass ratio of bamboo vinegar to bamboo charcoal6:1,which was consistent with the experimental results,which greatly demonstrated the effectiveness of polygeneration process.By optimizing the process,pure water stream was selected to promote the water vapor shift reaction.After optimizing the process,the flow rate of pure water stream was 20Kg/h,and the hydrogen increased by4.2%.By simulating different hydrogen production processes,comparing and analyzing the hydrogen output and gas calorific value,the new hydrogen production process by bamboo vinegar reforming studied in this paper is improved by 117%compared with the self-reforming reaction of bamboo vinegar and 84% compared with the traditional steam activated bamboo charcoal process,which shows that the new hydrogen production process by bamboo vinegar reforming is a very efficient hydrogen production process,and also shows the feasibility of bamboo pyrolysis activation polygeneration to produce coke,activated carbon and hydrogen.