| Biomass acid hydrolysis residue is the solid waste producted in the chemical conversion of biomass. Large amounts of industrial waste are generated in the production of furfural. In order to solve the problems of stacking furfural residue and superheated steam which is required in the furfural production process, the technology of using biochar-gas cogeneration is proposed in this paper, making the furfural residues into biochar, activated carbon and biomass gas. Acid hydrolysis residue has characteristics of high moisture content, high lignin content, acidity,hydrolysis of residual organic material, and its thermo-chemical conversion,briquette technologies are distinct from biomass raw materials. According to the characteristics of furfural residue itself, at first, it is dealed with constant temperature drying, screening and neutralization pretreatment, and analyzed by TG-DSC techniques for thermogravimetric analysis, dynamic analysis and thermal analysis. Furtherly, product distribution and biochar application performance were determined under different conditions using the pipe furnace pyrolysis experiment;Activated carbon is prepared by water vapour, compared with furfural residue,biochar and activated carbon adsorption of methylene blue.By thermogravimetric analysis of pyrolysis, the whole process can be divided into three stages: dry, escape of volatiles, and pyrolysis carbonization sections.Pyrolysis process of weightlessness occurs mainly in the phase of separating volatile, identifying the main temperature range from 300 ℃ to 600 ℃. The precipitation of moisture was inhibited after adding catalyst, and the rate peak of weight loss becomes larger, indicating that alkali metals sodium salt promote cellulose decomposition. Using isoconversional method of Friedman,activation energy changes slightly in the conversion rate from 0.3 to 0.7, showing the consistent of pyrolysis mechanism model at this stage, and the average activation energy is 191.82KJ/mol.When pyrolysis temperature of 600℃ and heating rate β =5, 10, 20 and 40 ℃/min, the required heat were 10.47, 3.46, 1.74 and 0.6 MJ/kg respectively.Considering the quality yield, reaction time, energy consumption, the heating rate of 10 ℃ /min was selected for pyrolysis in a tube furnace and the technological conditions of preparation of activated carbon.Pyrolysis temperature has greater influence on solid, gas and liquid product yield and solid products decrease more slowly when temperature increases; With high temperature, gas output increased; liquid yield reached the highest at 500℃.Accoding to quality yield and yield of fixed carbon, products and pellet biochar hashigher quality at pyrolysis temperature of 450 ℃. Water absorption of pellet biochar and biochar and PH value gradually increases as the temperature rises. Under the same conditions, PH value of briquette charcoal is larger. Volumetric shrinkage of pellet biochar nearly 50% at high temperature; Dropping strength more than 98%and before the 500 ℃,it is suitable for handling and transport. Resistivity down to0.58Ω·m, at 600 ℃, and higher temperature is required when used as a magnetic materials.At the pyrolysis temperature of 400 ℃, biochar achieved the highest rate of methylene blue decolorization 44.4%, and at 350℃, adsorption yield reached the maximum value of 1428.72mg·%/g. In the orthogonal experiment, 9 groups activated carbon has higher adsorption yields than biochar, and the 5th adsorption yield test reached the highest. Considering adsorption yield variance analysis of orthogonal experiment, the best optimum solution is A2B2C3D2. Additional experiments show that adsorption yield rate is higher, and ash content and catalyst agglomerate, activated carbon ash content is lower. |
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