| Bio-oil produced through the biomass vacuum pyrolysis technology, which can be used as alternative energy of fossil fuel because it has high energy density and better performance of storage and transportation. The development of biomass energy has the vital significance to relieve the energy crisis and environmental pressure. Biomass is mainly composed of cellulose, hemicellulose and lignin, and its pyrolysis behavior can be considered as the comprehensive performance of these three major components. Therefore, the pyrolysis reaction and mechanism of biomass can be effectively analyzed by the interaction pyrolysis experiments between three components. In this paper, the three biomass components interaction rules was analyzed. Three components pyrolysis experiments were carried out on the biomass vacuum pyrolysis system. The influence of the content of three components on the distribution and composition of pyrolysis liquefaction products was investigated. The main research contents of this paper are as follows:(1)The three components of biomass were characterized by Fourier Transform Infrared(FT-IR). The results showed that there were some obvious absorption peaks in 609.91, 655.11, 583.90, 530.65, 619.20 cm-1. These peaks were C-C stretching vibration peak, indicating the existence of aliphatic structure matter in the three components. The peak in the range of 2850-3000 cm-1 was C-H stretching vibration peak. There was an obvious absorption peak in the 3200-3500 cm-1 of the three components. The peak was O-H stretching vibration peak, indicating the existence of alcohol hydrogen bond association hydroxyl.(2)The proportions of the three components i.e. cellulose, xylan and lignin were reasonably designed, and there were seven experimental samples according to different quality proportions. The Thermo TGA/DSC 1 was used to analyze the thermo-gravimetric processes of the samples composed of the three components. And the pyrolysis characteristics of the cellulose, xylan and lignin were studied. The Coats integration method was adopted to calculate and analyze the three components’ pyrolysis dynamic parameters. The results showed that cellulose had good thermal stability, the pyrolysis range was narrow, and its pyrolysis was relatively intense which generated less solid residues Xylan with a poor thermal stability, and the pyrolysis temperature is low. Lignin with a poor thermal stability, the pyrolysis range was 200~600℃ and the solid residues as high as 36.65% at the end of pyrolysis. By analyzing the three components’ pyrolysis dynamic parameters, it could be concluded that cellulose had considerable effect on the activation energy and pre-exponential factors while xylan and lignin had greater effects on reaction order. Cellulose pyrolysis was beneficial to the reduction of the solid residue while lignin pyrolysis products could promote the decomposing of sugars. Xylan had a negative effect on the cellulose pyrolysis and could benefit the low-temperature pyrolysis of lignin.(3)On the basis of the biomass vacuum pyrolysis liquefaction system, the vacuum pyrolysis experiments of each component and the mixed samples were carried out. Taking biomass as a benchmark, oil and solid production rate and production rate of gas were calculated at the end of the pyrolysis. The(GC-MS) Agilent 7890 A were adopted to analyze the composition of bio-oil. By comparing the experimental and calculated value, the influence of those three components content on the distribution of pyrolysis product and bio-oil composition was also evaluated. The results indicated that the relative content of the aromatic compounds was almost unchanged compared with the calculated values of the aromatic compounds in the mixed pyrolysis oil of cellulose and lignin. Sugar is not detected. Content of carbohydrate was higher in the mixed pyrolysis oil of cellulose and xylan. The relative content of aromatic compounds was significantly increased in the mixed pyrolysis oil of the seven sample compared with the calculated values. |
PDF Full Text Request