Related content of wood and its thermal analysis
The reaction system has a significant thermal effect. Thermal analysis of the components of the material confirms that this is due to the intense thermal decomposition of the components. Based on the extraction rate of the material, the product characteristics and the extraction mechanism, the engineering material was constructed. Supercritical extraction process model. Less than 12o°C is the physical dissolution of low-molecular substances in the material.
The semi-continuous non-isothermal dynamic extraction experiments on extracted wood were performed on a solid material supercritical fluid extraction device made in Germany. The whole device can be divided into three parts: solvent supply system, material extraction system and product processing system. The lignin content in the extract was determined using 205nfl UV spectrophotometry.
Thermal analysis of wood and its components was performed on a PCT-1 differential thermobalance (manufactured by Beijing Optical Instrument Factory) with a heating rate of 10C/rain, a sample mass of about 5 nanog, and an atmosphere of still air.
Thermal effect of the extraction process The experiment was carried out on a solid material supercritical fluid extraction device made in Germany. Non-isothermal technology was used during the experiment, the heating rate was kept constant, and there was a good temperature control system. However, during the experiment, it was found that the temperature increase rate was not very stable in the 320-360°C region. Sometimes it is not well controlled. There is an abnormal phenomenon of rapid increase and slow decline. This shows that there is a significant thermal effect in the reaction system in this temperature zone.
The exothermic peak temperature for ethanol extraction is 355-359°C. With the increase of pressure, the duration has a tendency to shorten. When extracted with aqueous ethanol, the exothermic peak temperature shifts forward. For example, when the molar fraction of water is 0.22, the exothermic peak temperature is 340°C. When the molar fraction of water is 0.39, the exothermic peak temperature is 306°C. The time has also been shortened. It seems to be inferred that high pressure and water addition can inhibit exotherm. In addition, when the exothermic phenomenon occurs, both the rate of extract generation and the rate of gas generation are correspondingly maximal.
The above experimental phenomena can be scientifically and reasonably explained by the results of differential scanning calorimetry (osc) analysis of wood. The wood has a heat flow peak in the range of 214-415 qC. The thermal effect value is 5.2 kJ/g, and the maximum heat flow temperature is 341 qC. The exothermic bee temperature for wood extraction was 340359 qC, which is in good agreement with the DSC analysis of wood. From this. it can be seen that wood and its various components almost all show a pronounced exothermic effect in the area of 300 360 qC, which is in contrast to the Dsc curve of the timber material in the still air atmosphere.