Study On Catalytic Co-pyrolysis Characteristics And Mechanism Of Shenfu Coal And Biomass

To improve the efficient and clean utilization rate of coal in Shaanxi province and exploit the high-quality biomass resources effectively in the south of Shanxi, the pyrolysis and catalytic pyrolysis reaction characteristics of SFC, WS and CS which are the main research objects and loaded catalyst K2CO3, Na2CO3, CaO, MgO and Fe2O3 by mechanical chemical modification in planetary ball mill, were investigated in TG/DSC1 and fixed-bed pyrolysis device. The mechanism functions from pyrolysis and catalytic pyrolysis reaction was deduced by thermal decomposition kinetics with differential and integral methods. Results are as follows:The weight loss of SFS, WS and CS rapidly increased in accented phase of pyrolysis and catalytic pyrolysis, and greater weight loss rate peak was presented in DTG curves. Co-pyrolysis characteristics of SFC, WS and CS in different mixing proportion were divided into two stages, which were main pyrolysis stage of biomass and composite stage of biomass condensation and main pyrolysis process of SFC. Among them, the best collaborative effect was generated in the condition of w(WS)/w(SFC)=2:1 and w(CS)/w(SFC)=1:2 loaded with K2CO3.The loaded catalysts have certain influence on the pyrolysis process, in which K2CO3, CaO and Fe2O3 have apparent catalytic effect. The fast pyrolysis of WS and CS almost came to the end before 450 ℃, but the pyrolysis at 500 ℃ was violent. In the stage of 450~700 ℃,the fast pyrolysis of SFC(370~600 ℃) overlapped with dehydrogenation polycondensation of biomass(≥450 ℃),and then SFC entered into dehydrogenation polycondensation(≥600℃), which compounded with dehydrogenation polycondensation of biomass.Based on TGA, with FWO and Kissinger method to calculate pyrolysis and catalytic pyrolysis kinetics, it is turned out that pyrolysis activation energy of SFC, WS and CS was reduced by loaded K2CO3, Na2CO3, CaO, MgO and Fe2O3. K2CO3 has the most apparent effect on SFC which activation energy is reduced about 70KJ/mol, followed by CaO, but has opposite pyrolysis effect on WS and CS.Combine with the analysis of the most probable mechanism function which are 32 kinds of pyrolysis kinetics, and activation energy calculation and it is found that see blow.The mechanism of SFC, WS and CS accorded with Z-L-T equation, that is three-dimensional diffusion model.The mechanism of SFC and ones loaded with K2CO3, CaO and MgO conform to Z-L-T equation, that is three-dimensional diffusion model. The pyrolysis mechanism of SFC loaded with Na2CO3 and Fe2O3 belongs to Jander equation, that is three-dimensional cylindrical diffusion model. The pyrolysis mechanisms of WS and CS loaded with K2CO3 and Na2CO3 belong to three-dimensional diffusion model. The ones of WS and CS loaded with CaO, MgO and Fe2O3 belong to cylindrical three-dimensional diffusion model.