Western China Five Typical Coal Pyrolysis And Catalytic Hydrogenation Of Pyrolysis Behavior Of Heat Re-study

Coal is not only a kind of energy, but also a valuable chemical raw material. By pyrolysis, high-heating value gas, value-added chemicals and cleaned char can be gained. In this thesis, five coals (Shen Fu, Tong Chuan, Xin Jiang, Huo Lin He and Yun Nan) are subjected to pyrolysis under different conditions by a temperature-programmed TGA(30℃/min and the range of temperature from 100℃to 900℃),with the aim of increasing final rate of weightnessless and reducing reaction temperature. The investigated conditions include, pyrolysis atmosphere (pure N₂ and 90%N₂+10%H₂,vol%), different catalysts (MoS₂, NiS and ZnCl₂) and different catalyst additive(0.5%,1.0%,2.0%,5.0%andl0.0%). As the next step the kinetic properties of pyrolysis process is analysed and the essential results are listed as follow:1. Under the nitrogen pyrolysis condition, a linear relationship between volatile and corresponding rate of weightlessness at final pyrolysis temperature is found: W%=-1.086538+1.027778×V_daf. With the decrease of carbon content, the activation energy of coals in active pyrolysis stage is decreased.2. Under the pyrolysis condition in this study, the process of weightlessness for all of coals can be roughly divided into three stages. Both in the active pyrolysis stage and second degasification there is remarkable weightlessness phenomenon for Shen Fu, Tong Chuan and Xin Jiang coal. On the contrary, for Yun Nan, Huo Lin He coal the weightlessness peak appears only when the relative temperature is lower than 600℃, but there is no remarkable weightlessness peak in the second degasification. Moreover, the presence of catalysts and hydrogen has little effect on the general trend of coal's pyrolysis.3. Compared with pyrolysis in pure nitrogen atmosphere, the existence of H₂ has different positive contribution to both final rate of weightlessness and the reduction of hydropyrolysis temperature for all of studied coals except Shen Fu.4. By adding NiS and MoS₂ catalysts, the maximal velocities of weightlessness in the active hydropyrolysis stage speed up in all coals except Yun Nan coal. As far as the final rate of weightlessness is considered, the catalytic effect of MoS₂ is superior than that of NiS.5. Obviously, ZnCl₂ catalyst reduces the conversion temperature in the second hydropyrolysis for all of coals, and the effect is more notable with the increase of catalyst additive. However the hydropyrolysis rate of weightlessness goes lower by overmuch additive of ZnCl₂.6. There is no remarkable catalytic effect on Yun Nan coal with high volatile and ash amount in hydropyrolysis.7. As for Shen Fu coal, hydropyrolysis experiments are undertaken using the mixture of 0.5%NiS and 0.5%ZnCl₂- Obviously, the mixture of catalysts improves final rate of weightlessness and decreases hydropyrolysis temperature. On the contrary, the blending catalyst of 0.5%MoS₂ and 0.5%ZnCl₂ decreases the hydropyrolysis temperature barely.8. As to the facilitating effect on final rate of weightlessness of different coals in hydropyrolysis process, there is an optimum catalyst content for MoS₂, NiS and ZnCl₂.9. According to different coal types, single-reaction model of different reaction order is applied to calculate kinetics of hydropyrolysis process. Experimental datum exists fine linear relationship and the kinetic parameters, which are obtained from the model, are in good agreement with experimental datum, as the results, the applied model is suitable and the used catalysts in experiments can effectively promote the coal hydropyrolysis. At the same time, there is a compensation relationship between pre-exponential factor k₀ and activation energy E.