Tongchuan Coal Pyrolysis Behavior Of Tga

Pyrolysis of coal under mild reaction conditions can produce high heat-value coal gases, high value-added chemicals and clean char. It is an important method for coal "non-fuel" utilization. Tongchuan coal was choosed in this thesis. In the aim of increasing conversion rate and reducing reaction temperature, pyrolysis and catalytic pyrolysis under N₂ atmosphere, pyrolysis under reactive gas (H₂ or CH₄) atmosphere, catalytic hydropyrolysis, and hydropyrolysis of pretreated coal were studied using TG analysis. The main research results are as follows:1. Pyrolysis of coal under 10%(vol) H₂ atmosphere, the conversion rate increased by 6.5%, and the second peak temperature decreased by 36℃. So the coal pyrolysis process could proceed at lower temperature.2. The effect of CH4 on coal pyrolysis was smaller. Above 650℃, the carbon from decomposition of CH4 covered the coal and suppressed coal pyrolysis reactions.3. 5A zeolite and Y zeolite were effective for reducing pyrolysis temperature and increasing conversion rate. Adding 6% 5A zeolite, the catalytic hydropyrolysis conversion rate of coal increased by 10.3%, and the second peak temperature of the DTG curve decreased by 46℃compared with pyrolysis under N₂ atmosphere. When 5% Y zeolite was added, the conversion rate increased by 9.8%, the second peak temperature decreased by 85℃, and its onset temperature decreased by 125℃.4. Metal sulfides MoS₂ and NiS were more effective for increasing conversion rate than 5A zeolite and Y zeolite. The effect of NiS was outstanding. Adding 1% NiS, the catalytic hydropyrolysis conversion rate increased by 13.8%, and the second peak temperature decreased by 42℃compared with the pyrolysis under N₂.5. 5A zeolite and Y zeolite almost had no effect on the primary devolatilization, they were effective on the reactions between 550℃and 730℃. NiS had obvious catalysis for the primary devolatilization.6. The pyrolysis behaviour of pretreated coal was different from the raw coal. The second hydropyrolysis peak temperature of coal pretreated with supercritical CO₂ decreased by 23℃compared with hydropyrolysis of raw coal. Pretreating with steam, the conversion rate during 370℃and 600℃increased by 5.2%, and its second peak temperature decreased by 16℃. Pretreating coal with tetralin, its hydropyrolysis conversion rate during 370℃and 600℃increased by 9.7%, and the second peak temperature decreased by 16℃.7. The Tongchuan coal pyrolysis process was divided into two steps for kinetic calculation. The second order single-reaction model was choosed for the first step, and the first order single-reaction model for the second step. The kinetic parameters were in good agreement with experimental datas. The correlation of preexponential factor k₀ and activation energy E : lnk₀₁= -4.66561+ 0.15809E₁ ; lnk₀₂= -0.46602+ 0.10186E₂。...