【作者】 李玉洁；

【导师】 赵炜；

【作者基本信息】 太原理工大学 ， 化学工艺， 2007， 硕士

【摘要】 本研究采用管式炉反应器考察了半焦、改性半焦存在的条件下甲烷转化制备合成气以及H₂、CO对半焦中硫的脱除的影响，并对过程中主要反应的热力学和动力学进行了初步的探讨。主要研究结果如下：（1）半焦的存在对CH₄分解有明显的催化作用。一方面，半焦的存在能降低CH₄的开始分解温度（由800℃降低到600℃）；另一方面，半焦的存在能提高CH₄的转化率，在1000℃时，半焦存在的反应中CH₄的转化率达到约80％，远大于空管情况下CH₄的转化率（1000℃时空管情况下CH₄的转化率为10％）．这些充分证明了半焦对CH₄分解的催化作用。（2）碱半焦能降低CH₄的开始分解温度，但是CH₄在碱半焦作用下的转化率远远小于半焦作用下的转化率（1000℃下半焦存在时CH₄的转化率为80％左右，而碱半焦存在的条件下CH₄的转化率不到20％），半焦经碱金属改性后不利于CH₄的分解。而且，本实验的条件下在一定的温度范围内会出现CH₄含量增加的情况，碱半焦能促进CO加H₂生成CH₄的副反应的发生。（3）H₂对半焦的预处理并不影响半焦对CH₄的催化作用，但是H₂处理的半焦在高温下（＞1000℃）会放出大量的CH₄，1g半焦经H₂处理后在1000℃～1060℃能放出大约7ml的CH₄。（4）大量存在的H₂在反应过程中存在与CO作用生成CH₄的趋势。当反应体系中CO的浓度较大、同时又存在合适的催化环境时副反应就可以进行，表现在实验现象中就是CH₄的转化率下降。（5）H₂、CO气氛都能在一定程度上转化半焦中硫使其转化为气态的硫。其中，H₂气氛下半焦中的硫主要以H₂S的形式析出，半焦中硫约有6‰以H₂S的形式析出进入气相，H₂气氛对热分解COS的析出没有影响；CO气氛下半焦中硫主要以COS的形式析出，CO气氛下半焦中有2％～4％的硫以COS的形式析出。总的来说，在本实验的条件下，CO气氛最有利于半焦脱硫。通过热分析实验以及CO与HNO₃、NaOH处理后的半焦作用的实验初步考察了被H₂、CO还原的半焦中的硫的形态，但对于半焦中具体是有机硫还是无机硫在与H₂、CO作用还需进一步的实验验证。（6）在半焦催化CH₄转化体系中存在H₂、CO等还原性气体，而这些气体能与半焦中的S作用，使之以气态的形式析出，这在一定程度上降低了半焦中的硫含量，使气体产物中的气态硫含量增加。但由于脱硫率很低，因此双气头转化过程半焦中硫的转化进入气相对生成的合成气中硫含量增加的影响不大。从动力学上分析了H₂与CO分别与半焦中的硫的作用，结果表明，H₂与半焦中的硫作用的过程为一级反应，反应的活化能为Ea=89.8kJ／mol；CO与半焦中的硫作用的过程为二级反应，反应的活化能为Ea=111.7kJ／mnl更多还原

【Abstract】 A tubular reactor system has been used to study the conversion of themethane to produce syngas with the coal char or modified coal char holding inthe reactor, the effect of H₂ and CO atmosphere （the most important componentsof coke-oven gas） on the convesion of sulfur in the coal char was also evaluated.Then, the thermodynamics and kinetic analysis for the mainly-reactions havebeen discussed in this paper.The mainly results are:（1） The decomposition temperature of methane thermal cracking can bedecreased when the coal char holds in the reactor （from 800℃to 600℃）; andthe conversion of methane could be increased. The experimental results showthat the conversion of methane is about 80% at 1000℃with the coal char actingas a catalyst. Compared with the reference experiment, it is only 10% for the uncatalysis experiment using an empty tubar reactor. So, it is concluded that thecoal char can act as a catalyst for the thermal cracking of methane.（2） The decomposition temperature of methane can be also decreased underthe modified coal char holding in the reactor, but the results show that theconversion of methane is less than that of the coal char. At 1000℃, theconversion of methane is about 80% holding with the coal char, but it is only20% holding with the modified coal char. And moreover, the experimentalresults show that CH₄ can be produced at the temperatures more than 1000℃.After the analysis of the experimental results, it can be regarded that themodified coal char can act as the catalyst for both CH₄ thermal cracking and thereaction of CO and H₂ produce CH₄.（3） Some experimental results reveal that the coal char can act as thecatalyst for methane thermal cracking reaction. And the coal char pretreated byH₂ don’t influence the catalysis of the coal char to the decomposition of methane.But the coal char pretreated by H₂ could release a lot of CH₄ under the highertemperature （higher than 1000℃）. And under the temperature of 1000℃～1060℃, 7mL CH₄ could be released from 1g coal char pretreated by H₂.（4） The tendency of producing CH₄ from H₂ and CO maybe happens whenthe concentrations of H₂ and CO are high and there was an appropriate catalysiscondition. And the result is that the conversion rate of methane was decreasing.（5） Both H₂ and CO could convert the sulfur in the coal char to gaseous to acertain extent. Under the atmosphere of H₂, the sulfur in the coal char mainly release in the form of H₂S with the proportion of 0.6% and COS made from thecoal char pyrolysis process; Under the atmosphere of CO, the sulfur in the coalchar mainly released in the form of COS with the proportion of 2%～4%. Moreexperimental have been done using both TGA and the tubular reactor systemincluding the samples that after the pretreatment by HNO₃ or NaOH. But furtherresearches will fosus on the patterns of sulfur in the coal char, to understandwhether the inorganic sulfur or organic sulfur can react with H₂ and CO underthe experimental conditions.（6） During the experiment, a large number of reductive atmosphere such asH₂ and CO hold in the reactor. These gases could make the sulfur in coal charreleased in the form of gaseous sulfur which decreased the contents of sulfur inthe coal char and enhance the contents of gaseous sulfur in the gaseous products.But the influence of gaseous sulfur on the contents of sulfur in the generatedsyngas is slight for the low rate of desulfuration in the polygeneration systerms.According to the kinetic analysis, for the reaction of H₂ and sulfur and the thereaction of CO and sulfur in the coal char, the reaction orders were 1 and 2respectively. And the activity energies were 89.8kJ/mol and 111.7kJ/mol,respectively.更多还原