The behavior of the different catalysts for model carbon hydrogasification
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摘要: 在加压热天平中研究了活性炭/烟煤半焦/无烟煤半焦等模型炭催化加氢气化(CHG)的特性,并结合GC、BET等表征对炭的物理结构和化学反应过程的分析,初步获悉了Co对炭-氢反应的催化作用过程。结果表明,炭CHG过程中过渡金属(Fe、Co、Ni)的催化活性明显高于碱金属和碱土金属(K、CaO、MgO),过渡金属催化过程存在低温 (600−750 ℃)和高温 (> 800 ℃) 两个特征催化区域,低温催化区域的出现主要归因于过渡金属催化剂氧化物与炭发生相互作用,部分炭结构得到活化的同时过渡金属嵌入到炭层结构中更为有效的发挥供氢和断键作用。Co催化剂在850 ℃和1 MPa氢压以上的条件下,催化剂的供氢作用可达到饱和,炭的催化加氢气化过程主要为温度促使的催化断键反应。具有高比表面积和低致密程度炭结构的模型炭在较低的催化剂负载量下即可具有高的CHG活性。Abstract: The catalytic hydrogasification of activated carbon/bituminous char/anthracite char with the different catalysts were performed in a pressurized thermogravimetry analysis (PTGA). The GC, BET were used to characterize the physical structure and chemical reaction process of carbon. The function principle of Co to the carbon-hydrogen reaction was preliminarily obtained. The results showed that the catalytic activity of transition metals (Fe, Co, Ni) was significantly better than that of alkali metals and alkaline earth metals during the process of activated carbon hydrogasification. There were two catalytic zones of low temperature (600−750 ℃) and high temperature (> 800 ℃) in the catalytic process. The emergence of the low temperature catalytic zone could be attributed to the interaction between the transition metal oxides and carbon. The transition metal was embedded in carbon layer structure during the activated carbon hydrogasification, then parts of carbon structure was activated, resulting in the cleavage of carbon-carbon bonds. The adequate active hydrogen could be supplied by Co at 850 ℃ when the pressure was beyond 1 MPa. Briefly, the reaction temperature was the crucial factor for the cleavage of carbon-carbon bonds. The model carbon with higher specific surface area and weaker carbon structure could be converted efficiently even with lower loading amount of catalyst.
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Key words:
- model carbon /
- catalytic hydrogasification /
- PTGA
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表 1 不同焦样的工业分析和元素分析
Table 1 Proximate and ultimate analysis of char samples
Sample Proximate analysis wd/% Ultimate analysis wdaf/% A V FC C H N S Oa HXT 0 0.73 99.27 98.22 0.56 0.16 0.06 1.00 FG 0.83 1.00 98.17 91.65 0.73 1.94 0.24 5.44 FGKK 0.80 1.55 97.65 89.15 0.68 1.97 0.45 7.75 YQ 2.21 4.11 93.68 94.94 0.75 1.86 0.73 1.72 d: dry basis; daf: dry-ash free basis; a: by difference 表 2 不同模型炭的孔结构
Table 2 Pore structure parameters of modern carbon samples
Sample BET surface
area A/(m2·g−1)Pore
volume v/(cm3·g−1)Average pore
size d/nmHXT 1221 0.54 0.97 FG 0.77 0.005 26.1 FGKK 1114 0.63 2.25 YQ 3.22 0.029 35.5 -
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