The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity i...The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms （i.e. H-form, Na-form） of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char＇s reactivity. Addi- tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope （SEM）.展开更多
以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K^+和Na^+的影响以及浆体对K^+和Na^+的滞留能力;并采用29Si MAS NMR分析讨论了K^+和Na^+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随...以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K^+和Na^+的影响以及浆体对K^+和Na^+的滞留能力;并采用29Si MAS NMR分析讨论了K^+和Na^+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随着液固比的增大,浆体释放的K^+和Na^+的百分数逐渐增大;经去离子水充分洗涤后仍有一部分K^+和Na^+存在于浆体中,且浆体对K^+和Na^+的滞留能力随着纳米SiO_2掺量的增加以及拌合液碱浓度的增大而增强。29Si MAS NMR分析证实了K^+和Na^+能够进入C-S-H凝胶层间形成不可逆的化学结合。K^+和Na^+通过取代C-S-H凝胶层间≡SiOCa+中的Ca2+,缩短了C-S-H凝胶中[SiO4]4-四面体链长,从而使凝胶中Q1和Q2峰向左移动。展开更多
文摘The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms （i.e. H-form, Na-form） of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char＇s reactivity. Addi- tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope （SEM）.
文摘以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K^+和Na^+的影响以及浆体对K^+和Na^+的滞留能力;并采用29Si MAS NMR分析讨论了K^+和Na^+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随着液固比的增大,浆体释放的K^+和Na^+的百分数逐渐增大;经去离子水充分洗涤后仍有一部分K^+和Na^+存在于浆体中,且浆体对K^+和Na^+的滞留能力随着纳米SiO_2掺量的增加以及拌合液碱浓度的增大而增强。29Si MAS NMR分析证实了K^+和Na^+能够进入C-S-H凝胶层间形成不可逆的化学结合。K^+和Na^+通过取代C-S-H凝胶层间≡SiOCa+中的Ca2+,缩短了C-S-H凝胶中[SiO4]4-四面体链长,从而使凝胶中Q1和Q2峰向左移动。
