Investigation on desulfurization performance and pore structure of sorbents containing zinc ferrite
Investigation on desulfurization performance and pore structure of sorbents containing zinc ferrite
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铁酸锌吸附剂脱硫性能及孔结构研究
DOI：
10.1021/ef960231k
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
M. Nunokawa
中科院分区：
文献类型：
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作者：
Makoto Kobayashi;H. Shirai;M. Nunokawa
为了利用煤气燃料实现先进的发电，需要用于高温脱硫的可再生且耐用的吸附剂。本工作研究了使用氨和尿素的不同沉淀方法来制备铁酸锌-二氧化硅复合颗粒。将含有这些粉末的两种吸附剂挤出，并在加压模拟煤气条件下重复脱硫循环期间评估其脱硫性能和耐久性。在 723 K 和 0.98 MPa 下连续脱硫循环中，两种吸附剂均可将硫化合物降低至 1 ppm 以下。通过氨沉淀制备的吸附剂在初始硫化时表现出较高的性能，但在20个循环测试后硫化动力学有所下降。尿素沉淀吸附剂在相同的脱硫循环中保持其性能。尽管两种吸附剂的残留硫逐渐增加，但在测试结束时吸附剂仍保持其初始硫容量的 75% 以上。通过水银孔隙率测定法获得的孔分布显示，在循环过程中氨沉淀样品的中孔显着损失，而尿素沉淀吸附剂保持其中孔结构。使用 FE-TEM 观察新鲜和用过的吸附剂中铁酸锌的初级颗粒。氨沉淀粉末中铁酸锌的初级颗粒（10-20 nm）比尿素沉淀粉末（直径100 nm）小得多。氨沉淀吸附剂的快速下降是由于细小的初级颗粒的烧结。后者在循环脱硫后保持其尺寸。吸附剂的耐久性受到制备方法决定的初级粒径的强烈影响，吸附剂的制备是提高吸附剂耐久性的重要因素。
Regenerable and durable sorbents for high-temperature sulfur removal are desired to achieve advanced power generation using coal gas fuel. Different precipitation methods using ammonia and urea were studied in this work to prepare zinc ferrite-silica composite particles. Two sorbents containing those powders were extruded and were evaluated in desulfurization performance and durability during cycles of repeated desulfurization at pressurized simulated coal gas conditions. Both sorbents could reduced sulfur compounds to less than 1 ppm during consecutive desulfurization cycles operated at 723 K and 0.98 MPa. The sorbent prepared by ammonia precipitation exhibited higher performance at initial sulfidation but declined in sulfidation kinetics after 20 cycles of tests. The urea-precipitated sorbent maintained its performance during the same desulfurization cycles. Although the residual sulfur was gradually increased for both sorbents, the sorbents maintained over 75% of their initial sulfur capacity at the end of the test. Pore distribution obtained by mercury porosimetry showed significant loss of mesopores of the ammonia-precipitated sample during the cycles, while the urea-precipitated sorbent maintained its mesopore structure. The primary particles of zinc ferrite in the fresh and spent sorbents were observed using FE-TEM. Primary particles of zinc ferrite in the ammonia-precipitated powder were much smaller (10-20 nm) than those of the urea-precipitated powder (100 nm diameter). Rapid decline in the ammonia-precipitated sorbent was due to the sintering of the fine primary particles. The latter kept their size after cyclic desulfurization. The durability of the sorbent was strongly affected by the primary particle size as determined by the preparation method and sorbent preparation is an important factor to enhance durability of the sorbent.