程序升温测硫技术在研制钴钼耐硫变换催化剂中的应用

APPLICATION OF TPSD ON THE SULFUR TOLERANT WATER GAS SHIFT REACTION CATALYST

利用程序升温测硫技术（ＴＰＳＤ） 对自制的和一些工业的钴钼耐硫变换催化剂中硫的存在状态、作用等进行了研究。结果表明： （１） 负载在γ－Ａｌ２Ｏ３ 上的Ｍｏ 的硫化物较未负载Ｍｏ 的硫化物或９８％ ＭｏＳ２ 易与氧、氢和水蒸气反应， 载体不仅可提供大的反应表面， 而且活化了与Ｍｏ 相联的硫原子； （２） 负载在γ－Ａｌ２Ｏ３ 上的Ｃｏ 不能被硫化， 但是当Ｍｏ／γ－Ａｌ２Ｏ３ 中加入Ｃｏ 后， 与Ｍｏ 相联的硫变得更加活泼， 更易与氧、氢和水蒸气反应， 可见Ｃｏ 与Ｍｏ 作用减弱了Ｓ－Ｍｏ 键的强度； （３） Ｃｏ－Ｍｏ／γ－Ａｌ２ Ｏ３ 中加入Ｋ 后， 催化剂中的硫很难与氢反应， 但易与水蒸气反应； （４） 几乎所有的硫化物催化剂， 包括工业催化剂， 在与氧、氢和水蒸气反应过程中，其ＴＰＳＤ－Ｏ２ 谱图在２００～２８０℃和４００～４７０℃温区均有硫峰出现；（５）硫化物催化剂热稳定性不好的原因是催化剂经高温处理后，低温活性位不可逆地转变为高温活性位；（６）提出了硫化物催化剂上水煤气变换反应的机理， 硫在催化过程中起着十分重要的作用。

A series of sulfided catalysts as well as two commercial sulfur tolerant water gas shift reaction catalysts were investigated by using the technique of TPSD(Temperature programmed sulfur detection) The results showed as follows:(1)The behavior of γ Al 2O 3 supported Mo sulfide is quite different from that of the unsupported one The former reacts easily with O 2,H 2 and steam However the support γ Al 2O 3 not only provides large surface area,but also activates the sulfur atoms coordinated with Mo (2)γ Al 2O 3 supported CoO itself can not be sulfided It is proposed that Co,containing in sulfided Mo/γ Al 2O 3 catalyst,can weaken the S—Mo bond,and thus making the sulfur more active toward the water gas shift reaction (3)Adding K into sulfided Co Mo/r Al 2O 3 catalyst,the sulfur is difficult to be reduced by H 2,but easy to be oxidized by steam (4)Low thermal stability of catalyst containing K is due to the unstability of its low temperature active sites and the irreversible conversion into its more stable form at higher temperatures (5)Based on the experimental results,a mechanism of water gas shift reaction has been proposed which indicated that sulfur played an very important role in the catalytic reaction