TiO_2对H_2S/SO_2的作用特性

采用程序升温脱附(TPD)和程序升温电导(TPEC)两个平行的测量方法以及红外(IR)研究了TiO_2对H_2S/SO_2作用过程中化学和电导特性的变化。发现TiO_2可和H_2S、SO_2发生化学反应,Al_2O_3则不能。在大于200℃时,H_2S在TiO_2上可转化为S、H_2O和SO_2,SO_2可被氧化为SO_3。有趣的是,在经预还原处理的TiO_2上,H_2S可分解生成H_2,SO_2可被还原为S。在转化过程中,TiO_2本身的电导发生相应的变化。另外,H_2S和SO_2在TiO_2上比在Al_2O_3上容易脱附,不易发生硫酸盐化,因此,TiO_2在Claus反应中比Al_2O_3催化剂有更优良的催化性能与TiO_2中钛的变价有关。

Characteristic Interaction between TiO_2 and H_2S/SO_2

Parallel measurements of temperature programmed desorption (TPD) and electrical conductance (TPEC), and IR spectra were used to study the chemical and electrical behavior of TiO_2 subjected to H_2S/SO_2. It is found that TiO_2 interacts chemically with both H_2S and SO_2, whereas Al_2O_3 does not. Above 200℃, H_2S may be turned into S, H_2O and SO_2 on TiO_2, and SO_2 may be further oxidized forming SO_3. Interestingly, over the pre-reduced TiO_2, H_2 is generated from H_2S, and S is formed from SO_2. During the reaction course, the conductance of TiO_2 itself undergoes multistage change corresponding to the successive reaction mechanism. It is also shown that the adsorbed H_2S and SO_2 desorb from TiO_2 much more easily than from Al_2O_3, so that no severe sulfation is observed on TiO_2. Accordingly, it is understandable that TiO_2 can work more effectively in Claus reaction than the commonly used Al_2O_3 catalyst.