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以H_2S为毒物,用浸渍法制备了一系列不同载体的钯催化剂(Pd/Al_2O_3、Pd/MgO和Pd/TiO_2)以Na_2S与催化剂机械混合的方式,在载体上引入S~(2-),用H_2—O_2混合气对含硫的催化剂进行处理。藉XPS和IR谱对不同载体的催化剂上硫的吸附及转化进行了研究。结果表明,载体酸碱性对其上担载的贵金属的电子状态有一定的影响。酸性较强的载体对贵金属的分散作用较强,H_2S在这种载体的催化剂上的吸附和转化能力较差。在碱性较强的载体的催化剂上,结果相反。此外,载体上晶格氧的活性不同,对H_2S的转化能力也有差异。在Pd/Al_2O_3催化剂运行过程中,H_2S在A1_2O_3载体上主要发现为一种物理的吸附-脱附过程;而在MgO和TiO_2载体上,不仅存在H_2S的吸附过程,且有H_2S转化为SO_2或SO_4~(2-)的过程。结果还表明,载体性质对催化剂的自身再生能力具有较大影响。
A series of palladium catalysts (Pd / Al 2 O 3, Pd / MgO and Pd / TiO 2) with different carriers were prepared by impregnation method using H 2 S as poison. Sulfur-containing catalysts are treated with a H 2 O 2 mixture. The adsorption and conversion of sulfur on different supports were investigated by XPS and IR spectra. The results showed that the acidity and basicity of the carrier had a certain influence on the electronic state of the noble metal supported on it. The more acidic carriers have a stronger dispersion effect on noble metals, and H 2 S has poorer adsorption and conversion ability on the catalyst of this carrier. On the more basic supported catalysts, the result is reversed. In addition, the activity of lattice oxygen on the support is different, and the conversion ability to H 2 S is also different. During the operation of Pd / Al 2 O 3 catalyst, H 2 S mainly found as a physical adsorption-desorption process on the A1_2O_3 support. On the MgO and TiO_2 supports, not only the adsorption process of H_2S, but also the conversion of H_2S into SO_2 or SO_4 ~ (2-) process. The results also show that the nature of the support has a major impact on the catalyst’s own regenerability.