水蒸气对Pt-Sn-Ce催化剂的丙烷脱氢性能的影响

 摘要：以γ-Al2O3为载体, 采用连续等体积浸渍法制备了0.3%Pt/γ-Al2O3、0.3%Pt-0.9%Sn/γ-Al2O3和0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3 3种Pt金属催化剂。考察了在C3H8催化脱氢制C3H6的体系中, 引入不同量的水蒸气对3种催化剂的催化脱氢性能的影响。结果表明，水蒸气的存在加速了0.3%Pt/γ-Al2O3和0.3%Pt-0.9%Sn/γ-Al2O3催化剂的失活, 同时降低了C3H6的选择性, 但对0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3催化剂的稳定性影响较小。在0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3体系中，水蒸气可以明显地提高C3H8的脱氢反应转化率和降低催化剂上的积炭量。对水蒸气处理后的Pt催化剂进行H2-化学吸附量测定的结果表明, Ce可以通过与活性中心Pt的强相互作用, 提高Pt粒子在水蒸气气氛下的抗烧结能力。C3H8脱氢转化率的提高是由于CeO中的活泼O与活泼H反应产生OH基团，OH基团参与了C3H8的β-H的消除反应, 提高了C3H8的脱氢速率。以γ-Al₂O₃为载体, 采用连续等体积浸渍法制备了0.3%Pt/γ-Al₂O₃、 0.3%Pt-0.9%Sn/γ-Al₂O₃和0.3%Pt-0.9%Sn/2.2%Ce-γ-Al₂O₃3种Pt 金属催化剂。考察了在丙烷（C₃H₈）催化脱氢制丙烯（C₃H₆）的体系中，引入不同量的水蒸气对3种催化剂的催化脱氢性能的影响。结果表明，水蒸气的存在加速了0.3%Pt/γ-Al₂O₃和0.3%Pt-0.9%Sn/γ-Al₂O₃催化剂的失活,同时降低了C₃H₆的选择性,但对0.3%Pt-0.9%Sn/2.2%Ce-γ-Al₂O₃催化剂的稳定性影响较小。在0.3%Pt-0.9%Sn/2.2%Ce-γ-Al₂O₃体系中，水蒸气可以明显地提高 C₃H₈的脱氢反应转化率和降低催化剂上的积炭量。对水蒸气处理后的 Pt 催化剂进行 H₂-化学吸附量测定的结果表明,Ce 可以通过与活性中心 Pt 的强相互作用,提高 Pt 粒子在水蒸气气氛下的抗烧结能力。C₃H₈脱氢转化率的提高是由于CeO 中的活泼O 与活泼H 反应产生OH 基团，OH 基团参与了 C₃H₈的 β-H 的消除反应, 提高了C₃H₈的脱氢速率。

Effect of Steam on the Performance of Pt-Sn-Ce Catalyst for Propane Dehydrogenation

Abstract: 0.3%Pt/γ-Al2O3, 0.3%Pt-0.9%Sn/γ-Al2O3 and 0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3 catalysts were prepared by impregnation method with γ-Al2O3 as support. The effects of the steam addition to the system of the catalytic dehydrogenation of propane to propylene on the performance of Pt catalysts were investigated. The results showed that the addition of steam accelerated the deactivation of 0.3%Pt/γ-Al2O3 and 0.3%Pt-0.9%Sn/γ-Al2O3 catalysts and decreased the selectivity of propylene. However, the steam had no obvious effect on the stability of 0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3 catalyst. Moreover, the presence of steam in the reaction system of propane dehydrogenation could promote the conversion of propane and decrease the amount of coke over 0.3%Pt-0.9%Sn/2.2%Ce-γ-Al2O3 catalyst. H2-chemical adsorption of the Pt catalysts treated with steam showed that the ability of Pt particles to resist the sintering was increased by the strong interaction between Ce and Pt in steam atmosphere. The main reason for the increase of propane conversion is that the active oxygen species reacted with active hydrogen atom to produce OH groups, which may participate in the elimination of β hydrogen atom in propane, resulting in the increase of dehydrogenation rate. 0.3%Pt/γ-Al₂O₃, 0.3%Pt-0.9%Sn/γ-Al₂O₃ and 0.3%Pt-0.9%Sn/2.2%Ce-γ-Al₂O₃ catalysts were prepared by impregnation method with γ-Al₂O₃ as support. The effects of the steam addition to the system of the catalytic dehydrogenation of propane to propylene on the performance of Pt catalysts were investigated. The results showed that the addition of steam accelerated the deactivation of 0.3%Pt/γ-Al₂O₃ and 0.3%Pt-0.9%Sn/γ-Al₂O₃ catalysts and decreased the selectivity of propylene. However, the steam had no obvious effect on the stability of 0.3%Pt-0.9%Sn/2.2%Ce-γ-Al₂O₃ catalyst. Moreover, the presence of steam in the reaction system of propane dehydrogenation could promote the conversion of propane and decrease the amount of coke over 0.3%Pt-0.9%Sn/2.2%Ce-γ- Al₂O₃ catalyst. H₂-chemical adsorption of the Pt catalysts treated with steam showed that the ability of Pt particles to resist the sintering was increased by the strong interaction between Ce and Pt in steam atmosphere. The main reason for the increase of propane conversion is that the active oxygen species reacted with active hydrogen atom to produce OH groups, which may participate in the elimination of β hydrogen atom in propane, resulting in the increase of dehydrogenation rate.