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本文用UV/ViS,ESR,TPR等方法研究了 Rh/VOCl_2/SiO_2催化剂在浸渍、干燥、还原和合成气反应过程中V的状态的变化。溶液中的VOCl·5H_2O和HRhCl_5·H_2O或RhCl_3·3H_2O等在浸渍后的干燥过程中可以以络合的形式一起沉积在载体的表面,还原后的钒化合物紧紧地附到Rh的表面,对生成C-含氧化物的选择性(或活性)起着重要的促进作用。VOCl/SiO_2在H_2中热处理时VOCl_2易发生歧化反应生成VOCl和 VOCl_3,而不易被还原,Rh的存在可显著地促进VOCl还原为VOCl Rh/VOCl/SiO催化剂经 H_2 还原后钒的主要价态为三价,在合成气反应中没有发现钒的价态有升高的现象。
In this paper, the change of V state of Rh / VOCl 2 / SiO 2 catalyst during impregnation, drying, reduction and syngas reaction was studied by UV / ViS, ESR and TPR methods. The VOC1 · 5H2O and HRhCl5 · H2O or RhCl3 · 3H2O in the solution can be deposited on the surface of the carrier in complex form during the post-impregnation drying process. The reduced vanadium compound is tightly attached to the surface of Rh, Selective (or active) formation of C-oxides plays an important promoting role. When VOCl / SiO 2 is heat-treated in H 2, VOCl 2 is prone to disproportionation reaction to produce VOCl and VOCl_3, which is not easy to be reduced. The presence of Rh can significantly promote the reduction of VOCl to VOCl Rh / VOCl / SiO catalyst. Trivalent, vanadium in the synthesis gas reaction did not find the valence has increased phenomenon.