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本文采用TPR、TPO技术分别考察了氧处理Pt/TiO_2上氧物种的还原行为和氢还原样品的氧化过程.TPR结果表明,表面含有活泼氧物种的Pt/TiO_2样品对氢很活泼,室温条件下可以吸附大量氢,并且这些吸附氢又可以在TPR过程中脱附.表面活泼氧物种与氢的反应温度在500—673K之间,当大于673K时,Pt/TiO_2继续耗氢,可能是氢与还原产生的表面Ti~(3+)离子进一步反应生成钛—氢物种,并向TiO_2体相扩散与TiO_2体相晶格氧发生反应.对于773K还原的Pt/TiO_2作品,室温吸附氧在TPD过程中可以与表面吸附氢反应;473K氧化处理可以消除表面的吸附氢,但并不能完全去除体相储氢;573K氧化处理则基本上恢复了原样品的氧化状态.不同温度氢还原处理的Pt/TiO_2样品在动态氧化过程(TPO)中,在300-600K温区,气相氧与样品上表面吸附氢和表面氧空位反应;在大于600K温区,氧主要与表面钛—氢物种发生反应,并向体相扩散,与体相氢发生反应.文中描述了气相氢、氧分别与Pt/TiO_2催化剂存在的氧或氢物种作用的形式.
In this paper, TPR and TPO techniques were used to investigate the reduction behavior of oxygen species on Pt / TiO 2 and the oxidation process of hydrogen reduction samples respectively.TPR results show that Pt / TiO 2 samples with active oxygen species on the surface are very active for hydrogen, Can adsorb a large amount of hydrogen, and these adsorbed hydrogen can be desorbed in the TPR process.The reactive oxygen species and hydrogen reaction temperature between 500-673K, when greater than 673K, Pt / TiO_2 continue to consume hydrogen, hydrogen and may be hydrogen The Ti (3+) ion generated on the reduction further reacted to form a Ti-H species, and diffused into the bulk of TiO 2 to react with the lattice oxygen of TiO 2 phase. For the 773K reduced Pt / TiO 2 work, Can be adsorbed on the surface of the hydrogen reaction; 473K oxidation can eliminate adsorption of hydrogen on the surface, but does not completely remove the bulk hydrogen storage; 573K oxidation is basically restored the original sample oxidation state. Hydrogen reduction at different temperatures Pt / In the dynamic oxidation process (TPO) of TiO_2 samples, the gas phase oxygen reacted with the adsorbed hydrogen and the surface oxygen vacancies on the upper surface of the sample in the temperature range of 300-600K. At the temperature of more than 600K, oxygen reacts mainly with the surface titanium-hydrogen species To the body Diffusion, bulk and hydrogen react. Paper describes the gas phase of hydrogen, oxygen or hydrogen form of oxygen species acting Pt / TiO_2 presence of catalyst, respectively.