Translated Abstract
Caused by massive consumption of fossil fuels and severer environmental issues, it becomes an urgent need to find a kind of clean and sustainable energy source. Nowadays, hydrogen has attracted great attention due to its clean, recyclable and high-energy-density property. However, the storage and transportation of hydrogen remains a big problem which limits its utilization in hydrogen industry. Formic acid has attracted lots of attention because it is an organic hydrogen carrier which can be produced from many biomass processing factories and can be used in fuel cells directly or indirectly. For the reaction of formic acid decomposition, noble metal catalysts have the disadvantage of high cost and limited application, so the designing of bi-metallic catalysts is a promising strategy to regulate the reaction performance. Meanwhile, it is important to study the synergetic effect of two metals to guide the designing of high performance catalysts. This thesis is based on both experimental and theoretical study.
In the experimental section, first, PdCu/SiO2 and PdAg/SiO2 catalysts with different metal ratios were synthesized by impregnation method. Second, fixed-bed reactor was used to test catalysts’ reaction performance in 130-270 ＂℃＂ . Third, the activity and selectivity related to different temperature and dosage of the catalysts were figured out. Fourth, kinetic parameters such as activation energy, reaction rate constant and reaction orders were calculated. Besides, some characterization methods such as TEM, ICP-MS, XRD and XPS were used to study the morphology and electronic properties of the catalysts and clarify the alloy effect of the two metals. The result showed that both PdCu/SiO2 and PdAg/SiO2 catalysts exhibited high catalytic reactivity and explained the synergetic effect of the two metals.
In the theoretical section, the adsorption configurations and adsorption energy of HCOOH, HCOO, COOH HCO etc. were calculated. Furthermore, the transition states, energy barriers and ＂∆H＂ of different elementary reations were studied and worked out. The result showed that the optimized reaction pathway of HCOOH was ＂HCOOH→COOH+H→＂ 〖＂CO＂ 〗_＂2＂ ＂+＂ ＂H＂ _＂2＂ . It was found that experimental results and theoretical results fit well and both explained the synergetic effect.
Translated Keyword
[Bi-metallic catalysts, Formic acid, Reaction mechanism, Synergetic effect]
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