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Study on the Highly Active Nano-Gold Catalysts Used for CO Preferential Oxidation in H2-Rich Stream

Author: TuYunBao
Tutor: MengMing
School: Tianjin University
Course: Industrial Catalysis
Keywords: Ultrasonic pretreatment Synthesis solution pH Au loading Calcination temperature Ultrasonic time Carbon monoxide preferential oxidation Ceria
CLC: O643.36
Type: PhD thesis
Year: 2011
Downloads: 92
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Abstract


In this paper, coprecipitation a MnO x -CeO 2 Mixed Oxide (Mn / Ce = 1:1), corresponding deposition - precipitation method supported gold catalysts Au / the MnO x -CEO 2 . As a novel and simple preparation techniques, ultrasound-assisted pretreatment for nano-Au / the MnO x -CeO 2 catalyst preparation process that aims to improve the catalytic CO PROX reaction performance. First carrier ultrasonic pretreatment of Au / MnO x -CeO 2 structure and catalytic CO PROX performance; followed by emphasis on the ultrasound-assisted deposition - precipitation in the preparation of the catalyst parameters such as Au synthesis solution pH value (7.0-11.0), Au load (0.5-5.0 wt%), the calcination temperature (150-350 ° C) and Vectors ultrasonic dispersion time (0-30 min) The effects of the addition of Pt on Au / MnO x -CeO x -CeO 2 the PROX properties of the sample; > 2 catalyst PROX performance. MnO x -CeO 2 carrier ultrasonic pretreatment significantly improve the Au / MnO x -CeO 2 of catalytic activity at 120 ° C when the CO conversion rate increased by 24%; the O 2 to the selectivity of CO 2 in the entire investigated temperature range has been greatly improved especially in the 80-120 ° C range, increase the selectivity of 15-21%. Ultrasound-assisted deposition - precipitation prepared the MnO x -CEO 2 composite oxide load Au catalyst Au synthesis solution pH = 10.0, Au load the amount of w = 1.0 wt. %, calcination temperature of the catalyst is t = 250 ° C and Vectors ultrasonic dispersion time T = Au (1.0) / the MnO x -CeO prepared in under 5 min Condition 2 -10.0- 250-5 catalyst has the best PROX performance, not only in the reaction temperature of 120 ° C shows the best CO conversion rate of 90.9%, and in proton exchange membrane fuel cell operating temperature range (80 1 20 ° C) also shows the best the O 2 to CO 2 selective. PROX performance of the catalyst to 120 ° C within 100 h of test, no decline has better activity stability. The addition of Pt Au / MnO x -CeO 2 PROX catalyst performance is improved to some extent, especially the CO conversion rate in 100 ° C reached 100%. BET, XRD, TEM, SEM, XPS, UV-vis DRS and H 2 -TPR and other structure and morphology of the catalyst were characterized. HR-TEM, XRD and UV-vis DRS results showed that ultrasound broken sheet structure of the catalyst; XRD, TEM and XPS results have consistently shown that ultrasound Au (1.0) / the MnO x - CeO 2 the catalyst -10.0-250-5 has the highest Au particle dispersion and up to the surface adsorbed oxygen, promote the oxidation of CO; XPS and H 2 -TPR The results show that the the catalysts Au (1.0) / the MnO x -CEO 2 -10.0-250-5 there is a strong gold - vector interactions, reducing the catalyst H the dissociation ability 2 , effectively inhibit the occurrence of hydrogen spillover effect, leading to the catalyst has the highest O to of CO 2 selective ; Add Pt catalyst, XRD, SEM and H 2 -TPR results show that, after the introduction of the Pt catalyst, the formation of a new metal phase, changing the structure of the catalyst morphology and oxidation reduction behavior, the dual noble metal catalysts have better PROX response performance.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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