共查询到4条相似文献,搜索用时 78 毫秒
1.
Chaopeng Duan Ruitang Guo Yuanzhen Liu Guilin Wu Yufang Miao Jingwen Gu Weiguo Pan 《中国稀土学报(英文版)》2022,40(1):49-56
Alkali metal K in exhaust gas has a deactivation effect on NH3-SCR catalysts.In this work,it is discovered that the addition of Ho on CeTi catalyst can remarkably strengthen its K tolerance.The conclusions of Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),NH3 temperature programmed desorption(NH3-TPD)and H2temperature programmed reduction(H2-TPR)analyses demonstrate that the enhancement of K resistance mainly originates from its stronger surface acidity and redox capability,the higher concentration of Ce3+species and surface chemisorbed oxygen.In situ DRIFT analysis reveals that the introduction of Ho on CeTi can remarkably improve the adsorption of NH3 and NOx species on catalyst surface,accompanied by the intensified reactivity of ad-NH3 species,which should also administer to improve the K resistance. 相似文献
2.
The presence of oxygen vacancies and hydroxyl groups are both favorable for the methanol electrooxidation on Pt-based catalysts.Understanding and differentiating the enhancing mechanism between oxygen vacancies and hydroxyl groups for high activity of Pt catalysts in methanol oxidation reaction(MOR)is essential but still challenging.Herein,we developed two kinds of co-catalyst for Pt/CNTs,Pr6O11is rich in oxygen vacancies but contains substantially no hydroxyl groups,while Pr(OH)3 possesses abundant hydroxyl groups without oxygen vacancies.After a seque nce of designed experiments,it can be found that both oxygen vacancies and hydroxyl groups can improve the performance of Pt/CNTs electrocatalysts,but the enhancing mechanism and improving degree of oxygen vacancies and hydroxyl groups for the MOR are different.Since the oxygen vacancies are more conducive to increasing the intrinsic activity of the Pt catalyst,and the hydroxyl groups play a decisive role in dehydrogenation and deproto nation of methanol,the co-catalysts with both oxygen vacancies and hydroxyl groups mixed with Pt/CNTs have higher catalytic performance.Therefore,hydroxyl-rich Pr6O11·xH2O was prepared and used as MOR electrocatalyst after mixed with Pt/CNTs.Benefiting from the synergistic effect of oxygen vacancies and hydroxyl groups,the Pr6O11·xH2O/Pt/CNTs shows a high peak current density of 741 mA/mg,which is three times higher than that of Pt/CNTs.These new discoveries serve as a promising strategy for the rational design of MOR catalysts with low cost and high activity. 相似文献
3.
Jing Rong Wanxia Zhao Wen Luo Keke Kang Lulu Long Yang Chen Xiaojiang Yao 《中国稀土学报(英文版)》2023,41(9):1323-1335
The MnXOx catalysts(i.e.,MnSmOx,MnNdOx,MnCeOx) were prepared by reverse co-precipitation method and used for NH3-SCR reaction.It is found that MnCeOx catalyst presents the best low tempe rature catalytic activity(higher than 90% NOx conversion in the te mperature range from 125 to 225℃)and excellent H2O+SO2 resistance.In order to explore the reason for this result,the characterization of X-ray diff... 相似文献
4.
A superior Ce-Ta-Sb composite oxide catalyst prepared using homogeneous precipitation method exhibited excellent deNOx efficiency and nearly 100% N_2 selectivity with broad operation temperature window and better resistance to higher space velocity, meanwhile strong resistance to H_2 O and SO_2. This catalyst was systematically characterized using XRD, N_2 adsorption, SEM, TEM, XPS, ESR, Raman, H_2-TPR,NH3-TPD and in situ DRIFTS. There exists a synergistic effect between Ce, Ta and Sb species. It is further indicated that the prominent deNOx performance of the Ce3 Ta3 SbOx catalyst is attributed to the elevated Ce3+ concentrations, abundant active surface oxygen species, as well as surface acidity and reducibility,which is closely linked with the synergistic effect between Ce, Sb and Ta species. Results from DRIFTS reveal that the reaction mechanism of surface-adsorbed NH3 and NO_x species is linked to temperature,the L-H mechanism mainly occurs at low temperature(300 ℃),while the E-R mechanism occurs at high temperature(300 ℃). Overall,these findings indicate that Ce3 Ta3 SbOx is promising for NO_x practical abatement. 相似文献