摘要: A series of Co-doped Mn oxide catalysts with different Co/Mn molar ratios were prepared by co-precipitation method, which was systematically characterized by XRD, SEM, H2-TPR and NH3-TPD etc. Co-doped Mn oxide catalysts are evaluated for NH3-SCR activity and resistance to SO2 and/or H2O, and the Co(1)-MnOx catalyst with Mn/Co molar ratio of 1∶1 performs the best catalytic performance, which achieved higher than 90% NOx conversion in the temperature range of 100−275 °C and possessed better SO2 and H2O resistance. The Co(1)-MnOx catalyst presented a sphere-like structure possessing a relatively large surface area. Doping of cobalt greatly improved the high-valent metal ions and chemisorbed oxygen content of Co(1)-MnOx catalyst surface, and the catalyst possessed abundant active species and acid sites and apparent activation energy of the catalyst was reduced, which makes Co(1)-MnOx a highly effective NH3-SCR catalyst.
摘要: Nitrogen-doped carbons (Nano-NC) are often employed as functional supports for boosting oxygen reduction reaction (ORR) over Pt-based catalysts, however, the mechanism of N doping on the adsorption and activation of molecular oxygen on Pt active sites is still not clear. Herein, Nano-NCs as the supports were prepared by a facile NH3 antipyretic method, which allowed to tune the kinds of nitrogen species in carbon matrix and their contents by adjusting the NH3 antipyretic temperatures. With such an exquisite control, the Pt nanoparticles loaded on the as-obtained Nano-NC showed an optimal Pt particle size (2.10 nm), a higher content of Pt0, a large electrochemically active surface area, and fast electron transport ability. As a consequence, the Pt/Nano-NC-800 catalyst with the optimal N-doping showed an outstanding ORR performance with half-wave potential of 0.80 V vs. RHE, limit diffusion current of 5.37 mA/cm2 and improved methanol/CO anti-poisoning, which is superior to the commercial Pt/C catalyst (20%, JM), and most of previously reported Pt-based catalysts. This work may pave a way for the design of the advanced supports for Pt-based catalysts for the ORR applications.
摘要: Co/HZSM-5 catalyst was fabricated for catalytic dehydrogenation of propane to propylene, which was pretreated to allow the reaction to react at low temperatures. A response surface approach was employed to examine the effect of process conditions on the reaction. The morphological and oxidative performance of Co/HZSM-5 was characterized by XRD, XPS, SEM, NH3-TPD, H2-TPR, and nitrogen physical absorption-desorption. Besides, the in-situ catalyst performance was evaluated by a fixed-bed reactor. Combining the actual experimental conditions, the optimal process conditions parameters obtained by the response surface method were as follows: a reaction temperature of 461 °C, a Co loading of 2.4%, and a GHSV of 4300 h−1. At this point, the propylene yield reached 27.7% and the corresponding propylene selectivity was up to 93.8%.