纳米晶PbTiO3负载CuO催化NO分解

A large specific surface area perovskite-type mixed oxide PbTiO₃ supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H₂-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO₃ was inactive for the reactions, but 1wt % Cu/PbTiO₃ catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO₃. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO₃ support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.     

戊戌政变后蔡元培辞官直接动因考析

戊戌政变后，蔡元培毅然弃官归里，直接动因在于戊戌政变的刺激：崇拜之人如谭嗣同喋血，皇上遭囚禁。师友被革职。他愤懑却又无可奈何。这促使他认识到“清廷之不足为”，“无可希望”。愤激之余，惟有离京返乡探索救国之他路。