Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Porto, Portugal.
J Colloid Interface Sci. 2012 Mar 1;369(1):294-301. doi: 10.1016/j.jcis.2011.11.059. Epub 2011 Dec 6.
The effect of the support (activated carbon or titanium dioxide) on the catalytic activity and selectivity to nitrogen of Pt-Sn catalysts in nitrate reduction was studied. The effects of the preparation conditions and the Pt:Sn atomic ratio were also evaluated. It was observed that the support plays an important role in nitrate reduction and that different preparation conditions lead to different catalytic activities and selectivities. Generally, the catalysts supported on activated carbon were less active but more selective to nitrogen than those supported on titanium dioxide. The monometallic Pt catalyst is active for nitrate reduction only when supported on titanium dioxide, which is explained by the involvement of the support in the reaction mechanism. The catalysts were characterized by different techniques, and significant changes on metal chemical states were observed for the different preparation conditions used. Only metallic Pt and oxidized Sn were observed at low calcination and reduction temperatures, but some metallic Sn was also present when high temperatures were used, being also possible the formation of Pt-Sn alloys.
研究了载体（活性炭或二氧化钛）对 Pt-Sn 催化剂在硝酸盐还原中催化活性和选择性的影响。还评估了制备条件和 Pt:Sn 原子比的影响。结果表明，载体在硝酸盐还原中起着重要作用，不同的制备条件导致不同的催化活性和选择性。一般来说，负载在活性炭上的催化剂的活性较低，但对氮的选择性较高，而负载在二氧化钛上的催化剂则相反。只有当负载在二氧化钛上时，单金属 Pt 催化剂才对硝酸盐还原具有活性，这可以通过载体参与反应机制来解释。通过不同的技术对催化剂进行了表征，观察到不同制备条件下金属化学状态发生了显著变化。仅在较低的煅烧和还原温度下观察到金属 Pt 和氧化 Sn，但在使用较高温度时也存在一些金属 Sn，也可能形成 Pt-Sn 合金。
