FTIR Study of Adsorbed Nitrogen and hydrogen on Ruthenium Catalyst for Next Generation Ammonia Synthesis

铁催化剂易发生氨中毒，需控制一次转化以保持较低的氨中毒值。钌具有不被氨中毒的优点，但具有氢中毒的缺点，因此开始作为第二代氨催化剂使用。在单原子试验下研制的活性钌催化剂，在工业高压条件下，有时会因氢中毒而失去活性。本工作的目的是研制一种不强烈吸附氢的钌催化剂，并用FTIR技术考察其对氢和氮的吸附行为。1)以Ru_3 (CO)_<12>、不同载体（MgO、CeO_2、ac、Al_2O_3等）和不同促进剂（CsOH、BaO等）为原料合成了多种Ru催化剂。合成了由6个Ru原子组成的Ru簇，其中中心有1个N原子。2)利用EXAFS、XPS、XRD、TEM等分析了Ru簇的结构。计算了聚类大小和平均协调数。3) FTIR观察到两种类型的氢原子（上氢原子和桥氢原子）吸附。在Ru/MgO上观察到两种类型，而在Ru/CeO_2上主要观察到顶部氢。4)氨合成及动力学研究。氢中毒对Ru/MgO反应较强，对Ru/CeO_2反应较弱。Ru/CeO_2经873K氢处理后，具有较高的活性。

Iron catalysts suffer from ammonia poisoning, because of which one-pass conversion is controlled to keep the low value. Ruthenium was started to be used as a second generation ammonia catalyst because it has an advantage not to be poisoned by ammonia, however it has a disadvantage of hydrogen poisoning. The active ruthenium catalyst developed under 1 atom test some times are not active under the industrial high pressure condition because of the strong hydrogen poisoning. The purpose of this work is to develop a Ru-catalyst which does not adsorb hydrogen strongly and to check the adsorption behavior of hydrogen and nitrogen by FTIR technique.1) Various Ru catalysts were synthesized from Ru_3 (CO)_<12>, various supports (MgO,CeO_2, A.C., Al_2O_3, etc.), and various promoters (CsOH,BaO,etc.). Ru cluster composed by six Ru atoms including one N atom at the center was also synthesized and supported on MgO.2) The structure of Ru Cluster was analyzed by EXAFS,XPS,XRD,TEM,etc.The size of cluster and average co-ordination number was calculated.3) Two types of adsorbed hydrogen (on-top and bridge) atom were observed by FTIR.Two types were observed on Ru/MgO,but on Ru/CeO_2 mainly on-top hydrogen was observed.4) Ammonia synthesis and kinetics were studied. Hydrogen poisoning was strong in Ru/MgO but weak on Ru/CeO_2. Ru/CeO_2 was found to become highly active when it was treated by hydrogen at 873K.