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

铁系催化剂易发生氨中毒，因此需要控制单程转化率以保持较低的转化率。钌作为第二代氨催化剂开始使用，因为它具有不被氨中毒的优点，但它具有氢中毒的缺点。在1原子试验下开发的活性钌催化剂，在工业高压条件下由于强氢中毒而失去活性。本工作的目的是研制一种不强吸附氢的钌催化剂，并通过FTIR技术考察其对氢和氮的吸附行为。1）以Ru_3（CO）_2、<12>不同载体（MgO、CeO_2、A.C. Al_2O_3等），以及各种助催化剂（CsOH、BaO等）。2）用EXAFS、XPS、XRD、TEM等方法对Ru原子簇的结构进行了分析，计算了Ru原子簇的尺寸和平均配位数; 3）在MgO上吸附了两种类型的氢在Ru/MgO催化剂上存在两种氢原子，而在Ru/CeO_2催化剂上主要是氢原子被吸附在催化剂上。4）氨合成反应及动力学研究。Ru/MgO的氢中毒较强，而Ru/CeO_2的氢中毒较弱。Ru/CeO_2催化剂在873 K下经氢处理后具有较高的催化活性。

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.