THE ADSORPTION AND DECOMPOSITION OF FORMIC-ACID ON CLEAN AND OXYGEN-DOSED PD(110)
THE ADSORPTION AND DECOMPOSITION OF FORMIC-ACID ON CLEAN AND OXYGEN-DOSED PD(110)
复制标题
DOI：
10.1088/0953-8984/3/s/044
复制
发表时间：
1991-11-01
影响因子：
2.7
通讯作者：
BOWKER, M
中科院分区：
文献类型：
--
作者：
AAS, N;LI, YX;BOWKER, M
用TPD和XPS研究了甲酸（HCOOH）与Pd（110）的相互作用。在低剂量下，在140 K的吸附温度下，HCOOH在TPD过程中分解产生CO，CO2，H2-和H2O。CO和H-2分别在470和320 K的脱附极限峰中释放。CO和H2O解吸在非常低的剂量下饱和，表明在这样的瞬态实验中只有很小程度的甲酸盐脱水。的CO2和H-2的演变继续增加剂量和CO2演变在237 K在低剂量下，扩大到较低的温度下，随着覆盖率增加的分解限制峰。HCOOH的脱氢是一阶的活化能为40 kJ mol-1。在剂量高于0.5 L时，观察到分子化学吸附的HCOOH在210 K下解吸，在更高剂量时，存在物理吸附的多层膜，并在180 K下解吸。XPS证实了CO的存在高于250 K和甲酸低于此温度。当预先加入氧气时，甲酸盐显著稳定并且其覆盖度增加，CO解吸被去除，并且以320 K处的H-2峰为代价在较高温度下产生H-2。
The interaction of formic acid (HCOOH) with Pd(110) was studied using TPD and XPS. At low doses, at an adsorption temperature of 140 K, HCOOH decomposed to yield CO, CO2, H-2 and H2O during TPD. CO and H-2 were evolved in desorption-limited peaks at 470 and 320 K, respectively. The CO and H2O desorptions were saturated at very low doses indicating only a small degree of formate dehydration in such a transient experiment. The CO2 and H-2 evolution continued to increase with dose and the CO2 evolved in a decomposition-limited peak at 237 K at low doses which broadened to lower temperature with increasing coverage. This dehydrogenation of HCOOH was of first order with an activation energy of 40 kJ mol-1. At doses above 0.5 L molecularly chemisorbed HCOOH was observed to desorb at 210 K and at still higher doses physisorbed multilayers were present and desorbed at 180 K. XPS confirmed the presence of CO above 250 K and formate below this temperature. When oxygen was pre-dosed the formate was significantly stabilized and its coverage increased, the CO desorption was removed and H-2 was produced at higher temperatures at the expense of the H-2 peak at 320 K.