Promotion Effect of H2 on Ethanol Oxidation and NOx Reduction with Ethanol over Ag/Al2O3 Catalyst
详细信息 查看全文
文摘
The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol鈥揝CR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol鈥揝CR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing 鈭扤CO species again, leading to enhancement of ethanol鈥揝CR over Ag/Al2O3 by H2. Using VUV鈥揚IMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC鈥揝CR over Ag/Al2O3.