摘要
用脉冲反应考察了富氢条件下Au/γ Al2 O3 催化剂上CO的选择氧化反应 .结果表明 ,CO和O2 在Au/γ Al2 O3 催化剂表面同时发生吸附 ,其吸附活性中心都在催化剂的活性组分表面 ,CO的吸附强度大于O2 的吸附强度 ,吸附态的CO和吸附态的O2 之间反应生成CO2 .提高反应温度和增加原料中氧的含量都能提高CO的转化率 .在所考察的实验条件下 ,O2 的反应选择性基本上为 10 0 % .
To understand the reaction mechanism of CO oxidation as well as the effect of reaction conditions on CO conversion, we used pulse reaction method to investigate the reaction over Au/ γ Al 2O 3 in H 2 rich atmosphere. The catalyst was prepared by deposition precipitation method in HAuCl 4 solution using γ Al 2O 3 as support, the Au loading was 2%. The catalyst precursor was pretreated in H 2 at 300 ℃ for 2 h, then crashed into 80～100 mesh. The reaction conditions were as follows: m (cat) =20 mg, using H 2 as the carrier gas, p (H 2) =0 1 MPa, SV=45 ml/min , and V (CO) =1 ml. The product was analyzed using a GC equipped with a thermal conductivity detector and a 13X column, the column temperature was 40 ℃. The effects of pulse composition λ(λ = 2 p (O 2) / p (CO) ) as well as reaction temperature on CO conversion were studied. In addition, the CO 2 productivity in the case of preadsorbing O 2 on catalyst then pulsing CO or preadsorbing CO on catalyst then pulsing O 2 was investigated. In the case of preadsorbing O 2, at the first CO pulse the CO 2 productivity approached 20%(0 20 ml), at the same time accompanied with about 0 043 ml of O 2 desorption, from then on as the CO pulse numbers increased the CO 2 productivity in the product was sharply decreased to nearly zero. However, in the case of preadsorbing CO on catalyst, as the O 2 pulse numbers increased, the CO 2 productivity first increased through a maximum value then decreased. In both cases, the total CO 2 productivity was almost the same, namely was equal to about 0 20 ml. It was demonstrated that CO and O 2 were adsorbed simultaneously on the surface of Au/ γ Al 2O 3, the adsorption center was at Au surface but the adsorption strength of CO was more powerful than O 2. The reaction between CO and O 2 resulted in the formation of CO 2. Increasing reaction temperature or O 2 content could increase the CO conversion. Under the conditions of λ =1～4 and θ =-25～0 ℃, the O 2 reaction selectivity achieved 100%.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2003年第9期691-694,共4页
关键词
富氢
一氧化碳
氧
选择氧化
二氧化碳
金
氧化铝
负载型催化剂
hydrogen rich, carbon monoxide,oxygen, selective oxidation, carbon dioxide, gold, alumina, supported catalyst
