钡改性的Ni/γ-Al_2O_3催化剂用于甲烷部分氧化的研究

Study on partial oxidation of methane over Ba modified Ni/γ-Al_2O_3 catalyst

800℃、80 000h-1、CH4/O2/N2=14/7/79下比较了质量分数20%的N i/-γA l2O3和Ba改性的N i/-γA l2O3催化剂,用于甲烷部分氧化反应的活性和选择性。结果表明,Ba的添加提高了镍基催化剂的活性和稳定性。BET和XRD表明,Ba的加入有利于高温焙烧下抑制大颗粒的N iA l2O4的形成,保持了高比例的活性镍组分,提高了催化剂催化活性。常压下,xCH4接近100%,sCO、sH2达到92.2%和98.1%,催化剂15h内活性稍微下降。Ba的加入使A l2O3的晶型转化温度由800℃提高到900℃,提高了载体的稳定性。

Na2CO3-NaOH was used as precipitator to prepare Ba modified Ni/γ-Al2O3 catalysts with co-deposition method. XRD and BET showed that the catalyst prepared by this method had better dispersion of the active components and strong interaction between the active component and the support. Compared with Ni/γ-Al2O3 catalysts, the addition of Ba enhanced the activity and the stability of the catalysts for partial oxidation of methane. The CH4 conversion was close to 100% and H2 selectivity reached 98. 1% over Ba modified Ni/γ-Al2O3 catalysts under the condition of space velocity = 80 000 h^-1 and CH4/O2/N2 = 14/7/79 at 800 ℃. The addition of Ba did not change the BET area of the catalysts, but inhibited the formation of granular NiAl2O4, which favored the existence of activity component, and improved the stability of the support so as to improve the catalyst performance. After 15 h stability test at 800 ℃, the methane conversion was kept about 95%. The test results show that Ba modified Ni/γ-Al2O3 catalyst has higher activity for partial oxidation of methane.