载体中添加La对Ni／γ-Al_2O_3催化剂催化甲烷自热重整制氢反应的影响

采用共沉淀法制备了γ-Al2O3载体和La添加量不同的LaxAl100-xO(m(La):m(Al)=x:(100-x))载体,然后用浸渍法制备了Ni负载量(质量分数)为10％的Ni／γ-Al2O3和Ni／LaxAl100-xO催化剂。用X射线衍射技术对Ni/γ-Al2O3和Ni／ LaxAl100-xO催化剂进行了表征,并在固定床微反装置中考察了Ni／γ-Al2O3和Ni/LaxAl100-xO催化剂对甲烷自热重整制氢反应的催化性能。实验结果表明,添加La的催化剂催化性能有很大提高。考察了反应温度、原料气配比和甲烷空速对Ni/La30Al70O催化剂催化性能的影响。实验结果表明,反应温度和n(O2):n(CH4)对Ni/La30Al70O催化剂的催化性能影响较大;在n(CH4):n(O2): n(H2O)=1．00:0．50:2．50、反应温度800℃、甲烷空速4 800 h-1的条件下,甲烷转化率达到100％,H2收率为67％。

Addition of La to Support of Ni/γ-Al2O3 Catalyst Used in Methane Autothermal Reforming

γ-Al2O3 and LaxAl10-xO(m(La):m(Al)=x:(100-x)) supports were prepared by coprecipitation. Ni/γ-Al2O3 and Ni/LaxAl100-xO catalysts were prepared by impregnation. The catalysts were characterized by means of XRD. Their catalytic performances in methane autothermal reforming to produce hydrogen were studied in a fixed-bed reactor. Addition of La improved activity of catalyst. Effects of reaction conditions, namely reaction temperature, n (O2) : n (CH4 ), n (H2 O) : n( CH4) and gas hourly space velocity(GHSV) of CH4,on activity of Ni/La30Al70O catalyst (mass fraction of La in support was 30%) were investigated. CH4 conversion and H2 yield increased at higher reaction temperature. Catalytic activity of Ni/La30Al70O catalyst was the best when n( O2) : n( CH4) was 0.50. It was only slightly affected by change of n(H2O):n(CH4)and almost unchanged while GHSV of CH4 varied from 2 400 to 7 200 h-1. CH4 conversion and CO selectivity decreased when GHSV of CH4 was further raised to 9 600 h-1. Under n(CH4) :n(O2) :.n( H2O) = 1.00 : 0. 50 : 2.50,reaction temperature 800℃ ,and GHSV of CH4 4 800 h-1 ,CH4 conversion and H2 yield were 100% and 67% , respectively.