摘要
用甲烷氧化偶联反应评价了不同方法制备的Ｌａ－Ｂａ－Ｓｍ体系催化剂．结果表明，用机械混合Ｌａ２Ｏ３，Ｂａ（ＯＨ）２·８Ｈ２Ｏ和Ｓｍ２Ｏ３三组分及高温焙烧方法制备的催化剂，从Ｃ２收率和选择性总体看，较其它方法优越．在催化剂（Ⅳ）上进行了５００ｈ的稳定性实验，在整个过程中，催化剂的活性和选择性基本稳定；催化剂的起动温度较低，在较宽的温度范围内易于控制，对工业生产意义较大．通过ＸＲＤ，ＸＰＳ，ＩＲ，ＳＥＭ和元素分析等表面及体相结构分析方法，揭示了催化剂在薄层固定床反应器中甲烷氧化偶联反应的特点．
The catalytic properties for oxidative coupling of methane (OCM) of La Ba Sm system catalysts prepared by various methods were studied. It was shown that the higher C 2 yield and selectivity were obtained over catalyst (Ⅳ) prepared through simple mixing and calcination at high temperature. The results of stability test showed that catalyst (Ⅳ) was very stable during a period of 500 h. C 2 yield of 16 5%￣18 2% and C 2 selectivity of 66 2%￣69 5% were achieved at CH 4 conversion of 24 5%￣26 7%. XRD measurement revealed that the intensity ratio of La 2O 3 ( d =2 980) and BaCO 3 ( d =3 72) was higher over the catalyst in upper (B) and middle (C) positions of the reactor than that in lower position (D), which was similar to fresh catalyst (A). The extent of the reaction was different in various positions of the catalyst bed. The reaction was first took place on (B), then gradually moved to (C) and (D). In combination with XPS, IR etc, it was found that OCM reaction conditions could promote the formation of defect structure and the reason for catalyst deactivation was related to the disappearance of defect structure, which made the catalyst surface sintered.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
1996年第3期217-221,共5页
关键词
甲烷
氧化偶联
氧化镧
氧化杉
催化剂
Methane, Oxidative coupling, Lanthana, Samaria, Barium hydroxide
