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Rh/SiO2催化剂上甲烷部分氧化制合成气反应

Partial Oxidation of Methane to Syngas over Rh/SiO2 Catalyst

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【作者】 吴廷华严前古李少斌钟依均牛振江朱明乔李则林万惠霖

【Author】 WU Tinghua 1* , YAN Qiangu 2, LI Shaobin 3, ZHONG Yijun 1, NIU Zhenjiang 1, ZHU Mingqiao 1,3 , LI Zelin 1, WAN Huilin 1,2 (1 Institute of Physical Chemistry and Department of Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, China; 2 State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, Fujian, China; 3 Department of Chemistry, Ningde Teachers College, Ningde 352100, Fujian, China)

【机构】 浙江师范大学物理化学研究所和化学系厦门大学固体表面物理化学国家重点实验室宁德师范专科学校化学系浙江师范大学物理化学研究所和化学系 浙江金华321004福建厦门361005福建宁德352100浙江金华321004浙江金华321004宁德师范专科学校化学系浙江金华321004厦门大学固体表面物理化学国家重点实验室福建厦门361005

【摘要】 利用程序升温脱附、程序升温还原、程序升温表面反应、程序升温反应和化学捕获反应等手段 ,对Rh/SiO2 催化剂上甲烷部分氧化制合成气反应进行了研究 .结果表明 ,Rh/SiO2 催化剂上甲烷部分氧化制合成气机理属于热解 氧化反应机理 .甲烷首先在催化剂上发生解离吸附 ,产生具有不同H/C比的化学吸附物种CHx(x =1~ 3) .其中 ,具有较高H/C比的CHx 可能是甲烷部分氧化反应的活性物种 ,而具有较低H/C比的CHx 可能是催化剂上积碳并导致催化剂失活的来源 .活性物种CHx在活性氧物种的作用下 ,生成含氧中间体物种CHxO或继续脱氢 .含氧中间体物种进一步分解 ,即生成CO和H2 ;CO2 也可由CHx 或CHxO物种进一步氧化生成

【Abstract】 Partial oxidation of methane (POM) over Rh/SiO 2 catalyst was investigated by using several techniques, such as TPD, TPR, TPSR and trapping agent, combined with MS. At the beginning of POM reaction, only gaseous CO 2 can be detected over the catalyst. With the increase in space velocity, the conversion of CH 4 and the selectivity for CO and H 2 increase, while the selectivity for CO 2 decreases. During the pulse reaction with CH 4 as reactant, over the catalyst prereduced at 700 ℃, CO and H 2 can be detected as main products with trace C 2H 6 and C 2H 4. When the catalyst is exposed to CH 4 He, there are two kinds of carbonaceous species formed, and they are designated CH α and CH β , as identified by their hydrogenation temperature of 210~260 ℃ and 450~800 ℃, respectively. The CH α is assigned to H rich form and the CH β is assigned to H deficient form. When the catalyst is exposed to CH 4 O 2 He, the carbonaceous species are mainly CH α with trace CH β . The two kinds of carbonaceous species may play different roles in POM reaction. The CH β accumulated during CH 4 activation is the possible cause for catalyst deactivation, and the CH α may be responsible for CO formation. The CH x may be the intermediate of POM reaction. In the trapping reaction, a series of ions with M r/z =2~46 have been detected at 300~600 ℃. The CH x O ( x =1~3) may be the O containing intermediate of POM reaction. Based on the above results, the POM mechanism has been proposed. Over the reduced catalyst, CH 4 is firstly dissociated, forming the surface species CH x . By reacting with the active species OH -, the CH α is oxidized to O containing intermediate, CH x O, which can be dehydrogenated to give the adsorbed and gaseous CO.

【关键词】 氧化硅负载型催化剂甲烷部分氧化合成气
【Key words】 rhodiumsilicasupported catalystmethanepartial oxidationsyngas
【基金】 国家重点基础研究发展规划项目 (G19990 2 2 40 8);国家自然科学基金资助项目 ( 2 0 0 2 3 0 0 1)
  • 【文献出处】 催化学报 ,Chinese Journal of Catalysis , 编辑部邮箱 ,2003年06期
  • 【分类号】O643.3
  • 【被引频次】12
  • 【下载频次】223
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