| Since Kelter and Bhasin reported the reaction of oxidative coupling of methane (viz.OCM) in1982, it became one of hotspot topic in the realm of multi-phase catalysts.The research of OCM helps not only to obtain the fundamental production--ethane,but also provide a path to make use of natural gas. Moreover, this topic can provide better catalysts with high performance, realize its industrialization and make foundmental research for little molecule. Up to now, to obtain catalysts with high activity and high selectivity is still one of nudoses in the research of OCM.For the complexities of OCM reaction process, unicomponent or dicompomponent can't meet with the require of high C2 yield. Therefore, multi-component catalyst was applied and showed better reaction performance in the reaction of OCM. For example, Huang kai in the Chemical Engineering Department in Zhejiang University had optimized a muli-component catalyst with artifical neural network aided-design. And the conversion of methane would be 37.79% and the total selectivity of ethane and ethylene would be 73.50% (C2 yield being 27.78%) when GHSV was 33313 ml g-1 hr-1, the proportion CH4 to O2 was 3 to 1 at 1069K.In the reaction of oxidative coupling of methane, Whether basicity is favorable to the performance of catalyst is uncertain. Howerver, According to two acpects that activation of methane is the key of the reaction and activation of methane have a consanguineous relationship with acidity-basicity of OCM catalyst, the effects of acidity-basicity on the catalyst performance in the process of OCM were investigated. Here the catalysts prepared by our lab were multi-component transition metal catalysts. The results of exiperiments were described as following.(1) The surface acidity or basicity of six-component transition metal catalyst was studied. After a series of experiment, acidity-basicity on the six-component catalysts surface weren't obvious by CO2-TPD and NH3-TPD.(2)These six-component catalysts modified acid-basic compound such as H3PO4, LiOH, BaO, MgO, CaO Na2CO3 were investigated. The results showed that the differrent modifiers have distinct influencing on the performance of catalysts. For jx-2catalyst, the reaction performance was increased a little with its surface modified with BaO and MgO, but decreased with CaO. However, the performance of catalyst whose surface was modified LiOH or Na2CO3 was decreased with the increasing of modifying amount.(3) Acidity-basicity of catalyst support influencing on the performance of reaction were studied. The value of pH was adjusted to 1,3, 5, 7, 9 and 12. The experimental data showed that C2 yield and C2 selectivity were improved when the catalyst support was acid or neutral. In special, for catalyst jx-3-13, CH4 conversion would be 37.79% and C2 selectivity would be 73.50%(C2 yield being 27.78%) when GHSV was 33313 ml g-1 hr-1, the proportion CH4 to O2 was 3 to 1 at 1073K. However, the performance was some decreased when the catalyst support was basic.(4) Some different methods are used to characterize catalyst micro-properties. When a few H3PO4 was added to the catalyst support, that surface structure was changed from dense to loose by SEM. And the catalyst jx-3-13 existed in interlaced reticulation and SiO2 was disperse extensively in the form of a -cristobalite by XRD. In addition, the BET surface of jx-3-13 was approximately 1.9 times than the original catalyst prescription. In a word, Addition of a few H3PO4 could improved the performance of catalysts comparing to original catalyst.In conclusion, the six-component catalyst would be good reaction performance with acidity or neutral in support and weak basicity in surface.
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