Role of support nature (γ-Al2O3 and SiO2-Al2O3) on the performances of rhenium oxide catalysts in the metathesis of ethylene and 2-pentene

Journal of Natural Gas Chemistry Pub Date : 2012-03-01 DOI:10.1016/S1003-9953(11)60348-4

Weena Phongsawat , Benjamas Netiworaruksa , Kongkiat Suriye , Siraprapha Dokjampa , Piyasan Praserthdam , Joongjai Panpranot

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引用次数: 19

Abstract

The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re₂O₇/γ-Al₂O₃ and Re₂O₇/SiO₂-Al₂O₃ catalysts. Both NH₃ temperature-programmed desorption (NH₃-TPD) and H₂ temperature-programmed reduction (H₂-TPR) results showed that Re₂O₇/SiO₂-Al₂O₃ exhibited stronger acidity and weaker metal-support interaction than Re₂O₇/γ-Al₂O₃. At 35–60 °C, isomerization free metathesis was observed only over Re₂O₇/γ-Al₂O₃, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re₂O₇/SiO₂-Al₂O₃, hydrido-rhenium species ([Re]-H) were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.

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载体性质(γ-Al2O3和SiO2-Al2O3)对氧化铼催化剂乙烯和2-戊烯反应性能的影响

以Re2O7/γ-Al2O3和Re2O7/SiO2-Al2O3为催化剂，研究了乙烯和2-戊烯的复合反应制备丙烯的替代路线。NH3程序升温解吸(NH3- tpd)和H2程序升温还原(H2- tpr)结果表明，Re2O7/SiO2-Al2O3比Re2O7/γ-Al2O3表现出更强的酸性和更弱的金属-载体相互作用。在35-60℃下，Re2O7/γ-Al2O3只发生了无异构化的复分解，这表明金属-碳复分解活性位点的形成只需要弱酸性。结果表明，在Re2O7/SiO2-Al2O3上，除了还原活性位点外，还形成了氢铼([Re]-H)，导致初始的1-丁烯产物异构化为2-丁烯。这些2-丁烯与过量的乙烯之间随后发生的二次复分解反应可以解释所观察到的丙烯收率的提高。结果表明，从替代原料中获得高产量丙烯的潜力。

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来源期刊

Journal of Natural Gas Chemistry 化学-工程：化工

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审稿时长

2 months