Oxidative coupling of methane: catalytic behaviour assessment via comprehensive microkinetic modelling
Oxidative coupling of methane: catalytic behaviour assessment via comprehensive microkinetic modelling
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DOI：
10.1016/j.apcatb.2013.12.043
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发表时间：
2014-05-05
影响因子：
22.1
通讯作者：
Marin, G. B.
中科院分区：
文献类型：
--
作者：
Alexiadis, V. I.;Thybaut, J. W.;Marin, G. B.
一个综合的微观动力学模型，包括催化剂描述符，解释了甲烷氧化偶联反应中的热、均相和催化、多相反应步骤，已被用于评估在不同催化剂上获得的动力学数据。该模型的适用范围从以Li/MgO和SnLi/MgO为代表的碱式氧化镁催化剂扩展到以锶/La2O为代表的一类新材料--碱土促进的氧化镧催化剂。为了充分模拟用后一种催化剂获得的大量实验数据，对微观动力学模型的表面反应网络进行了扩展。所得到的模型成功地模拟了C-2，即乙烷和乙烯的产生，无论是在回归过程中单独产生还是作为一个整体产生。结果表明，在甲烷转化率方面，Sr/La_2O_3催化剂的甲烷转化率分别是Li/MgO和SnLi/MgO催化剂的33倍和5倍。这主要归因于吸附羟基的稳定性较高，吸附氧的稳定性较高，以及锶/镧的活性密度较高。对C-2产物的选择性取决于甲基自由基粘着系数和吸附氧的稳定性，并在锡促进的LiMgO催化剂上最高，即在1023K，190kPA，入口CH4/O-2比为4的条件下，甲烷转化率约为5%时，选择性为70%。(C)2014爱思唯尔公司版权所有。
A comprehensive microkinetic model, including catalyst descriptors, that accounts for thermal, homogeneous and catalytic, heterogeneous reaction steps in the oxidative coupling of methane has been used in the assessment of kinetic data acquired on different catalysts. The applicability of the model was extended from alkali magnesia catalysts represented by Li/MgO and Sn-Li/MgO, to a new class of materials, namely alkaline earth-promoted lanthana catalysts, represented by Sr/La2O3. To simulate adequately the large experimental dataset, acquired with the latter catalyst, the surface reaction network of the microkinetic model was expanded. The resulting model succeeded in adequately simulating the C-2, that is, ethane and ethene, production, both individually and as a lump during regression. It was found that the activity of Sr/La2O3, in terms of methane conversion, is 33 and five times higher than that of Li/MgO and Sn-Li/MgO, respectively. This is attributed mainly to the higher stability of adsorbed hydroxyl, the higher stability of adsorbed oxygen, and the higher active density of Sr/La2O3. The selectivity toward C-2 products was found to depend on the methyl radical sticking coefficient and the stability of the adsorbed oxygen and was the highest on the Sn-promoted LiMgO catalyst, that is, 70% at about 5% methane conversion at 1023 K, 190 kPa, and inlet molar CH4/O-2 ratio of 4. (C) 2014 Elsevier B.V. All rights reserved.