Oxidative coupling of methane (OCM) conversion into C2 products through a CO2/O2 co-transport membrane reactor
Oxidative coupling of methane (OCM) conversion into C2 products through a CO2/O2 co-transport membrane reactor
复制标题
通过 CO2/O2 共输送膜反应器将甲烷 (OCM) 氧化偶联转化为 C2 产品
DOI：
10.1016/j.memsci.2022.120915
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发表时间：
2022
影响因子：
9.5
通讯作者：
Huang, Kevin
中科院分区：
文献类型：
--
作者：
Zhang, Kangkang;Sun, Shichen;Huang, Kevin
甲烷氧化偶联反应（OCM）是甲烷直接转化反应（DMC）中研究最多的反应之一，它以分子氧为氧化剂，将甲烷转化为C2产物（C2 H6和C2 H4）。然而，OCM工艺的主要技术障碍是在高C2（C2 H6和C2 H4）选择性下实现高CH 4转化率。这种“折衷”行为的一个基本原因是产物（C2 H6或C2 H4）的高化学反应性，其可以被O2再氧化。为了克服这一热力学挑战，最大限度地减少氧化剂的氧化能力和降低局部氧分压是关键。在这项工作中，我们展示了一种新的膜反应器，从烟道气中捕获CO2/O2，并将其用于OCM转化。结果表明，在2%Mn-5%Na2WO4/SiO2催化剂存在下，CO2/O2共捕混合气可将CH 4转化为C2 H6，然后将C2 H6热裂解为C2 H4和H2。CO2的存在降低了O2的局部分压，从而降低了C2产物再氧化的倾向，并导致更高的C2选择性。我们发现，一个小型的按钮式膜反应器可以达到12%的C2产率与约57%的C2-选择性使用稀释的CH 4-Ar混合物作为原料。我们期望在未来的管式推流式膜反应器更高的C2产率。我们还强调了膜反应器的独特优势，在强化CO2捕获从烟气和OCM净化过程到一个单一的步骤。
Oxidative coupling of methane (OCM), which transforms CH4into C2products (C2H6and C2H4) with molecular O2as the oxidant, is one of the most studied direct methane conversions (DMCs). However, a major technical hurdle to the OCM process is to achieve high CH4conversion at high C2(C2H6and C2H4) selectivity. One rudimentary cause for this “tradeoff” behavior is the high chemical reactivity of the products (C2H6or C2H4), which can be re-oxidized by O2. To overcome this thermodynamic challenge, minimizing the oxidizing power of the oxidant and lowering the local oxygen partial pressure are keys. In this work, we demonstrate a new membrane reactor that capture CO2/O2from a flue gas and uses it for OCM conversion. The results show that the co-captured CO2/O2mixture converts CH4into C2H6in the presence of a 2%Mn–5%Na2WO4/SiO2catalyst, followed by thermal cracking of C2H6into C2H4and H2. The presence of CO2decreases the local partial pressure of O2, thus reducing the propensity of C2-products re-oxidation and leading to a higher C2selectivity. We show that a small button-type membrane reactor can achieve 12% C2yield with ∼57% C2-selectivity using a diluted CH4-Ar mixture as the feedstock. We expect higher C2yield with tubular plug-flow membrane reactors in the future. We also highlight the unique advantage of the membrane reactor in intensifying CO2capture from both flue gas and OCM purification process into one single step.