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    低水碳比甲烷干重整工况寻优及积碳实验研究

    Experimental study on operating condition optimization and carbon deposition in methane dry reforming with low steam-to-carbon ratio

    • 摘要: 低水碳比甲烷干重整是兼顾减排与合成气制备的潜在路径,该过程反应耦合强、积碳风险高,导致甲烷转化率、合成气组成和积碳难以协同优化。为了优化低水碳比甲烷干重整过程,在固定床实验装置上研究转化温度(T)、n(CO2)∶n(CH4)、n(H2O)∶n(CH4)及进气总流量(QV)等关键因素对甲烷转化率(XCH4)和n(H2)∶n(CO)的影响;在单因素筛选基础上,将QV固定为3 L·min−1,采用Box-Behnken设计构建响应面模型,开展多因素耦合效应分析与工况寻优;使用程序升温氧化质谱联用(O2-TPO-MS)对最优工况下的催化剂进行表征。结果表明:Tn(CO2)∶n(CH4)、n(H2O)∶n(CH4)的增加会提高XCH4QV的增加会降低XCH4T=1000 ℃、CH4 =1 L·min−1、H2O =1 L·min−1、CO2 =1 L·min−1时,XCH4达到最高为96%,n(H2)∶n(CO)≈1;最优工况下的催化剂积碳量为1.59 mg·g−1,以较易氧化碳物种为主。研究结论为后续反应器的开发与抑制积碳提供依据。

       

      Abstract: Low steam-to-carbon ratio dry reforming of methane is a potential route for simultaneously achieving emission reduction and syngas production. However, the strong coupling among the reactions and the high risk of carbon deposition in this system make it difficult to simultaneously optimize methane conversion, syngas composition, and carbon deposition. To optimize the operating conditions of low steam-to-carbon ratio methane dry reforming , a fixed-bed experimental setup was used to investigate the effects of key factors such as reforming temperature (T), n(CO2)∶n(CH4), n(H2O)∶n(CH4), and total inlet flow rate (QV) on methane conversion (XCH4) and the n(H2)∶n(CO) . Based on single-factor screening , QV was fixed at 3 L·min−1, and a Box–Behnken design was employed to establish a response surface model for multi-factor coupling analysis and operating-condition optimization. The catalyst under the optimal conditions was further characterized by temperature-programmed oxidation coupled with mass spectrometry (O2-TPO-MS). The results show that increasing T, n(CO2)∶n(CH4), and n(H2O)∶n(CH4) enhance XCH4, while increasing QV reduce XCH4. At T=1000 °C, CH4 =1 L·min−1、H2O =1 L·min−1、CO2 =1 L·min−1, XCH4reach a maximum of 96%,while the n(H2)∶n(CO) is approximately 1. Under the optimal conditions, the carbon deposition amount is determined to be 1.59 mg·g−1, and the deposited carbon is dominated by relatively easy-to-oxidize carbon species. These results provide a reference for subsequent reactor development and carbon suppression strategies in low steam-to-carbon ratio methane dry reforming.

       

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