Catalysis Science & Technology
·
2025
·
IF 4.2
Yilin Zhao,Fangwei Liu,Jingbo Hu,Yang Yang,Jianzhou Wu,Shihui Zou,Jie Fan
The Mn–Na2WO4/SiO2 catalyst for oxidative coupling of methane (OCM) is highly appealing and promising but its high light-off temperature (>800 °C) hinders its industrial application. Engineering catalysts for efficient catalytic performance is attractive yet challenging. In this study, we demonstrate that the incorporation of small amounts of silver into the Mn–Na2WO4/SiO2 catalyst significantly improves its performance, achieving a C2 yield of up to 20% at 750 °C. Characterization results indicate that silver facilitates O2 activation and promotes C–H bond activation, thereby further enhancing CH4 conversion. The findings offer valuable insights into advancing the design concept of high-performance OCM catalysts.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2017
·Vol. 17
·期 12
·8818-8826
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IF 1.483
Liu Jingwei,Huo Minfeng,Zhu Yan
Mn–Na2WO4/SiO2 synthesized by Urea-assisted hydrothermal-Impregnation route has more and stronger surface basic sites, and more surface lattice oxygen, leading to higher methane conversion with higher selectivity toward ethane and ethylene in oxidative
coupling of methane reaction, compared to Mn–Na2WO4/SiO2 produced by Co-precipitation-Impregnation (CPI) and Sequential Impregnation (SI) methods.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Pengwei Wang,Xin Zhang,Guofeng Zhao,Ye Liu,Yong Lu
Mn 2 O 3 -Na 2 WO 4 /SiO 2 is considered as the most promising catalyst for the oxidative coupling of methane (OCM) process; however, it only has a better catalytic performance over 800 °C. To improve its low-temperature performance, an attempt has been made to modify the Mn 2 O 3 -Na 2 WO 4 /SiO 2 catalyst using TiO 2 , MgO, Ga 2 O 3 , and ZrO 2 . Among the synthesized catalysts, the TiO 2 -modified Mn 2 O 3 -Na 2 WO 4 /SiO 2 catalyst shows markedly improved low-temperature OCM performance, achieving a high CH 4 conversion of ~23% and a good C 2 -C 3 selectivity of ~73% at 700 °C (the catalyst bed temperature), along with promising stability for at least 300 h without signs of deactivation. In comparison with the unmodified Mn 2 O 3 -Na 2 WO 4 /SiO 2 catalyst, the TiO 2 modification results in significant improvement in the low-temperature activity/selectivity, whereas the MgO modification has almost no impact and the Ga 2 O 3 and ZrO 2 modifications have a negative effect. The X-ray diffraction (XRD) and Raman results reveal that the formation of a MnTiO 3 phase and a MnTiO 3 -dominated catalyst surface is crucial for the improvement of the low-temperature activity/selectivity in the OCM process.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
·
2022
·Vol. 61
·期 18
·e202117201
·
IF 16.823
Jiaqi Si,Guofeng Zhao,Weidong Sun,Jincun Liu,Cairu Guan,Yong Yang,Xue-Rong Shi,Yong Lu
Graphical For the oxidative coupling of methane (OCM) reaction, the MnO x -Na 2 WO 4 /SiO 2 catalyst enriched with Q 2 units in the SiO 2 carrier achieves 23 % CH 4 conversion and 72 % C 2–3 selectivity at 660 °C. A large number of Q 2 units in MnO x -Na 2 WO 4 /SiO 2 is a trigger for markedly lowering the light-off temperature of the Mn 3+ ↔Mn 2+ redox cycle because of the easy formation of MnSiO 3 . Oxidative coupling of methane (OCM) catalyzed by MnO x -Na 2 WO 4 /SiO 2 has great industrial promise to convert methane directly to C 2–3 products, but its high light-off temperature is the most challenging obstacle to commercialization and its working mechanism is still a mystery. We report the discovery of a low-temperature active and selective MnO x -Na 2 WO 4 /SiO 2 catalyst enriched with Q 2 units in the SiO 2 carrier, being capable of converting 23 % CH 4 with 72 % C 2–3 selectivity at 660 °C. From experiments and theoretical calculations, a large number of Q 2 units in the MnO x -Na 2 WO 4 /SiO 2 catalyst is a trigger for markedly lowering the light-off temperature of the Mn 3+ ↔Mn 2+ redox cycle involved in the OCM reaction because of the easy formation of MnSiO 3 . Notably, the MnSiO 3 formation proceeds merely through the SiO 2 -involved reaction in the presence of Na 2 WO 4 : Mn 7 SiO 12 +6 SiO 2 ↔7 MnSiO 3 +1.5 O 2 . The Na 2 WO 4 not only drives the light-off of this cycle but also gets it working with substantial selectivity toward C 2–3 products. Our findings shine a light on the rational design of more advanced MnO x -Na 2 WO 4 based OCM catalysts through establishing new Mn 3+ ↔Mn 2+ redox cycles with lowered light-off temperature.
研究领域:
催化化学
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材料科学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Science Advances
·
2017
·Vol. 3
·期 6
·
IF 0
Pengwei Wang,Guofeng Zhao,Yu Wang,Yong Lu
Oxidative coupling of methane (OCM) is a promising method for the direct conversion of methane to ethene and ethane (C2 products). Among the catalysts reported previously, Mn2O3-Na2WO4/SiO2 showed the highest conversion and selectivity, but only at 800° to 900°C, which represents a substantial challenge for commercialization. We report a TiO2-doped Mn2O3-Na2WO4/SiO2 catalyst by using Ti-MWW zeolite as TiO2 dopant as well as SiO2 support, enabling OCM with 26% conversion and 76% C2-C3 selectivity at 720°C because of MnTiO3 formation. MnTiO3 triggers the low-temperature Mn2+↔Mn3+ cycle for O2 activation while working synergistically with Na2WO4 to selectively convert methane to C2-C3. We also prepared a practical Mn2O3-TiO2-Na2WO4/SiO2 catalyst in a ball mill. This catalyst can be transformed in situ into MnTiO3-Na2WO4/SiO2, yielding 22% conversion and 62% selectivity at 650°C. Our results will stimulate attempts to understand more fully the chemistry of MnTiO3-governed low-temperature activity, which might lead to commercial exploitation of a low-temperature OCM process.
研究领域:
化学工程
·
催化
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
ACS Omega
·
2024
·
IF 3.7
Qingjing Liu,Ruisheng Wang,Ranjia Li,Xiaosheng Wang,Suoqi Zhao,Changchun Yu
Mn–Na2WO4-based catalysts with different supports were prepared using the incipient wetness impregnation method and evaluated for their oxidative coupling of methane (OCM) reaction performance. The results demonstrated that the SiO2- supported catalyst exhibited the best catalytic performance, and the introduction of H2O further enhanced its activity. Under the conditions of a feed gas mixture of CH4/O2/H2O = 6:1:24 at 800 °C and atmospheric pressure, the CH4 conversion and C2+ selectivity over the Mn–Na2WO4/SiO2 catalyst increased from 28.4% and 77.4% (without H2O) to 33.2% and 84.9%, respectively. In contrast, the catalytic activity using TiO2 and MgO supports drastically declined. Characterizations using X-ray diffraction (XRD), in situ infrared spectroscopy (In-situ IR), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD) revealed that the introduction of steam not only served as a diluent to decrease the partial pressures of the reactants CH4 and O2, thereby reducing deep oxidation reactions in the gas phase, but also interacted with surface oxygen species (O22–) and silica to form adjacent surface-bonded disilanol free radicals Si–OIH. This interaction facilitated the dehydrogenation and coupling of two methane molecules on the catalyst surface, resulting in the generation of C2+ products, significantly enhancing the catalytic activity and selectivity of OCM.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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