APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Weidong Sun,Guofeng Zhao,Ya Gao,Jiaqi Si,Ye Liu,Yong Lu
Chemical looping concept paves way toward intrinsically safe and efficient oxidative coupling of methane (CL-OCM) process, because it permits the reaction to proceed via repeating reduction-oxidation cycle in two reactors. It is calling for a ground-breaking catalyst with enough high selective CH 4 -converting lattice-oxygen carrying capacity but represents a grand challenge. Herein, we report an efficient catalyst obtainable by decorating an oxygen carrier FeMnO 3 with Na 2 WO 4 , with good cycling performance, achieving a high space time yield of 29.8 g C2-C3 kg cat. −1 h −1 with 20% CH 4 conversion and 80% C 2 -C 3 selectivity at 800 °C and a low catalyst/CH 4 weight ratio of 13.5. CL-OCM process is established by “FeMnO 3 ↔ [MnFe 2 O 4 + MnO]” redox cycle. Na 2 WO 4 -decoration gets lattice oxygen stored in FeMnO 3 transformed from non-selective to selective due to mitigation of lattice-oxygen evolution. Scaled up CL-OCM testing with 10-gram catalyst also yields comparable results seen in the case of using 1-gram catalyst, validating great application potential.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
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
ACS Catalysis
·
2025
·
IF 13.1
Lingfang Liu,Liangyan Deng,Yachao Wang,Yu Wang,Yaxiong Wei,Guofeng Zhao,Cong Fu
Photocatalytic oxidative coupling of methane (OCM) represents a promising route for chemical and fuel synthesis, yet the development of photocatalysts with high activity and selectivity remains challenging. Here, we demonstrate a synergistic ensemble of Au nanoparticles and Li-doped TiO2 that significantly enhances photocatalytic OCM performance in a flow reactor. The optimized catalyst achieved a C2 hydrocarbon production rate of 4.1 mmol g–1 h–1 with selectivity up to 97% and maintained robust stability over 50 h. Comprehensive mechanistic studies, employing in situ transient absorption spectroscopy (TAS), in situ electron paramagnetic resonance (EPR), and operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques, indicate that Li dopants facilitate the formation of bulk/surface defects by a unique bulk-to-surface-to-gas Li migration process. These induced defects serve a dual role: bulk defects act as effective hole traps, while surface defects provide active sites that enhance charge transfer and promote O2 adsorption/activation. Combined with Au acting as a methane activation center, this synergy promotes efficient C–H activation and C–C coupling, thus contributing to its superior catalytic performance. This work provides critical mechanistic insights into photocatalytic OCM and underscores the potential of surface and bulk engineering for efficient photocatalytic processes.
研究领域:
材料科学
·
化学工程
·
催化科学
✓ 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
FUEL
·
2023
·
IF 7.4
Jiayong Ni,Jiaqi Si,Tian Lan,Weidong Sun,Guofeng Zhao,Ye Liu,Yong Lu
The fluidized-bed reactor is a preferred option for the design of an intrinsic-safety oxidative coupling of methane (OCM) process, because it permits such strongly exothermic reaction to proceed isothermally. However, the widely studied Mn-Na 2 WO 4 /SiO 2 catalyst cannot meet the requirements of the fluidized-bed reaction. Ground-breaking fluid catalyst coupling high activity/selectivity with good anti-agglomeration and high attrition resistance represents a grand challenge. Herein, we report an Mn 2 O 3 -Na 3 PO 4 /TiO 2 catalyst (280–355 μm) for the fluidized-bed OCM process, achieving 28.5% CH 4 conversion with 70.1% C 2 -C 3 selectivity at 760 °C for a feed gas of CH 4 /O 2 of 5/1 while remaining unchanged within 16 h test. This catalyst shows significant fluidization behavior under OCM reaction conditions. It is found that TiO 2 nanorods tangle up with each other to form an interpenetrating nano-structure thereby inducing strong mechanical strength and robustness with a low attrition index of only 2.8%. Moreover, high melting-point Na 3 PO 4 and use of TiO 2 support impart the catalyst to good anti-agglomeration because of eradication of formation of the sticky Na 2 Si 2 O 5 and molten Na 2 WO 4 (main cause for agglomeration) encountered in the Mn-Na 2 WO 4 /SiO 2 .
研究领域:
化学工程
·
催化化学
✓ 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
·
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
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Asia-Pacific Journal of Chemical Engineering
·
2022
·Vol. 18
·期 2
·e2863
·
IF 1.777
Jingyi Wang,Lili Cai,Zhongwei Cao,Xuefeng Zhu,Weishen Yang
Oxidative coupling of methane (OCM) is an effective route for methane direct conversion to ethylene. Perovskite oxides (ABO 3 ) with variable properties are potential catalysts for OCM by adjusting the compositions. In this study, four perovskite catalysts, BaMO 3-δ and BaM 1-x Y x O 3-δ (M = Zr, Ce; x = 0.2), were prepared by the sol–gel method to explore their catalytic performance of OCM. All catalysts are active toward OCM and reach the highest catalytic performance at 800°C. The OCM performance of Ce-based catalysts is higher than that of Zr-based catalysts. The selectivity of C 2 compounds is significantly improved by Y-doping. At CH 4 /O 2 mol ratio of 8, a C 2 selectivity of 67% was achieved on BaCe 0.8 Y 0.2 O 3-δ . Compared with Zr-based catalysts, more amounts of active oxygen species, which are beneficial to OCM, were observed on BaCeO 3-δ and BaCe 0.8 Y 0.2 O 3-δ . Meanwhile, higher contents of moderate and strong basic sites, which are beneficial to OCM, were found on the Y-doped catalysts. This is attributed to the generation of oxygen vacancies caused by Y-doping in the B-site. Therefore, BaCe 0.8 Y 0.2 O 3-δ with more active oxygen species and stronger basicity exhibits the highest performance among the four catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Jiayong Ni,Tian Lan,Pu Liu,Yong Lu
The fluidized-bed reactor with excellent heat and mass transfer features has great appeal for application in the oxidative coupling of methane (FB-OCM), whereas qualified fluid catalysts represent a grand challenge. Herein, we report a high-performance Mn 2 O 3 -Na 2 WO 4 /TiO 2 fluid catalyst (5.4 wt% Mn 2 O 3 and 2 wt% Na 2 WO 4 ), which was obtained by the incipient-wetness impregnation method and examined in the OCM reaction in an electric-heating quartz fluidized-bed reactor (i.d., 2 cm). The standard normalization method on the basis of carbon atom was used for calculating the CH 4 conversion and C 2- C 3 selectivity. This catalyst achieves 35.5 % CH 4 conversion, 66 % C 2 -C 3 selectivity and particularly 15.1 % single-pass yield of C 2 H 4 for a feed of CH 4 /O 2 /H 2 O=3/1/1 with a catalyst dosage of 20 mL at 700 °C and a total GHSV of 7200 h −1 . Such catalyst is stable for at least 50 h without signs of deactivation and agglomeration/defluidization. The catalyst particle size is crucial for the FB-OCM reaction with respect to the reaction light-off and catalyst fluidization. The catalyst with preferable particle size of 450–600 μm can not only trigger the OCM reaction at a relatively low temperature of 630 °C but also warrant active bubbling fluidization. Furthermore, thanks to the low amount of Na 2 WO 4 and interpenetrating structure of TiO 2 -nanorod, such catalyst achieves good anti-aggregation and robust mechanical strength (with a low attrition index of 1.9 %). The effects of water-adding amount in feedstock and catalyst particle size distribution on the hydrodynamics behaviour were investigated in a laboratory-scale fluidized-bed OCM reactor by using numerical simulation method.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2021
·
IF 13.084
Qiuyue Zhou,Zhi-Qiang Wang,Zhinian Li,Junxing Wang,Minggao Xu,Shihui Zou,Jiuzhong Yang,Yang Pan,Xue-Qing Gong,Liping Xiao,Jie Fan
Methyl radicals (CH3•) are the key intermediates in the heterogeneous–homogeneous reaction processes of catalytic oxidative coupling of methane (OCM). Here, by applying in situ synchrotron-based vacuum ultraviolet photoionization mass spectrometry, we quantitatively detected CH3• being desorbed from various metal oxides and validated the CH3•-generating capability as an effective descriptor for the catalytic performance of the metal oxides in OCM. It is found that the C2 yield is linearly correlated to the amount and the desorption temperature of CH3•, with the better OCM catalyst showing stronger CH3• intensity and lower CH3• desorption temperature. Furthermore, experimental characterizations together with density functional theory calculations suggest that the intrinsic electronic properties of metals and the subsequent generated electrophilic oxygen species are the decisive factors for CH3• generation. Then, the CH3•-generating capability can bridge the gap between the OCM performance and the structure of the catalyst and help us better understand the intrinsic structure–performance relationship in OCM over metal oxide catalysts.
研究领域:
化学
·
催化科学
·
材料科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 8
·2493-2499
·
IF 5
Junxing Wang,Fangwei Liu,Jianzhou Wu,Shihui Zou,Jie Fan
Engineering Mn–Na2WO4 catalysts for efficient oxidative coupling of methane (OCM) at low temperatures (T ≤ 700 °C) is appealing yet challenging. Herein, we report a LaCeZr ternary oxide supported Mn–Na2WO4 catalyst, which achieves 20.9% C2 yield at 700 °C with at least 50 hour stability. Characterizations suggest that LaCeZr ternary oxides can promote the redox properties of Mn–Na2WO4 catalysts, which facilitate O2 activation at low reaction temperatures and generate more active oxygen species to activate CH4 into C2 products.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
ChemNanoMat
·
2018
·Vol. 4
·期 5
·487-495
·
IF 3.173
Zhinian Li,Shenliang Wang,Wei Hong,Shihui Zou,Liping Xiao,Jie Fan
Graphical Smart screens : An intelligent approach was developed to screen Na−Mn−W/SiO 2 catalysts for the oxidative coupling of methane (OCM). Effective composition regions other than the standard composition were successfully excavated. The wide range of the optimal composition allowed a fluctuation of composition during the reaction, which secured its excellent stability in the OCM reaction. Optimizing the performance and understanding the mechanism of metal oxide catalysts in the oxidative coupling of methane (OCM) is one of the most important projects in industrial catalysis. Here, we report an intelligent approach to screen Na−Mn−W/SiO 2 catalysts for the OCM reaction via ink-jet printing and multidimensional group testing. The ink-jet-printing-assisted (IJP-A) synthetic methodology ensured a fast synthesis of 1536 catalysts that were evaluated in 24 tests via a multidimensional group testing strategy (m-GT). After two-round synthesis-and-screening processes, several excellent groups with different composition space were screened out. Among the excellent catalysts, the OCM performance of Na−Mn−W/SiO 2 catalyst with higher Na, Mn and W content (G3 and G7) was less sensitive to its constituent than that of Na−Mn−W/SiO 2 catalyst with lower Na, Mn and W content (G1). These results indicated the sensitivity of performance to its Na, Mn and W content decreased in larger Na, Mn and W spaces, consistent with the complex homogeneous/heterogeneous reaction mechanism and multi-active sites. A series of Na−Mn−W/SiO 2 formulas with good performance also provide a reasonable explanation to its excellent stability for the OCM reaction. In addition, this intelligent optimization in total space offers a pathway to study the multicomponent metal oxide catalyst in the OCM reaction.
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
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
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）