CATALYSIS COMMUNICATIONS
·
2023
·
IF 3.7
Jiuhu Zhao,Huiying Li,Yungang Wang,Rongshu Zhu,Senlin Sun,Jingwen Zhang,Chaolin Li,Mei Hong
Mesoporous In/Hβ-X series catalysts were prepared by desilication method with tetrapropylammonium hydroxide (TPAOH) and indium incorporation for selective catalytic reduction of NO with methane (CH 4 -SCR). The post desilication treatment conditions for preparing In/Hβ-X were optimized. Etching time is the most important desilication parameter influencing the resulting CH 4 -SCR performance of the catalyst. The In/Hβ-3 sample which was etched for 3 h presents the highest NO x conversion, 22% higher than In/H-Beta counterparts using commercial microporous beta. Obvious analysis reveals that besides generating mesopores, controlled desilication can modulate the proportion of InO + active sites and surface oxygen species, allowing more active sites to be exposed.
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Nature Catalysis
·
2022
·Vol. 5
·期 1
·45-54
·
IF 40.706
Qi Guodong,Davies Thomas E.,Nasrallah Ali,Sainna Mala A.,Howe Alexander G. R.,Lewis Richard J.,Quesne Matthew,Catlow C. Richard A.,Willock David J.,He Qian,Bethell Donald,Howard Mark J.,Murrer Barry A.,Harrison Brian,Kiely Christopher J.,Zhao Xingling,Deng Feng,Xu Jun,Hutchings Graham J.
The oxidation of methane, the main component of natural gas, to selectively form oxygenated chemical feedstocks using molecular oxygen has been a long-standing grand challenge in catalysis. Here, using gold nanoparticles supported on the zeolite ZSM-5, we introduce a method to oxidize methane to methanol and acetic acid in water at temperatures between 120 and 240 °C using molecular oxygen in the absence of any added coreductant. Electron microscopy reveals that the catalyst does not contain gold atoms or clusters, but rather gold nanoparticles are the active component, while a mechanism involving surface adsorbed species is proposed in which methanol and acetic acid are formed via parallel pathways.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Sulong Geng,Zhanguo Zhang,Junjie Li,Jianguo Qian,Jiao Liu,Jian Yu,Guangwen Xu
Catalyst samples for CH 4 decomposition were prepared from red mud (RM) by an acid-leaching neutralization precipitation approach. Water-washing the resultant precipitates multiple times, followed by drying at 105 °C and calcination at 500 °C, resulted in a threshold of residual Na 2 O, equivalent to 96% Na 2 O removal. Drying the precipitate at a higher temperature of 200 °C, followed by repeated water washing, provided a deeper Na 2 O removal of 99% and made the resultant samples more active for the targeted reaction. Subsequently, four catalyst samples with a simulated red mud composition and NaOH contents from 0 to 0.3 wt% were prepared and the catalytic test results revealed that the Na 2 O remaining in the RM-derived catalysts did not only inhibit their activation in CH 4 but also lower their maximal activities for CH 4 decomposition. Finally, two catalysts with the same simulated red mud composition and their Na impregnated respectively on Fe 2 O 3 and a mixture support of Al 2 O 3 -SiO 2 -TiO 2 were prepared and tested to explore the effect of Na distribution on the activation behavior of RM-derived catalysts for CH 4 decomposition. The activity testing results showed that it was the Na residual dispersed on iron oxides in the RM-derived samples to significantly inhibit the activation of CH 4 decomposition.
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Science Bulletin
·
2022
·
IF 20.577
Kunhao Liu,Chao Yang,Ruilin Wei,Xingyu Ma,Chen Peng,Zhengzheng Liu,Yangshen Chen,Yaqin Yan,Miao Kan,Yaoyue Yang,Gengfeng Zheng
Although many catalysts have been reported for the CO 2 electroreduction to C 1 or C 2 chemicals, the insufficient understanding of fundamental correlations among different products still hinders the development of universal catalyst design strategies. Herein, we first discover that the surface *CO coverage is stable over a wide potential range and reveal a linear correlation between the partial current densities of CH 4 and C 2 products in this potential range, also supported by the theoretical kinetic analysis. Based on the mechanism that *CHO is the common intermediate in the formation of both CH 4 (*CHO → CH 4 ) and C 2 (*CHO + *CO → C 2 ), we then unravel that this linear correlation is universal and the slope can be varied by tuning the surface *H or *CO coverage to promote the selectivity of CH 4 or C 2 products, respectively. As proofs-of-concept, using carbon-coated Cu particles, the surface *H coverage can be increased to enhance CH 4 production, presenting a high CO 2 -to-CH 4 Faradaic efficiency ( FE CH 4 ∼52%) and an outstanding CH 4 partial current density of –337 mA cm −2 . On the other hand, using an Ag-doped Cu catalyst, the CO 2 RR selectivity is switched to the C 2 pathway, with a substantially promoted FE C 2 of 79% and a high partial current density of –421 mA cm −2 . Our discovery of tuning intermediate coverages suggests a powerful catalyst design strategy for different CO 2 electroreduction pathways.
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Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Bingying Jia,Bang Xu,Liujie Bing,Jihong Sun,Shiyang Bai
With the assistance of cetyltrimethyl ammonium bromide (CTAB), the delamination of disorderly layered clinoptilolite (CP) was performed. The introduction of CTAB in hydrothermal system was beneficial to stratification of CP lamellas by enlarging interlayer spacing, and thus accelerating the formation of disordered CP nanosheets . The hydrophobic alkyl chain restricts the crystal growth along a-axis and the few-layer CP lamellas with integrally preserved heulandite structures were obtained by ultrasonic treatment and HNO 3 modification at room temperature. Meanwhile, the CTAB-assisted crystallization mechanism was further elucidated, in which, the amorphous spherical nanoparticles were firstly generated and then transformed into the fibrous and lamellar species. Finally, the flower-like CP morphologies with the aggregated nanosheets appeared. Meanwhile, the selective adsorptions and separations of CO 2 and CH 4 using these delaminated CPs as the absorbents were preliminarily explored, showing a strong potential in the mixed gases separation applications. This approach is a promising strategy for constructing delaminated zeolites with low n(SiO 2 /Al 2 O 3 ), which may open a new avenue for the delaminated CP nanosheet applications in gas adsorption and separation fields.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Ke Chen,Linhan Ni,Hao Zhang,Jia Xie,Xin Yan,Saisai Chen,Junwen Qi,Chaohai Wang,Xiuyun Sun,Jiansheng Li
The interfacial compatibility between fillers and polymers essentially influences the separation performance of mixed matrix membranes (MMMs). In this work, an one-pot synthesized functional layer veiled zeolite imidazolate frameworks-67 (VZIF-67) was used as an efficient nanofillers to fabricate MMMs via physical blending with 6FDA-Durene polyimide. Benefiting from the CO 2 affinity from functional layer and the intrinsic characteristics of porous nanofillers, significant enhancement on separation performance was observed on the resultant MMMs. Specifically, the optimized VZIF-67 MMMs (30 wt% loading) exhibited CO 2 /CH 4 selectivity of 32.5 with CO 2 permeability of 1210 Barrer, which is 1.7 and 1.5 times higher than those of the control membrane, respectively. More importantly, the surface organic attribute and abundant amine groups of VZIF-67 reinforced the interfacial compatibility between the nanofillers and polymer matrix, leading to a doubled CO 2 /CH 4 selectivity compared with the ZIF-67 MMMs. Overall, the performance of the VZIF-67 membrane toward CO 2 /CH 4 separation surpasses the 2008-updated Robeson upper bound. These results indicate the functionalization strategy on porous nanofillers is a promising approach to fabrication of high performance of MMMs.
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JOURNAL OF CATALYSIS
·
2022
·
IF 8.047
Wenhao Li,De-Kun Ma,Xia Hu,Faliang Gou,Xiaogang Yang,Walker MacSwain,ChenZe Qi,Weiwei Zheng
Rationally designing and controlling the interactions between reaction intermediates and the surface of photocatalysts is critical to obtain high product selectivity in photocatalysis. Herein, using CdS-based photocatalytic CO 2 reduction reaction (CO 2 RR) as a model system, we demonstrate that CH 4 selectivity can be significantly enhanced through the introduction of La 3+ ions with high oxophilicity on the surface of the photocatalysts. The high surface oxophilicity of the photocatalysts can increase CO* desorption energy and promote further hydrogenation to CH 4 . In contrast, when Au 3+ ions with low oxophilicity were doped in CdS, reduced CH 4 selectivity was observed in the CO 2 RR. Significantly, enhanced CH 4 selectivity can be achieved by doping oxophilic La 3+ ions into a broad range of alternative photocatalysts including ZnO, SnS 2 , BiOBr, BiVO 4 , TaON, and CsPbBr 3 , which demonstrates the general strategy to enhance CH 4 selectivity of photocatalytic CO 2 RR through increased surface oxophilicity of the photocatalysts by rare earth La 3+ ion doping.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Wenbo Lu,Degong Ding,Qingzhong Xue,Yonggang Du,Ya Xiong,Jianqiang Zhang,Xinglong Pan,Wei Xing
In this study, unloaded and Pt-loaded SnO 2 nanofibers (NFs) with 100–150 nm diameters were synthesized by a simple electrospinning technology and then calcined at 600 °C in air. It was observed that the Pt-SnO 2 NFs were comprised of strings of tiny SnO 2 nanoparticles decorated with Pt and PtO nanoparticles, resulting in the formation of PtO/SnO 2 heterojunction and high porosity. And then, we studied the methane (CH 4 ) sensing performance of the sensors fabricated from these NFs and found that 20 mol% Pt-SnO 2 NFs exhibited excellent CH 4 sensing properties over a temperature range of 100–350 °C, for example, the 20 mol% Pt-SnO 2 NFs showed an obvious response of 1.11–1 ppm CH 4 at 350 °C, which was 2 orders of magnitude lower than the minimum detection limit of the current SnO 2 based CH 4 sensors. The great enhancement of the CH 4 sensing properties of Pt-SnO 2 NFs can be understood by the PtO/SnO 2 heterogeneous sensitization and Pt catalytic effect. Our findings present a novel strategy for the application of SnO 2 based NFs in highly effective CH 4 detection.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2026
·
IF 9.1
Ke Chen,Ruishan Li,Chengming Xiao,Xin Guo,Junwen Qi,Jiansheng Li
Efficient gas separation is essential for sustainable energy generation and industrial applications; however, membrane materials often encounter an intrinsic trade-off between permeability and selectivity. In this work, we overcome this limitation by incorporating phenolate-based metal-organic frameworks (termed as SU-102) into polyimides (6FDA-Durene) via a physical blending method. Attributable to the strong CO 2 affinity, significant porosity, and distinctive pore size of SU-102, the resulting mixed matrix membranes (MMMs) demonstrate a synergistic enhancement in both CO 2 permeability and selectivity. Specifically, MMMs with 30 wt% SU-102 amounts achieved a CO 2 /CH 4 selectivity of 33.6 and a CO 2 permeability of 1572.3 Barrer, representing increases by 1.8 and 2.2 times, respectively, compared to the pristine 6FDA-Durene membranes. Furthermore, the MMMs exhibited remarkable long-term stability over 72 h of continuous operation. Importantly, hydrogen-bonding interactions between the carboxyl and hydroxyl groups on SU-102 and the imide groups on 6FDA-Durene significantly enhanced the plasticization resistance of the MMMs, which withstood CO 2 pressures up to 12 bar. This work provides a feasible strategy for the design of high-performance gas separation membranes for practical applications.
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Frontiers of Chemical Science and Engineering
·
2024
·Vol. 18
·期 4
·1-10
·
IF 4.3
Li Ying,Wang Lu,Xie Junyan,Dai Yong,Gu Xuehong,Wang Xuerui
Membrane gas separation is considered an energy-saving technique to extract He from natural gas due to no phase change and room temperature operation. However, the membrane performance was strongly limited by the trade-off between permeance and selectivity. Herein, novel 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-2,2′-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF)-5-amino-2-(4-aminobenzene) benzimidazole (BIA) asymmetric membranes with a thickness of 300 nm were successfully prepared by the non-solvent induced phase separation method. The membrane performance was modulated by regulating dope solution compositions (e.g., tetrahydrofuran and polymer concentration). The ideal He/CH 4 selectivity was 124 and the optimized He permeance reached 87 GPU, beyond the current upper bound. He/CH 4 selectivity was 75 and He permeance was 73 GPU for the binary mixture feed containing 0.2 mol % He. The membrane showed good resistance to CO 2 and C 2 H 6 , which are the typical impurities in natural gas. The 6FDA-APAF-BIA membranes have good stability (> 160 h), which can provide great potential in He extraction from natural gas.
研究领域:
膜科学
·
气体分离
·
聚合物工程
·
相分离
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节能分离
·
材料科学
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Junjie Zhou,Hao Liu,Yichao Lin,Chen Zhou,Aisheng Huang
A well-shaped Ce (IV)-based metal organic framework (Ce-BDC) is prepared under solvothermal method. The influence of synthesis time, temperature and the amount of acetic acid (HAc) as a modulator is studied to develop a new strategy for the synthesis of well-shaped Ce-based MOF. The relationship between the synthesis parameters and morphology as well as crystallinity of Ce-BDC is investigated by XRD and SEM. Furthermore, the obtained well-shaped Ce-BDC shows a CO 2 uptake capacity of 2.28 mmol g −1 at 0 °C and 1.0 bar. Meanwhile, the breakthrough curve behaviors of Ce-BDC are investigated for a CO 2 /CH 4 and CO 2 /N 2 mixture gas . It is found that the Ce-based MOF adsorbs CO 2 under ambient temperature and pressure, but completely excludes CH 4 and N 2 , suggesting that it is a promising adsorbent for efficient separation of CO 2 from natural gas.
研究领域:
材料科学
·
无机化学
·
多孔材料
·
气体分离
·
环境催化
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PETROLEUM CHEMISTRY
·
2025
·
IF 1.1
Jiang Ning,Mao Min,Wang Qingyin,Wang Gongying
MOF-5 is a classic metal-organic framework (MOF) crystal. However, synthesis of high-quality crystals usually requires an expensive N , N ′-diethylformamide (DEF) solvent, and a high molar ratio of a raw material (Zn 2+ : BDC 2– = 3‒5 : 1). More critically, its extreme instability against water vapor has caused researchers to do not use it. In this study, we achieved some important breakthroughs by using inexpensive N , N ′-dimethylformamide (DMF) solvent and meticulously optimizing synthesis parameters combined with a specialized micro-open solvothermal method. With a reduced molar ratio of a raw material (1.47 : 1), we successfully synthesized crystals exhibiting excellent phase structure and morphology, high surface area, out standing water vapor stability, and strong CO 2 adsorption capacity. The results show that the DEF replacement with DMF and reduction of the raw material molar ratio from 3 : 1 to 1.47 : 1 provides an increase of the BET surface area from ~935 to 2388 m 2 /g, and an improvement of the CO 2 adsorption capacity from ~0.8 to 2.5 mmol/g (298 K, 100 kPa). Breakthrough curves reveal that in simulated separation experiments for the flue gas and natural gas containing low CO 2 concentrations (10‒20%), the dynamic separation selectivity for CO 2 /N 2 reaches 22, while that for CO 2 /CH 4 remains stable at 4. Notably, the selectivity remained nearly unaffected by the pressure variation; this phenomenon is promising for enhancing the capture and purification of a low-concentration CO 2 from the flue gas and natural gas. It is important that the improved MOF-5 crystals prepared under optimal synthetic conditions maintained the stable phase structure and morphology even after 14-day exposure to humid air (relative humidity >70%), successfully overcoming the challenge posed by a water vapor.
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