FUEL
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2022
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IF 8.035
Xinyu Yang,Zezhi Chen,Huijuan Gong,Feng Lin,Tingting Zhu,Ziyi Yang
Deoxygen is a crucial step for landfill gas (LFG) recycling and purification. Pt/γ-Al 2 O 3 is the most active catalyst for LFG deoxygen via catalytic methane oxidation . It is challenging but significant to further improve the performance of this type of catalyst. In regard of homogeneous and heterogeneous activation of methane by superacids , here we demonstrate LFG deoxygen via catalytic methane oxidation using a solid superacid catalyst, Pt/SO 4 2- /Al 2 O 3 , synthesized using pre-sulfated γ-Al 2 O 3 support by impregnated with sulfuric acid . In comparison to Pt/γ-Al 2 O 3 , Pt/SO 4 2- /Al 2 O 3 catalysts exhibit exceptionally improved activity and minimum complete O 2 conversion at a temperature of 264 ℃, a decrease of about 51 ℃. This value is superior to the state-of-the-art Pt-based deoxygen catalysts. Characterizations and theoretical calculations indicate that sulfation enhances the amount of acid sites on γ-Al 2 O 3 support and induces electron deficiency of the supported Pt species (+0.28|e|), thus boosting the low-temperature activity. Furthermore, the Pt/SO 4 2- /Al 2 O 3 catalyst maintained its initial activity after six runs without any detectable coke deposition. This discovery offers simple and effective strategies to precisely design higher performance application-oriented Pt based deoxygen catalysts.
研究领域:
催化
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环境工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
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2023
·
IF 7.3
Qiangqiang Wu,Hanke Li,Guangxing Yang,Yonghai Cao,Hongjuan Wang,Feng Peng,Hao Yu
A variety of adsorbed intermediates have been extensively assigned during CO 2 hydrogenation on Pt/γ-Al 2 O 3 . However, the surface sites where the surface species reside have not been well resolved, which are extremely important to depict the reaction pathways of CO 2 hydrogenation. In the current work, surface species adsorbed on three regions were distinguished by in situ diffuse-reflectance infrared Fourier transform spectroscopy, i.e., contiguous Pt region of Pt nanoparticle, interfacial Pt int -O-Al int region between Pt nanoparticle and γ-Al 2 O 3 , and surface region of γ-Al 2 O 3 away from Pt nanoparticle. The dynamics of adsorbed H species, carbonyl species, bicarbonates, formate species, and adsorbed CO 2 , were identified at different sites, proving that the reaction occurs at the Pt/γ-Al 2 O 3 interface. We found that only the C-containing species at the Pt perimeter are directly active intermediates for the reaction. Such spatial analysis bridges the gap between the hydrogen activation and CO 2 activation, providing a deep understanding of CO 2 hydrogenation. In addition, the interface structure with oxygen vacancy is important for CO 2 activation, driving the reaction through carboxylate (*HOCO) pathway to form CO at the interface rather than formate (*HCOO) pathway and then be hydrogenated at the Pt surface.
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
CATALYSIS TODAY
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2020
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IF 5.825
Juan Liu,Wen-Ying Li,Jie Feng,Xiang Gao
The improvement of the sulfur tolerance over Pt catalyst is critical for the hydrotreatment of crude oil. Fe was co‒impregnation with Pt on γ-Al 2 O 3 at different calcination temperature. Results revealed that adding Fe significantly facilitated the reduction of Pt oxides for the catalyst calcined at 400 °C. The morphological analysis and CO chemisorption showed Fe improved the dispersion of Pt nanoparticles. The surface chemical state analysis implied the co‒existence of the electron‒deficient Pt and metallic Fe. However, the increase of calcination temperature caused a decreased reducibility of Pt oxides due to strong metal support interaction. A higher dibenzothiophene hydrodesulfurization conversion of 97.7 % with a dominant biphenyl selectivity of 96.7 % were acquired for the catalysts incorporated with Fe. The density functional theory calculations confirmed the alloyed Fe led to the formation of electron‒deficient Pt atoms, and the higher affinity to sulfur made Fe be a favorable additive for noble metal catalyst in the hydrodesulfurization.
研究领域:
催化
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化工
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
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IF 16.744
Yunhan Bai,Xiaoshu Ding,Ying Sun,Yucong Song,Yanji Wang
The reverse water gas shift (RWGS) reaction is one kind of the catalytic conversion of CO 2 to reduce an enormous amount of CO 2 . However, the RWGS reaction has the safety hazards associated with the use of hydrogen and thermodynamic limitation. Therefore, this work proposes a new safe and efficient reaction route (CO 2 -MCH) to get CO from CO 2 and methylcyclohexane (MCH). Thermodynamic calculations showed that the equilibrium CO 2 conversion at 350 °C increased from 17.8 % of the RWGS reaction to 53.5 % of the CO 2 -MCH reaction. In the CO 2 -MCH reaction, the relationship of the catalytic performance with the metal dispersion, the Pt particle size and the acidity of Pt-based catalysts on the different supports was investigated, respectively. The results showed that the Pt/γ-Al 2 O 3 catalyst with high dispersion of Pt particles, small particle size and medium acidity had good activity and selectivity. The relationships among Pt loading and Pt particle size on the Pt/γ-Al 2 O 3 catalyst and the catalytic performance were evaluated. The Pt particle size gradually increased with the metal loading. A positive correlation was observed between Pt particle size and CO 2 conversion; a volcano-type relationship was observed between CO selectivity and Pt particle size. In the CO 2 -MCH reaction at 350 °C, 0.1 MPa, LHSV = 6 h −1 , the CO 2 conversion was 24.7 %, the CO selectivity reached 95.2 %, and the Pt/γ-Al 2 O 3 catalyst within 40 h showed good stability. Moreover, the mechanism of the CO 2 -MCH catalytic reaction over the Pt/γ-Al 2 O 3 catalyst was speculated.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
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2020
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IF 3.687
Juan Liu,Wen-Ying Li,Jie Feng,Xiang Gao
The hydrodenitrogenation of nitrogen-containing heterocycles over noble metals has fundamental importance for energy and environmental science. To develop more efficient catalyst, mechanistic investigation has been conducted with a method combining in situ Fourier transformation infrared experiments and density functional theory calculations in this work. The in situ experiments indicate flatly adsorbed pyridine molecules convert to pyridinium and α -pyridyl species at higher temperature on metallic Pt of Pt/γ-Al 2 O 3 catalysts. Pyridine hydrogenation distinctly takes place at 150 °C with the appearance of methylene stretching vibrations, and a stepwise mechanism is identified as the temperature further increases. The adsorption, hydrogenation and hydrogenolysis of pyridine on Pt are studied in detail by theoretical calculations. In line with these findings, the geometry optimization confirms pyridine preferentially adsorbs on Pt(111) and Pt(211) both in a parallel configuration. Based on the Langmuir–Hinshelwood mechanism, the results show successive hydrogenation markedly lowers the energy barrier for subsequent hydrogenolysis. The C N bond cleavage occurs via nucleophilic attack of pentahydropyridine, rather than piperidine, which determines the reaction products, including piperidine, n -pentylamine and n -pentane. The comparative study reveals both hydrogenation and hydrogenolysis are kinetically and thermodynamically more competitive on Pt(211) than Pt(111). Especially for hydrogenolysis, the coordinatively unsaturated Pt step atoms play an essential role in C N bond cleavage. Thus, hydrogenolysis is more geometric‒dependent than hydrogenation. This provides instructive information for the design of catalysts with adjustable product selectivity.
研究领域:
催化化学
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环境科学
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计算化学
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能源科学
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表面化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2016
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IF 8.328
Tengfei Yang,Ying Huo,Yang Liu,Zebao Rui,Hongbing Ji
Rational design of efficient noble metal catalysts and its application process by the interface promoted strategy is an emerging research field. Herein, highly efficient nickel hydroxide promoted PtNi(OH)x/γ-Al 2 O 3 catalysts for room temperature HCHO oxidation was developed. PtNi(OH)x/γ-Al 2 O 3 demonstrates remarkably better performance than the state of the art non-reductive oxide supported Pt catalysts, and ranges among the best performance of the reductive metal oxide supported Pt catalysts. A (>)99% HCHO conversion and a (>)100 h stable performance at 30 °C were obtained over PtNi(OH)x/γ-Al 2 O 3 with a 0.3 wt% Pt loading amount. Various characterizations, including in situ DRIFTS study, were performed to understand the reason for the enhanced performance of PtNi(OH)x/γ-Al 2 O 3 . The superior performance is attributed to the formation of enormous Pt/Ni(OH)x interface, and the preferred hydroxyl facilitated HCHO oxidation pathway through formate oxidation by the abundant associated hydroxyl groups nearby the Pt active sites. Such hydroxyl groups confined interface promotion strategy may bring new insight into the designing of highly efficient bimetallic catalysts and its potential technological applications for HCHO removal.
研究领域:
催化化学
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环境科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2022
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IF 3.898
Xinyu Yang,Zezhi Chen,Huijuan Gong
Catalytic oxidation of CH 4 has been proved to be an attractive option for landfill gas (LFG) upgrading. However, coking of catalysts in catalytic LFG deoxygen has been clearly observed in industrial applications. In this regard, it is necessary to investigate whether coke deposition originates from CH 4 or volatile organic compounds present in LFG, and the influence of coke deposition on catalytic performance. Herein, we evaluate the LFG deoxygen on Pt/γ-Al 2 O 3 catalyst in simulated LFG (CH 4 , CO 2 , O 2 , N 2 ) and its co-feed with representative volatile organic compounds, ethylbenzene , toluene, benzene and cyclohexane . The results show that the coking of the catalyst is originated from volatile organic compounds rather than CH 4 . The Pt/γ-Al 2 O 3 catalyst does not deactivate during LFG deoxygen process, even significant amount of coke deposited, up to 18.15% (mass). Characterization analyses reveal that although coke deposition overall covers the catalyst surface, resulting in mesopores blockage and a reduced number of accessible Pt sites, however, the coke formed, H-rich carbonaceous components, behaves as counterpart for O 2 elimination. Besides, the coke deposited is mainly filamentous. Thus, coke formation has little negative effect on the overall catalytic performance of Pt/γ-Al 2 O 3 catalyst ultimately. The results obtained in this work are helpful for the rational design of robust Pt based catalysts for LFG deoxygen without undue attention to their coking properties, and also favor the innovation of more attractive purification scheme configurations.
✓ 已验证
产品关联
DOI
高影响因子
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