ACS Catalysis
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2021
·
IF 13.084
Dongdong Chen,Huarong Lei,Wuwan Xiong,Ying Li,Xiang Ji,Jia-Yue Yang,Baoxiang Peng,Mingli Fu,Peirong Chen,Daiqi Ye
Phosphorus (P) originating from lubricant oil additives or biofuels is an emerging chemical poison in catalytic systems for automotive exhaust after-treatment. Here, we demonstrate that P-poisoning led to severe deactivation of small-pore Pd-SSZ-13 zeolites (with CHA framework) as passive NOx adsorbers (PNA) and CO oxidation catalysts for cold-start exhaust purification applications. Deactivation mechanisms of P-poisoning were unraveled by comparatively examining the P-free and P-loaded Pd-SSZ-13 zeolites using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), temperature-programmed reduction by hydrogen (H2-TPR), CO pulse adsorption, temperature-programmed desorption using NH3 as a probe molecule (NH3-TPD), ultraviolet/visible light (UV/vis) spectroscopy, and in situ diffuse relectance infrared Fourier transform spectroscopy (DRIFTS). The loss of isolated Pd sites─namely, [Pd(OH)]+ and Pd2+ (located in the eight- and six-membered rings of CHA framework, respectively)─was revealed to be largely responsible for the deactivation of Pd-SSZ-13 in passive NOx adsorption and catalytic CO oxidation. In situ DRIFTS studies using NO or CO as a probe molecule suggest that [Pd(OH)]+ was more susceptible to P-poisoning than Pd2+. Specifically, P-poisoning led to a migration of [Pd(OH)]+ from cationic exchange sites to the zeolite surface, forming inactive metaphosphate (i.e., [Pd(OH)]+PO3–) and bulk PdOx species at high temperatures. In contrast, P-poisoning of Pd2+ sites proceeded via a sequential transformation to [Pd(OH)]+ first, and then to [Pd(OH)]+PO3– and bulk PdOx. This study provides a comprehensive mechanistic understanding on the deactivation of Pd-SSZ-13 by P-poisoning, and may guide the design of high-performance, phosphorus-resistant Pd-zeolite catalysts for cold-start exhaust after-treatment.
研究领域:
催化材料
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环境科学
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化学工程
✓ 已验证
DOI
高影响因子
Materials
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2021
·Vol. 14
·期 6
·1514
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IF 3.623
Sitong Chen,Shubo Wang,Xueke Wang,Weiwei Li,Baorui Liang,Tong Zhu,Xiaofeng Xie
We added microencapsulated phase change materials (MPCMs) into the homemade antifreeze fluid to take advantage of the latent heat of phase change materials, and explored the possibility of solving the cold start problem of proton exchange membrane fuel cells (PEMFC) with variable specific heat capacity antifreeze. The physical and chemical properties of the MPCMs and their suspensions were tested, and a PEMFC platform for cold start with a thermal management system was established to compare the exothermic performance of MPCS and commercial antifreeze fluid. According to the output voltage, temperature and polarization curves before and after cold start, the MPCMs has a stronger heat transfer capacity than the commercial antifreeze fluid, and the addition of MPCMs can transform the latent heat generated during the phase transition into apparent specific heat capacity, leading to a better solution to the problem of PEMFC cold start.
研究领域:
能源科学
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材料科学
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化学工程
✓ 已验证
DOI
高影响因子
FUEL
·
2024
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IF 6.7
Hao Sun,Wugao Zhang,Yixuan Wang
CeO 2 nanoparticles are effective fuel additives that enhance fuel spray, atomization, and combustion characteristics due to their high catalytic activity and excellent thermal properties. When added to fuel, CeO 2 nanoparticles significantly improve in-cylinder combustion, and engine performance, and reduce pollutant emissions under normal engine operating conditions. Diesel engines encounter persistent challenges during cold starts at low temperatures and high altitudes. However, there is limited research on the effects of CeO 2 nanoparticles on ignition and combustion at low temperatures and cold start performance. This study aims to evaluate the impact of CeO 2 nanoparticles doping in diesel fuel on the cold start performance of diesel engines in high-altitude and low-temperature environments. Diesel fuel doped with CeO 2 nanoparticles at various concentrations was prepared using magnetic stirring and ultrasonication. The cold start performance of the test engine was assessed in an environmental chamber. This work investigated and evaluated the improvements of CeO 2 nanoparticles on cold start performance from three perspectives: general low-temperature conditions, high-altitude environments, and extreme low-temperature scenarios with diethyl ether premixing. Experimental results indicate that incorporating CeO 2 nanoparticles expanded the critical temperature required for a successful cold start from 0 °C to −5 °C. At high altitudes, the addition of CeO 2 nanoparticles effectively increased the proportion of efficient combustion, evidenced by single peak and parent peak patterns during cold starts. CeO 2 nanoparticles facilitated the transition from low-temperature to high-temperature reactions, promoting fuel ignition during the first injection cycle and reducing speed fluctuations during cold starts with diethyl ether premixing at −40 °C. Furthermore, adding CeO 2 nanoparticles prevented detonation and rapid pressure surges during cold starts. Overall, doping diesel fuel with CeO 2 nanoparticles proves to be an effective method for enhancing cold start performance in diesel engines. This study offers a novel approach for improving diesel engine cold start performance in high-altitude and low-temperature conditions.
研究领域:
能源工程
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Energies
·
2021
·Vol. 14
·期 15
·4520
·
IF 3.004
Xiaokang Yang,Jiaqi Sun,Guang Jiang,Shucheng Sun,Zhigang Shao,Hongmei Yu,Fangwei Duan,Yingxuan Yang
Membrane water content is of vital importance to the freezing durability of proton exchange membrane fuel cells (PEMFCs). Excessive water freezing could cause irreversible degradation to the cell components and deteriorate the cell performance and lifetime. However, there are few studies on the critical membrane water content, a threshold beyond which freezing damage occurs, for cold storage of PEMFCs. In this work, we first proposed a method for measuring membrane water content using membrane resistance extracted from measured high frequency resistance (HFR) based on the finding that the non-membrane resistance part of the measured HFR is constant within the range of membrane water content of 2.98 to 14.0. Then, freeze/thaw cycles were performed from −50 °C to 30 °C with well controlled membrane water content. After 30 cycles, cells with a membrane water content of 8.2 and 7.7 exhibited no performance degradation, while those higher than 8.2 showed significant performance decay. Electrochemical tests revealed that electrochemical surface area (ECSA) reduction and charge transfer resistance increase are the main reasons for the degradation. These results indicate that the critical membrane water content for successful cold storage at −50 °C is 8.2.Keywords:freezing durability;cold start;membrane water content;performance degradation;proton exchange membrane fuel cell
研究领域:
能源科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Liuyang Yang,Meiqing Shen,Xinhua Li,Liwei Jia,Feng Gao,Wei Li,Xinyu Li,Gurong Shen
Passive NO x adsorbers (PNAs) are promising materials for mitigating cold-start NO x emissions, yet their performance is often limited by poor adsorption kinetics and insufficient hydrothermal durability. Herein, we report a triethanolamine (TEOA)-assisted synthesis strategy for Mn/CeZrO x PNAs that enables highly dispersed MnO x species with strengthened Mn-support interactions. Compared with conventionally prepared Mn/CeZrO x , the TEOA-modified materials exhibit (i) faster NO x adsorption rates during the initial cold-start relevant stage, (ii) a higher nitrate formation rate and a more suitable nitrate decomposition window (200–400 °C) in which the downstream selective catalytic reduction unit utilizing Cu-SSZ-13 SCR catalysts typically displays optimized NO x reduction efficiency, and (iii) enhanced hydrothermal stability with reduced MnO x agglomeration after aging. A combination of spectroscopic and microscopic techniques (XPS, UV–vis, DRIFTS, TEM/EDS) reveal that TEOA modulation promotes uniform MnO x dispersion, increases surface O ads species, and shifts MnO x speciation toward more active states. These structural and chemical modifications collectively account for the improved PNA performance. This work demonstrates a simple yet effective synthesis approach to optimize Mn-based PNAs, providing new insights into the design of thermally robust, precious-metal-free cold-start NO x control materials.
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产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2023
·
IF 19
Zhipeng Xu,Qiuping Wang,Liang Guo,Yeyang Li,Junyao Wang,Shuaijun Yu,Junbin Liao,Yanqing Xu,Jiangnan Shen
High-temperature proton-exchange membrane fuel cells (HT-PEMFCs) fabricated with phosphoric acid (PA)-doped polybenzimidazole (PBI) show apparent technical advantages. In practical automotive applications, achieving cold start-up capability is crucial. In this work, a kind of branched block proton exchange membrane (PEM) based on PBI with a low content of porphyrin ring (<1 mol.%) is reported as a branched monomer. Self-assembly into high-density helical nanochannels under the synergistic effect of phase separation and porphyrin π−π stacking, thus the PEM can maintain a high level of PA doping. Specifically, the PA/1.8TCPP-BrPy-OPBI membrane shows a proton conductivity of 0.169 and 0.071 S cm −1 , as well as an H 2 -O 2 fuel cell peak power density of 1077 and 357 mW cm −2 at 180 and 80 °C without humidification and backpressure, respectively. The membrane electrode assembly (MEA) can exhibit good fuel cell stability, with a voltage decay rate of only 7.0 µV h −1 at 80 °C. Furthermore, it maintains a peak power density of 93% even after 150 start-up/shut-down cycles at 25 °C. This work expands the operating temperature range of conventional PBI membranes between 25 and 200 °C and thus provides a novel strategy for high-performance PBI-based HT-PEMFCs.
研究领域:
材料科学
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化学工程
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电化学
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能源技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
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IF 13.2
Chao Chen,Yan Chen,Bing Zhao,Mingjie Ma,Ningbo Wang,Zheng Li,Yunchu Cheng,Ling Zhou,Congjie Gao,Fei Huang,Lixin Xue
Phosphoric acid (PA)-doped high-temperature proton exchange membranes (HT-PEMs) face significant challenges from PA leaching, particularly under low temperatures, which severely compromises their operational durability and flexibility. Herein, we developed innovative polybenzimidazole (PBI)-based PEMs featuring a comb-shaped cationic bridge structure, synthesized via a combined polyphosphoric acid process and heterogeneous free radical polymerization. The resulting membranes exhibited a distinctive porous microstructure characterized by aligned nanosheet arrangements and double dense skin layers, effectively suppressing PA leaching. Strong ion-pair interactions between imidazolium cations and biphosphate enhanced PA retention and promoted PA dissociation, substantially improving proton conductivity. The optimized PA/PBI-AMim-2 membrane achieved exceptional proton conductivity, exceeding 10 mS/cm at −20 °C and reaching 0.34 S/cm at 220 °C, enabling efficient fuel cell operation across a wide temperature range. It demonstrated outstanding single-cell performance, delivering peak power densities of 820 mW/cm 2 at 80 °C and 1605 mW/cm 2 at 160 °C, along with cold start-up capability of 46 mW/cm 2 at −20 °C. Its superior PA retention ensured stable performance with a minimal decay rate of 23.7 μV/h at 40 °C and enabled reliable functionality through 100 frequent start-up/shutdown cycles. This breakthrough bridges the gap between conventional low-temperature and high-temperature PEMFCs, paving the way for robust, flexible and durable systems under real-world operating conditions.
研究领域:
能源材料
·
高分子科学
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电化学
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燃料电池
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膜技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）