MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Yanliang Zhai,Yunshan Shang,Luoming Zhang,Xiaoling Meng,Yanjun Gong,Lirong Zheng,Jing Zhang,Ping Liu
Hydrothermally modified nanosheet ZSM-5 zeolite by directly using MnO x nanoparticles was carried out and this substantially offered a high performance catalyst for methanol to propylene (MTP) reaction. The properties of as synthesized ZSM-5 nanosheets with different MnO x amounts (NS-x) were compared with ZSM-5 nanosheets modified by impregnation method (IM-0.5) and physically mixed method (PM-0.5), respectively. The initial state of MnO x nanoparticles was close to Mn 2 O 3 with 20 nm in size. XRD , H 2 -TPR and XAFS results confirmed under high temperature hydrothermal condition, the Mn 2 O 3 nanoparticles disaggregated into Mn 2 O 3 clusters and entered the framework defects of nanosheet zeolite with high dispersion. Infrared spectra of hydroxyl groups (OH-IR) showed that the Mn 2 O 3 clusters were bonded with silanol defects both on the surface and inside zeolite, which substantially increased the stability of Mn 2 O 3 clusters and healed the framework defects. In contrast, the Mn species in the impregnated sample was close to the co-existence of Mn 2+ ions and MnO 2 nanoparticles with 2–3 nm, no interaction between Mn species and Si–OH group was determined. Notably, the typical sample (NS-0.5) with MnO x cluster modification performed much higher propylene selectivity and catalytic stability (~52%, 240 h, WHSV = 3 h −1 ), while the conventional IM-0.5 and PM-0.5 showed poor propylene selectivity (48%, 46%) and catalytic stability (166 h, 133 h) in MTP reaction. The excellent result should be attributed to the subtle control of external strong acid and the less structural defects, due to specific existence of bonded Mn 2 O 3 clusters.
研究领域:
化学
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材料科学
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催化
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
SCIENTIA HORTICULTURAE
·
2020
·
IF 2.769
Yu Tao Huang,Shu Yu Cai,Xiao Li Ruan,Shan Yu Chen,Gao Fu Mei,Guan Hai Ruan,Dong Dong Cao
Zinc (Zn 2+ ) stress is an important abiotic constraint affecting crop seed germination and plant growth. It is vital to exploit and utilize zinc-polluted soil by exploring technologies for promoting seed germination under Zn 2+ stress. This study aims to explore the effects of salicylic acid (SA) and 2-aminoindan-2-phosphonic acid (AIP, SA synthesis inhibitor) on the Zn 2+ stress resistance of sunflower during seed germination. Zn 2+ treatment significantly inhibited seed germination and seedling growth of sunflower. In addition, Zn 2+ treatment increased Zn 2+ and abscisic acid (ABA) contents, while decreased SA and gibberellins (GA) contents of sunflower seeds. Exogenous SA effectively alleviated the inhibition of Zn 2+ stress on sunflower seed germination, promoted endogenous SA anabolism, and increased the expression of zinc transporter-related genes family ( MTP and HMA ), which leading to decreased Zn 2+ accumulation. Moreover, exogenous SA increased GA content and decreased ABA content by regulating the gene expressions of metabolic related enzymes. On the contrary, AIP treatment further aggravated the inhibitory effect of Zn 2+ stress on sunflower seed germination. This study demonstrated that exogenous SA could affect the Zn 2+ metabolic balance in sunflower seeds by regulating the expression of Zn 2+ transport-related gene ( MTP and HMA ), promote the biosynthesis of endogenous SA and GA, inhibit the accumulation of ABA content, and improve the germination ability of sunflower seed under zinc stress.
研究领域:
植物生理学
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环境科学
·
农学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Huimin Luan,Wei Chen,Qinming Wu,Anmin Zheng,Xiangju Meng,Trees De Baerdemaeker,Andrei-Nicolae Parvulescu,Ulrich Müller,Feng-Shou Xiao
Despite very successful synthesis of many pure silica or germanosilicate zeolites, there are still challenges for direct synthesis of their aluminosilicate forms. As a typical example, it is easy to synthesize germanosilicate ITH, but difficult for direct synthesis of its aluminosilicate form. Recently, cationic oligomer has been successfully templated for direct formation of aluminosilicate ITH, but relatively complex steps for controlling molecular weight of the cationic oligomer strongly hinder the practical production of zeolite products. Herein, it is shown an alternative route for direct synthesis of aluminosilicate ITH zeolite in the presence of a small organic template with both structural directing ability for the ITH structure and strong interaction ability to aluminum species. Characterizations of the zeolite products with Si/Al ratios from 46 to 148 show high crystallinity, nanosheet-like crystal morphology, large microporous surface area (338 m 2 /g), high micropore volume (0.16 cm 3 /g), four-coordinated Al species, controllable acidic sites, and extraordinary hydrothermal stability (hydrothermal aging at 800 °C for 5 h with 10% water steaming). Catalytic tests in methanol-to-propylene (MTP) show that the aluminosilicate ITH zeolite has higher selectivity for propylene than that of commercial ZSM-5 zeolite with similar Si/Al ratio, which provides a candidate catalyst for MTP reaction in the near future.
研究领域:
化学
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材料科学
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催化
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Jingce Bi,Qingfeng Zhan,Yujing Chen,Zhiqiang Liang,Ningning Liu,Xia Zhang,Zhuopeng Wang,Yide Han
At present, the construction of hierarchically porous ZSM-5 molecular sieves using only cetyltrimethylammonium bromide (CTAB) as the template represents a major challenge in the field of molecular sieve synthesis. In this work, hierarchically porous ZSM-5 zeolite was synthesized via a straightforward conventional static hydrothermal method, employing CTAB as the sole template agent derived from CTAB-encapsulated silica sphere precursors. By controlling the dissolution rate of silica spheres, the release rate of CTAB is regulated, enabling the synthesis of pure-phase hierarchical porous ZSM-5 zeolite. The influences of alkalinity, aging time, Si/Al ratio, CTAB content and addition method, and crystallization time on the construction of hierarchically porous ZSM-5 molecular sieves were examined. The experimental results indicate that the crystallization process in this system proceeds in the order: MFI → MFI + kenyaite → MFI + quartz. Additionally, by managing the crystallization process, we systematically examined the formation process of impurities and established the optimal conditions for synthesizing pure-phase hierarchically porous ZSM-5 molecular sieves in this system. Moreover, the as-prepared hierarchically porous ZSM-5 molecular sieves demonstrated enhanced selectivity towards light olefins in the MTP reaction.
研究领域:
材料科学
·
化学合成
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催化化学
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纳米技术
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无机化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2018
·Vol. 9
·期 3
·659-671
·
IF 5.365
Yanliang Zhai,Shaolong Zhang,Yunshan Shang,Yu Song,Wenxuan Wang,Tong Ma,Luoming Zhang,Yanjun Gong,Jun Xu,Feng Deng
Herein, a specific core–shell MFI zeolite was designed for the methanol to propylene (MTP) reaction. The core–shell structure of Al-ZSM-5@B-ZSM-5 and Al-ZSM-5@silicalite-1 were easily obtained via a two-step procedure, in which Al-ZSM-5 aggregate acted as the core and B-ZSM-5 or silicalite-1 as the shell. Their core–shell structures, acidity distribution and pore properties were characterized systemically, and new insights were gained into the synergetic effect of acid property and diffusion on the MTP reaction. The Al-ZSM-5@B-ZSM-5 zeolite exhibited a superior catalytic performance with a lifetime of 350 h (WHSV = 3 h−1), propylene selectivity of 49% and high turnover number of 4.3 × 106, while for the Al-ZSM-5 core, the corresponding values were 210 h, 43% and 5.2 × 105, respectively. Al-ZSM-5@silicalite-1 displayed the second best performance with the values of 250 h, 45% and 2.9 × 106, respectively. Gradient strong acid reduction from the core to the shell via the epitaxial growth of the silicalite-1 or B-ZSM-5 shell combined with an appropriate strong/weak acid ratio plays a vital role in inhibiting the hydrogen transfer reaction and thus gives a low consumption of propylene and low coke deposition. For the hydrogen transfer reaction of alkenes to form alkanes and aromatics, strong acid sites are required. Moreover, the acid sites originally existing on the external surface of the Al-ZSM-5 core were converted into internal acid sites due to the formation of an interface zone in the core–shell zeolite, possessing micropore characteristics, which in turn improve the shape selectivity and suppress coke deposition. Especially, the Al-ZSM-5@B-ZSM-5 zeolite displayed more weak acid sites and few strong acid sites on its shell surface, which are beneficial for the low formation of external coke and also account for the highest utilization of acid sites in the MTP reaction, high propylene selectivity and long lifetime.
研究领域:
催化
·
化学工程
·
材料科学
✓ 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）