MICROPOROUS AND MESOPOROUS MATERIALS
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2021
·
IF 5.455
Guochao Yang,Lingtao Wang,Haoxi Jiang
The conversion of ethanol to butadiene catalyzed by modified β zeolites has attracted wide attention. The construction of intracrystalline mesoporosity in β zeolite is a challenging way to improve the catalytic activity. In this work, a surfactant-template strategy was used to construct intracrystalline mesoporosity successfully in the alkali treatment of β zeolite using long-chain quaternary ammonium salt with different alkyl chain length (C10~C16) as the template. The intracrystalline pore size can be adjusted by varying the surfactant alkyl chain length (C10~C16) (1.9–3.4 nm). To get more information about this process, CTAB was chosen as the template in further investigations. The mesoporosity can be generated within 1 h. The BET surface area can reach up to 600 m 2 /g while the pore volume can reach up to 0.568 cm 3 /g, which are 1.23 and 1.5 times that of the parent zeolite, respectively. The template action of CTA + is essential for forming mesoporosity, and CTA + interacts with the zeolite during the alkali treatment process, protects the zeolite framework from being etched, and does not form a separated mesoporous phase. To demonstrate the effect of intracrystalline mesoporosity on the catalytic performance, Zr-β zeolite was prepared and used as the catalyst for ethanol-acetaldehyde conversion. The hierarchical Zr-β zeolite was prepared using a dealumination-metallization strategy, and both the zeolite crystallinity and the mesoporosity were preserved in this process. The total conversion increased by 10%, while the BD selectivity was well maintained. The catalytic performance showed that the introduction of mesoporosity effectively mitigated decreasing conversion while preserving BD selectivity.
研究领域:
催化材料
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 126
·103982-103988
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IF 3.84
Zheng Han,Xiang Li,Minhua Zhang,Zongzhang Liu,Meixiang Gao
A series of ZrO2–SiO2 catalysts synthesized by sol–gel method were investigated for the 1,3-butadiene formation from bioethanol and acetaldehyde. The influence of ZrO2 content and reaction conditions on catalytic performance were studied. The catalysts were characterized by N2 adsorption–desorption analysis, temperature-programmed desorption of NH3 (NH3-TPD), IR spectroscopy of adsorbed pyridine (Py-IR), Fourier Transform Infrared Resonance (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). These characterization results indicated that suitable intensity of acid sites, especially Lewis acid, are very crucial to obtain an active catalyst. The catalysts showed significantly higher selectivity for C4 chemicals, and 2 wt% ZrO2 content reached the highest selectivity to BD (69.7%), at space velocity (WHSV) of 1.8 h−1.
研究领域:
催化化学
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可再生资源转化
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2022
·Vol. 139
·期 26
·e52464
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IF 3.057
Yingjie Song,Guangyi Lin,Lin Zhang,Chuanbao Geng,Qiao Li,Hong Wang,Fumin Liu,Zhenning Liang,Yuan Jing,Yong Li
The wear resistance of rubber composite materials has always been the focus of research. The wear resistance will not only affect the service life of products and the safety of equipment, but also have an important impact on the environment. In this work, the preparation and properties of wear-resistant rubber nanocomposites based on natural rubber (NR) were studied. It is dedicated to improving the wear resistance of NR composites. On this basis, the dispersibility of montmorillonite (MMT) hybrid materials in NR-based rubber composites was explored. SiO 2 @MMT, SiO 2 @MMT@KH560, PDA@GO, and MMT@GO hybrid materials were prepared, and the hybrid materials were applied to the NR/butadiene rubber (NR/BR) system, and NR/BR/hybrid material composite materials were successfully prepared. The results show that the interlayer spacing of MMT in hybrid materials increases, which effectively improves the dispersibility of MMT in rubber matrix. The tensile strength of NR/BR/MMT@GO composite material increased by 12%, the elongation at break increased by 25%, the DIN abrasion decreased by 16.5% compared with the optimum wear rubber formula, and the wear resistance was greatly improved. This work provides a feasible way for the design of functional polymer composites.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 48
·e53224
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IF 3.057
Lv Xiaojing,Jinwei Wang,Yong Guo
Phosphorus containing liquid epoxidate polybutadiene (P-LEPB) is synthesized and used as the additive to improve the flame retardancy and toughness of epoxy resin (EP). The structure of P-LEPB is confirmed by Fourier transform infrared (FTIR), 1 H and 13 C nuclear magnetic resonance (NMR). With the addition of P-LEPB, EP composites show earlier degradation; and P-LEPB plays flame retardancy functions as reflected by the increase of limiting oxygen index (LOI) and its promotion of carbonization as seen from the char scanning electron microscopy images after LOI tests. The addition of P-LEPB improves the water proof performance of EP composites, playing positive effect on resisting water spreading on the surface and immersing in the EP composites as supported by the water absorption rates and contact angle measurements. The elongation at break increases with addition of P-LEPB and reaches nearly three times higher than the neat epoxy at P-LEPB addition of 10%, the toughening effect of P-LEPB is attributed to the diverting function by the P-LEPB microspheres upon stress loading, which is related to the size and distribution of P-LEPB additions as seen from their cross-sectional images of the composites.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER COMPOSITES
·
2013
·Vol. 34
·期 7
·1013-1019
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IF 1.482
Jianjun Han,Haifeng Lu,Lin Zhang,Jie Zhang,Shengyu Feng
A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with gadolinium salt (GS) particles was prepared for the first time and vulcanized via coordination reactions. The resulting materials exhibit good mechanical properties. Structural analyses indicate that the composite is a kind of elastomers based on coordination cross-linking interactions between the nitrile groups (–CN) of NBR and gadolinium ions. The mechanical properties of vulcanized GS/NBR rubber are altered when the cross-link density is changed in the composites. These materials show good irradiation resistance because of the introduction of GS. POLYM. COMPOS., 34:1013–1019, 2013. © 2013 Society of Plastics Engineers
研究领域:
材料科学
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高分子化学
✓ 已验证
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
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2021
·
IF 4.598
Qiang Gui,Changou Pan,Pengwei Xie,Mingliang Pei,Peng Liu
Fluorination could efficiently improve the comprehensive performance of nitrile-butadiene rubber (NBR). However, severe gelation usually occurred in the radical graft polymerization onto the diene-based polymers. Here, a facile approach has been established for the facile fluorination of NBR without gelation via radical graft polymerization in presence of n -dodecylmercaptan (NDM) as chain transfer agent, with 2,2,3,4,4,4-hexafluorobutyl acrylate (F6) as the model fluorinating monomer. The gel content decreased with increasing the feeding ratio of NDM and reached 0 with a feeding ratio of NDM of 50 mol% of the initiator, with a fluorination degree of 0.50%. The graft polymerization mechanism was proposed with the 1 H NMR analysis. The proposed strategy is expected to provide a promising approach for the functionalization of diene-based polymers.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2016
·Vol. 7
·期 1
·168-180
·
IF 5.287
Xiaoxiong Huang,Yong Men,Jinguo Wang,Wei An,Yuanqiang Wang
A series of magnesia–silica binary composite catalysts with different molar ratios were prepared using various preparation methods and evaluated for the one-step production of 1,3-butadiene (BD) from bio-ethanol. The MgO–SiO2 catalyst prepared by wet-kneading is distinguished from the samples prepared by other methods by its superior activity. An exceptionally high productivity of butadiene with the high ethanol conversion of 95% and BD selectivity of 77% was obtained over wet-kneaded hierarchical flower-like MgO nanostructures with the catalytic material made up of SiO2 spheres (with a MgO : SiO2 molar ratio of 65 : 35 at 450 °C and an WHSV of 4.1 h−1), which translates into an unprecedented BD yield of 0.025 mol gcat−1 h−1. The as-prepared catalysts were characterized by XRD, FESEM, BET, FT-IR, UV/vis, CO2-TPD and NH3-TPD. The Mg precursor used and the preparation method are found to influence the extent of MgO and SiO2 interactions during preparation, as estimated by various techniques, which, in turn, was found to correlate with the catalytic performance. A subtle balance of surface acidity/basicity was found to be necessary to achieve a high butadiene yield which can be obtained by variation of MgO : SiO2 ratios in wet-kneaded samples. In view of the difference in catalytic activity and the physicochemical properties of the MgO–SiO2 composite catalysts, the Si–O–Mg chemical bond formed by the strong MgO and SiO2 interaction is suggested to be essential for the balanced surface acid/base sites in relation to the strong interaction between MgO and SiO2 and the consequent high catalytic performance.
研究领域:
催化化学
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材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
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IF 3.375
Munir Hussain,Sohail Yasin,Muhammad Adnan Akram,Huilong Xu,Yihu Song,Qiang Zheng
Nanoparticle dispersion is important for the performance of rubber compounds. Herein, ionic liquids (ILs) and silane are used to prepare silica-filled butadiene rubber vulcanizates. The results show that replacement of a half of silane by ILs could greatly improve the dispersions of silica and zinc oxide, restrain the migration of sulfur and other additives inside the composite, and maintain the cross-linking degree of the matrix possibly by suppressing the adsorption of sulfur and other additives by silica. The regulated filler dispersity and matrix cross-linking strongly influence the dynamic rheological behaviors of the vulcanizates as a function of silica volume fraction. In comparison with silane, the introduction of ILs could improve the reinforcement effect, reduce energy dissipation, and lower the frequency dependences of loss modulus and loss tangent in the linear region.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 59
·34069-34077
·
IF 2.936
Minhua Zhang,Xuechao Tan,Tong Zhang,Zheng Han,Haoxi Jiang
A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO2–SiO2 catalyst prepared by a sol–gel method was performed. The samples were characterized by N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), NH3 temperature programmed desorption (NH3-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), 13C magic-angle spinning nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn0.5–Zr–Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C–O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2013
·Vol. 4
·期 3
·773-779
·
IF 3.753
Qinzhuo Zhou,Bo-Geng Li,Suyun Jie,Na Zheng
A series of phosphine-containing cobalt complexes [CoCl2(PRPh2)2, R = Ph (1), Cy (2), nPr (3), Et (4), Me (5), H (6)] has been used for the highly active and stereospecific polymerization of 1,3-butadiene upon activation with ethylaluminum sesquichloride (EASC). The high catalytic activities and polybutadienes with high cis-1,4 selectivity were obtained in the solution polymerization in toluene. The conversion of butadiene and the microstructure and molecular weight of the resulting polymers were affected by reaction parameters and the R group on the phosphine ligand. The dispersion medium was also a sensitive factor for the current catalytic systems, influencing the catalytic activity and properties of products. In comparison with the solution polymerization in toluene, the heterogeneous polymerization in isooctane yielded slightly lower catalytic activity, cis-1,4 content and molecular weight under similar reaction conditions.
研究领域:
高分子化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 22
·4879
·
IF 4.967
Fang Xie,Zhongxin Ping,Wanting Xu,Fenghua Zhang,Yuzhen Dong,Lianjie Li,Chengsen Zhang,Xiaobo Gong
Rubber materials are widely used in aerospace, automotive, smart devices and artificial skin. It is significant to address the aging susceptibility of conventional vulcanized rubber and to impart it rapid self-healing performance for destructive crack damage. Herein, a novel supramolecular rubber elastomer is prepared by introducing metal coordination between carboxyl-terminated polybutadiene and polystyrene-vinylpyridine copolymer. Based on the metal coordination interaction, the elastomer exhibits shape memory and self-healing properties. Moreover, a rapid closure-repair process of destructive cracks is achieved by presetting temporary shapes. This shape memory-assisted self-repair model is shown to be an effective means for rapid repair of severe cracks. An approach to enhance the mechanical and self-healing properties of elastomer was demonstrated by adding appropriate amounts of oxidized carbon nano-onions (O-CNO) into the system. The tensile strength of the elastomer with an O-CNOs content of 0.5 wt% was restored to 83 ± 10% of the original sample after being repaired at 85 °C for 6 h. This study confirms that metal coordination interaction is an effective method for designing shape memory self-healing rubber elastomer. The shape memory-assisted self-healing effect provides a reference for the rapid self-repairing of severe cracks.Keywords:self-healing;polybutadiene;metal coordination;shape memory;oxidized carbon nano-onions
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MACROMOLECULES
·
2022
·
IF 6.057
Wenhui Ren,Fen You,Jingjing Zhai,Xiaohui Kang,Yat-Ming So,Xiaochao Shi
The preparation of polymers with different stereo-blocks, especially by a single catalyst, is a promising yet highly challenging issue. In this study, we report a single rare-earth metal catalyst bearing an unsymmetrical PNN ligand that promoted the polymerization of isoprene (IP) and butadiene (BD) with unparallel stereoselectivity to yield cis-1,4-PIP and trans-1,4-PBD, respectively. Density functional theory (DFT) studies suggested that the insertion–isomerism mechanism is kinetically more favorable than other pathways in the yttrium-based catalytic system for generating trans-1,4-PBD. Remarkably, it is unprecedented that using a single yttrium catalyst, copolymers with the coexistence of cis-1,4-PIP and trans-1,4-PBD sequences could be prepared, and the copolymeric compositions could be easily tailored by varying the co-monomer feed ratio with the special polymerization dynamics (rIP = 2.44, rBD = 0.77). Moreover, taking advantage of the excellent livingness in the yttrium-based catalytic system, the sequential addition of IP and BD afforded precisely controlled diblock and multiblock copolymers with differently stereoselective adjacent blocks. Complete hydrogenation of the produced block copolymers was achieved, with their mechanical properties being studied via stress–strain experiments to confirm the influence of the sequence length.
研究领域:
高分子化学
·
催化化学
✓ 已验证
DOI
高影响因子
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