JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
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2019
·
IF 2.752
Xiao Jiang,Qing-Da An,Zuo-Yi Xia,Shang-Ru Zhai,L. Zhong-Cheng,Kai Wang
In this study, N-doped platelet-like metal-loaded Zr/SBA-15 was synthesized and employed for reducing 4-nitrophenol to remove this contaminant from water. Dopamine hydrochloride was used as a novel CN source for the modification of ZrSBA-15. The N doping process occurred readily at a low temperature due to the polymerization of dopamine, which could save energy and simplify the experimental fabrication of catalysts. In addition, polydopamine can immobilize Pd ions in a facile manner and the trapped Pd ions are reduced to Pd nanoparticles due to the reducibility of the polydopamine polymer. The utilization of dopamine allows the catalyst to be obtained in a facile and cost-effective synthetic process, while the production of the CN layer as well as the reduction and immobilization of the Pd ions can occur simultaneously. Characterization of the product showed that the catalyst had a platelet-like structure after decoration with elemental Zr, which enhanced the catalytic reaction compared with the natural fiber-like SBA-15. The optimal Pd loading capacity was determined as ~3.0 wt% and the materials obtained could reduce 4-nitrophenol to 4-aminophenol within 120 s with a conversion ratio above 90%.
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Catalysts
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2019
·Vol. 9
·期 9
·770
·
IF 3.444
Jianghua Zhang,Shasha Yang,Weijie Cai,Fawen Yin,Jin Jia,Dayong Zhou,Beiwei Zhu
It is highly desirable that efficient recoverable heterogeneous catalysts should be developed to replace the costly biocatalysts used in producing structured phospholipids (SPLs) with medium-chain fatty acids (MCFAs). Thus, mesoporous propyl and phenyl sulfonic acid-functionalized SBA-15 materials synthesized via surface modification methods were investigated for the soybean lecithin interesterification with methyl caprate or caprylate. The physicochemical properties of the synthesized solid acids were deeply studied by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared and pyridine adsorption, etc. to build the possible structure–performance relationships. The results revealed that amounts of organosulfonic acid groups were successfully grafted onto the SBA-15 support, and most of the surface acid sites contained in the as-prepared organic–inorganic hybrid samples were assigned as strong Brӧnsted acid sites. Notably, the functionalized SBA-15 materials exhibited promising catalytic behaviors in producing MCFA-enriched SPLs under mild conditions (40 °C, 6 h) when compared with commercial Amberlyst-15 and typical phospholipases or lipases, mostly due to their high surface area, ordered structure and adequate Brӧnsted acid sites. Besides, the as-prepared materials could be easily recycled five times without obvious deactivation. This work might shed light on alternative catalysts for SPL production instead of the costly enzymes.Keywords:structured phospholipid;medium-chain fatty acid;heterogeneous catalyst;interesterification;lecithin
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Inorganic Chemistry Frontiers
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2019
·Vol. 6
·期 7
·1799-1812
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IF 5.934
Xiaosong Hu,Chaoyue Zhao,Qingxin Guan,Xin Hu,Wei Li,Jun Chen
The chemical transformation of CO2 not only mitigates CO2 released into the atmosphere but also produces fuels and chemicals with important additional value. The activation of stable CO2 molecules is the key difficulty for the efficient conversion of CO2. Herein, we designed a ternary catalyst containing Cu, ZnO, and CeOx and dispersed them in SBA-15 using incipient wetness impregnation. Interestingly, the catalytic performances were improved greatly when the related active components were dispersed inside and outside the pore channels of SBA-15 using the incipient wetness impregnation method. Methanol and CO were controllably produced on the interface of Cu and metal oxides (ZnO and CeOx) due to the synergistic effects between the three active components. The metal oxides play a more important role in CO2 conversion as well as the product selectivity compared to Cu. CeO2 is more efficient than ZnO in promoting the dispersion of Cu nanoparticles and methanol generation. The suitable pore channels of SBA-15 promote the mass transfer and heat transfer while the high specific surface area is favorable to the dispersion of active components, which will facilitate the production of methanol and CO. After continuous hydrogenation evaluation for 100 h, the catalytic performance of the catalyst was still very stable. This work provides a viable strategy to prepare a supported catalyst with highly dispersed active sites, and the catalyst exhibits an efficient catalytic effect on producing methanol and CO.
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JOURNAL OF POROUS MATERIALS
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2019
·Vol. 27
·期 1
·95-105
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IF 1.947
Xu Xiang,Zeng Yanning,Yu Caili,Zhang Faai
A series of mesoporous SBA-15 with various pore diameter (8, 15, 22 and 27 nm) were synthesized and used as “microreactor”. Reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was conducted in the channels of SBA-15 using azodiisobutyronitrile (AIBN) as initiator, ethyl xanthate ethyl propionate as chain transfer agent. The obtained PMMA/SBA-15 composites and neat PMMAs from composites were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption and desorption, Fourier transform infrared spectroscopy, thermogravimetry analysis, differential scanning calorimetry, hydrogen nuclear magnetic resonance. Results showed that compared with PMMA from conventional RAFT polymerization, PMMAs obtained from internal SBA-15 featured with narrower molecule weight distribution (1.34–1.55) and higher thermal stability due to confinement effects. With the increment of pore size of SBA-15, the molecular weight and glass transition temperature (T g ) of PMMA obtained from internal SBA-15 were distinctly improved whereas isotacticity of the PMMA decreased. The properties of the PMMA were managed with controllable RAFT polymerization by regulation the pore size of SBA-15.
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CHINESE JOURNAL OF POLYMER SCIENCE
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2018
·Vol. 36
·期 9
·1027-1035
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IF 2.016
Shen Xiao-Long,Wang Zi-Qing,Wang Qing-Yin,Liu Shao-Ying,Wang Gong-Ying
Ca/SBA-15 solid bases with different Ca/Si atomic ratios were prepared by a one-pot route and employed as catalysts for the production of poly(isosorbide carbonate) (PIC) from diphenyl carbonate and isosorbide via a transesterification polymerization process. The relationship between physicochemical properties and catalytic performance for Ca/SBA-15 in this melt process was investigated by means of various characterization techniques. It was found that basic site amount and strength were responsible for this transesterification process; the weak and medium basic sites inclined to promote polycondensation reaction. It was worth noting that strong basic sites could favor the decomposition of the resultant PIC, resulting in the decrease of weight-average molecular weight ( M w ) and yield, and the sample with Ca/Si atomic ratio of 0.4 exhibited the best catalytic performance, giving PIC with M w of 4.88 × 10 4 g/mol and T g of 169 °C at the optimal conditions. This excellent activity can be ascribed to the presence of rich basic sites and specific basic strength on the surface of 0.4Ca/SBA-15.
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Carbon Resources Conversion
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2018
·
IF 0
Yu Chen,Kejing Wu,Qisong Lin,Yulong Wu,Yin Tang,Mingde Yang
Hydrothermal liquefaction (HTL) is one of the most promising technologies for conversion of microalgae, and catalysts with high hydrothermal stability are required for controllable HTL. In this article, SBA-15 incorporated with transition metals (Ni, Pd, Co and Ru) were synthetized via double-template method for catalytic HTL of microalgae. The results showed that metal incorporated SBA-15 represented high hydrothermal stability at 613 K. The incorporated Ni, Co and Ru was dispersed in SBA-15 enhancing the hydrothermal stability. The catalysts greatly influenced the chemical composition of the obtained bio-oil, which contained a higher percentage of furfural derivatives and a lower content of fatty acids and N-containing compounds, thus bio-oil quality was improved significantly. Higher hydrothermal stability and specific surface areas of Co-SBA-15 contribute to the highest preformation with 78.78% conversion and 24.11 wt% bio-oil yield. Metal incorporated SBA-15 provides a potential application for biomass conversion in high-temperature aqueous phase.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2017
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IF 3.615
Mingsen Chen,Lanmei Qin,Yuanli Liu,Faai Zhang
Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) was employed for controlled grafting of poly(glycidyl methacrylate) (PGMA) and poly(glycidyl methacrylate)-b-poly(methyl methacrylate) (PGMA-PMMA) brushes from mesoporous silica SBA-15. Initiator 2-bromoisobutyryl bromide (BiBB) was immobilized onto the inner surface of SBA-15 by reaction with free silanol groups. The polymerizations were conducted in the mixed solvents cyclohexanone /N, N-dimethylformamide. The strategy of utilizing mixed solvents gave rise to a suitable polymerization rate and resulted in a good control of the PGMA growth within the SBA-15 framework and could obtain polymer chains with well-preserved chain end functionality. Molecular weight of grafted polymer, structure, morphology, and composition of the functionalized SBA-15 were characterized by using gel permeation chromatography (GPC), X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N 2 adsorption/desorption measurements, fourier transform infrared spectroscope (FT-IR), and thermogravimetry analysis (TGA), respectively. The thickness, polymer grafting density and molecular weight of the grafted polymer can be controlled by adjusting the polymerization time. The deactivator cannot efficient diffuse to convert the propagating chains to the dormant species when the pores are nearly completely filled with the polymer, therefore, increasing grafting density resulted in higher molecular weight and polydispersity index (PDI) values for the grafted polymer chains. This work provides a facile route for preparation of well-defined mesoporous silica/polymer hybrids.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2018
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IF 3.141
Yuan Cai,Xiaofeng Xu,Hu Wang,Lei Wang,Lulu Chen,Rui Li,Jing Ding,Hui Wan,Guofeng Guan
Production of alternative, clean aviation fuel from biomass synthesis gas via Fischer–Tropsch (FT) synthesis has attracted much attention. In this paper, Al-SBA-15 supported cobalt catalysts with different Al/Si ratios were successfully prepared for the production of aviation fuel by FT synthesis. The physical and acidic properties of the Co/Al-SBA-15 catalysts were characterized by XRF, XRD, N2 adsorption–desorption, TEM, H2-TPR, 27Al NMR, NH3-TPD, and Py-FTIR. The formation of long-chain hydrocarbons was inhibited by the ordered mesoporous structure. Fischer–Tropsch activity and selectivity were demonstrated to be affected by the acidity of the Al-SBA-15 supports. The selectivity turned to lighter iso-paraffin products. Co-based catalyst with Al/Si ratio of 0.01 exhibited the highest selectivity (52.4%) for aviation fuel (C8–C18 products) and much higher ratio of iso-paraffin/normal-paraffin (iso/n) (20.2%). This study might provide useful information for the selective production of aviation fuel via FT synthesis.
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JOURNAL OF POROUS MATERIALS
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2015
·Vol. 23
·期 2
·529-537
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IF 1.108
Ma Beibei,Zhuang Linzhou,Chen Shuixia
The well-ordered hexagonal short-pore SBA-15 (SSBA-15) has been successfully synthesized via an energy-efficient process under the microwave-hydrothermal condition, in which the formation duration [stirring duration (ripening step) and microwave-hydrothermal treatment duration (aging step)] has been greatly decreased from 48 h for conventional hydrothermal treatment to <2 h. The extension of the ripening duration led to the evidently improved uniformity and regularity of particles while the increase of aging duration resulted in less intrawall pores and more structural mesopores. The optimal condition to get highly ordered SSBA-15 in this work was the duration of 2 h for both steps, and the SSBA-15 obtained was composed of cuboid-like particles, whose pore length was ca. 450 ± 50 nm and pore size was around 10 nm. The SSBA-15 was modified with different amine agents to prepare solid amine adsorbent, the obtained adsorbents showed considerable CO 2 adsorption ability, indicating that this fast-prepared SSBA-15 can be a promising support of CO 2 adsorbents.
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RSC Advances
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2015
·Vol. 5
·期 110
·90904-90912
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IF 3.84
Yueling Cao,Junwei Wang,Maoqing Kang,Yulei Zhu
Hydrogenolysis of glucose and cellobiose, used as the model feedstocks, over Ni–WO3/SBA-15 catalysts has been investigated to probe the influencing factors for the conversion of cellulose to ethylene glycol (EG). The conversion of glucose and cellobiose to EG showed different dependencies on reaction temperature; a lower reaction temperature was needed for the former. Additionally, the surface atomic ratio of W to Ni on the Ni–WO3/SBA-15 catalysts was the key factor for the product distribution. Both glucose and cellobiose had their own optimum W–Ni ratio for the production of EG, and the ratio of W to Ni for glucose was slightly lower than that of cellobiose. On the other hand, the Ni–WO3/SBA-15 catalysts were thoroughly characterized by N2 adsorption–desorption, X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results indicated that the reducibility of Ni–WO3/SBA-15 catalysts with high Ni loading was more similar to that of pure NiO. More importantly, the change of surface atomic content of Ni and W of Ni–WO3 catalysts with various Ni loadings resulted from the surface W species of the catalysts being gradually covered by Ni species with the increase of Ni loading.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
·
IF 8.1
Jialong Ou,Yuanhao Wang,Fei Liu,Tianxiang Zhao
The development of metal-free and high-efficiency heterogeneous catalysts for the chemical conversion of CO 2 into value-added chemicals is crucial for carbon cycling. Here, we report the synthesis of a four-armed urea-functionalized ionic salt that incorporates active bromide ions (Br − ) and urea groups. This salt was subsequently grafted onto ordered mesoporous SiO 2 (SBA-15) to catalyze the cycloaddition reaction between CO 2 and epoxides. The impacts of structure features, grafting density of the urea-functionalized ionic salts, and pore size of SBA-15 on catalytic performance were systematically investigated. The results obtained emphasize that SBA-15–5@TEU(1:1) demonstrates remarkable synergistic catalytic efficacy, facilitating the efficient transformation of various epoxides into cyclic carbonates through cycloaddition reactions in the absence of both solvents and cocatalysts. Notably, this catalyst achieves a maximum yield of up to 99%. Additionally, SBA-15–5@TEU(1:1) demonstrates excellent reusability, with no significant decrease in catalytic activity observed over multiple cycles. Mechanistic studies further elucidate the crucial roles of Br − and urea groups in facilitating the synergistic catalysis of CO 2 cycloaddition reaction. This work presents novel insights the design of metal-free and co-catalyst-free heterogeneous catalysts for efficient CO 2 conversion.
研究领域:
化学
·
材料科学
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JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
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2015
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IF 2.128
Xiaoyao Fei,Shaoyun Chen,Chunjie Huang,Dai Liu,Yongchun Zhang
Bovine carbonic anhydrase (BCA) has been immobilized on glycidoxypropyl-functionalized SBA-15 (GFS) for biomimetic carbonation reaction. GFS was characterized by N 2 adsorption–desorption, Fourier transform infrared analysis, 13 C and 29 Si CP MAS NMR spectroscopy. The immobilization time and material dose were optimized. The influences of pH value and temperature on the activity of free and immobilized BCA, storage stability and reusability of immobilized BCA were investigated using a para-nitrophenyl acetate (p-NPA) assay. The kinetic parameters K m and K cat / K m for free and immobilized BCA were found to be 2.4 mM and 896.4 M −1 s −1 , and 3.1 mM and 757.4 M −1 s −1 , respectively. It was observed that the immobilized BCA can retain around 91% of its initial activity up to 30 days at 4 °C, which showed higher storage stability than free BCA. Reusability studies suggested that immobilized BCA could keep high activity after 20 cycles of carbonation reaction. BCA immobilized on GFS (BCA-GFS) were used for hydration of CO 2 . The CO 2 sequestration capacity in terms of conversion CO 2 to calcium carbonate was quantified by organic elemental analysis. The amount of CaCO 3 precipitated over GFS-BCA was nearly the same as that precipitated over free BCA, 227 mg of CaCO 3 /mg of BCA-GFS as compared to CO 2 sequestration capacity of 241 mg of CaCO 3 /mg of BCA.
研究领域:
生物化学
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环境科学
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材料科学
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