POLYMER SCIENCE SERIES B
·
2016
·Vol. 58
·期 5
·495-502
·
IF 0.737
Geng Jieting,Sun Yanjie,Hua Jing
Polyisoprene with relatively high content of 1,2/3,4 structure was synthesized using a novel catalyst system composed of MoO 2 Cl 2 supported by phosphorus ligand and Al(OPhCH 3 )( i -Bu) 2 as co-catalyst. The effects of phosphites, phosphates and phosphoric acid as ligands were investigated in the coordination polymerization of isoprene in the chosen catalyst system. The studied ligands significantly affected the catalytic activity of the Mo–Al catalytic active center without significant effect on the stereoselectivity. Mo(VI)-based catalyst system was proved to be highly effective in the polymerization of isoprene even at low [Al]/[Mo] ratio (10), affording polyisoprene with 1,2- and 3,4-% structural units in the range of 44.6–52.5%, high molecular weights M
n ~ 10 5 , and relatively broad molecular weight distributions ( M
w / M
n = 3.0–4.4). The effect of molar ratio of phosphorous ligand to Mo-catalyst on catalyst activity of isoprene polymerization was discussed, and the structures of Mo–phosphite complexes were preliminarily studied by IR.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Biomass Conversion and Biorefinery
·
2025
·
IF 4.1
Luo Shiwei,Alam Mohammad Asraful,Gao Die,Li Yuexin,Zhao Lei,Xu MinQiang,Xu Jingliang,Zhang Shen
Mannose has demonstrated high value and versatility in various fields, leading to a growing interest in the catalytic epimerization of glucose to mannose using solid catalysts. Herein, zeolite-supported molybdenum (Mo) catalysts were prepared by impregnation-calcination (Mo/Z) and hydrothermal-calcination methods (Mo/Z-HT), respectively. HR-STEM characterization showed the diameter of Mo active sites (MoO 2 ) in Mo/Z and Mo/Z-HT are 57.83 ± 18.05 and 8.37 ± 1.62 nm, respectively. The hydrothermal-calcination process decreased the spatial scale of Mo active sites. The specific surface area of Mo/Z-HT (363.75 cm 3 /g) is higher than that of Mo/Z (200.46 cm 3 /g). The hydrothermal process promotes the formation of hierarchical structure of ZSM. Mo can be embedded in the hierarchical structure during the hydrothermal process, which improved the stability of catalysts significantly. Catalytic performance shown that Mo/Z-HT achieves a mannose yield of 32.81% with a selectivity of 94.20% in water at 130 °C for 30 min. Mo/Z achieved a mannose yield of 33.13% with a selectivity of 92.50% in ethanol-aqueous at 80 °C after 40 min. The recycling experiment showed that Mo/Z-HT exhibits high stability at the sixth cycle with a 30.76% yield and a selectivity of 94.55%. The different reaction temperatures may be attributed to ethyl glucoside was synthesized in ethanol media, which is more easily selectively epimerized in mild conditions. The protecting groups (-OC 2 H 5 ) at C1 position may decrease the activation energy of epimerization and realize kinetic control of site selectivity.
研究领域:
化学工程
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Shuisen He,Xueman Wang,Chenglong Wen,Yu Fan
A novel (C 11 H 26 N) 2 Co(MoS 4 ) 2 complex was prepared via the n-octyltrimethylammonium bromide-assisted self-assembly of CoMo precursors for the selective hydrodesulfurization (HDS) of thiophene. The complex was generated by the interaction between the negatively charged CoMo compound and the positively charged n-octyltrimethylammonium ions. Then positively charged bimolecular layers were formed owing to van der Waals forces between the C 11 H 26 N + and the complex, and they were anchored on the negatively charged γ-Al 2 O 3 . Compared with CoMoS/γ-Al 2 O 3 catalysts prepared by impregnation, the optimal CoMoN-0.3/γ-Al 2 O 3 catalyst exhibited better performance for selective HDS due to the enhanced Mo dispersion, the close contact between Co and Mo, and the increased amount of CoMoS phases on γ-Al 2 O 3 . Among these catalysts, the optimal CoMoN-0.3/γ-Al 2 O 3 catalyst with the highest concentration of CoMoS phases exhibited the highest HDS reaction rate constant of 6.95 × 10 -6 mol·g −1 ·s −1 and the best selective factor of 26.1 for the selective HDS of thiophene with 1-hexene.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Liang Dan,Long Hu,Hui Wang,Min Zhu
To improve the hydrogen sorption kinetics of MgH 2 , the MoO 3 nanobelts were added into MgH 2 by mechanical milling, leading to fine distribution of MoO 3 in the MgH 2 matrix. Compared to uncatalyzed MgH 2 , the hydriding and dehydriding rates of MoO 3 -catalyzed MgH 2 were significantly improved. The MgH 2 doped with 2 mol% MoO 3 exhibited fast dehydrogenation without activation, and the initial dehydrogenation amount of 5 wt% could be reached within 900 s at 300 °C. The dehydrogenation apparent activation energy is decreased down to 114.7 kJ/mol. The excellent catalytic effect of MoO 3 originates from its specific role as fast hydrogen diffusion pathways. In the hydrogenation process , the MoO 3 transformed to MoO 2 , resulting in the fading of catalytic activity .
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Xinhui Zhang,Aiping Wu,Dongxu Wang,Yanqing Jiao,Haijing Yan,Chengxu Jin,Ying Xie,Chungui Tian
The easily coupled HER and OER catalysts are highly desired for the hydrogen evolution by overall water splitting. Here, we design and synthesize Co-Mo based catalysts with adjustable electronic structure by tuning the Mo/Co ratio to give easily coupled, effective HER/OER catalysts. At lower Mo/Co ratio, the Mo component can move up the d-band center of the catalysts, rendering an enhanced capability of activating H 2 O to improve OER performance with a low overpotential of 223 mV at 10 mA cm −2 (η 10 ). Contrastingly, the Co component in the catalyst with higher Mo/Co ratio can induce the downward shift of the d-band center, optimizing the Gibbs free energy of hydrogen adsorption to enhance the HER activity (a low η 10 of 52 mV). These HER and OER catalysts with similar components can be coupled for overall water splitting. The electrolyzer can be driven by a solar panel to achieve effective H 2 production.
研究领域:
材料科学
·
催化化学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Beining Luo,Yan Wang,Yingqi Zhang,Caifeng Qiu,Guoqiang Yu,Liang Li,Xianzai Yan,Guoqiang Wu
Catalytic epoxidation limitations of conventional ellipsoid titanosilicate-1 (TS-1) remains owing to the narrow microporous channels and low efficiency of the Ti species. Herein, two-dimensional planer TS-1 zeolite (TS-1-P) was synthesized by adding crystal growth regulator in the hydrothermal synthesis process, and then TS-1-P supported molybdenum (Mo/TS-1-P) and mesoporous Mo/TS-1-P (Mo/MTS-1-P) were prepared and applied in epoxidation of olefins. The TS-1-P and the modified TS-1-P catalysts show a similar MFI framework and grain morphology but the different pore structure and coordination environment of Ti or Mo species. Especially, the Mo/MTS-1-P possesses many mesoporous pore and highly dispersed Mo species, which can improve the coordination environment of Ti species and weaken the Ti-O bond, the results are beneficial for the framework Ti species to combine more easily with H 2 O 2 to C=C band of the olefin molecules. Therefore, compared with TS-1-P, Mo/MTS-1-P exhibits the highest conversion of ACH (91.78 %) and 1-hexene (47.44 %) in the epoxidation of ACH and 1-hexene, respectively, the selectivity of epoxidized products simultaneous is above 96.42 % and 94.04 %, respectively. Moreover, the deactivation behavior of carbon deposit on the catalyst surface and regeneration method were also proposed. The successful preparation of Mo/MTS-1-P not only results in an efficient catalyst for epoxidation process but also provides a possible approach for surface and pore structure modification of TS-1 zeolite.
研究领域:
催化化学
·
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
NANOTECHNOLOGY
·
2020
·Vol. 31
·期 49
·495404
·
IF 3.551
Saman Sajjad,Chao Wang,Xianfu Wang,Tariq Ali,Tao Qian,Chenglin Yan
Due to their good conductivity and catalytic performance, Ni—Mo-based catalysts are well-established for highly effective water splitting. However, the know-how required to fabricate distinct interfaces and electronic structures for metal oxides is still a challenge, and the synergistic effect between metal and metal oxides that enhances electrocatalytic activity is still ambiguous. As described here, by controlling the lithium-induced conversion reaction of metal oxides, metal/metal-oxide composites with plentiful interfaces and prominent electrical interconnections were fabricated, which can boost active sites and accelerate mass transfer during electrocatalytic reactions. As a consequence, the superior catalytic activity of ECT-NiMo/NiMoO4 exhibited a low overpotential of 61 mV at a current density of 10 mA cm−2 for the hydrogen evolution reaction and 331 mV at 100 mA cm−2 for the oxygen evolution reaction. When integrated into a two-electrode system, the ECT-NiMo/NiMoO4 revealed a highly stable and efficient performance in overall water splitting. This work provides a promising approach to enhance the metallicity and electron redistribution of catalysts for numerous water-splitting applications and many other possibilities for energy storage devices.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Xiu Gao,Yingqi Zhang,Yanping Hong,Beining Luo,Xianzai Yan,Guoqiang Wu
Methyl oleate (MO) macromolecules are unable to access the microporous channel of conventional titanium silicalite-1 (TS-1) zeolite , which leads to the low catalytic activity of epoxidation of MO. Herein, the small-size TS-1 (TS-1-s) zeolite with a large surface area was synthesized successfully through steam-assisted crystallization, and then a novel blocked TS-1-s supported molybdenum (Mo/TS-1-bs) catalysts were prepared for efficient epoxidation of MO with clean H 2 O 2 to produce epoxidized methyl oleate (EMO). Various characterization results show the introduced Mo species are highly dispersed on the outer surface of TS-1-s without destroying the structure of the MFI type zeolite and the tetrahedral framework titanium (Ti 4+ ). Interestingly, a large number of Mo 6+ species exhibit certain epoxidation activity attributing to the generating of electrophilic molybdenum hydroperoxide (Mo–OOH) species via Mo species combined with H 2 O 2 , which could adsorb and react easily with MO molecules. Furthermore, the Mo species are also coordinated with Ti 4+ species through the O atom resulting in the facile attack of the Ti–O bonds by H 2 O 2 and easy to form an active intermediate. Therefore, compared with the conventional TS-1, the Mo/TS-1-bs shows higher catalytic activity in the epoxidation reaction. However, the acidity of Mo/TS-1-bs catalysts increases with increasing the Mo-loading owing to the formation of Lewis acid, which leads to the side reactions and the decrease of EMO selectivity. As a consequence, the efficient, non-corrosive and green catalytic system for epoxidation of MO was developed, and the activity improvement of Mo species and the influence of acid were also demonstrated.
研究领域:
催化化学
·
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2024
·
IF 2.6
Guixin Zhao,Sixuan Zhang,Jinzhao Huang,Zehui Liu,Feng Jiao,Ke Zhang,Yu Zhang,Xiaolong Deng
NiMo-based polyalloy catalyst is a non-precious metal-based high-entropy alloy catalyst that has been extensively studied in recent years. It exhibits superior electrochemical performance in electrocatalytic water splitting for hydrogen production, and the combination of NiMo-based polyalloy catalysts with carbon black substrates is expected to produce better electrochemical supports. In this paper, we prepared a series of carbon-based high-entropy heterogeneous material catalysts using zero-dimensional carbon black, one-dimensional carbon nanotubes and two-dimensional graphene as substrates, respectively. Analytical results through structural characterization of the synthesized materials as well as electrochemical tests revealed that carbon black, which is in the form of nanoparticles, can be more tightly wrapped with Ni shells compared to tubular nanotubes and flake graphene, which can effectively increase the number of active sites, thus promoting the outstanding performance of the zero-dimensional carbon-based transition metal nanomaterial catalysts NiMoCoMnLa/CB@Ni in alkaline electrocatalytic hydrogen precipitation reaction . Driven by these findings, this work may provide new ideas in the pathway of rationally designing zero-dimensional carbon-based high-entropy alloy nanoparticle catalysts as efficient electrocatalysts in green hydrogen production processes.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Daobin Tang,Xuebin Lin,Qi Zhang,Zhenni Wang,Yuhang Liu,Yanqiao Jin,Xinru Wu,Cejun Hu,Pei Yuan
Lignin is continuously investigated by various techniques for valorization due to its high content of oxygen-containing functional groups. Catalytic systems employing hydrolysis‑hydrogenolysis, leveraging the synergistic effect of redox metal sites and acid sites, exhibit efficient degradation of lignin. The predominance of either hydrolysis or hydrogenolysis reactions hinges upon the relative activity of acid and metal sites, as well as the intensity of the reductive atmosphere. In this study, the Pd-MoO x /TiO 2 catalyst was found to primarily catalyze hydrolysis in the lignin depolymerization process, attributed to the abundance of moderate acidic sites on Pd and the redox-assisted catalysis of MoO x under inert conditions. After subjecting the reaction to 240 °C for 30 h, a yield of 48.22 wt% of total phenolic monomers , with 5.90 wt% consisting of diphenols, was achieved. Investigation into the conversion of 4-propylguaiacol (4-PG), a major depolymerized monomer of corncob lignin, revealed the production of ketone intermediates, a phenomenon closely linked to the unique properties of MoO x . Dehydrogenation of the propyl is a key step in initiating the reaction, and 4-PG could be almost completely transformed, accompanied by an over 97 % of 4-propylcatechol selectivity. This distinctive system lays a new theoretical groundwork for the eco-friendly valorization of lignin.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2018
·
IF 4.908
Li Kang,Hongyu Liu,Huijun He,Chunping Yang
Cost-effective removal of refractory sulfur-containing compounds from oils is still a challenge. In this paper, a novel catalyst of molybdenum supported on Ti-pillared interlayer clay (Ti-PILC) was successfully prepared which performed well in oxidative desulfurization (ODS) with cyclohexanone peroxide (CYHPO) as oxidant under mild conditions. Performance of catalytic oxidation and removal of oxidation product were also studied. The oxidation rate of dibenzothiophene (DBT) reached 99.90% under the optimum reaction conditions. Mo/Ti-PILC catalyst showed higher activity than Mo/Na-MMT in ODS not only due to the pillared interlayer structure which contributed to better molybdenum dispersion and faster diffusion of reactants, but also the catalytic activity of titanium in the oxidative desulfurization of DBT. Oxidative product of sulfone which appeared as crystal in the model oil was filtered and sulfur concentration was reduced to below 10 mg/L. Catalytic activity would be almost unaffected after regenerating for 9 times, and the leaching of active species did not appear in the leaching experiment of the catalyst, which proved that it was real heterogeneous catalysis. Besides, kinetics data conformed to the pseudo-first-order equation pretty well. These results indicated that this desulfurization system was cost-effective for the removal of DBT from oils.
研究领域:
化学工程
·
催化科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2022
·
IF 5.089
Zhengting Xiao,Qingyang Li,Wentai Wang,Guangci Li,Guannan Lin,Xuebing Li,Song Chen
A Co-Mo sulfide catalyst with tube-like structure was prepared through a low-temperature pre-sulfurization process using rod-like CoMoO 4 as the precursor. The pre-sulfurization temperature greatly affected the total pore volume, the concentration of CoMoS species, the microstructure of (Co)MoS 2 slabs and the catalytic desulfurization activity. The increased temperature can promote the formation of hollow structure and the sulfurization degree of the precursor. It was found that the excessive temperature induced the Co atoms to form more isolated Co 9 S 8 species, hindering the formation of highly active CoMoS species. Therefore, appropriate temperature is more favorable to form the (Co)MoS 2 slabs with shorter length and higher stacking number, leading to more coordinatively unsaturated sites, especially the corner sites. According to the results of hydrodesulfurization reaction, the reaction rate of dibenzothiophene and the yields of liquid products are highly depended on the number of surface-active sites, which are mainly originated from the Type II CoMoS species. Moreover, the extended pre-sulfurization time can further improve the catalytic desulfurization activity of the catalyst at an appropriate pre-sulfurization temperature.
研究领域:
催化化学
·
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）