Catalysts
·
2023
·Vol. 13
·期 3
·640
·
IF 3.9
Cong Wang,Gang Li,Hongchen Guo
MOFs have attracted widespread attention in the field of catalytic ethylene dimerization. Compared with post-synthetic modification, ion exchange and other methods to introduce external active centers, the direct use of MOF materials as catalysts is still the most convenient and prospective. Herein, the NiBTCs are synthesized using a one-pot method in two kinds of solvent and characterized by XRD, FT–IR, ICP–OES, XPS, TGA and N2physical adsorption. After treatment at 150 °C, the catalytic activities of both materials in ethylene dimerization are up to 470.9, and 647.0 gpro./(gcat.·h) and the selectivity of 1-butene in all products could reach 83.2% and 81.7%, respectively. Stability testing of the catalysts demonstrated that they do not decompose during the reaction, but their reuse performance is degraded. In addition, a probable Cossee–Arlman–type mechanism is proposed. The NiBTCs are shown to have superior catalytic performance in ethylene dimerization compared to employing Ni(pyz)2Cl2or α–Ni(im)2as catalysts.Keywords:ethylene dimerization;NiBTCs;MOFs;1-butene
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
ORGANOMETALLICS
·
2016
·
IF 4.186
Wenlong Luo,Antai Li,Shaofeng Liu,Hongqi Ye,Zhibo Li
A series of chromium(III) complexes, LCrCl3 (Cr1–Cr4: L = 2-(N-R2-benzimidazol-2-yl)-6-(3,5-R1-pyrazol-1-yl)pyridine; Cr1: R1 = H, R2 = H; Cr2: R1 = Me, R2 = H; Cr3: R1 = Me, R2 = Me; Cr4: R1 = Me, R2 = Bn), were synthesized and characterized by IR spectroscopy and elemental analysis. The studies of the solid state of Cr2 and Cr3 revealed distorted octahedral geometries around the chromium centers by X-ray diffractions. In the presence of MAO, Cr1–Cr4 exhibited high activities toward ethylene oligomerization (up to 2.17 × 106 g·mol–1(Cr)·h–1) and ethylene polymerization (up to 6.78 × 105 g·mol–1(Cr)·h–1). The oligomers were produced with high selectivity for α-olefins (>99%), confirmed by FT-IR and 13C NMR, and the distributions followed the Schulz–Flory equation. Various reaction parameters including the amount of cocatalyst, reaction temperature, and time were evaluated in detail, and it was evident that the title complexes had good thermal stability and the substituents on imidazole-N of the ligands dramatically impacted the catalytic activities as well as the distribution of the products.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Cong Wang,Gang Li,Zheng Huang,Anfeng Peng
The cumbersome air isolation process is one of the main constraints in the development of linear α-olefins prepared by ethylene oligomerization. An effective way to solve this problem is to eliminate the use of an alkyl-aluminum cocatalyst. Herein, two forms of Versailles/Santa Barbara-5 (VSB-5) (VSB-5-H3PO4 and VSB-5-NaH2PO2) are prepared and used as heterogeneous catalysts in ethylene oligomerization in the presence of LiAlH4 as a cocatalyst. Compared to other Ni-MOFs and Ni silica–aluminate catalysts, VSB-5s maintain a wider distribution of Linear α-olefin (LAO) products at relatively high activity. In the reuse test of the catalyst, the Al species from LiAlH4 cover the surface of the catalyst and decrease its activity, which could be removed by acid treatment. In situ IR studies show that active centers for ethylene oligomerization may form in VSB-5 assisted by LiAlH4. In addition, a Cossee–Arlman-type mechanism is proposed.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Macromolecular Reaction Engineering
·
2023
·Vol. 17
·期 3
·2300013
·
IF 1.5
Ying Zhang,Jian Ye,Yinzhi Jiang,Shuqin Jiang,Wei Xiao,Dongchu Wei
The bis(imino)pyridyl iron-based ethylene oligomerization catalysts have the advantages of mild reaction conditions, high activity and high selectivity to linear α -olefins. However, barriers, such as high polymer content in the product mixture and large methylaluminoxane (MAO) dosage, are still limitations for the development of these systems at the industrial scale. In this study, new cocatalysts are prepared by the reaction of alkylaluminums with urea and its derivatives, and successfully used to activate iron-based catalysts. It is found that the type and molar ratio of alkylaluminum and urea have significant influence on the performance of the cocatalysts. The activity of the preferred triisobutylaluminum/urea activated systems reaches more than 3.0 × 10 8 g (mol-Fe) −1 h −1 , and the polymer content can be controlled to be less than 2 wt.%. Notably, the catalytic system exhibits good high temperature stability, the activity can still reach 1.0 × 10 8 g (mol-Fe) −1 h −1 even at 120 °C. Further 1 H NMR studies show that alkylaluminum can react with the N H moieties of urea, forming complex alkylaluminum clusters, even aluminoxane-like structures. This study offers a promising family of cocatalysts, making it possible to simultaneously improve their performance and reduce their cost.
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
Catalysis Science & Technology
·
2024
·
IF 4.4
Yao Ning,Yuqi Yang,Dongming Shan,Shuxing Mei,Yibai Yan,Linjie Ding,Ying Zhang
Ethylene oligomerization plays an important role in industrial production. However, when taking the traditional non-metallocene catalysts and MOF catalysts for ethylene oligomerization, they typically require methylaluminoxane (MAO), aluminum alkyl, and other cocatalysts, which is neither environmentally friendly nor helpful in reducing production costs. Here, three sulfonic acid-modified MOFs (SA/MIL-101(Cr), UiO-66-NS and MIL-101(Cr)-NS) were prepared and used as catalysts for ethylene oligomerization at room temperature without using any cocatalysts. All of them exhibited excellent catalytic performances (e.g., 10SA/MIL-101(Cr), 21 953 g molCr−1 h−1, with C8 selectivity greater than 70.32%), and their oligomerization activity increased by almost tenfold compared to unmodified MOFs. The presence of Lewis acid (L acid) and Brønsted acid (B acid) sites in modified MOFs is the key to improved performances. In particular, the presence of B acid weakens the role of metal clusters and ligands in MOFs, making it easier for metal centers to bind to ethylene molecules for further oligomerization. This work first demonstrates that bifunctional MOF catalysts can catalyze ethylene tetramerization under mild conditions without cocatalysts.
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
RSC Advances
·
2025
·Vol. 15
·期 12
·9467-9478
·
IF 4.6
Fuchao Li,Jianqiang Liu,Enhui Xing,Xiaoli Wei,Jianhong Gong,Yibin Luo,Xingtian Shu
A series of steam and phosphorus modified ZSM-5 samples were prepared to investigate the effect of pore structure and acid property on ethylene oligomerization. Characterization results showed that steam treatment contributed to generate mesopores with pore sizes of 2–3 nm and 10–20 nm, while progressive aggregation of phosphorus species on the exterior surface resulted in blockage of channels. Dealumination of framework aluminum led to a gradual decline in total acidity and acid strength with an increase of steam temperature or P/Al ratio. Sufficient strong acid sites and enhanced accessibility to the inner active sites were crucial factors in conversion of ethylene to liquid fuels. The steam modified sample at 700 °C (HZ-700) obtained the highest yield of liquid fuels up to 78.1%, which demonstrated an increase of 40% in comparison with the unmodified sample. Due to improved diffusional capacity originating from mesopores, HZ-700 showed a higher deactivation stability than the phosphorus modified sample at similar conversion levels. This work will provide some insight into the development of zeolite-based catalyst for ethylene oligomerization to liquid fuels.
研究领域:
催化化学
·
能源材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2024
·
IF 4.7
Cong Wang,Gang Li,Zheng Huang,Anfeng Peng
Alkyl-aluminum, which is sensitive to air, has been a major obstacle to the development of ethylene oligomerization. Herein, LiAlH 4 is used as an effective alkyl-aluminum substitute. The performance of LiAlH 4 itself in the reaction is investigated, proving that it possesses moderate activity. Further addition of Versailles/Santa Barbara-1 (VSB-1) catalysts with different morphologies can effectively improve the reaction, in which VSB-1/LiAlH 4 presents the activity of 32.1 g ‧ g LiAlH4 −1 ·h −1 (154.1 g ‧ g VSB-1 −1 ‧h −1 ) and the selectivity of 1-butene, 1-hexene and 1-octene in all products could reach 51.4 %, 18.9 % and 7.9 %, respectively. The co-catalytic system is stable and the VSB-1 catalyst therein can be effectively reused at least three times under the suitable treatment conditions. In addition, the product analysis of the co-catalyzed system reveals that the addition of VSB-1 catalyst tended to produce 1-butene, 1-hexene and 1-octene at 20 bar. Based on above result, a possible reaction mechanism is proposed.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Canadian Journal of Chemistry
·
2019
·Vol. 97
·期 4
·
IF 1.252
Jun Wang,Junyi Xie,Libo Wang,Yan Jiang,Na Zhang
A salen nickel complex has been prepared in good yield with ethylenediamine, salicylaldehyde, and NiCl2·6H2O as raw materials. The structure of the complex was characterized by FTIR, 1H NMR, UV, and ESI-MS. Upon activation with methylaluminoxane (MAO), the precatalyst showed high activity for ethylene oligomerization. To reduce the simultaneous production of insoluble polymers during the nickel-catalyzed ethylene oligomerization, a series of phenolic compounds were introduced as modifiers for the production of linear α-olefins. The researched result showed that the phenolic compounds have a significant impact on the selectivity of oligomers and the concentration of polymers. With the increase of phenolic compounds, the content of polymers decreased and the distribution of oligomers gradually shifted toward lighter olefins. The sterically hindered 4-tert-butyphenol proved to be an especially efficient polymer-retarding modifier among the studied phenolic compounds in this work. Furthermore, the retarding effect of phenolic compounds toward insoluble polymers may be mainly related to their interaction with MAO, giving rise to larger MAO aggregates.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
INORGANICA CHIMICA ACTA
·
2016
·
IF 1.918
Cuiqin Li,Fengfeng Wang,Zhiyu Lin,Na Zhang,Jun Wang
Two novel nickel complexes with hyperbranched structure were synthesized with 1.0 generation hyperbranched polyamine molecules (1.0G), salicylaldehyde and anhydrous nickel chloride as materials via the Schiff’s base and the complexation reactions. The structures of the novel hyperbranched ligands and their nickel complexes were characterized by FT-IR, 1 H NMR, UV, ESI-MS and elemental analysis. The hyperbranched nickel complexes were evaluated as catalyst precursors for ethylene oligomerization after being activated with methylaluminoxane (MAO), diethylaluminum chloride (Et 2 AlCl) and ethylaluminum sesquichloride (EASC). The influence of Al/Ni ratio, temperature and ethylene pressure on ethylene oligomerization was also investigated using the novel hyperbranched nickel complexes as pre-catalysts and MAO as co-catalyst. The catalytic activities of the two hyperbranched nickel complexes with dodecyl and octadecyl as cores (R 12 -complex and R 18 -complex) were 2.33 × 10 5 g/(mol Ni·h) and 1.23 × 10 5 g/(mol Ni·h), respectively, and the selectivities for C 8+ oligomers of R 12 -complex and R 18 -complex were 56.16% and 88.64% respectively, when the Al/Ni molar ratio was 500:1, the temperature was 25 °C, the pressure of ethylene was 0.5 MPa and the co-catalyst was MAO. The catalytic activities and product distribution were largely dependent on the nature of the co-catalysts and the structures of nickel complexes. The catalytic activities decreased with increasing of the length of alkyl chain of the hyperbranched nickel complexes.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
HELVETICA CHIMICA ACTA
·
2017
·Vol. 100
·期 12
·e1700162
·
IF 1.071
Jun Wang,Rui Gao,Na Zhang,Xiangkun Tan,Libo Wang,Lili Ma,Weiguang Shi
Three dendritic PNP ligands with ethylenediamine, 1,4-butanediamine, 1,6-diaminohexane as bridged groups are synthesized in good yields, respectively. Three dendritic PNP chromium complexes ( C1 – C3 ) are prepared with the ligands and chromium(III) chloride tetrahydrofuran complex (CrCl 3 (THF) 3 ) as materials. The dendritic PNP ligands and the synthetic chromium complexes are fully characterized by spectroscopic and analytical methods. All chromium complexes activated with methylaluminoxane (MAO) exhibited moderate activities on ethylene oligomerization (7.90 × 10 4 – 2.15 × 10 5 g (mol Cr h) −1 ] and had better selectivity for C 6 and C 8 oligomer, reaching up to 81%. The chromium complex ( C1 ) activated with diethylaluminium chloride (Et 2 AlCl) has higher catalytic activity than the chromium complex C1 activated with MAO, although the chromium complex ( C1 ) activated with Et 2 AlCl had lower selectivity for C 6 and C 8 oligomer. The effects of solvent and reaction parameters on ethylene oligomerization are also studied using the chromium complex C1 as pre - catalyst and MAO as co - catalyst. Under optimized conditions ([complex] = 2 μmol, Al/Cr = 500, 25 °C, 0.9 MPa ethylene, 30 min), the catalytic activity of complex C1 in toluene is 2.15 × 10 5 g (mol Cr h) −1 and the selectivity for C 6 and C 8 oligomer is 36.76%. In addition, the structure of complexes significantly affects both the catalytic activity and the selectivity on ethylene oligomerization.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
TRANSITION METAL CHEMISTRY
·
2021
·Vol. 47
·期 1
·1-9
·
IF 1.588
Guo Lijun,Huang Jin,Chen Na,Hu Yue,Li Miao,Li Feng,Li Cuiqin
A phosphorus dendrimer with multiple amino groups was synthesized via a two-step reaction with phosphonitrilic chloride trimer and 4-acetamidophenol. The trinuclear nickel complex was subsequently prepared with the phosphorus dendrimer and nickel chloride hexahydrate as starting materials. The structures of the phosphorus dendrimer and the trinuclear nickel complex were characterized by physicochemical and spectroscopic methods. The trinuclear nickel complex based on the phosphorus dendrimer was evaluated as catalyst precursor for ethylene oligomerization using methylaluminoxane (MAO) as an activator. Under the conditions of 0.5 h, 0.9 MPa, 25 °C and Al/Ni molar ratio of 700, the catalytic activity of the trinuclear nickel complex showed a maximum value of 2.31 × 10 5 g/(mol Ni h), and the oligomerization products were mainly low-carbon olefins (C 4 and C 6 ). The ligand structure and the coordination mode showed notable variations in the catalytic activities and the product distribution due to the influence of electronic and steric effects. The catalytic activity of the nickel complex based on the ligand with an aryl backbone was superior to the nickel complex based on the ligand with an alkyl backbone.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ORGANOMETALLIC CHEMISTRY
·
2020
·Vol. 34
·期 11
·e5904
·
IF 3.14
Cuiqin Li,Dan Li,Fengfeng Wang,Yuxin Gao,Jin Huang,Feng Li
Series of hyperbranched PNP ligands ( L1 – L3 ) were prepared using three low-generation hyperbranched molecules with the same branching chains and functional groups but different alkyl chain length as backbones in a mixed solvent of acetonitrile and dichloromethane. The chromium complexes ( Cr1 – Cr3 ) were obtained by reacting with CrCl 3 (THF) 3 and the corresponding ligands ( L1 – L3 ). Both L1 – L3 and Cr1 – Cr3 were characterized by elemental analysis, Fourier transform infrared and electrospray ionization–mass spectrometry as well as 1 H nuclear magnetic resonance (NMR) and 31 P NMR measurements in the case of the ligands. When activated with different aluminum co-catalysts, all three chromium complexes were able to catalyze the ethylene oligomerization, but the products of the ethylene oligomerization were mainly dependent on ethylene pressure, co-catalyst and ligand backbone. Upon activation with methylaluminoxane, the catalytic activity and the selectivity of C8 olefin increased with increasing of ethylene pressure for Cr1 , the catalytic activity was 13.83 × 10 5 g·(mol Cr·h) −1 and the main product was C8 olefin (50.68%) at the ethylene pressure of 4.0 MPa. When activated with diethylaluminium chloride, ethylaluminium dichloride and ethylaluminum sesquichloride, Cr1 showed the lower catalytic activity and the higher selectivity of C4 olefin in toluene. An increase in the length of alkyl chain in the hyperbranched PNP ligand backbone caused a decrease in the catalytic activity and an increase in the selectivity of C8 + olefin. The PNP chromium complexes exhibited higher selectivity for higher carbon number olefins compared with the dendritic PNP chromium complex ( Cr5 ).
研究领域:
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）