Catalysis Science & Technology
·
2016
·Vol. 6
·期 8
·2647-2652
·
IF 5.287
Hualei Hu,Jinghui Lyu,Jiayao Rui,Jie Cen,Qunfeng Zhang,Qingtao Wang,Wenwen Han,Xiaonian Li
Ethylbenzene is the major side product in benzene alkylation with methanol and it is difficult to be suppressed over hierarchical porous ZSM-5. Moreover, the separation of ethylbenzene from xylene still remains a great challenge. Our research indicated that ethylbenzene formation could be highly suppressed by changing the Si/Al ratio of the catalyst. Hierarchical porous ZSM-5 catalysts with different Si/Al ratios were prepared via reducing the amount of Al in the solvent evaporation assisted dry gel conversion method. In this method, tetra-n-propylammonium hydroxide was used as the direct agent to create micropores, and hexadecyltrimethoxysilane was added to create additional porosities by forming organic assemblies which occupied a certain space between zeolitic walls. The catalyst with a Si/Al ratio of 1800 could achieve high benzene conversion (59.5%) and high xylene selectivity (39.0%) as well as excellent suppression of ethylbenzene formation (<0.1%).
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Guoqiang Hou,Tingjun Fu,Xin Li,Qian Ma,Zhong Li
HZSM-5 catalysts with abundant silanol nests were fabricated by removing framework Al, which effectively promoted the selective alkylation of toluene with methanol by inhibiting the deep alkylation of aromatics to heavy aromatics and the conversion of methanol to light hydrocarbons. Correspondingly, the alkylation efficiency reached 65.3% at a toluene conversion of 31.3% over dealuminated HZSM-5, higher than the 55.2% efficiency and 28.0% conversion of parent zeolites, respectively. In situ DRIFTS and single-factor experimental clarified that toluene adsorption was enhanced and methanol to hydrocarbons was inhibited with the presence of silanol nests. Additionally, by increasing the crystal size of HZSM-5 with silanol nests from 2 to 5 µm, para-xylene selectivity was increased from 36.1% to 65.5% because of the enhanced diffusion barrier . The finding of the positive effect of the silanol nests on toluene alkylation can provide a solid fundamental basis for the rational design of catalysts.
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
APPLIED ORGANOMETALLIC CHEMISTRY
·
2021
·Vol. 35
·期 4
·e6147
·
IF 4.105
Sujuan Ge,Yuming Zhou,Xiaoli Sheng,Chunfeng Mao,Lina Zhao,Jianxing Xu,Lei Qiu
Piperidinium-based ionic liquids (ILs) were synthesized under mild conditions by coordinating N -alkyl- N -methylpiperidinium bromide ([Pip 1,x ]Br) with anhydrous AlCl 3 . The weak basicity of N -methylpiperidine had little impact on downstream problems from proton impurities and catalyst poisoning. The results of Fourier transform infrared (FT-IR), electrospray ionization mass spectrometry (ESI-MS), and nuclear magnetic resonance ( 27 Al NMR) confirmed that the active components in [Pip 1,x ]Br-2AlCl 3 ( χ = 0.67) were [Al 3 Cl 9 Br] − and [Al 2 Cl 6 Br] − . Besides, the reaction performance of [Pip 1,8 ]Br-2AlCl 3 under different conditions was carried out by single-factor experiment and further confirmed by orthogonal experimental method. Among these reaction conditions, the optimal combination was the reaction temperature of 40°C, ILs/O molar ratio of 0.2:1, px/O molar ratio of 12:1, and the reaction time of 30 min. Furthermore, [Pip 1,8 ]Br-2AlCl 3 had excellent stability and can be recycled 14 times. It was the high-efficiency catalytic activity and prominent recyclability that made continuous industrial production possible.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Tingjun Fu,Lihan Jia,Guoqiang Hou,Zhong Li
Dealuminization over aluminium-containing ZSM-5 could create silanol nests and improve catalytic activity for alkylation of toluene with methanol. However, obviously damaged microporous structure seriously accelerated catalyst deactivation. Here, we demonstrate highly stable alkylation on ZSM-5 by deboronation treatment over boron-containing ZSM-5. 11 B MAS NMR, 1 H MAS NMR and OH-IR suggested that silanol nests with hydrogen bonds were created at the expenses of the removal of skeleton-B atoms. The formed silanol nests promote the adsorption of toluene, inhibit the methanol self-reaction and corresponding the deep alkylation process. Therefore, alkylation efficiency and toluene conversion could reach 70.8% and 33.5%, respectively. Importantly, the microporous structure of deboronized ZSM-5 was well maintained during deboronation, which determined a greatly improved catalytic stability compared with that of traditional dealuminized ZSM-5. Moreover, the deboronized ZSM-5 still presented relatively good catalytic stability under a higher methanol feedstock although the coke deposition was accelerated.
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
Inorganic Chemistry Frontiers
·
2022
·Vol. 9
·期 13
·3348-3358
·
IF 7.779
He Han,Hong Yang,Anfeng Zhang,Limin Ren,Xiaowa Nie,Chaoqiu Chen,Min Liu,Chuan Shi,Chunshan Song,Xinwen Guo
This work aims to achieve high para-selectivity while maintaining catalytic stability for the alkylation of toluene with methanol to para-xylene over ZSM-5 catalysts under demanding reaction conditions. A high para-selectivity of greater than 97% is achieved by applying consecutive SiO2–P2O5–MgO (SPM) and SiO2 surface coatings on the surface of pristine ZSM-5. This surface modification passivates the external acid sites and at the same time narrows the pore openings of the ZSM-5 particles, which are both beneficial for the high para-selectivity. The catalytic stability of the surface modified catalysts is achieved by loading with metals including Pt, Ni and (Pt + Ni). This study shows that catalysts co-loaded with (Pt + Ni) exhibit superior catalytic stability, not only in pure H2 but also in a carrier gas containing a very low H2 fraction of 5% H2 and 95% Ar. This is because the co-existence of Pt and Ni effectively inhibits the formation of low-carbon olefins (the coke precursors) via the dehydrogenation of methanol to carbon oxides and the hydrogenation of olefins to paraffins. By studying the different locations of metal loading on the catalysts, this work also confirms that the most effective location of metal loading is on the external surface of the modified catalysts.
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）