CATALYSIS SURVEYS FROM ASIA
·
2020
·Vol. 24
·期 2
·115-122
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IF 2.194
Gao Meixiang,Jiang Haoxi,Zhang Minhua
This paper has systematically investigated the structures and properties of the ZrO 2 , Nano-SiO 2 and their composition. The catalysts were prepared by impregnation, characterized by N 2 adsorption–desorption, TEM, XRD, Raman, temperature-programmed desorption of NH 3 and CO 2 , FTIR spectroscopy of adsorbed pyridine and CO 2 , and UV–vis spectra. Compared with dry-mixed samples, these catalysts have larger average pore diameter, enabling ZrO 2 to be dispersed more uniformly on the surface of Nano-SiO 2 . With the Zr–O–Si bonds, ZrO 2 could interact intensely with Nano-SiO 2 . The catalyst prepared shows the best performance, with the selectivity of 93.18% and conversion of 58.52%. The preparation methods have a significant influence on the interaction between ZrO 2 and Nano-SiO 2, which then affects the acid–basic properties. This paper finds that weak acid–basic sites with moderate-intensity are more suitable for ethanol conversion to BD, with the amount of acid and basic sites as close as possible.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
Clean Energy
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2025
·
IF 3.7
Jiang Zhenhua,Xia Wei,Zhang Yanli,Wang Xinrui,Dong Mingyuan,Chen Kun,Liu Dong,Lu Baowang
This study aims to compare the catalytic performance of ZSM-5 and SAPO-34 zeolite catalysts in the conversion of ethanol. Through experiments conducted at different temperatures (773 K and 673 K), it was found that SAPO-34 initially exhibits superior propylene selectivity compared to ZSM-5. However, the propylene yield on SAPO-34 gradually decreases, while the ethylene yield increases with time on stream. density functional theory calculations were employed for the investigation of reaction mechanism. The results indicate that the SAPO-34 catalyst surface favors propylene desorption, which beneficial for its initial high propylene selectivity. Nevertheless, the smaller pore structure of SAPO-34 limits the effective diffusion of products, leading to product accumulation within the pores and potentially causing catalyst coking and deactivation. By combining the experimental results with theoretical calculation, this study not only explored the selectivity difference between SAPO-34 and H-ZSM-5 in ethanol conversion reaction, but also revealed the influence of different molecular sieve catalyst structures on product distribution and catalyst stability.
研究领域:
催化化学
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材料科学
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计算化学
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DOI
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 41
·21479-21491
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IF 3.708
Quanyi Wang,Shutao Xu,Jingrun Chen,Yingxu Wei,Jinzhe Li,Dong Fan,Zhengxi Yu,Yue Qi,Yanli He,Shuliang Xu,Cuiyu Yuan,You Zhou,Jinbang Wang,Mozhi Zhang,Baolian Su,Zhongmin Liu
In this work, two kinds of mesoporous ZSM-5 were synthesized successfully using a hydrothermal methodology by utilizing different soft templates, namely, dimethyl octadecyl [3-(trimethoxysilyl)propyl]ammonium chloride ([(CH3O)3SiC3H6N(CH3)2C18H37]Cl, TPOAC) and hexadecyl trimethyl ammonium bromide (C16H33(CH3)3NBr, CTAB). The obtained mesoporous ZSM-5 samples were compared with conventional ZSM-5, and the effects of different surfactant usages during the synthesis of mesoporous ZSM-5 on the physicochemical and catalytic properties were systematically investigated. Multiple techniques, such as XRD, SEM, N2 adsorption techniques, HP 129Xe NMR, 27Al MAS NMR, 29Si MAS NMR, and 1H MAS NMR, were employed for the characterization. Although the synthesized mesoporous ZSM-5 samples had equal surface areas, they presented different relative crystallinities, morphologies, pore-size distributions, micropore–mesopore interconnectivity, framework atom coordination states and acidities. When using these synthesized ZSM-5 samples as catalysts for methanol conversion, the mesoporous ZSM-5 templated with TPOAC exhibited an extremely long catalyst lifespan compared to conventional ZSM-5, while mesoporous ZSM-5 templated with CTAB showed no advantage in prolonging the catalyst lifetime during the reaction. The differences in the catalytic lifespan and the reduction of coke deposition were correlated to the variation of acidity and porosity with the mesopore generation in the ZSM-5 catalysts by the usage of different structure-directing agents. Compared to the mesopore structure-directing agent, CTAB, with the use of TPOAC as the template and part of the Si source, mesoporous ZSM-5 could be synthesized with good mesopore–micropore interconnectivity, which accounted for the improved catalytic performance in the reaction of methanol conversion.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Chuang Liu,Jun Liang,Duozheng Ma,Xiangcheng Li,Liyuan Li,Yu Wang,Tiezhu Zhang,Wenhua Fu,Zhendong Wang,Weimin Yang
The synthesis of zeolite nanosheets is an effective strategy to obtain advanced catalysts with enhanced catalytic performance due to the improved diffusion properties. ZSM-22 zeolite nanosheets (F-ZSM-22, U-ZSM-22) with a controllable orientation and a thickness of less than 20 nm were obtained through hydrothermal crystallization by introducing NaF or urea into the synthetic system of conventional ZSM-22 (C-ZSM-22). In the presence of both NaF and urea, a zeolite nanosheet (FU-ZSM-22) with a decreased width was synthesized. In comparison with C-ZSM-22, all ZSM-22 nanosheets displayed better diffusion properties. On testing catalysts in the methanol-to-hydrocarbon reaction, ZSM-22 nanosheets showed better stability than C-ZSM-22, and FU-ZSM-22 was the best catalyst.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Jiaxing Hou,Guohao Zou,Xinrui Liu,Mingge Li,Pengyu Yang,Xiaobin Zhang,Yan Chen,Qian Zhang,Xiaoping Wu,Tiejun Wang
The one-step hydrothermal reconstruction of bioethanol into higher alcohols represents a pivotal advancement in green chemistry, addressing both environmental sustainability and energy regeneration. Herein, a rational design of Ni@C-CeO2 catalysts via a sol–gel method for efficient aqueous-phase ethanol C–C coupling was reported. Systematic investigation of Ni loading and precursor carbonization temperature revealed their critical roles in modulating catalyst microstructure and performance. The optimized Ni-2@C-CeO2-500 catalyst demonstrated exceptional activity under 190 °C and 12 h, achieving ethanol conversion of 72.0% and C4+ alcohol yield of 55.6%. Advanced characterization techniques unveiled structure-performance relationships: (1) controlled Ni loading ensured optimal nanoparticle dispersion, while excessive loading induced aggregation; (2) carbonization at 500 °C balanced carbon matrix architecture and CeO2 reducibility. XPS analysis revealed that oxygen vacancy concentration critically modulates strong metal–support interactions through Ce3+-induced charge redistribution, facilitating interfacial electron transfer during reaction. Furthermore, the Ni-2@C-CeO2-500 catalyst demonstrated excellent stability with sustained activity retention over five consecutive cycles. This work establishes a renewable and technologically viable alternative to conventional petroleum-derived chemicals widely utilized in the chemical industry, demonstrating significant potential for applications in green and sustainable chemistry.
研究领域:
绿色化学
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催化化学
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材料科学
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DOI
高影响因子
ACS Catalysis
·
2019
·
IF 12.221
Liu Yang,Tingting Yan,Chuanming Wang,Weili Dai,Guangjun Wu,Michael Hunger,Weibin Fan,Zaiku Xie,Naijia Guan,Landong Li
The formation of the initial carbon–carbon (C–C) bonds in the methanol-to-hydrocarbon (MTH) conversion on acidic zeolite has been hotly debated for decades. Recently, the formation of surface-bound acetyl groups involving C–C bonds during the initial period of the MTH conversion has been disclosed. Understanding the exact C–C bond-containing intermediates triggering the MTH conversion and the critical roadmap of the MTH conversion is essential for the further development of this important reaction. Herein, acetaldehyde from the hydrogenation of surface-bound acetyl species was identified to be responsible for triggering the MTH conversion on H-ZSM-5 zeolite. By combining kinetic studies, spectroscopic analyses, and theoretical calculations, the mechanism and roadmap of zeolite-catalyzed MTH conversion from the initial C–C bonds to the hydrocarbon pool compounds were clearly depicted.
研究领域:
化学工程
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催化科学
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DOI
高影响因子
Catalysis Science & Technology
·
2017
·Vol. 7
·期 8
·1776-1791
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IF 5.773
Yanming Jia,Junwen Wang,Kan Zhang,Shibin Liu,Guoliang Chen,Yufei Yang,Chuanmin Ding,Ping Liu
ZnSiF6-modified nano-sized HZSM-5 zeolites (NZ2, NZ3 and NZ4 catalysts) were prepared and investigated as catalysts for the conversion of methanol to aromatics. Moreover, the ZnNZ1 catalyst, prepared by ion exchange using zinc nitrate, was also introduced as a reference sample. The effects of modification on the framework, textural properties and acidity of the parent nano-sized HZSM-5 zeolite (NZ1) were investigated by XRD, FT-IR, 29Si MAS-NMR, SEM, N2 adsorption–desorption, ICP, NH3-TPD, infrared spectroscopy of adsorbed pyridine (Py-IR), UV-vis spectra, X-ray photoelectron spectroscopy (XPS) and n-butylamine and tert-butylamine titration. The results showed that the amount of total acid sites, especially the external surface acid sites of the NZ2, NZ3 and NZ4 catalysts, significantly decreased, which may largely be attributed to the passivation effect of SiF62− on the surface acidity of the parent NZ1 catalyst. Moreover, the amount of Lewis acid sites (L acid sites) increased, whereas the amount of Brønsted acid sites (B acid sites) obviously decreased with the introduction of zinc species. The emergence of new Zn-Lewis acid sites (⊖ZO⋯H⋯O–Zn⊕ species) was beneficial to improving the selectivity to BTX (benzene (B), toluene (T) and xylene (X)) due to their high activity for dehydroaromatization. The FT-IR spectra in the OH− vibration region and the 29Si MAS-NMR spectra show that the treatment of ZnSiF6 could effectively repair partial lattice defects of zeolite and could thus improve the catalyst stability. TG analysis of all the deactivated catalysts showed that the coke amount and the average rate of coke formation decreased over NZ2, NZ3 and NZ4 catalysts, and this may largely be ascribed to their lower surface acidity. The catalytic performance of these materials on the conversion of methanol to aromatics showed that the NZ3 catalyst had the highest selectivity to BTX of about 51.3% and the longest catalytic lifetime of about 234 h under the operating conditions of T = 425 °C, p = 0.1 MPa and WHSV = 0.8 h−1. The improvement in the selectivity to BTX and the catalyst lifetime of the NZ3 catalyst could be ascribed to the synergistic effect among the Zn-Lewis acid sites (⊖ZO⋯H⋯O–Zn⊕ species), external surface acidity and intact framework structure.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 9
·2037
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IF 4.2
Zhaohui Liu,Min Mao,Ruixue Yangcheng,Shuang Lv
Small-pore zeolites catalyze the methanol-to-olefins (MTO) reaction via a dual-cycle mechanism, encompassing both olefin- and aromatic-based cycles. Zeolite topology is crucial in determining both the catalytic pathway and the product selectivity of the MTO reaction. Herein, we investigate the mechanistic influence of MCM-35 zeolite on the MTO process. The structural properties of the as-synthesized MCM-35 catalyst, including its confined cages (6.19 Å), were characterized, confirming them as the catalytic centers. Then, the MTO reactions were systematically performed and investigated over a MCM-35 catalyst. Feeding pure methanol to the reactor yielded minimal MTO activity despite the formation of some aromatic species within the zeolite. The results suggest that the aromatic-based cycle is entirely suppressed in MCM-35, preventing the simultaneous occurrence of the olefin-based cycle. However, cofeeding a small amount of propene in methanol can obviously enhance the methanol conversion under the same studied reaction conditions. Thus, the exclusive operation of the olefin-based cycle in the MTO reaction, independent of the aromatic-based cycle, was demonstrated in MCM-35 zeolite.
研究领域:
催化化学
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材料科学
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DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 21
·7258-7266
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IF 4.174
Guanqun Zhang,Yaqi Fan,Ju Huang,Lijin Wang,Chengguang Yang,Meng Lyu,Haiming Liu,Yanhang Ma
The increasing demands for catalysts with improved accessibility to reactants call for a rational synthesis of nanosized zeolites. Herein we developed a facile approach for highly crystalline MFI-type (Silicalite-1 and ZSM-5) and beta zeolites with variable Si/Al ratios and high yield. This was achieved by kinetically decoupling the nucleation from the growth process of the zeolites in a highly concentrated gel system via a temperature-staged treatment. The carefully controlled low-water environment ensures only nucleation in stage I (aging), and hence the generation of abundant nuclei for the subsequent rapid crystallization within a self-confined space at stage II (growth). The method, without using expensive templates or additives, allows the syntheses of nanosized, well-isolated ZSM-5 (Si/Al = 100–∞, 36–88 nm, yield >85%) and Beta (Si/Al = 25–100, 21–66 nm, yield >95%). The ultra-small crystal size endows ZSM-5 zeolites with good catalytic activity, product selectivity and remarkably longer lifetime in methanol conversion reactions.
研究领域:
化学工程
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材料科学
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产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2019
·
IF 1.911
Fushan Chen,Songlin Zhao,Tao Yang,Taotao Jiang,Jun Ni,Houfeng Xiong,Qunfeng Zhang,Xiaonian Li
A novel template-free oxalate route was applied to synthesize different mesoporous manganese oxides (amorphous manganese oxide (AMO), Mn 5 O 8 , Mn 3 O 4 , MnO 2 ) in the narrow temperature range from 350 °C to 400 °C by controlling the calcination conditions, which were employed as the efficient catalysts for the oxidative coupling of imines from alcohols and amines. The chemical and structural properties of the manganese oxides were characterized by the methods of thermal analysis and heat flow (TG-DSC), X-ray diffraction (XRD), nitrogen sorption , scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR), and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The structures of different manganese oxides were confirmed by characterization. The M-350 (AMO) presented the maximum surface area, amorphous nature, the lowest reduction temperature, the higher (Mn 3+ + Mn 4+ )/Mn 2+ ratio, and the higher adsorbed oxygen species compared to other samples. Among the catalysts, M-350 showed the best catalytic performance using air as an oxidant, and the conversion of benzyl alcohol (BA) and the selectivity of N -benzylideneaniline (NBA) reached as high as 100% and 97.1% respectively at the lower reaction temperature (80 °C) for 1 h. M-350 had also the highest TOF value (0.0100 mmol·mg −1 ·h −1 ) compared to the other manganese oxide catalysts. The catalyst was reusable and gave 95.8% conversion after 5 reuse tests, the XRD pattern of the reactivated M-350 did not show any obvious change. Lattice oxygen mobility and (Mn 3+ + Mn 4+ )/Mn 2+ ratio were found to play the important roles in the catalytic activity of aerobic reactions.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 4
·320
·
IF 3.444
Yuehong Yu,Daoming Sun,Shuanjin Wang,Min Xiao,Luyi Sun,Yuezhong Meng
Phosphotungstic and silicotungstic acid salt catalysts (CuPW, CuSiW, FePW, FeSiW) were synthesized by substitution of protons with ferric and copper ions through a simple replacement reaction. The structure and thermal stability were characterized by IR, XRD and TG, and the salts showed a keggin structure and a thermal tolerance near 450 °C. Temperature programmed reactions indicated that the four catalysts showed similar trends in the change of methanol conversion, DME selectivity, and light olefins selectivity at 100–400 °C. Copper salt catalysts showed a 100% DME selectivity at temperatures ranging from 100–250 °C, while FeSiW and FePW catalysts had a 100% DME selectivity near 250 °C. Moreover, the heteropolyacid salt catalysts also produced a certain number of light olefins at the temperature ranging from 250–350 °C, and the CuSiW catalyst exhibited the highest ethylene and propylene selectivity of 44%. In the stability test evaluated at 200 °C, the catalysts showed different tendencies during the induction period and the same trends during the reduction period for the methanol conversion to DME, due to the differences in the strengths of the strong acid sites. Finally, the silicotungstic acid salt catalysts showed the longest lifetime of 120 h, much longer than the heteropolyacids. This approach provides an effective way to synthesize hydrocarbons through methanol, especially DME, at different temperatures using one catalyst.Keywords:methanol to hydrocarbons;heteropolyacid salts;dimethyl ether;temperature programmed reaction
研究领域:
化学工程
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催化科学
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DOI
高影响因子
JOURNAL OF BASIC MICROBIOLOGY
·
2019
·Vol. 59
·期 9
·924-935
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IF 1.76
Wan-Ju Sun,Yong-Jun Liu,Hao-Hao Liu,Jie-De Ma,Yu-Hong Ren,Feng-Qing Wang,Dong-Zhi Wei
Some species of mycobacteria have been modified to transform sterols to valuable steroid synthons. The unique cell wall of mycobacteria has been recognized as an important organelle to absorb sterols. Some cell wall inhibitors (e.g., vancomycin and glycine) have been validated to enhance sterol conversion by interfering with transpeptidation in peptidoglycan biosynthesis. Therefore, two transpeptidase genes, pbpA and pbpB , were selected to rationally modify the cell wall to simulate the enhancement effect of vancomycin and glycine on sterol conversion in a 22-hydroxy-23,24-bisnorchol-4-ene-3-one (4-HBC) producing strain (WIII). Unexpectedly, the pbpA or pbpB gene augmentation was conducive to the utilization of sterols. The pbpB augmentation strain WIII- pbpB was further investigated for its better performance. Compared to WIII, the morphology of WIII- pbpB was markedly changed from oval to spindle, indicating alterations of the cell wall. Biochemical analysis indicated that the altered cell wall properties of WIII- pbpB might contribute to the positive effect on sterol utilization. The productivity of 4-HBC was enhanced by 28% in the WIII- pbpB strain compared to that of WIII. These results demonstrated that the modification of peptidoglycan synthesis can improve the conversion of sterols to steroid synthons in mycobacteria.
研究领域:
微生物学
·
生物化学
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产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）