Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution
The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al<sub>F</su...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-09-01
|
| Series: | Catalysts |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4344/13/9/1295 |
| _version_ | 1797580904935194624 |
|---|---|
| author | Shu Ren Fan Yang Chao Tian Yinghong Yue Wei Zou Weiming Hua Zi Gao |
| author_facet | Shu Ren Fan Yang Chao Tian Yinghong Yue Wei Zou Weiming Hua Zi Gao |
| author_sort | Shu Ren |
| collection | DOAJ |
| description | The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al<sub>F</sub>) distributions, but otherwise quite similar textural and acidic properties, have been prepared by employing tetrapropylammonium hydroxide (TPAOH) and <i>n</i>-butylamine (NBA) as organic structure-directing agents (OSDAs). Systematical investigations demonstrate that Al<sub>F</sub> is preferentially located at the intersections in MFI topology when TPAOH is adopted. In contrast, less Al<sub>F</sub> is positioned therein as NBA is utilized. Density functional theory (DFT) calculations reveal that the transition-state complexes cannot be formed in the straight and sinusoidal channels due to their much smaller sizes than the dynamic diameters of transition states, whereas there are adequate spaces for the formation of transition states at the intersections. Benefitting from abundant Al<sub>F</sub> at the intersections, which provides more acid sites therein, H-ZSM-5 synthesized from TPAOH is more active relative to the counterpart obtained from NBA. At a WHSV of 4 h<sup>−1</sup> and 400 °C, the former catalyst gives a 52.8% conversion, while the latter one affords a 45.9% conversion. Both catalysts display close total selectivity towards toluene and xylene (ca. 84%). This study provides an efficient way to regulate the distribution of acid sites, thereby enhancing the catalytic performance of H-ZSM-5 zeolite in the titled reaction. |
| first_indexed | 2024-03-10T22:56:41Z |
| format | Article |
| id | doaj.art-d7570d8efd7b48b8aba6382083557c78 |
| institution | Directory Open Access Journal |
| issn | 2073-4344 |
| language | English |
| last_indexed | 2024-03-10T22:56:41Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Catalysts |
| spelling | doaj.art-d7570d8efd7b48b8aba6382083557c782023-11-19T09:58:27ZengMDPI AGCatalysts2073-43442023-09-01139129510.3390/catal13091295Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial DistributionShu Ren0Fan Yang1Chao Tian2Yinghong Yue3Wei Zou4Weiming Hua5Zi Gao6Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, ChinaState Key Laboratory of Green Chemical Engineering and Industrial Catalysis, SINOPEC Shanghai Research Institute of Petrochemical Technology Co., Ltd., Shanghai 201208, ChinaShanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, ChinaState Key Laboratory of Green Chemical Engineering and Industrial Catalysis, SINOPEC Shanghai Research Institute of Petrochemical Technology Co., Ltd., Shanghai 201208, ChinaShanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, ChinaThe alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al<sub>F</sub>) distributions, but otherwise quite similar textural and acidic properties, have been prepared by employing tetrapropylammonium hydroxide (TPAOH) and <i>n</i>-butylamine (NBA) as organic structure-directing agents (OSDAs). Systematical investigations demonstrate that Al<sub>F</sub> is preferentially located at the intersections in MFI topology when TPAOH is adopted. In contrast, less Al<sub>F</sub> is positioned therein as NBA is utilized. Density functional theory (DFT) calculations reveal that the transition-state complexes cannot be formed in the straight and sinusoidal channels due to their much smaller sizes than the dynamic diameters of transition states, whereas there are adequate spaces for the formation of transition states at the intersections. Benefitting from abundant Al<sub>F</sub> at the intersections, which provides more acid sites therein, H-ZSM-5 synthesized from TPAOH is more active relative to the counterpart obtained from NBA. At a WHSV of 4 h<sup>−1</sup> and 400 °C, the former catalyst gives a 52.8% conversion, while the latter one affords a 45.9% conversion. Both catalysts display close total selectivity towards toluene and xylene (ca. 84%). This study provides an efficient way to regulate the distribution of acid sites, thereby enhancing the catalytic performance of H-ZSM-5 zeolite in the titled reaction.https://www.mdpi.com/2073-4344/13/9/1295benzene alkylationH-ZSM-5 zeoliteAl spatial distributionDFT calculation |
| spellingShingle | Shu Ren Fan Yang Chao Tian Yinghong Yue Wei Zou Weiming Hua Zi Gao Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution Catalysts benzene alkylation H-ZSM-5 zeolite Al spatial distribution DFT calculation |
| title | Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution |
| title_full | Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution |
| title_fullStr | Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution |
| title_full_unstemmed | Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution |
| title_short | Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution |
| title_sort | selective alkylation of benzene with methanol to toluene and xylene over h zsm 5 zeolites impact of framework al spatial distribution |
| topic | benzene alkylation H-ZSM-5 zeolite Al spatial distribution DFT calculation |
| url | https://www.mdpi.com/2073-4344/13/9/1295 |
| work_keys_str_mv | AT shuren selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT fanyang selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT chaotian selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT yinghongyue selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT weizou selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT weiminghua selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution AT zigao selectivealkylationofbenzenewithmethanoltotolueneandxyleneoverhzsm5zeolitesimpactofframeworkalspatialdistribution |