Methanol to Gasoline Conversion over CuO/ZSM-5 Catalyst Synthesized Using Sonochemistry Method

2018 ◽  
Vol 17 (2) ◽  
Author(s):  
Ehsan Kianfar ◽  
Mahmoud Salimi ◽  
Saeed Hajimirzaee ◽  
Behnam Koohestani
Keyword(s):  
Copper Oxide ◽  
Lewis Acid ◽  
Active Sites ◽  
Fixed Bed ◽  
Acid Sites ◽  
High Specific Surface Area ◽  
Fixed Bed Reactor ◽  
Lewis Acid Sites ◽  
Hydrocarbon Production ◽  
Methanol To Gasoline

Abstract In this research, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over CuO (5 %)/ZSM-5 and CuO (7 %)/ZSM-5 catalysts prepared via sonochemistry methods. Conversion of methanol to gasoline (MTG) has been carried out in a fixed bed reactor under atmospheric pressure and 400˚C temperature, over copper oxide on the synthesized ZSM-5 catalyst. The samples were characterized by XRD, SEM, TEM, BET, and FTIR techniques; in which good crystallinity and high specific surface area of synthesized zeolite were proved after impregnation of zeolite with copper. The present investigation suggests that the CuO/ZSM-5 catalyst made by sonochemistry method can increase the yield toward hydrocarbon production. It was concluded that impregnation of zeolite with copper oxide can alter the Brønsted/Lewis acid sites ratio and provide new Lewis acid sites over the surface of the ZSM-5. The main products of methanol to gasoline reaction over the catalyst that prepared via sonochemistry method were toluene, xylene, ethylbenzene, ethyl toluene, tetra methylbenzene, diethyl benzene and butylbenzene. The total amount of aromatics in the products was 80 % by using this catalyst. Our results suggest that catalyst synthesized by using sonochemistry shows better production yield toward hydrocarbons by affecting the distribution of active sites on the surface of the ZSM-5.

scholarly journals HZSM-5 and H-Ferrierite Acidity Modification by Silylation and Their Activities in n-Butene Isomerisation

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Emre Kilic ◽  
Selahattin Yilmaz
Keyword(s):  
Lewis Acid ◽  
Room Temperature ◽  
Fixed Bed ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Total Acidity ◽  
Lewis Acid Sites ◽  
Chemical Liquid Deposition ◽  
Liquid Deposition ◽  
Brønsted And Lewis Acid

H-ZSM5 and H-Ferrierite acidities were modified by chemical liquid deposition using tetraethylorthosilicate (TEOS), silicontetratchloride (SiCl4) and triaminopropyltriethoxysilane (3-APTES). All depositions were carried out at room temperature for deposition times of 0.5 and 1 h. Reaction tests were performed in a tubular quartz fixed bed reactor at 375°C for weight hour space velocities of 22 h-1. Surface area and pore volume of the catalysts were decreased upon modifications. The least modification of acidity was achieved by TEOS. However, SiCl4 and 3-APTES deposition modification strongly decreased the number of Bronsted and Lewis acid sites. As the effect of the modification increased, total acidity of the SiCl4 modified catalyst decreased. The catalysts were tested in isomerization of n-butene. Modification decreased the activity of the catalysts, but improvement in selectivity was observed with TEOS deposition. TEOS deposition increased the selectivity of the catalysts; for synthesized H-ZSM5 from 57.95 to 63.74 percent, for commercial H-ZSM5-C from 26.78 to 32.52 percent, and for H-FER from 63.06 to 81.23 percent. However, modification with SiCl4 and 3-APTES decreased both conversion and selectivity of the parent catalysts.

The role of weak Lewis acid sites for methanol thiolation

2019 ◽  
Vol 9 (2) ◽  
pp. 509-516 ◽  
Author(s):  
Manuel Weber-Stockbauer ◽  
Oliver Y. Gutiérrez ◽  
Ricardo Bermejo-Deval ◽  
Johannes A. Lercher
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Strong Base

Weak Lewis acid sites combined with strong base sites of Cs+ supported on WS2 and γ-Al2O3 are the active sites in the thiolation of methanol.

A study on the acidity of sulfated CuO layers grown by surface reconstruction of Cu2O with specific exposed facets

2020 ◽  
Vol 10 (12) ◽  
pp. 3985-3993
Author(s):  
Yanan Wu ◽  
Xin Chen ◽  
Daofeng Huang ◽  
Li Zhang ◽  
Yuanhang Ren ◽  
...  
Keyword(s):  
Surface Reconstruction ◽  
Lewis Acid ◽  
Active Sites ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Pechmann Condensation ◽  
Exposed Facets

Surface reconstruction and sulfation improve the acidity of Cu2O, and moderate Lewis acid sites are the active sites in Pechmann condensation.

scholarly journals Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1033
Author(s):  
Zahra Gholami ◽  
Zdeněk Tišler ◽  
Pavla Vondrová ◽  
Romana Velvarská ◽  
Kamil Štěpánek
Keyword(s):  
Organic Compounds ◽  
Lewis Acid ◽  
Flow Reactor ◽  
Fixed Bed ◽  
Acid Sites ◽  
Economic Benefits ◽  
Solvent Free ◽  
Molar Ratio ◽  
Lewis Acid Sites ◽  
Solvent Free Synthesis

In spite of the rapid developments in synthesis methodologies in different fields, the traditional methods are still used for the synthesis of organic compounds, and regardless of the type of chemistry, these reactions are typically performed in standardized glassware. The high-throughput chemical synthesis of organic compounds such as fragrant molecules, with more economic benefits, is of interest to investigate and develop a process that is more economical and industrially favorable. In this research, the catalytic activity of Mg-Al catalyst derived from hydrotalcite-like precursors with the Mg/Al molar ratio of 3 was investigated for the solvent-free synthesis of jasminaldehyde via aldol condensation of benzaldehyde and heptanal. The reaction was carried out in a fixed-bed flow reactor, at 1 MPa, and at different temperatures. Both Brønsted and Lewis (O2− anions) base sites, and Lewis acid sites exist on the surface of the Mg-Al catalyst, which can improve the catalytic performance. Increasing the reaction temperature from 100 °C to 140 °C enhanced both heptanal conversion and selectivity to jasminaldehyde. After 78 h of reaction at 140 °C, the selectivity to jasminaldehyde reached 41% at the heptanal conversion 36%. Self-condensation of heptanal also resulted in the formation of 2-n-pentyl-2-n-nonenal. The presence of weak Lewis acid sites creates a positive charge on the carbonyl group of benzaldehyde, and makes it more prone to attack by the carbanion of heptanal. Heptanal, is an aliphatic aldehyde, with higher activity than benzaldehyde. Therefore, the possibility of activated heptanal reacting with other heptanal molecules is higher than its reaction with the positively charged benzaldehyde molecule, especially at a low molar ratio of benzaldehyde to heptanal.

scholarly journals Resolving the Acid Site Distribution in Zn-Exchanged ZSM-5 with Stimulated Raman Scattering Microscopy

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1331
Author(s):  
Guillaume Fleury ◽  
Maarten B. J. Roeffaers
Keyword(s):  
Ion Exchange ◽  
Lewis Acid ◽  
Active Sites ◽  
Stimulated Raman Scattering ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Site Distribution ◽  
Particle Level ◽  
The Impact ◽  
Brønsted And Lewis Acid

Zeolites are widely used acid catalysts in research and in industrial processes. The catalytic performance of these materials is affected by the nature and concentration of Brønsted and Lewis acid sites. The balance between these types of active sites—and thus the activity and selectivity of the zeolite—can be altered by the introduction of metal species, e.g., by ion exchange. Although the acidic properties of zeolites are routinely characterized by bulk-scale techniques, this ensemble-averaged approach neglects the local variations in the material. Insights into the distribution of active sites at the single-particle level are thus critical to better understand the impact of post-synthetic modifications on the zeolite acidity. In this contribution, we spatially resolve Brønsted and Lewis acid sites in protonated and Zn-exchanged ZSM-5 crystals. To this end, the vibrational modes of pyridine chemisorbed on active sites are mapped with stimulated Raman scattering (SRS) microscopy. The SRS images reveal sharp inter- and intra-particle heterogeneities in the distribution of Lewis acid sites introduced upon ion exchange, ascribed to local variations in the Al content. Besides assessing the impact of Zn exchange on the active site distribution in ZSM-5 crystals, this approach enables uniquely to map the distribution of Lewis acid sites in catalysts at the single-particle level.

scholarly journals Design and control of Lewis acid sites in Sn-substituted microporous architectures

2016 ◽  
Vol 4 (15) ◽  
pp. 5706-5712 ◽  
Author(s):  
Khaled M. H. Mohammed ◽  
Arunabhiram Chutia ◽  
June Callison ◽  
Peter P. Wells ◽  
Emma K. Gibson ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Lewis Acid Sites ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
And Control

Modulation of tetrahedral Sn(iv) active sites in framework architectures influences the generation of Lewis and Brønsted acid sites in heterogeneous catalysts.

scholarly journals Tungsten Oxide-Modified SSZ-13 Zeolite as an Efficient Catalyst for Ethylene-To-Propylene Reaction

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 553
Author(s):  
Mansurbek Urol ugli Abdullaev ◽  
Sungjune Lee ◽  
Tae-Wan Kim ◽  
Chul-Ung Kim
Keyword(s):  
Tungsten Oxide ◽  
Fixed Bed ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Efficient Catalyst ◽  
X Ray ◽  
Propylene Selectivity ◽  
Temperature Programmed

Among the zeolitic catalysts for the ethylene-to-propylene (ETP) reaction, the SSZ-13 zeolite shows the highest catalytic activity based on both its suitable pore architecture and tunable acidity. In this study, in order to improve the propylene selectivity further, the surface of the SSZ-13 zeolite was modified with various amounts of tungsten oxide ranging from 1 wt% to 15 wt% via a simple incipient wetness impregnation method. The prepared catalysts were characterized with several analysis techniques, specifically, powder X-ray diffraction (PXRD), Raman spectroscopy, temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of ammonia (NH3-TPD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and N2 sorption, and their catalytic activities were investigated in a fixed-bed reactor system. The tungsten oxide-modified SSZ-13 catalysts demonstrated significantly improved propylene selectivity and yield compared to the parent H-SSZ-13 catalyst. For the tungsten oxide loading, 10 wt% loading showed the highest propylene yield of 64.9 wt%, which was 6.5 wt% higher than the pristine H-SSZ-13 catalyst. This can be related to not only the milder and decreased strong acid sites but also the diffusion restriction of bulky byproducts, as supported by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) observation.

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