scholarly journals Application of Sulfated Tin (IV) Oxide Solid Superacid Catalyst to Partial Coupling Reaction of α-Pinene to Produce Less Viscous High-Density Fuel

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1905
Author(s):  
Seong-Min Cho ◽  
Chang-Young Hong ◽  
Se-Yeong Park ◽  
Da-Song Lee ◽  
June-Ho Choi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Coupling Reaction ◽  
High Density ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Solid Superacid ◽  
Brönsted Acid ◽  
Superacid Catalyst ◽  
Partial Coupling ◽  
Solid Superacid Catalyst

Brønsted acid-catalyzed reactions of α-pinene have been studied because of their ability to produce various types of fragrance molecules. Beyond this application, dimeric hydrocarbon products produced from coupling reactions of α-pinene have been suggested as renewable high-density fuel molecules. In this context, this paper presents the application of a sulfated tin(IV) oxide catalyst for the partial coupling reaction of α-pinene from turpentine. Brønsted acid sites inherent in this solid superacid catalyst calcined at 550 °C successfully catalyzed the reaction, giving the largest yield of dimeric products (49.6%) at 120 °C over a reaction time of 4 h. Given that the low-temperature viscosity of the mentioned dimeric products is too high for their use as a fuel in transportation engines, lowering the viscosity is an important avenue of study. Therefore, our partial coupling reaction of α-pinene provides a possible solution as a considerable amount of the isomers of α-pinene still remained after the reaction, which reduces the low-temperature viscosity. On the basis of a comparison of the reaction products, a plausible mechanism for the reaction involving coinstantaneous isomerization and coupling reaction of α-pinene was elucidated.

Brønsted acid cocatalysis in photocatalytic intramolecular coupling of tertiary amines: efficient synthesis of 2-arylindols

2016 ◽  
Vol 14 (31) ◽  
pp. 7447-7450 ◽  
Author(s):  
Xiaoqian Yuan ◽  
Xinxin Wu ◽  
Shupeng Dong ◽  
Guibing Wu ◽  
Jinxing Ye
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Coupling Reaction ◽  
Bronsted Acid ◽  
Tertiary Amines ◽  
Brønsted Acid ◽  
Efficient Synthesis ◽  
Unsaturated Ketones ◽  
Brönsted Acid

We report herein a highly efficient intramolecular coupling reaction of tertiary amines and ketones (α,β-unsaturated ketones) by using a Brønsted acid as a cocatalyst, affording 2-arylindols in good to excellent yields (up to 92%) under visible light irradiation at room temperature.

scholarly journals Bulk tungsten-substituted vanadium oxide for low-temperature NOx removal in the presence of water

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yusuke Inomata ◽  
Hiroe Kubota ◽  
Shinichi Hata ◽  
Eiji Kiyonaga ◽  
Keiichiro Morita ◽  
...  
Keyword(s):  
Low Temperature ◽  
Vanadium Oxide ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Lewis Acid Sites ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

AbstractNH3-SCR (selective catalytic reduction) is important process for removal of NOx. However, water vapor included in exhaust gases critically inhibits the reaction in a low temperature range. Here, we report bulk W-substituted vanadium oxide catalysts for NH3-SCR at a low temperature (100–150 °C) and in the presence of water (~20 vol%). The 3.5 mol% W-substituted vanadium oxide shows >99% (dry) and ~93% (wet, 5–20 vol% water) NO conversion at 150 °C (250 ppm NO, 250 ppm NH3, 4% O2, SV = 40000 mL h−1 gcat−1). Lewis acid sites of W-substituted vanadium oxide are converted to Brønsted acid sites under a wet condition while the distribution of Brønsted and Lewis acid sites does not change without tungsten. NH4+ species adsorbed on Brønsted acid sites react with NO accompanied by the reduction of V5+ sites at 150 °C. The high redox ability and reactivity of Brønsted acid sites are observed for bulk W-substituted vanadium oxide at a low temperature in the presence of water, and thus the catalytic cycle is less affected by water vapor.

Palladium/ Zeolite Low Temperature Passive NOx Adsorbers (PNA): Structure-Adsorption Property Relationships for Hydrothermally Aged PNA Materials

2019 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Nicholas R. Jaegers ◽  
Libor Kovarik ◽  
Jian Zhi Hu ◽  
Yong Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Hydrothermal Aging ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Small Pore ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

<p>Zeolites with different framework structures (SSZ-13, ZSM-5, BEA) but similar Si/Al ratios and Pd loading (~1 wt%) were synthesized and evaluated as low temperature passive NOx adsorbers (PNA). These materials exhibit high NOx adsorption efficiency with atomically dispersed Pd the active adsorption site. Hydrothermal aging at 750 ºC for 16 hours in the presence of 10% water vapor in air resulted in the formation of PdO nanoparticles in all three samples as evidenced by high energy XRD. Hydrothermal aging of the small-pore Pd/SSZ-13 (Si/Al = 6), which contain ~100-90% atomically dispersed palladium ions, decreases its PNA performance only by ~10-20%, indicating agglomeration of only ~10-20% of all atomically dispersed Pd into PdO. High-field solid state <sup>27</sup>Al NMR studies on the fresh and aged samples substantiate dealumination and significant changes in the distribution of Al (and thus, Brönsted acid) sites after hydrothermal aging. FTIR measurements with NO probe molecule and titration of Brönsted acid sites with nitrosyl (NO<sup>+</sup>)<sup> </sup>ions further corroborate the <sup>27</sup>Al NMR data. Because framework aluminum atoms are the anchoring sites for atomically dispersed Pd ions, their elution from the framework causes the loss of active atomically dispersed Pd species. With the aid of HAADF-STEM imaging and synchrotron XRD studies, we further confirm and visualize the fate of these Pd species – they agglomerate into PdO nanoparticles on the external surface of zeolite. Consequently, these changes lead to the decrease in PNA performance of these materials after hydrothermal aging. The thus formed agglomerates cannot be re-dispersed back to their ionic state due to the loss of framework Al T-sites and/or inherent stability of such large PdO particles.</p> <p>Our study demonstrates that, unlike in previous studies that found increased PNA performance upon HTA, high temperatures hydrothermal aging of PNA materials, that contain atomically dispersed Pd initially, results in a decrease in NOx storage efficiency due to the formation of PdO agglomerates. However, we also highlight the high hydrothermal stability of predominantly atomically dispersed 1-3 wt% Pd/SSZ-13 (Si/Al = 6), whose performance decreases only marginally after prolonged hydrothermal aging at 750 ºC. This study shows that hydrothermally stable passive NOx materials can be prepared using small-pore SSZ-13 zeolite. </p>

Palladium/ Zeolite Low Temperature Passive NOx Adsorbers (PNA): Structure-Adsorption Property Relationships for Hydrothermally Aged PNA Materials

2019 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Nicholas R. Jaegers ◽  
Libor Kovarik ◽  
Jian Zhi Hu ◽  
Yong Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Hydrothermal Aging ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Small Pore ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

<p>Zeolites with different framework structures (SSZ-13, ZSM-5, BEA) but similar Si/Al ratios and Pd loading (~1 wt%) were synthesized and evaluated as low temperature passive NOx adsorbers (PNA). These materials exhibit high NOx adsorption efficiency with atomically dispersed Pd the active adsorption site. Hydrothermal aging at 750 ºC for 16 hours in the presence of 10% water vapor in air resulted in the formation of PdO nanoparticles in all three samples as evidenced by high energy XRD. Hydrothermal aging of the small-pore Pd/SSZ-13 (Si/Al = 6), which contain ~100-90% atomically dispersed palladium ions, decreases its PNA performance only by ~10-20%, indicating agglomeration of only ~10-20% of all atomically dispersed Pd into PdO. High-field solid state <sup>27</sup>Al NMR studies on the fresh and aged samples substantiate dealumination and significant changes in the distribution of Al (and thus, Brönsted acid) sites after hydrothermal aging. FTIR measurements with NO probe molecule and titration of Brönsted acid sites with nitrosyl (NO<sup>+</sup>)<sup> </sup>ions further corroborate the <sup>27</sup>Al NMR data. Because framework aluminum atoms are the anchoring sites for atomically dispersed Pd ions, their elution from the framework causes the loss of active atomically dispersed Pd species. With the aid of HAADF-STEM imaging and synchrotron XRD studies, we further confirm and visualize the fate of these Pd species – they agglomerate into PdO nanoparticles on the external surface of zeolite. Consequently, these changes lead to the decrease in PNA performance of these materials after hydrothermal aging. The thus formed agglomerates cannot be re-dispersed back to their ionic state due to the loss of framework Al T-sites and/or inherent stability of such large PdO particles.</p> <p>Our study demonstrates that, unlike in previous studies that found increased PNA performance upon HTA, high temperatures hydrothermal aging of PNA materials, that contain atomically dispersed Pd initially, results in a decrease in NOx storage efficiency due to the formation of PdO agglomerates. However, we also highlight the high hydrothermal stability of predominantly atomically dispersed 1-3 wt% Pd/SSZ-13 (Si/Al = 6), whose performance decreases only marginally after prolonged hydrothermal aging at 750 ºC. This study shows that hydrothermally stable passive NOx materials can be prepared using small-pore SSZ-13 zeolite. </p>

Solvent-Free Acetalization of Glycerol with n-Octanal using Combined Brønsted Acid-Surfactant Catalyst

2017 ◽  
Vol 54 (1) ◽  
pp. 54-63 ◽  
Author(s):  
Xu Li ◽  
Lan Wu ◽  
Qiong Tang ◽  
Jinxiang Dong
Keyword(s):  
Solvent Free ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid
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