scholarly journals Phosphoric Acid Modification of Hβ Zeolite for Guaiacol Hydrodeoxygenation

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 962
Author(s):  
Xun Wang ◽  
Yongkang Lv ◽  
Shanhui Zhu ◽  
Xuefeng Wang ◽  
Cunbao Deng
Keyword(s):  
Phosphoric Acid ◽  
Lewis Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Acid Property ◽  
Bronsted Acid ◽  
Lewis Acid Sites ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites

Regulating the acid property of zeolite is an effective strategy to improve dehydration of intermediate alcohol, which is the rate-determining step in hydrodeoxygenation of lignin-based phenolic compounds. Herein, a commercial Hβ (SiO2/Al2O3 = 25) was modified by phosphoric acid, and evaluated in the catalytic performance of guaiacol to cyclohexane, combined with Ni/SiO2 prepared by the ammonia evaporation hydrothermal (AEH) method. Incorporating a small amount of phosphorus had little impact on the morphology, texture properties of Hβ, but led to dramatic variations in acid property, including the amount of acid sites and the ratio of Brønsted acid sites to Lewis acid sites, as confirmed by NH3-TPD, Py-IR, FT-IR and 27Al MAS NMR. Phosphorus modification on Hβ could effectively balance competitive adsorption of guaiacol on Lewis acid sites and intermediate alcohol dehydration on Brønsted acid sites, and then enhanced the catalytic performance of guaiacol hydrodeoxygenation to cyclohexane. By comparison, Hβ containing 2 wt.% phosphorus reached the highest activity and cyclohexane selectivity.

Synergy between Brønsted acid sites and Lewis acid sites

2008 ◽  
pp. 4631 ◽  
Author(s):  
Selvedin Telalović ◽  
Jeck Fei Ng ◽  
Rajamanickam Maheswari ◽  
Anand Ramanathan ◽  
Gaik Khuan Chuah ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Lewis Acid Sites ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

Effective co-sensitization using D–π–A dyes with a pyridyl group adsorbing at Brønsted acid sites and Lewis acid sites on a TiO2 surface for dye-sensitized solar cells

RSC Advances ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 2531-2535 ◽  
Author(s):  
Yousuke Ooyama ◽  
Koji Uenaka ◽  
Takafumi Sato ◽  
Naoyuki Shibayama ◽  
Joji Ohshita
Keyword(s):  
Lewis Acid ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Lewis Acid Sites ◽  
Brønsted Acid Sites ◽  
Pyridyl Group ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

Effective and convenient co-sensitization method for DSSC have been newly developed by employing two kinds of D–π–A dyes with pyridyl group capable of adsorbing at the Brønsted acid sites and the Lewis acid sites on TiO2 surface.

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.

PHOSPHOTUNGSTIC ACID SUPPORTED ON ACID-LEACHED POROUS KAOLIN FOR FRIEDEL-CRAFTS ACYLATION OF ANISOLE

2015 ◽  
Vol 76 (13) ◽  
Author(s):  
Norsahika Mohd Basir ◽  
Hendrik Oktendy Lintang ◽  
Salasiah Endud
Keyword(s):  
Lewis Acid ◽  
Phosphotungstic Acid ◽  
Acid Sites ◽  
Impregnation Method ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

Porous clay heterostructures (PCH) was derived from natural kaolin through intercalation with cationic potato starch as the template. Leaching of PCH was performed in concentrated acid solutions consisting of HCl and H2SO4. Phosphotungstic acid (HPW) supported on PCH and modified PCH were synthesized by wet impregnation method. The resulting PCH showed remarkable increase in surface area starting from 15 m2g–1 for the parent kaolin to maximium value of 725 m2g–1 for PCH. Acidity studies by pyridine adsorption and FTIR spectra showed that both natural kaolin and PCH possessed strong Lewis acid sites. In contrast, the surface acidity of HPW supported on PCH was significantly enhanced and comprising mainly Brönsted acid sites. The correlation between the Brönsted to Lewis acid ratios (B/L) and either conversion or selectivity of the catalysts has been studied in Friedel-Crafts acylation of anisole. The PCH/30HPW catalyst with the highest number of Brönsted acid sites showed excellent catalytic activity giving 86% conversion of anisole and high selectivity of 95% toward p-methoxypropiophenone.

Efficient conversion of glucose to 5-hydroxymethylfurfural using bifunctional partially hydroxylated AlF3

RSC Advances ◽  
2016 ◽  
Vol 6 (16) ◽  
pp. 12782-12787 ◽  
Author(s):  
Ye-Min Lu ◽  
Hu Li ◽  
Jian He ◽  
Yan-Xiu Liu ◽  
Zhi-Bing Wu ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Efficient Conversion ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

Mesoporous AlF3 material bearing both Lewis and Brønsted acid sites exhibits high catalytic performance in glucose-to-fructose isomerization and subsequent dehydration to HMF (57.3% yield).

One-pot transformation of furfural into γ-valerolactone catalyzed by hierarchical Hf-Al-USY zeolite with balanced Lewis and Brønsted acid sites

2021 ◽  
Author(s):  
Bo Tang ◽  
Shuang Li ◽  
Wei-Chao Song ◽  
Yan Li ◽  
En-Cui Yang
Keyword(s):  
Lewis Acid ◽  
Value Added ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Lewis Acid Sites ◽  
One Pot ◽  
Usy Zeolite ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brønsted And Lewis Acid

Upgrading of furfural to high value-added chemicals are currently an attractive and challenging route in biorefineries. Herein, hierarchically structured bifunctional Hf-Al-USY zeolite with balanced Brønsted and Lewis acid sites has...

scholarly journals Achieving acid sites accessibility and pore compatibility in MWW nanosheets for alkylation of benzene with 1-dodecene

2021 ◽  
Author(s):  
Baoyu Liu ◽  
Zhantu Liao ◽  
Jianwen Zhang ◽  
Yeqing Huang
Keyword(s):  
Shape Selectivity ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Alkylation Of Benzene ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

Regularly spaced MWW nanosheets combined with single-unit-cell thickness and optimized Al species distribution are highly effective for the alkylation between benzene with 1-dodecene, high conversion of 1-dodecene (ca. 85 %) and selectivity of 2-LAB (ca. 80 %) can be obtained. Detailed studies of this MWW nanaosheets system reveal that ultra-thin MWW nanosheets with ordered arrangement can expose more accessible Brønsted acid sites (ca. ~89 %), and specially place framework Al species on the T2 sites (ca. ~13 %), in which the alkylation mainly occurred under the catalysis of accessible Brønsted acid sites. Besides, the desired 2-LAB is produced on the unique 12-MR hemicavities with solid binding energy and perfect steric configuration. As a proof-of-concept study, we integrate the highly exposed Brønsted acid sites and unrivalled shape-selectivity in the regularly spaced MWW nanosheets system with well characterized acid sites accessibility and pore adaptability, leading to the excellent catalytic performance.

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