Consequences of Acid Strength and Diffusional Constraints for Alkane Isomerization and β-Scission Turnover Rates and Selectivities on Bifunctional Metal-Acid Catalysts

2018 ◽  
Vol 122 (44) ◽  
pp. 25475-25497 ◽  
Author(s):  
Gina Noh ◽  
Stacey I. Zones ◽  
Enrique Iglesia
Keyword(s):  
Acid Strength ◽  
Acid Catalysts ◽  
Turnover Rates ◽  
Alkane Isomerization

Preparation of Strong Acid Catalysts by Sulfate Treatment of Calcined Boehmite

1992 ◽  
Vol 57 (11) ◽  
pp. 2241-2247 ◽  
Author(s):  
Tomáš Hochmann ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Aluminum Sulfate ◽  
Solid Acid ◽  
Strong Acid ◽  
Acid Strength ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Preparation Methods ◽  
Indicator Method

Solid acid catalysts with acid strength of -14.52 < H0 < -8.2 were prepared by sulfate treatment of the samples of boehmite calcined at 105-800 °C. Two preparation methods were used: impregnation of the calcined boehmite with 3.5 M H2SO4 or mixing of the boehmite samples with anhydrous aluminum sulfate, in both cases followed by calcination in nitrogen at 650 °C. The catalysts were characterized by measurements of surface area, adsorption of pyridine and benzene, acid strength measurements by the indicator method and by catalytic activity tests in the isomerization of cyclohexene, p-xylene and n-hexane. Properties of the catalysts prepared by both methods were comparable.

scholarly journals Cover Feature: “Click” Silica‐Supported Sulfonic Acid Catalysts with Variable Acid Strength and Surface Polarity (Chem. Eur. J. 27/2019)

2019 ◽  
Vol 25 (27) ◽  
pp. 6648-6648
Author(s):  
Palraj Kasinathan ◽  
Charlotte Lang ◽  
Sambhu Radhakrishnan ◽  
Josefine Schnee ◽  
Cécile D'Haese ◽  
...  
Keyword(s):  
Sulfonic Acid ◽  
Acid Strength ◽  
Acid Catalysts ◽  
Surface Polarity

scholarly journals Active, Selective, and Recyclable Zr(SO4)2/SiO2 and Zr(SO4)2/Activated Carbon Solid Acid Catalysts for Esterification of Malic Acid to Dimethyl Malate

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 384
Author(s):  
Pei Yu ◽  
Can Chen ◽  
Guangci Li ◽  
Zhong Wang ◽  
Xuebing Li
Keyword(s):  
Activated Carbon ◽  
Electron Density ◽  
Malic Acid ◽  
Solid Acid ◽  
Supported Catalysts ◽  
Acid Strength ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Bronsted Acid ◽  
Brönsted Acid

The esterification of malic acid using traditional homogenous catalysts suffers from the difficulty in reuse of the catalyst and undesirable side reactions. In this work, Zr(SO4)2/SiO2 and Zr(SO4)2/activated carbon (AC) as solid acid catalysts were prepared for malic acid esterification with methanol. The conversion of malic acid over these two catalysts is comparable to that over H2SO4 and unsupported Zr(SO4)2∙4H2O catalysts; however; a 99% selectivity of dimethyl malate can be realized on these two supported catalysts, which is much higher than that of conventional H2SO4 (75%) and unsupported Zr(SO4)2∙4H2O (80%) catalysts, highlighting the critical role of AC and SiO2 supports in tuning the selectivity. We suggest that the surface hydroxyls of AC or lattice O2− ions from SiO2 donate electrons to Zr4+ in Zr(SO4)2/AC and Zr(SO4)2/SiO2 catalysts, which results in the increase in electron density on Zr4+. The enhanced electron density on Zr4+ reduces the degree of H delocalization from crystal water and then decreases the Brønsted acid strength. Consequently, the reduced Brønsted acid strength of Zr(SO4)2/AC and Zr(SO4)2/SiO2 catalysts suppresses the intermolecular dehydration side reaction. In addition, these two supported catalysts can be easily separated from the reaction system by simple filtration with almost no loss of activity.

Sign in / Sign up

Export Citation Format

Share Document