Effect of sequential desilication and dealumination on catalytic performance of ZSM-5 catalyst for pyridine and 3-picoline synthesis

2010 ◽  
Vol 25 (2) ◽  
pp. 272-282 ◽  
Author(s):  
Fang Jin ◽  
Yugang Cui ◽  
Zebao Rui ◽  
Yongdan Li
Keyword(s):  
Alkaline Treatment ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Acid Strength ◽  
Strength Distribution ◽  
Major Function ◽  
Hierarchical Pores ◽  
Pyridine Bases ◽  
The Stability ◽  
Acid Strength Distribution

A sequential procedure of alkaline treatment followed by SiCl4 or hydrothermal treatment has been investigated to obtain a tailored ZSM-5 catalyst for the synthesis of pyridine bases. The major function of alkaline treatment is desilication; however, it is accompanied by the extraction of framework aluminum, which formed the extra-framework alumina and amorphous alumina by realumination. Moreover, a large number of intracrystalline meso- and macropores and silanol groups are created. The desilication and realumination cause the ratio of Lewis acid sites to Brönsted acid sites (L/B) to increase. The subsequent SiCl4 or hydrothermal dealumination increases both L/B ratio and acid strength. The introduced hierarchical pores and changed acid strength distribution by the alkaline treatment improve the stability of the catalysts; the generated stronger acid sites by dealumination benefits the yields of pyridine bases; and the increased L/B by the sequential treatment promotes the selectivity of pyridine over 3-picoline.

Performance of Ag-HZSM-5 Zeolite Catalysts in n-heptane Conversion

2017 ◽  
Vol 68 (1) ◽  
pp. 116-120
Author(s):  
Iuliean Vasile Asaftei ◽  
Neculai Catalin Lungu ◽  
Lucian Mihail Birsa ◽  
Ioan Gabriel Sandu ◽  
Laura Gabriela Sarbu ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Metal Content ◽  
Pulse Method ◽  
Acid Strength ◽  
Strength Distribution ◽  
Zeolite Catalysts ◽  
Benzene Toluene ◽  
Acid Strength Distribution ◽  
Silver Cations ◽  
Heptane Conversion

The conversion of n-heptanes into aromatic hydrocarbons benzene, toluene and xylenes (BTX), by the chromatographic pulse method in the temperature range of 673 - 823K was performed over the HZSM-5 and Ag-HZSM-5 zeolites modified by ion exchange with AgNO3 aqueous solutions. The catalysts, HZSM-5 (SiO2/Al2O3 = 33.9), and Ag-HZSM-5 (Ag1-HZSM-5 wt. % Ag1.02, Ag2-HZSM-5 wt. % Ag 1.62; and Ag3-HZSM-5 wt. % Ag 2.05 having different acid strength distribution exhibit a conversion and a yield of aromatics depending on temperature and metal content. The yield of aromatic hydrocarbons BTX appreciably increased by incorporating silver cations Ag+ into HZSM-5.

Effect of acid strength distribution on conversion of FCC gasoline over a ZSM-5 zeolite catalyst

2005 ◽  
Vol 84 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Zhihua Wu ◽  
Shenglin Liu ◽  
Sujuan Xie ◽  
Qingxia Wang ◽  
Xinhua Qian ◽  
...  
Keyword(s):  
Zeolite Catalyst ◽  
Acid Strength ◽  
Strength Distribution ◽  
Fcc Gasoline ◽  
Acid Strength Distribution

Transition metal ions regulate the catalytic performance of Ti0.8M0.2Ce0.2O2+x for the NH3-SCR of NO: the acidic mechanism

RSC Advances ◽  
2015 ◽  
Vol 5 (10) ◽  
pp. 7597-7603 ◽  
Author(s):  
Yuesong Shen ◽  
Yun Su ◽  
Yifan Ma
Keyword(s):  
Transition Metal Ions ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Acid Strength ◽  
Maximum Activity ◽  
Lewis Acid Sites ◽  
Nh3 Scr ◽  
Scr Of No ◽  
Temperature Window ◽  
Active Temperature

The maximum activity is dependent on the number of Lewis acid sites, and the active temperature window is dependent on the acid strength.

Characterization of coal hydrogenation catalysts. Determination of acid strength distribution

Fuel ◽  
1988 ◽  
Vol 67 (6) ◽  
pp. 803-807 ◽  
Author(s):  
Maria T. Martinez ◽  
Maria D. Martinez ◽  
J. Osácar ◽  
JoséL. Miranda
Keyword(s):  
Acid Strength ◽  
Strength Distribution ◽  
Hydrogenation Catalysts ◽  
Acid Strength Distribution

scholarly journals Optimized Pore Structures of Hierarchical HY Zeolites for Highly Selective Production of Methyl Methoxyacetate

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 865 ◽  
Author(s):  
Fei Chen ◽  
Dongxi Zhang ◽  
Lei Shi ◽  
Yan Wang ◽  
Guangwen Xu
Keyword(s):  
Strong Acid ◽  
Treatment Method ◽  
Alkaline Treatment ◽  
Acid Sites ◽  
Relative Crystallinity ◽  
Mesoporous Zeolites ◽  
Pore Structures ◽  
The Stability ◽  
Strong Acid Sites ◽  
Hy Zeolites

Several organic templates were introduced during acid or alkaline treatment to optimize pore structures of hierarchical HY zeolites. The influences of category and concentration of templates on the pore structures and acidity of hierarchical HY zeolites were systemically studied. The N2 adsorption-desorption showed that the micropore amount of the optimized HY zeolites obviously increased, while both the large mesopore size and amount remained almost unchanged. The XRD and NH3-TPD revealed that the optimized HY zeolites exhibited higher relative crystallinity and medium-strong acid sites amount than those of hierarchical HY zeolites produced without the addition of templates. The optimized HY zeolites were used for the synthesis of methyl methoxyacetate (MMAc) from dimethoxymethane (DMM) carbonylation. In comparison with parent HY, the conversion and the selectivity clearly increased from 36.43% to 96.32% and from 11.06% to 92.35%, respectively. The stability of the optimized zeolite was also conducted under the same conditions. The conversion and the selectivity remained nearly unchanged even through 24 h reaction, showing that the performance was extremely stable. The TG-DTA and GC-MS also indicated that the generation of coke was effectively inhibited. This catalyst treatment method, which is facile and highly efficient, provided a route for producing mesoporous zeolites.

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