From low silica zeolite to high silica zeolite（1）
From 1954 to the early 1980s, it can be
said to be the heyday of the development of zeolite molecular sieves, which is
characterized by the comprehensive development of low-silicon ratio to
high-silicon and all-silica zeolites, and greatly promoted the application and
industrial development of butyl molecular sieves. From imitating the formation
conditions of natural zeolites to the successful synthesis of the first batch
of low silica zeolite molecular decorations (silicon to aluminum ratio =
1~1.5), due to the impetus of practical needs, the stability around zeolite
molecular sieves (thermal and hydrothermal stability and their In 1964, DW
Breck successfully synthesized and developed Y-type molecular sieves
(silicon-aluminum ratio = 1.5~3.0), and in the catalytic conversion of alkanes
(cracking, hydrocracking and isomerization) It has played an extremely
important role, thus promoting the development of medium silicon-aluminum ratio
molecular sieves. Subsequently, scientists have developed a large number of
molecular sieves with a silicon-aluminum ratio = 2~5.
Such as large pore mordenite (Norton
company named after zeolon), L-type zeolite, erionite, badger zeolite
clinoptilolite, etc. The development of milestone properties is that since the
early 1960s, scientists from Mobil Corporation of the United States began to
introduce organic amines and quaternary ammonium salts as templates into the
hydrothermal synthesis system of zeolite molecular sieves, and synthesized a
batch of high-silica molecular sieves. The most important progress is that in
1972, R J. Argauer and GR Lan-delt used PTANCI or PI.NOH as a template agent in
Na2O: Al203: 24.2SiO2 : 14.4Pr4NOH: 410H2O system crystallization at 120 ° C to
obtain "pentasil famnily" "The first important member of ZSM-5,
then in 1973 P. Chu used Bu4N+ as a template agent to successfully synthesize
ZSM-11, in 1974 EJ Rosinski and MK Rubin used Et4N+ as a template agent to
successfully synthesize ZSM-12, 1977 ~1978 again successful
ZSM-21 and ZSM-34 were synthesized. Then R.
L. Wadlinger and G. T. Kerr successfully synthesized high-silicon BEA.
The "pentasil family" high-silica
zeolite has a lipophilic and hydrophobic surface and two-dimensional crossed
10-membered ring pores, and has played an important role in the field of
shape-selective catalytic materials since its first appearance. On this basis,
in 1978, E.M. Flanigen of U.C.C. Company successfully synthesized all-silicon
ZSM-5-Silicalite-1 and all-silicon ZSM-11- the last members of the
"pentasil family".
-Silicalite-2. Due to the rapid development
of the field of high silica zeolite synthesis, it has also promoted the
research on the secondary synthesis of zeolite molecular sieve with high
silicification. Some high-silica zeolites that cannot be directly synthesized,
such as ultra-stable Y-type zeolite, high-silica mordenite, erionite, BEA,
clinoptilolite
preparation was successful. A number of
high-silicon and full-silicon zeolites have emerged in the field of molecular
sieves. In the past 25 years, in the field of zeolite from low silicon (silicon
to aluminum ratio = 1.0~1.5), medium silicon to aluminum ratio (silicon to
aluminum ratio = 2.0 to 5.0) to high silicon (silicon to aluminum ratio = 10 to
100) and full silicon, etc. The emergence of a large number of zeolite
molecular sieves has promoted the research on the structure and properties of
molecular sieves and microporous compounds, and greatly promoted the progress
in application.
