钛硅分子筛催化剂的研究进展

Research progress of titanium silicalite catalys

t

Zhangxiaoming

Zhangzhaorong

Soujiquan

Lishuben

(Lanzhou Institute of Chemical Physics fine petrochemical intermediates National

Engineering Research Center, Lanzhou 730000)

The role of titanium catalyst in the oxidation reaction of organic

compounds is well known [1, 2]. Introduced in the molecular sieve framework

due to the molecular sieve having a regular pore structure and large specific

surface area characteristics, hetero atom, having an oxidation-reduction ability

to preparenovel catalytic oxidation catalyst, has been more interesting subject

in 1983 ENI [3] the T ar amasso its collaborators first successful synthesis of

the titanium-containing zeolite catalyst of TS-1, a subsequent study found,

Tammonia oxidation [7] S-1 with H2O2 aqueous solution as oxidant and the

oxidation reaction of a series of organic compounds, such as olefin epoxidation

[4], the aromatic hydrocarbon ring hydroxylation [5, 6], ketone, alkane

oxidation[8, 9] and the alcohol oxidation [10] and so the process has a unique

shape-selective catalytic function as compared with other types of catalytic

systems, the system (1) the mild reaction conditions (atmospheric pressure, 0 -

100 °

C); (2) the unique function of the shape-selective catalytic oxidation; (3)

environmental friendliness.

TS-1 has been very limited because the aperture is only about 0. 55 nm,

and its range of applications where the aerodynamic diameter is greater than 0.

60 nm substrate molecules can not enter within its pores without reactivity.

Orderovercome this limitation, the type of catalyst to get a wider range of

applications, the majority of scientists have successfully synthesized T S-2 [11],

Ti-Beta [12] and a series of large aperture zeolite catalysts.

In recent years, with the development of the petroleum refining and fine

petrochemical technology requires the use of some reorganization of the oil to

be effective. M41S [13, 14], HMS [15] and MSU [16] series of mesoporous

molecular sieves Tiheteroatom derivatives T i-MCM-41 [17], Ti-MCM-48 [18],

Ti-HMS [19, 20] and of Ti-the MSU [16] emerged, the latter in the selective

oxidation of organic compoundsshowed higher catalytic activity.

This

paper

reviews

the

recent

years,

the

progress

made

in

terms

of

microporous

and

mesoporous titanium silicalite catalyst preparation, characterization, and catalytic reaction.

T S-1 is first synthesized, and also so far been studied most, and more thoroughly of

a

class

of

titanium

silicalite

catalyst.

T

S-1

is

a

Silicalite-1

isomorphously

substituted

derivatives

thereof,

having

the

MFI

structure.

TS-

work

and

the

results

achieved

many

comments

have

been

reported

[10,

21

-

24]

here

only

a

brief

overview

of

the

TS-1

preparation, characterization, and their corresponding catalytic reaction.

The

classical

method

of

preparing

a

zeolite

catalyst

is

a

hydrothermal

synthesis method in the the earliest patent literature, Tar amasso [3] reported

two preparation T S-1 The method of one is tetraethyl orthosilicate (T EOS)

and

tetraethylammonium

n-titanate

(TEOT)

as

silica

source

and

a

titanium

source, and tetrapropyl ammonium hydroxide (TPA OH) as templating agent;

other is a silica sol as a silicon source, and to dissolve in H2O2 the titanate as

titanium

source

TPAOH

templating

agent

in

addition

to

the

hydrothermal

synthesis method, the TS -1 can also be obtained by the method of secondary

synthesis TiCl4 and dealumination of ZSM-5 for vapor phase reaction, to give

with

hydrothermal

synthesis

method

is

similar

to

the

structure

[25],

but

this

method is easy to cause anatase. Huanxin et al [26] for the titanium source,

TEOS as a silicon source, and succeeded in synthesizing a T S-1 to T iCl3 The

same

catalytic

activity,

with

the

same

reported

in

the

literature,

and

the

process can be effectively prevented from generation of anatase In addition,

Tuel and T aarit, continuous coverage positive ions with phosphorus [27], 1, 6 -

hexamethylene

diammonium

ion

(Di

-TPA)

[28],

tetraethyl

ammonium

hydroxide (TEAOH) / T PAOH and T EAOH / tetrabutyl ammonium hydroxide

(T

BA

OH)

[29]

as

a

template

to

prepare

T

S-1

process.

described

using

different Preparation of Template T S-1 is likely the. Preparation of Titanium

Silicalite

reagent

over

Na

+,

K

+

and

other

alkali

metal

ions

of

the

concentration

should

be

sufficiently

low,

because

the

alkali

metal

ions

will

hinder the titanium atom in the molecular sieve framework embedded; another

the

one

hand,

to

prevent

the

preparation

process

difficult

to

dissolve

the

anatase

anatase

formation

will

lead

to

subsequent

reaction

of

H2O2

decomposition

and

reduce

the

catalytic

activity

in

order

to

prevent

the

generation of anatase, the preparation process should be vigorously stirred, so

that titanium source in the silicon source is highly fragmented., Thangaraj, [7]

the

slower

rate

of

hydrolysis

the

of

tetrabutylammonium

positive

titanate

(TBOT) Alternate TEOT, with anhydrous isopropyl alcohol as a co-solvent, and

achieved good effect.

TS-1 zeolite catalyst unique shape- selective catalytic oxidation function,

undoubtedly has a direct relationship with the skeleton of T i (

Ⅳ

) Therefore,

the focus of such zeolite characterization is to determine the existence of T i

(

Ⅳ

) in the molecular sieveits ligand environment. characterization of TS-1,

except for routine characterization of X-ray diffraction (XRD), N2 adsorption /

desorption method, Fourier transform infrared spectroscopy (FT-IR) 29Si

magic anglespinning nuclear magnetic resonance spectroscopy

(29Si-MAS-NMR), diffuse reflectance UV - visible spectrum (DR UVVis), X-ray

photoelectron spectroscopy (XPS), extended X-ray absorption fine structure

(EXAFS) and X-ray absorption near edge structure analysis (XANES) and

other technologies exist in the form of tetrahedral coordination T i (

Ⅳ

) provided

the basis for

According to the naming of IUPAC [40], the aperture between 2 - 50 nm

molecular sieves for mesoporous molecular sieves. 1990s, class zeolite

inorganic materials separation, ion exchange and catalytic disciplines one of

the hot to longchain surfactants as templating agent, have been successfully

synthesized M41S [13, 14], HMS [15] and MSU [16] and a series of

mesoporous molecular sieves. formation mechanism of the pore structure of

mesoporous molecular sieve research has been reported[41 - 46] At the same

time, Ti [17 - 20], V [47], Zr [48], Mn [49] and Cr [50] with the redox ability of

transition metal atoms into mesoporous molecular sieveskeleton structure, get

a lot of new catalysts for the preparation of fine chemicals which T i atom

isomorphous substitution in the hole titanium silicalite has important

significance of theoretical research and industrial application value.

The Gont ier and T uel [20] also Press T anev to method prepared T

i-HMS, and preparation process of various factors such as the proportion of T

iO2 / SiO2, isopropanol, surface active agent chain length, characteristic of the

titanium source and of Surf / SiO2 system. found that in the preparation

process, when the two reagents is mixed for 15 min, the resulting product had

with Hex ago nal various characteristics of most of Surf / SiO2 the best ratio of

0.3 increase this proportion of the aperture increases, but the specific surface

area and adsorption capacity is greatly reduced.

Reviewed above on the synthesis, characterization and catalytic

oxidation properties of titanium silicalite and mesoporous molecular sieves

prepared its heteroatom derivatives can be seen, the titanium silicalite as a

new type of selective oxidation catalyst demandis very important to the

increasing volume of the preparation of fine chemicals. especially in recent

years, the success of a series of mesoporous molecular sieves synthesis and

application, making the range of applications greatly broaden the field has

attracted more and more attention of researchersbut we should also see that

there are still many problems in the field, such as the titanium silicalite catalytic

reaction mechanism, the formation mechanism of mesoporous molecular

sieves and skeleton in the presence of T i (

Ⅳ

) way for further exploration of

these issuesand research will become a research focus in the coming period.