- Email: [email protected]
The Templating Effect during the Formation of ZSM-5 Type Zeolite
The Templating Effect during the Formation of ZSM-5 Type Zeolite
Liyun-,
Song Ti~ou*, Xu Ruren*, Li and Ye Zhaohui** Jilin University, Changchun, P, R, China * Department of ** Wuhan Institute of Aoademia Sinioa, Wuhan, P. R. China 13C solid-state MAS NMR, and 23Na solid-state MAS NMR teohnique, thermal analysis and ohemioal analysis were used to investigate ZSM-5 type zeolite synthesized with organio oompounds and direot method. As a result, a meohanism of templating effect during the formation of ZSM-5 type zeolite and the model of "positive oharge tetrahedron" templating agent were proposed. INTRODUCTION + In 1982, Z.Ga.bel1oa, et al, studied the oonformation and filling of TPA in the ohannel of ZSM-5 type zeolite by' 13C MAS NMR speotra and 111'A-'l'G analysis, and oonoluded that there is one TPA+ in each of 4 ohannel interseotions of each unit oell [1 ,2J. Reoently, it has been sucoeeded in synthesizing out ZSM-5 type zeolite with some aloohols and amines OJ. Partioularly, that it in synthesizing ZSM-5 type zeolite by' a direot method [4J (from H2O system only and in the absence of organio oompounds) makes us a problem whioh gives us much food for thought for theoretical research. At the same time, a great deal of M-Si-ZSM-5 type zeolits have been synthesized sucoessfully [5-1J. The progress in synthesizing work has laid foundation for the theoretical researoh of ZSM-5 type zeolite. We have studied several samples of ZSM-5 type zeolite synthesized with organio or inorganio oOlllpounde. On the basis of summing-up the templating effeot in the process of synthesis, we have proposed general oonsensus meohanism of templating effeot of ZSM-5 type zeolite. EXPERDIEN'l'AL 1. The Smthesis of Products The product was synthesized by b;y'drothermal synthesis method in a 25m! stainless steel autoolave at 160 0-20000 for 1-3 days' orystallization. The product was fil tered, washed to neutrality, and dried. The organio or inorganio oOlllpounds used in the synthesis are listed in Table 1. Table 1. The organio and inorganio coapounds used in the synthesis No.
M-5i-ZSM-5
oompound
S-1 S-8
Al Al Al Al Cr Ti Fe Zr
TPABr TPABr TPABr TPABr TPABr TPABr TP.:u3r TPABr
S-9
S-10 M-1 !~2
M-3
M-4
No. 002 Z-3 F-1 30-21 40-18 Y-11 60-2 J-13 A-5 201
M-Si-ZSM-5 Al A.l Al Al Al A1
Al Al A.l
oompound NaOH NaOH NaF n-propyl aloohol n-butyl aloohol n-pentyl aloohol n-he:z;yl aloohol 1,6-hexanediol 1,6-hexanediamine
202 (5Y-11-1)
2. The Characterization and Anal.ysis of the Products Having been ground in an agate mortar, the sample was baked for 2 hr. at 1000C and was stored over saturated NE4Cl for 24 hr. in a desiccator. Characterization was carried out on an XD-3A type X-Ray Diffractometer (made in Japan). The content of organic compounds in the sample was measured by thermogravimetric analyzer [2J. The contents of A1203 and Na20 were measured by ICPAES. The conformation of organic molecules in the channel was measured by XL-200 Type superconductive Nl~ spectrometer equipped with ~~ of Doty Type. RESULTS AND DISCUSSION The XRD patterns showed that there were not any impurities in the sample and the crystallinity was high. This makes the results confident. 1. Studies of the Synthesis of ZSM-5 '1YPe Zeolite with TPA+ It is specially effective to use TPA+ to synthesize ZSM-5 type zeolite [8J. We have studied the chemical composition of Si-Al-ZSM-5 and also M-3i-ZSM-5 (M = Cr, Ti, Fe, Zr) type zeolites synthesized with TPA+ and the results were shown in Table 2. Table 2 The quantity of TPA+ in unit cell and the percent of filling to the channel No. S-1 S-8 S-9 S-10 M-1 M-2 M-3
14-4
M-3i-ZSM-5
compound
Al A1 A1 Al Cr Ti Fe Zr
TPA+ TPA+ TPA+ TPA+ TPA+ TPA+ TPA+ TPA+
organic compound wt. loos 'to 12.1 11.6 11.4 11.6 11.1 11.1 11.6 11.8
TPA+/u.c.
'to filled channel space
3.8 3.6 3.5 3.6 3.6 3.4 3.6 3.1
102 98 96 98 98 94 98 99
The results showed that there are about 3.6 TPA+ in every unit cell of ZSM-5 type zeolite. Assuming that in ZSM-5 type zeolite the central nitrogen atom is located at the Channel intersection and 4 propyl groups extend in the two type ohannels. Just like the model proposed by Z. Gabelica et al. (1]. 2. Studies of the Synthesis of ZSI&-5 'lZpe Zeolite with Alcohol and Amine 2.1. We have successfully synthesized out high purity ZSM-5 type zeolites by respectively adding n-propyl alcohol, n-buty1 alcohol, n-penty1 alcohol, n-hexy1 alcohol, 1, 6-hexanedio1, and 1,6-hexanediamine into Na20-Si02-A1203-H20 systems. It can be seen from batch oomposition, reaction temperature, orysta1lization time that conditions of the formation of zeolite with the above reaotion mixture are more preoise and diffioult than with TPA+ [8-10]. Thus the temp1ating effect of alcohol and amine is less than that of TPA+. 2.2. The chemical composition of the samples is shown in Table 3. We can see + from it that the zeolites are similar to ZSM-5 type zeolite synthesized with TPA • The number of Na+ in unit cell is nearly equal to the number of intersection of channels, i.e., there is possible one Na+ in each interaection of channels. 2.3. We have also studied the number of alcohol or amine in unit cell of the zeolite and their fillings to the channel, as shown in Table 4. 2.4. Studies of samples by NMR speotra (13 0 MAS NMR at 50.3 MHz, 23Na at 52.9 MHz) We have investigated the conformation of organic molecules in the channels of ZSM-5 type zeolite by 130 solid-state MAS mm spectra and compared the 130-
S. Tianyou et al. Table 3. Uo. 30-21 40-18 Y-11 J-13 A-5
203
'lhe chemical composition of ZSM-5 type zeolite
compound
composition (wt.%)
n-propyl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
3i02 95.3 93.4 94.9 95·0 97.8
A1203 2.62 2.97 2.97 2.97 0.44
number of atoms/u.c.
Ua20 2.17 2.17 2.17 2.07 2.17
3i 93.0 91•1 92.6 92.6 95.5
Al 3.0 4.9 3.4 3.4 0.5
Na 4.1 4.1 4.1 3·9 4.1
Table 4. The number of alcohol and amine molecules in the unit cell of lSM-5 type zeolite and filling percent to channels
no. 30-21 40-18 Y-11 J-13 A-5
Table 5.
channel space 13-16 32-40 51-62 61-75 75-94
13C_NIlR spectra data (in ppm from TIllS)
compound
40-18
%filled
mol./u.c. 2.1 4.3 5·7 5·3 6.6
compound n-propyl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
4 3 2 1
CH3CH2CH2CH20H/Z** 4 3 2 1 CH3Cll2CH2CH20rr/L** 5 4 3 2 1 Y-11 CH3CH2CH2CH2CH20H/Z 5 4 3 2 1 CR3CH2C!I2CH2CH20H/L 654321 60-2 CH3CH2CH2CH2CH2CH20H/Z 654321 CH3CH2CH2CH2CH2CH20H/L 123321 J-13 HOCH2CH2CH2CH2CH2CH20H/Z 123321 HOCH2CH2CH2CH2CH2CH20H/L 123321 A-5 H2UClI2CH2CH2CH2CH2CH2NH2/Z 123321 H2UCH2CH2CH2CH2CH2CH2NH2/L
1*
chemical shift (ppm) 3 4 5
2
65. 1 29.7
19.3
61.4
19. 1 13.6
35.0
64.5 33.2
change of C1 6 shift (ppm)
12.8 +3.7
28.2
23.4
13.7
61.8
32.5 28.2
22.6
13.8
65.4
33.2
+2.7
25.8 33.0 24.1
14.5
61.9 32.8 25.8 32.0 22.8
14.2
63.6
33.4 26.1
61.6
32.7 25.6
40.6
32.2 25.8
42.8 34.7
27.6
+3.5
+2.0
-2.2
* numbering of oarbon atom ** Z: zeoliteL: solid-state l~S NMR spectra with the 13C-ID4R speotra of li~.. Table 5 shows these results and the change of C1 shift. The C1 shifts of aloohol and amine are ohanged very olearly. This shows that the ohemioal speoies in the ohannel interaots with the terminal groups of aloohol and amine strongly. Table 6 shows 23Na solid-state MAS m,m spectra data from whioh the conolusions oan be obtained. (1). The chemioal shift of the zeolite preouraor synthesized with aloohol is about -26 ppm.
204 (SY-ll-l)
(2). After baking, the chemical shift value of Na is -30'\--50 ppm. This shows the environment of Na is different from (1) clearly. (3). After absorbing water Na is in the environment of hydration,its chemical shift is about -20 ppm. 23Na MAS
Table 6.
a b c
I
spectra data (in ppm from NaCI)
a
chemical shift (ppm) b
c
-24.7 -29.5 -26.7 -26.3 -26.3 -12.3 -12.7
-34.2 -43.2 -31.7 -29.8 -48.6 -44.0 -43.1
-18.7 -18.2 -19.0 -19.5 -19.1 -22.0 -17.8
No. 30-21 40-18 Y-11 60-2 J-13 A-5 002
m.m
zeolite precursor baking for 2 hr. at 6000 c after baking, adsorb water saturately
2.5. Table 7 shows DTA results of the zeolites. We can see that there is not any rule between the decomposition temperature of organic compounds from the zeolite and their molecular weight as well as their boiling point. The decomposition temperature of these molecules depends on their attractive force with the cations in the channel. The decomposition temperature varies with the attractive force of alcohol and amine with the cation. Table 7. No. 30-21 40-18 Y-11 J-13 A-5
JY.['A result of samples
compound
mol.wt.
b.p. (00)
d oomposition temp. (OC)
n-prop,yl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
60 74 88 118 116
97.8 117 138 250 205
310 318 312 400 450
2.6. From what has been said above, there are positive charge tetrahedron chemical species similar to TPA+ in the channel of ZSM-5 type zeolite synthesized with alcohol and amine. The centre of the chemical species is Na+ that is located in the intersection of the channel. The four long chain molecules surrounding the Na+ ion extend into the channel. These molecules coordinate with Na+ through lone pair of electrons on -OR, -NH2 or attract with Na+ to each other. Na+ can form coordination compounds with coordination number 4 tetrahedron framework with H2O as well as -OR and -NH2 in organic compounds [11]. In the Na2D-Si02-A!203-H20 system for synthesizing ZSM-5 type zeolite, the aluminosilicate anions surrounding TPA+ or the positive charge tetrahedron above mentioned rearrange or polymerize, thus forming ZSM-5 type zeolite with oross ohannel [12]. Na+ is located in the intersection of ohannel, the long ohain extends into the ohannel. There are 4 Na+ in each unit oell. This positive oharge tetrahedron is formed in the prooess of orystallization, while TPA+ exists originally in the system. The positive oharge tetrahedron formed in the prooess of reaotion is less stable than TPA+. The templating effeot of synthesizing ZSM-5 type zeolite with aloohol and amine is less than with TPA+. The long ohain surrounding Ua+ may be associated with H2O ohain which makes organic moleoules combine with Na+ in different number and peroent of the filling of different organio moleoules is different.
s.
Tianyou et al.
205
It is the interaction of Na+ and -0J, -NH2 that makes the change of C1 chemical shift of alcohol and amine (in section 2.4.). It is the combination of Na+ with aloohol, amine or H20 that makes the differenoe in Na shift in 23Na-NMR speotra. The nature and strength of the interaotion of Na+ with aloohol or amine molecules deoide on the decomposition temperature of these organic moleoules. 3. Studies of the Synthesis of ZSM-5 TYpe Zeolite with Direot Method It has been reported to synthesize ZS~~5 type zeolite with direot method. We have suooessfully synthesized out ZSM-5 type zeolite by this method, e.g., sample Z-3. Its XRD-pattern is shown in Fig. 1.
Fig. 1.
XRD-pattern of sample Z-3.
In order to asoertain the templating effeot of ZSM-5 type zeolite in a system of Na20-5i02-A1203-H20 without adding organic oompounds, firstly we studied the oontent of Na+ during synthesizing ZSI~-5 type zeolite with direot method, and the results are shown in Table 8. The ratio si7Al is low for the ZSM-5 type zeolite
Table 8. The oontent of Na+ in ZSr.~5 type zeolite synthesized with direot method No.
before exohange Na+/u.o. Si/Al
after exohange* Si/Al Na+/u.o.
002 Z-3 F-1
18.3 15·9 16.5
22.2 25.3 22.0
*
6.5 5.3 9.0
4.2 3.5 4.1
The aoid (pH=4.5) used, 100 ml/g sample, at the room temp. , for 2 hr.
without organio coapounds , When Si/Al less than 23, the number of Al04 tetrahedron in eaoh unit oell must be more than 4 too. The result of left oolumn in Table 8 just illustrates this point. The result of right oolumn in Table 8 shows that Na+ ions aoting as templating agent are not easy plaoed by H+, the number of whioh is about 4. Other Na+ ions besides the four only balanoe out the oharge. They are easy plaoed by a+. Na+ forms a tetrahedron with 4 H2O in the firet hydration layer. Other water moleoules assooiate with the first ~ayer of H20 moleoules by hydrogen bonding, forming chains, then templating oluster of positive oharge tetrahedron. Thus this leads to the formation of ZSM-5 type zeolite. Reoently ZSM-5 type zeolite has been synthesized by adding NaF. The batoh
206 (5Y-11-1)
composition is Si02/A12031 50-70, H20/A1203: 3450-3500, ITa20/A12031 9-12 (13]. On synthesizing sample Z-3, the composition of reaction mixture was similar to that of NaF method, i.e., Si02/...12031 40-60, H20/A1203: 3000-3600, Na,20/A1203 about 10. We oonsider that besides the funotions mentioned in literature, F- ions can form H-Q-H F- H-o-H, strengthening the association between H2O molecules. This makes templating cluster formed easily. In the synthesis of ZSM-5 type zeolite by direot method, H20 molecules not only interact with Na+ but also with themselves so that the positive charge tetrahedron can be formed. Thus the probability of forming templating cluster is very low, and the templating effect is not strong. In order to produce the sample with high purity, the direct method is only applied the system with low silicon content, and the Si/Al ratio in ZSM-5 type zeolite by direct method is naturally low. Similarly, the synthesizing ZSM-5 type zeolite by direot method is more diffioult than by using aloohol or amine and muoh more diffioult than by using TPAT. CONCWSION The present paper reports the positive oharge tetrahedron model of the templating agent synthesizing ZSM-5 type zeolite. The positive oharge tetrahedron templating olusters oan be divided into 3 oategories. They are TPA+, the positive oharge tetrahedron with lTa+ as the oenter formed by the interaotion of Na+ with some organio oompounds, and the positive oharge tetrahedron with Na+ as the center formed by the interaction of NaT with water. This model illustrates the mechanism of templating effect during the prooess of synthesizing ZSM-5 type zeolite by adding organic or inorganic oompounds and explains the reason for different templating effect. REFERENCE 1. J.B. Nagy, Z. Gabelica, and E.G. Derouane, Zeolitss, l, 43(1983). 2. Z. Gabelica, G.G. Derouane, and N. Blom, Appl. Catal., 2" 109(1983). 3. B.M. Lok, T.R. Cannan, and C.A. Messina, Zeolites, lJ 282(1983). 4. Li Hezuan, Xiang Shouhe, WU Deming, Liu Yueting, Zhang Xiaosent and..Liu Shuquan, Chemical Journal of Chinese Universities, ,g" 517(1981). 5. M. Laszlo, S. Joaohim, and S. Matthias, Ger. Offen. 2831630, Ger. Offen. 2831631, Ger. Offen. 2831611. 6. M. Taramasso, G. Perago, and B. Notari, in "Proc. Fifth Intern. Conf. Zeolite", Naples, 1980(L.V.C. Rees, ed) Heyden and sons, London 1980, p.40. 7. Pang Wenqin, Jing Xiaoyant and Zhang Milin, Chemioal Journal of Chinese Universities, lJ 577( 1982)' 8. R.J. Argauer, and G.R. 3702886. Eur. Pat. 7098. 9. M. Laszlo, S. Joaohim, and S. 10. C.J. Leonello, L.B. Milner, and W.T. Vincent, Eur. Pat. 42225. 11. P.J. Durrant, and B. Durrant, "Introduotion to Advanced Inorganio Chemistry", ~. Clowes, London, 1962, p.400, p.417. 12. D.W. Breok, "Zeolite Molecular Sieves", Wiely, N.Y., 1974, p.340. 13. Xu Wen;rang, Li Wenyua.n, Cao Jinghui, and Zhao Zhenhua, Petroohemical Teohnology, ~ 739(1983).
Liyun-,
Song Ti~ou*, Xu Ruren*, Li and Ye Zhaohui** Jilin University, Changchun, P, R, China * Department of ** Wuhan Institute of Aoademia Sinioa, Wuhan, P. R. China 13C solid-state MAS NMR, and 23Na solid-state MAS NMR teohnique, thermal analysis and ohemioal analysis were used to investigate ZSM-5 type zeolite synthesized with organio oompounds and direot method. As a result, a meohanism of templating effect during the formation of ZSM-5 type zeolite and the model of "positive oharge tetrahedron" templating agent were proposed. INTRODUCTION + In 1982, Z.Ga.bel1oa, et al, studied the oonformation and filling of TPA in the ohannel of ZSM-5 type zeolite by' 13C MAS NMR speotra and 111'A-'l'G analysis, and oonoluded that there is one TPA+ in each of 4 ohannel interseotions of each unit oell [1 ,2J. Reoently, it has been sucoeeded in synthesizing out ZSM-5 type zeolite with some aloohols and amines OJ. Partioularly, that it in synthesizing ZSM-5 type zeolite by' a direot method [4J (from H2O system only and in the absence of organio oompounds) makes us a problem whioh gives us much food for thought for theoretical research. At the same time, a great deal of M-Si-ZSM-5 type zeolits have been synthesized sucoessfully [5-1J. The progress in synthesizing work has laid foundation for the theoretical researoh of ZSM-5 type zeolite. We have studied several samples of ZSM-5 type zeolite synthesized with organio or inorganio oOlllpounde. On the basis of summing-up the templating effeot in the process of synthesis, we have proposed general oonsensus meohanism of templating effeot of ZSM-5 type zeolite. EXPERDIEN'l'AL 1. The Smthesis of Products The product was synthesized by b;y'drothermal synthesis method in a 25m! stainless steel autoolave at 160 0-20000 for 1-3 days' orystallization. The product was fil tered, washed to neutrality, and dried. The organio or inorganio oOlllpounds used in the synthesis are listed in Table 1. Table 1. The organio and inorganio coapounds used in the synthesis No.
M-5i-ZSM-5
oompound
S-1 S-8
Al Al Al Al Cr Ti Fe Zr
TPABr TPABr TPABr TPABr TPABr TPABr TP.:u3r TPABr
S-9
S-10 M-1 !~2
M-3
M-4
No. 002 Z-3 F-1 30-21 40-18 Y-11 60-2 J-13 A-5 201
M-Si-ZSM-5 Al A.l Al Al Al A1
Al Al A.l
oompound NaOH NaOH NaF n-propyl aloohol n-butyl aloohol n-pentyl aloohol n-he:z;yl aloohol 1,6-hexanediol 1,6-hexanediamine
202 (5Y-11-1)
2. The Characterization and Anal.ysis of the Products Having been ground in an agate mortar, the sample was baked for 2 hr. at 1000C and was stored over saturated NE4Cl for 24 hr. in a desiccator. Characterization was carried out on an XD-3A type X-Ray Diffractometer (made in Japan). The content of organic compounds in the sample was measured by thermogravimetric analyzer [2J. The contents of A1203 and Na20 were measured by ICPAES. The conformation of organic molecules in the channel was measured by XL-200 Type superconductive Nl~ spectrometer equipped with ~~ of Doty Type. RESULTS AND DISCUSSION The XRD patterns showed that there were not any impurities in the sample and the crystallinity was high. This makes the results confident. 1. Studies of the Synthesis of ZSM-5 '1YPe Zeolite with TPA+ It is specially effective to use TPA+ to synthesize ZSM-5 type zeolite [8J. We have studied the chemical composition of Si-Al-ZSM-5 and also M-3i-ZSM-5 (M = Cr, Ti, Fe, Zr) type zeolites synthesized with TPA+ and the results were shown in Table 2. Table 2 The quantity of TPA+ in unit cell and the percent of filling to the channel No. S-1 S-8 S-9 S-10 M-1 M-2 M-3
14-4
M-3i-ZSM-5
compound
Al A1 A1 Al Cr Ti Fe Zr
TPA+ TPA+ TPA+ TPA+ TPA+ TPA+ TPA+ TPA+
organic compound wt. loos 'to 12.1 11.6 11.4 11.6 11.1 11.1 11.6 11.8
TPA+/u.c.
'to filled channel space
3.8 3.6 3.5 3.6 3.6 3.4 3.6 3.1
102 98 96 98 98 94 98 99
The results showed that there are about 3.6 TPA+ in every unit cell of ZSM-5 type zeolite. Assuming that in ZSM-5 type zeolite the central nitrogen atom is located at the Channel intersection and 4 propyl groups extend in the two type ohannels. Just like the model proposed by Z. Gabelica et al. (1]. 2. Studies of the Synthesis of ZSI&-5 'lZpe Zeolite with Alcohol and Amine 2.1. We have successfully synthesized out high purity ZSM-5 type zeolites by respectively adding n-propyl alcohol, n-buty1 alcohol, n-penty1 alcohol, n-hexy1 alcohol, 1, 6-hexanedio1, and 1,6-hexanediamine into Na20-Si02-A1203-H20 systems. It can be seen from batch oomposition, reaction temperature, orysta1lization time that conditions of the formation of zeolite with the above reaotion mixture are more preoise and diffioult than with TPA+ [8-10]. Thus the temp1ating effect of alcohol and amine is less than that of TPA+. 2.2. The chemical composition of the samples is shown in Table 3. We can see + from it that the zeolites are similar to ZSM-5 type zeolite synthesized with TPA • The number of Na+ in unit cell is nearly equal to the number of intersection of channels, i.e., there is possible one Na+ in each interaection of channels. 2.3. We have also studied the number of alcohol or amine in unit cell of the zeolite and their fillings to the channel, as shown in Table 4. 2.4. Studies of samples by NMR speotra (13 0 MAS NMR at 50.3 MHz, 23Na at 52.9 MHz) We have investigated the conformation of organic molecules in the channels of ZSM-5 type zeolite by 130 solid-state MAS mm spectra and compared the 130-
S. Tianyou et al. Table 3. Uo. 30-21 40-18 Y-11 J-13 A-5
203
'lhe chemical composition of ZSM-5 type zeolite
compound
composition (wt.%)
n-propyl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
3i02 95.3 93.4 94.9 95·0 97.8
A1203 2.62 2.97 2.97 2.97 0.44
number of atoms/u.c.
Ua20 2.17 2.17 2.17 2.07 2.17
3i 93.0 91•1 92.6 92.6 95.5
Al 3.0 4.9 3.4 3.4 0.5
Na 4.1 4.1 4.1 3·9 4.1
Table 4. The number of alcohol and amine molecules in the unit cell of lSM-5 type zeolite and filling percent to channels
no. 30-21 40-18 Y-11 J-13 A-5
Table 5.
channel space 13-16 32-40 51-62 61-75 75-94
13C_NIlR spectra data (in ppm from TIllS)
compound
40-18
%filled
mol./u.c. 2.1 4.3 5·7 5·3 6.6
compound n-propyl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
4 3 2 1
CH3CH2CH2CH20H/Z** 4 3 2 1 CH3Cll2CH2CH20rr/L** 5 4 3 2 1 Y-11 CH3CH2CH2CH2CH20H/Z 5 4 3 2 1 CR3CH2C!I2CH2CH20H/L 654321 60-2 CH3CH2CH2CH2CH2CH20H/Z 654321 CH3CH2CH2CH2CH2CH20H/L 123321 J-13 HOCH2CH2CH2CH2CH2CH20H/Z 123321 HOCH2CH2CH2CH2CH2CH20H/L 123321 A-5 H2UClI2CH2CH2CH2CH2CH2NH2/Z 123321 H2UCH2CH2CH2CH2CH2CH2NH2/L
1*
chemical shift (ppm) 3 4 5
2
65. 1 29.7
19.3
61.4
19. 1 13.6
35.0
64.5 33.2
change of C1 6 shift (ppm)
12.8 +3.7
28.2
23.4
13.7
61.8
32.5 28.2
22.6
13.8
65.4
33.2
+2.7
25.8 33.0 24.1
14.5
61.9 32.8 25.8 32.0 22.8
14.2
63.6
33.4 26.1
61.6
32.7 25.6
40.6
32.2 25.8
42.8 34.7
27.6
+3.5
+2.0
-2.2
* numbering of oarbon atom ** Z: zeoliteL: solid-state l~S NMR spectra with the 13C-ID4R speotra of li~.. Table 5 shows these results and the change of C1 shift. The C1 shifts of aloohol and amine are ohanged very olearly. This shows that the ohemioal speoies in the ohannel interaots with the terminal groups of aloohol and amine strongly. Table 6 shows 23Na solid-state MAS m,m spectra data from whioh the conolusions oan be obtained. (1). The chemioal shift of the zeolite preouraor synthesized with aloohol is about -26 ppm.
204 (SY-ll-l)
(2). After baking, the chemical shift value of Na is -30'\--50 ppm. This shows the environment of Na is different from (1) clearly. (3). After absorbing water Na is in the environment of hydration,its chemical shift is about -20 ppm. 23Na MAS
Table 6.
a b c
I
spectra data (in ppm from NaCI)
a
chemical shift (ppm) b
c
-24.7 -29.5 -26.7 -26.3 -26.3 -12.3 -12.7
-34.2 -43.2 -31.7 -29.8 -48.6 -44.0 -43.1
-18.7 -18.2 -19.0 -19.5 -19.1 -22.0 -17.8
No. 30-21 40-18 Y-11 60-2 J-13 A-5 002
m.m
zeolite precursor baking for 2 hr. at 6000 c after baking, adsorb water saturately
2.5. Table 7 shows DTA results of the zeolites. We can see that there is not any rule between the decomposition temperature of organic compounds from the zeolite and their molecular weight as well as their boiling point. The decomposition temperature of these molecules depends on their attractive force with the cations in the channel. The decomposition temperature varies with the attractive force of alcohol and amine with the cation. Table 7. No. 30-21 40-18 Y-11 J-13 A-5
JY.['A result of samples
compound
mol.wt.
b.p. (00)
d oomposition temp. (OC)
n-prop,yl alcohol n-butyl alcohol n-pentyl alcohol 1,6-hexanediol 1,6-hexanediamine
60 74 88 118 116
97.8 117 138 250 205
310 318 312 400 450
2.6. From what has been said above, there are positive charge tetrahedron chemical species similar to TPA+ in the channel of ZSM-5 type zeolite synthesized with alcohol and amine. The centre of the chemical species is Na+ that is located in the intersection of the channel. The four long chain molecules surrounding the Na+ ion extend into the channel. These molecules coordinate with Na+ through lone pair of electrons on -OR, -NH2 or attract with Na+ to each other. Na+ can form coordination compounds with coordination number 4 tetrahedron framework with H2O as well as -OR and -NH2 in organic compounds [11]. In the Na2D-Si02-A!203-H20 system for synthesizing ZSM-5 type zeolite, the aluminosilicate anions surrounding TPA+ or the positive charge tetrahedron above mentioned rearrange or polymerize, thus forming ZSM-5 type zeolite with oross ohannel [12]. Na+ is located in the intersection of ohannel, the long ohain extends into the ohannel. There are 4 Na+ in each unit oell. This positive oharge tetrahedron is formed in the prooess of orystallization, while TPA+ exists originally in the system. The positive oharge tetrahedron formed in the prooess of reaotion is less stable than TPA+. The templating effeot of synthesizing ZSM-5 type zeolite with aloohol and amine is less than with TPA+. The long ohain surrounding Ua+ may be associated with H2O ohain which makes organic moleoules combine with Na+ in different number and peroent of the filling of different organio moleoules is different.
s.
Tianyou et al.
205
It is the interaction of Na+ and -0J, -NH2 that makes the change of C1 chemical shift of alcohol and amine (in section 2.4.). It is the combination of Na+ with aloohol, amine or H20 that makes the differenoe in Na shift in 23Na-NMR speotra. The nature and strength of the interaotion of Na+ with aloohol or amine molecules deoide on the decomposition temperature of these organic moleoules. 3. Studies of the Synthesis of ZSM-5 TYpe Zeolite with Direot Method It has been reported to synthesize ZS~~5 type zeolite with direot method. We have suooessfully synthesized out ZSM-5 type zeolite by this method, e.g., sample Z-3. Its XRD-pattern is shown in Fig. 1.
Fig. 1.
XRD-pattern of sample Z-3.
In order to asoertain the templating effeot of ZSM-5 type zeolite in a system of Na20-5i02-A1203-H20 without adding organic oompounds, firstly we studied the oontent of Na+ during synthesizing ZSI~-5 type zeolite with direot method, and the results are shown in Table 8. The ratio si7Al is low for the ZSM-5 type zeolite
Table 8. The oontent of Na+ in ZSr.~5 type zeolite synthesized with direot method No.
before exohange Na+/u.o. Si/Al
after exohange* Si/Al Na+/u.o.
002 Z-3 F-1
18.3 15·9 16.5
22.2 25.3 22.0
*
6.5 5.3 9.0
4.2 3.5 4.1
The aoid (pH=4.5) used, 100 ml/g sample, at the room temp. , for 2 hr.
without organio coapounds , When Si/Al less than 23, the number of Al04 tetrahedron in eaoh unit oell must be more than 4 too. The result of left oolumn in Table 8 just illustrates this point. The result of right oolumn in Table 8 shows that Na+ ions aoting as templating agent are not easy plaoed by H+, the number of whioh is about 4. Other Na+ ions besides the four only balanoe out the oharge. They are easy plaoed by a+. Na+ forms a tetrahedron with 4 H2O in the firet hydration layer. Other water moleoules assooiate with the first ~ayer of H20 moleoules by hydrogen bonding, forming chains, then templating oluster of positive oharge tetrahedron. Thus this leads to the formation of ZSM-5 type zeolite. Reoently ZSM-5 type zeolite has been synthesized by adding NaF. The batoh
206 (5Y-11-1)
composition is Si02/A12031 50-70, H20/A1203: 3450-3500, ITa20/A12031 9-12 (13]. On synthesizing sample Z-3, the composition of reaction mixture was similar to that of NaF method, i.e., Si02/...12031 40-60, H20/A1203: 3000-3600, Na,20/A1203 about 10. We oonsider that besides the funotions mentioned in literature, F- ions can form H-Q-H F- H-o-H, strengthening the association between H2O molecules. This makes templating cluster formed easily. In the synthesis of ZSM-5 type zeolite by direot method, H20 molecules not only interact with Na+ but also with themselves so that the positive charge tetrahedron can be formed. Thus the probability of forming templating cluster is very low, and the templating effect is not strong. In order to produce the sample with high purity, the direct method is only applied the system with low silicon content, and the Si/Al ratio in ZSM-5 type zeolite by direct method is naturally low. Similarly, the synthesizing ZSM-5 type zeolite by direot method is more diffioult than by using aloohol or amine and muoh more diffioult than by using TPAT. CONCWSION The present paper reports the positive oharge tetrahedron model of the templating agent synthesizing ZSM-5 type zeolite. The positive oharge tetrahedron templating olusters oan be divided into 3 oategories. They are TPA+, the positive oharge tetrahedron with lTa+ as the oenter formed by the interaotion of Na+ with some organio oompounds, and the positive oharge tetrahedron with Na+ as the center formed by the interaction of NaT with water. This model illustrates the mechanism of templating effect during the prooess of synthesizing ZSM-5 type zeolite by adding organic or inorganic oompounds and explains the reason for different templating effect. REFERENCE 1. J.B. Nagy, Z. Gabelica, and E.G. Derouane, Zeolitss, l, 43(1983). 2. Z. Gabelica, G.G. Derouane, and N. Blom, Appl. Catal., 2" 109(1983). 3. B.M. Lok, T.R. Cannan, and C.A. Messina, Zeolites, lJ 282(1983). 4. Li Hezuan, Xiang Shouhe, WU Deming, Liu Yueting, Zhang Xiaosent and..Liu Shuquan, Chemical Journal of Chinese Universities, ,g" 517(1981). 5. M. Laszlo, S. Joaohim, and S. Matthias, Ger. Offen. 2831630, Ger. Offen. 2831631, Ger. Offen. 2831611. 6. M. Taramasso, G. Perago, and B. Notari, in "Proc. Fifth Intern. Conf. Zeolite", Naples, 1980(L.V.C. Rees, ed) Heyden and sons, London 1980, p.40. 7. Pang Wenqin, Jing Xiaoyant and Zhang Milin, Chemioal Journal of Chinese Universities, lJ 577( 1982)' 8. R.J. Argauer, and G.R. 3702886. Eur. Pat. 7098. 9. M. Laszlo, S. Joaohim, and S. 10. C.J. Leonello, L.B. Milner, and W.T. Vincent, Eur. Pat. 42225. 11. P.J. Durrant, and B. Durrant, "Introduotion to Advanced Inorganio Chemistry", ~. Clowes, London, 1962, p.400, p.417. 12. D.W. Breok, "Zeolite Molecular Sieves", Wiely, N.Y., 1974, p.340. 13. Xu Wen;rang, Li Wenyua.n, Cao Jinghui, and Zhao Zhenhua, Petroohemical Teohnology, ~ 739(1983).