SAPO-34 molecular sieve and method for preparing the same

Abstract

A SAPO-34 molecular sieve and method for preparing the same, whose chemical composition in the anhydrous state is expressed as: mSDA.(Si.sub.xAl.sub.yP.sub.z)O.sub.2, wherein m is 0.08-0.3, x is 0.01-0.60, y is 0.2-0.60, z is 0.2-0.60, and x+y+z=1. The template agent SDA is in micropores of the molecular sieve. SDA is an organic amine with the structural formula (CH.sub.3).sub.2NRN(CH.sub.3).sub.2, wherein R is a saturated straight-chain or branched-chain alkylene group with having from 2-5 carbon atoms. There is a slight Si enrichment phenomenon on the crystal surface of the molecular sieve crystal, and the ratio of the surface Si content to the bulk Si content of the crystal ranges from 1.50-1.01. Said SAPO-34 molecular sieve, after being calcined at a temperature range from 400-700° C. in air, can be used as a gas adsorbent and catalyst for an acid-catalyzed reaction or oxygenate to olefin reaction.

Claims

1. A SAPO-34 molecular sieve with a chemical composition in the anhydrous state expressed as:
mSDA.Math.(Si.sub.xAl.sub.yP.sub.z)O.sub.2; wherein, SDA represents the template agent existing in micropores of the molecular sieve; SDA is organic amine with the structural formula as (CH.sub.3).sub.2NRN(CH.sub.3).sub.2, wherein R is saturated straight-chain or branch-chain alkylene group with the number of carbon atoms at a range from 2 to 5; m is the molar number of the template agent per one mole of (SixAlyPz)O.sub.2, and m is from 0.08 to 0.3; x, y, z respectively represents the molar number of Si, Al, P, and x is from 0.01 to 0.60, and y is from 0.2 to 0.60, and z is from 0.2 to 0.60, and x +y +z =1; and wherein the molecular sieve is a crystal, there is a slight Si enrichment phenomenon on a crystal surface molecular sieve crystal, and the ratio of surface Si content to bulk Si content of the crystal ranges from 1.50 to 1.01; wherein the Si content is calculated by the molar ratio of Si/(Si+Al+P).

2. The SAPO-34 molecular sieve according to claim 1, wherein the ratio of the surface Si content to the bulk Si content of the crystal ranges from 1.42 to 1.02.

3. The SAPO-34 molecular sieve according to claim 1, wherein the template agent SDA is one or more selected from N,N,N′,N′-tetramethyl ethylenediamine, N,N,N′,N′-tetramethyl -1,3-diaminopropane, N,N,N′,N′-tetramethyl-1,4- butanediamine, N,N,N′,N′-tetramethyl-1,5-pentane diamine, N,N,N′,N′-tetramethyl-1,2-diaminopropane, N,N,N′,N′-tetramethyl-1,3-butanediamine, and N,N,N′,N′-tetramethyl-1,4-pentane diamine.

4. The SAPO-34 molecular sieve according to claim 1, wherein the surface Si content to the bulk Si content of the crystal ratio ranges from 1.30 to 1.03.

5. A method for preparing the SAPO-34 molecular sieve according to claim 1, including the steps as follows: (a) mixing a silicon source, an aluminum source, a phosphorus source, deionized water and SDA thereby obtaining an initial gel mixture with following molar ratio: SiO.sub.2/Al.sub.2O.sub.3 is from 0.01 to 1; P.sub.2O.sub.5/Al.sub.2O.sub.3 is from 0.5 to 1.5; H.sub.2O/Al.sub.2O.sub.3 is from 1 to 19; SDA/Al.sub.2O.sub.3 is from 5 to 30; and SDA/H.sub.2O is from 0.27 to 30; wherein, SDA is organic amine with the structural formula as (CH.sub.3).sub.2NRN(CH.sub.3).sub.2, wherein R is saturated straight-chain or branch-chain alkylene group with the number of carbon atoms at a range from 2 to 5; (b) transferring the initial gel mixture into a synthetic kettle, then sealing and heating to crystallization temperature range from 170° C. to 220° C., crystalizing for a crystallization time range from 0.5 h to 48 h under autogenous pressure; and (c) after finishing the crystallization, centrifuging and separating the solid product, followed by washing to neutral using deionized water and drying to obtain the SAPO-34 molecular sieve; wherein the initial gel mixture is mixed with the following order of ingredient addition is: firstly, mixing homogeneously the aluminum source and the organic amine SDA by stirring to obtain a Mixture A; separately and continuously stirring a mixture of the silicon source, the phosphorus source and deionized water, and adding the homogeneously the Mixture A thereto and stirring to obtain the initial gel mixture.

6. The method according to claim 5, wherein in the initial gel mixture, the silicon source is one or more selected from silica sol, active silica, orthosilicate esters and metakaolin; the aluminum source is one or more selected from aluminum salts, activated alumina, aluminum alkoxide and metakaolin; and the phosphorus source is one or more selected from phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, organophosphorous compounds and phosphorus oxides.

7. The method according to claim 5, wherein in the initial gel mixture, the molar ratio of organic amine SDA to water SDA/H.sub.2O is from 0.5 to 30 .

8. The method according to claim 5, wherein in the initial gel mixture, the molar ratio of organic amine SDA to Al.sub.2O.sub.3 SDA/Al.sub.2O.sub.3 is from 7.0 to 30 .

9. The method according to claim 5, wherein the organic amine SDA is selected from N,N,N′,N′-tetramethyl ethylenediamine, N,N,N′,N′-tetramethyl-1,3-diaminopropane, N,N,N′,N′-tetramethyl-1,4-butanediamine, N,N,N′,N′-tetramethyl-1,5-pentane diamine, N,N,N′,N′-tetramethyl-1,2-diaminopropane, N,N,N′,N′-tetramethyl-1,3-butanediamine, and N,N,N′,N′-tetramethyl-1,4-pentane diamine.

10. The method according to claim 5, wherein the crystallization temperature ranges from 180° C. to 210° C. and the crystallization time ranges from 1 h to 24 h.

11. The method according to claim 5, wherein in the initial gel mixture the molar ratio of organic amine SDA to water SDA/H.sub.2O is from 1.0 to 30 .

12. The method according to claim 5, wherein the crystallization temperature ranges from 190° C. to 210° C.

13. The method according to claim 5, the crystallization time ranges from 1 h to 12 h.

14. A process for producing ethylene from ethanol using a catalyst, wherein the catalyst is obtained by calcining at least one of the SAPO-34 molecular sieves according to claim 1, at a temperature from 400 to 700° C. in air.

15. A process for producing olefins from oxygenates using a catalyst, wherein the catalyst is obtained by calcining at least one of the SAPO-34 molecular sieves according to claim 1, at a temperature from 400 to 700° C. in air.

Description

EXAMPLES 1 TO 18

(1) The amount of ingredients and the crystallization condition are shown in Table 1. The synthesis process was as follows: the aluminum sources were mixed with the organic amines (with purity of 99.5 wt %), mixing homogeneously by stirring to obtain the mixture A. The silicon sources were mixed with the phosphorus sources and deionized water and the mixtures were stirred for 30 min and added into the mixture A, then under sealed condition vigorously stirred for 30 min to obtain initial gel mixtures. The initial gel mixtures were transferred into the stainless steel synthetic kettle, then sealed and heated to crystallization temperature, crystallized dynamically for crystallization time. After finishing the crystallization, the solid product was centrifugal separated, washed, and dried at 100° C. in air to obtain raw powder samples. The samples prepared were detected by XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of the sample obtained in Example 1 were shown in Table 2. XRD results of the samples obtained in Examples 2 to 18 were similar to the sample obtained in Example 1, which showed that each corresponding peak had the same peak position and the ±10% difference of peak intensity, indicating that all the samples prepared in Examples 2 to 18 were SAPO-34 molecular sieve. The inorganic elemental analysis of the surface composition and the bulk composition of the samples were detected with XPS and XRF, respectively, and results were shown in Table 1. The organic content of the samples were detected with CHN analyzer. The chemical compositions of the raw powders of molecular sieves were obtained by normalization of CHN and XRF results, which were shown in Table 1.

(2) TABLE-US-00001 TABLE 1 The list of amount of ingredients and crystallization conditions of the molecular sieves* Crystal- lization Tem- Crystal- Exam- Aluminum Phosphorus Silicon per- lization Product Chemical ple organic amine source source source H.sub.2O ature Time Yield .sup.a A .sup.f Composition .sup.g 1 N,N,N′,N′-tetramethyl 10 g 14.7 g 4.3 g 1.0 g 190° C. 12 h 90.4% 1.37 0.15R•(Al.sub.0.49P.sub.0.40Si.sub.0.11)O.sub.2 ethylenediamine 60 g 2 N,N,N′,N′-tetramethyl- 10 g 14.7 g 4.3 g 1.0 g 190° C. 12 h 88.2% 1.30 0.13R•(Al.sub.0.50P.sub.0.40Si.sub.0.10)O.sub.2 1,3-diaminopropane 65.3 g 3 N,N,N′,N′-tetramethyl- 10 g 14.7 g 2.2 g 1.0 g 180° C. 12 h 87.6% 1.35 0.11R•(Al.sub.0.52P.sub.0.42Si.sub.0.06)O.sub.2 1,4-butanediamine 72 g 4 N,N,N′,N′-tetramethyl- 10 g 14.7 g 4.3 g 1.0 g 190° C. 12 h 88.9% 1.21 0.08R•(Al.sub.0.50P.sub.0.41Si.sub.0.09)O.sub.2 1,5-pentane diamine 79 g 5 N,N,N′,N′-tetramethyl- 10 g 14.7 g 4.3 g 1.0 g 210° C. 12 h 91.5% 1.02 0.13R•(Al.sub.0.50P.sub.0.40Si.sub.0.10)O.sub.2 1,2-diaminopropane 65.3 g 6 N,N,N′,N′-tetramethyl- 10 g 14.7 g 2.2 g 1.0 g 190° C. 12 h 88.9% 1.23 0.10R•(Al.sub.0.53P.sub.0.42Si.sub.0.05)O.sub.2 1,3-butanediamine 72 g 7 N,N,N′,N′-tetramethyl- 10 g 14.7 g 4.3 g 1.0 g 190° C. 1 h 85.2% 1.30 0.10R•(Al.sub.0.50P.sub.0.42Si.sub.0.08)O.sub.2 1,4-pentane diamine 79 g 8 N,N,N′,N′-tetramethyl 7.8 g .sup.c 14.7 g 4.3 g .sup.b 0 g 210° C. 24 h 92.1% 1.35 0.17R•(Al.sub.0.50P.sub.0.40Si.sub.0.10)O.sub.2 ethylenediamine 60 g 9 N,N,N′,N′-tetramethyl 7.8 g .sup.c 11.5 g 2.8 g .sup.d 0 g 190° C. 12 h 90.0% 1.30 0.14R•(Al.sub.0.48P.sub.0.39Si.sub.0.13)O.sub.2 ethylenediamine 60 g 10 N,N,N′,N′-tetramethyl 20 g .sup.e 14.7 g 4.3 g 0 g 190° C. 12 h 89.3% 1.20 0.13R•(Al.sub.0.50P.sub.0.40Si.sub.0.10)O.sub.2 ethylenediamine 60 g 11 N,N,N′,N′-tetramethyl 7.8 g .sup.c 14.7 g 4.3 g .sup.b 0 g 190° C. 12 h 90.3% 1.25 0.14R•(Al.sub.0.50P.sub.0.41Si.sub.0.09)O.sub.2 ethylenediamine 120 g 12 N,N,N′,N′-tetramethyl 7.8 g .sup.c 14.7 g 4.3 g .sup.b 0 g 210° C. 6 h 91.0% 1.01 0.14R•(Al.sub.0.50P.sub.0.41Si.sub.0.09)O.sub.2 ethylenediamine 120 g 13 N,N,N′,N′-tetramethyl 7.8 g .sup.c 14.7 g 4.3 g .sup.b 0 g 170° C. 48 h 87.6% 1.39 0.13R•(Al.sub.0.50P.sub.0.41Si.sub.0.09)O.sub.2 ethylenediamine 60 g 14 N,N,N′,N′-tetramethyl- 2.5 g 3.6 g 1.1 g 0 g 220° C. 0.5 h 85.3% 1.40 0.11R•(Al.sub.0.50P.sub.0.42Si.sub.0.08)O.sub.2 1,3-diaminopropane 58 g 15 N,N,N′,N′-tetramethyl- 7.8 g .sup.c 14.7 g 4.3 g .sup.b 0 g 180° C. 24 h 86.8% 1.30 0.10R•(Al.sub.0.50P.sub.0.41Si.sub.0.09)O.sub.2 1,4-butanediamine 92 g 16 N,N,N′,N′-tetramethyl- 7.8 g .sup.c 19.6 g 4.3 g .sup.d 0 g 185° C. 20 h 88.2% 1.10 0.11R•(Al.sub.0.42P.sub.0.31Si.sub.0.27)O.sub.2 1,2-diaminopropane 84 g 17 N,N,N′,N′-tetramethyl 10 g 16.4 g 4.3 g 5.3 g 210° C. 10 h 86.1% 1.35 0.14R•(Al.sub.0.50P.sub.0.43Si.sub.0.07)O.sub.2 ethylenediamine 60 g 18 N,N,N′,N′-tetramethyl 10 g 16.4 g 2.2 g 1.0 g 190° C. 12 h 89.2% 1.25 0.14R•(Al.sub.0.50P.sub.0.44Si.sub.0.06)O.sub.2 ethylenediamine 60 g *All of the organic amines were analytically pure (with the mass percent of 99.5%); the aluminum source was pseudoboehmite (with Al.sub.2O.sub.3 mass percent of 72.5%); the phosphorus source was phosphoric acid (with H.sub.3PO.sub.4 mass percent of 85%); the silicon source was silica sol (with SiO.sub.2 mass percent of 30%). .sup.a Product yield = the mass of solid product (after calcined at 600° C. to remove the template agent) × 100%/the total mass of inorganic oxides in the initial gel mixture. .sup.b the silicon source was tetraethoxysilane. .sup.c the aluminum source was γ-alumina with Al.sub.2O.sub.3 mass percent of 93%. .sup.d the silicon source was fumed silica (with SiO.sub.2 mass percent of 93%). .sup.e the aluminum source was aluminium isopropoxide. .sup.f A = Si.sub.surface/Si.sub.bulk, wherein Si.sub.surface, is the surface Si content calculated by the molar ratio of Si/(Si + Al + P) according to the result of XPS; Si.sub.bulk is the bulk Si content calculated by the bulk molar ratio of Si/(Si + Al + P) according to the result of XRF. .sup.g R represented the organic amines.

(3) TABLE-US-00002 TABLE 2 XRD result of the sample obtained in Example 1 No. 2θ d(Å) 100 × I/I.sub.0 1 9.4545 9.35457 95.82 2 12.8344 6.8977 18.65 3 13.9189 6.3626 15.31 4 15.9622 5.55246 46.38 5 17.6853 5.01515 28.06 6 18.5142 4.79245 4.10 7 18.9682 4.67876 9.28 8 20.5336 4.32546 100 9 21.9097 4.05682 4.38 10 22.3181 3.98348 1.91 11 22.9725 3.87147 3.98 12 24.0990 3.69299 31.06 13 24.8162 3.58786 43.74 14 25.8284 3.44951 14.2 15 27.5669 3.23579 6.67 16 28.0275 3.18365 5.6 17 29.4615 3.03188 3.28 18 30.5062 2.92796 28.80 20 30.9433 2.88759 14.27 21 31.4801 2.83956 18.49 22 32.2688 2.77194 1.71 23 33.3591 2.68379 2.51 24 34.4001 2.60492 6.21 25 34.8399 2.57304 1.75 26 35.8666 2.50171 3.61 27 38.3234 2.34679 1.02 28 39.5752 2.27539 2.70 29 42.6257 2.11935 3.96 30 43.2903 2.08834 2.09 31 47.5413 1.91105 4.00 32 48.6651 1.86951 3.80 33 49.0438 1.85596 3.21

EXAMPLE 19

(4) The synthesis process, the amount of ingredients and the crystallization condition were the same as Example 1, except that the organic amine template was changed to 30 g of N,N,N′,N′-tetramethyl ethylenediamine and 30 g of N,N,N′,N′-tetramethyl-1,3-diaminopropan. After the crystallization, the solid product was centrifuged for separation, washed and dried at 100° C. in air. 19.4 g of the raw powder sample was obtained (with mass loss of 15% after calcined at 600° C.) and the product yield was 88.5%. The sample was detected with XRD. XRD data of sample were similar to the sample obtained in Example 1, which showed that each corresponding peak had the same peak position and the ±10% difference of peak intensity, indicating the sample prepared was SAPO-34 molecular sieve. The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, showing the ratio of Si.sub.surface/Si.sub.bulk was 1.25.

EXAMPLE 20

(5) The synthesis process, the amount of ingredients and the crystallization condition were the same as Example 1, except that the organic amine template agent was changed to 40 g of N,N,N′,N′-tetramethyl-1,3-diaminopropan and 20 g of N,N,N′,N′-tetramethyl-1,2-diaminopropan. After the crystallization, the solid product was centrifuged for separation, washed and dried at 100° C. in air. 20.1 g of the raw powder sample was obtained (with mass loss of 16.5% after calcined at 600° C.) and the product yield was 90.1%. The sample was detected with XRD. XRD data of sample were similar to the sample obtained in Example 1, which showed that each corresponding peak had the same peak position and the ±10% difference of peak intensity, indicating the sample prepared was SAPO-34 molecular sieve. The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, showing the ratio of Si.sub.surface/Si.sub.bulk was 1.15.

EXAMPLE 21

(6) 3 g of the samples obtained in Examples 1 to 3 respectively, were put into plastic beakers, adding 3 ml of 40% hydrofluoric acid to dissolve the framework of molecular sieve, and then adding 15 ml of tetrachloromethane to dissolve the organic compounds. The organic compounds were analyzed with GC-MS. The results indicated that the organic compounds in the samples obtained in Examples 1 to 3 were N,N,N′,N′-tetramethyl ethylenediamine, N,N,N′,N′-tetramethyl-1,3-diaminopropan, and N,N,N′,N′-tetramethyl butanediamine, respectively.

EXAMPLE 22

(7) The sample obtained in Example 1 (with the rhombohedral morphology and the crystal size from 1 μm to 5 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.18 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.28.

(8) The sample obtained in Example 2 (with the rhombohedral morphology and the crystal size from 1 μm to 5 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.17 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.25.

(9) The sample obtained in Example 3 (with the rhombohedral morphology and the crystal size from 1 μm to 5 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.10 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.16.

(10) The sample obtained in Example 18 (with the rhombohedral morphology and the crystal size from 1 μm to 5 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.09 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.14.

EXAMPLE 23

Recycle of Organic Amine Solution

(11) The synthesis process, the amount of ingredients and the crystallization condition were the same as Example 1. The stainless steel synthetic kettle was kept at 190° C. for 12 h, taken out from the oven and cooled rapidly with water. Then, the stainless steel synthetic kettle was open, from which the organic amine was separated in fume cupboard (Due to the low water amount in the synthesis system, after finishing the crystallization, under quiescent condition the synthesis system automatically separated into two phases which were the organic amine phase in upper layer and the gel-like substance phase with low fluidity in under layer. 57.6 g of the organic amine solution was collected and analyzed with gas chromatography and combination of gas chromatography and mass spectrometry (capillary column SE-30). The result indicated there were 1.5 g of water and 56.1 g of N,N,N′,N′-tetramethyl ethylenediamine.

(12) The organic amine solution collected was recycled in the preparation of molecular sieve (adding a few fresh N,N,N′,N′-tetramethyl ethylenediamine), and the synthesis process, the amount of ingredients and the crystallization condition were the same as Example 1. After the crystallization, the solid product was centrifuged for separation, washed and dried at 100° C. in air. 20.3 g of the raw powder sample was obtained (with mass loss of 16.1% after calcined at 600° C.) and the product yield was 91.4%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of the sample were similar to Table 2, which showed that each corresponding peak had the same peak position and peak shape, and the intensity of the strongest peak was about 105% of the sample obtained in Example 1.

COMPARATIVE EXAMPLE 1

(13) 16.4 g of phosphoric acid (85 wt %), 17.6 g of water and 10 g of pseudo-boehmite (72.5 wt %) were added into the synthetic kettle in sequence, stirred for 30 min to obtain a homogeneous mixture. 8.3 g of N,N,N′,N′-tetramethyl ethylenediamine, 2.3 g of tetraethoxysilane, 1.4 g of HF solution (50%) and 11.2 g of deionized water were homogeneously mixed by stirring, and added to the homogeneous mixture obtained above. After stirring for 2 h under sealed condition, an initial gel mixture was obtained. The initial gel mixture was transferred into the stainless steel synthetic kettle, then heated to 150° C., dynamically crystallized for 12 h. The stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain a raw powder sample. 8.5 g of the raw powder sample was obtained (with mass loss of 16.4% after calcined at 600° C.) and the product yield was 39.5%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of sample were similar to Table 2, which showed that each corresponding peak had the same peak position, and the intensity of each corresponding peak was less than the sample obtained in Example 1, and the intensity of the strongest peak was about 70% of the sample obtained in Example 1. The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, respectively, showing that the bulk composition was Al.sub.0.50P.sub.0.44Si.sub.0.06 and the ratio of Si.sub.surface/Si.sub.bulk was 2.0.

(14) The sample (with the rhombohedral morphology and the crystal size from 1 μm to 3 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.08 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.22.

COMPARATIVE EXAMPLE 2

(15) 16.4 g of phosphoric acid (85 wt %), 17.6 g of water and 10 g of pseudo-boehmite (72.5 wt %) were added into the synthetic kettle in sequence, stirred for 30 min to obtain a homogeneous mixture. 8.3 g of N,N,N′,N′-tetramethyl ethylenediamine, 4.6 g of tetraethoxysilane, 1.4 g of HF solution (50%) and 11.2 g of deionized water were homogeneously mixed by stirring, and added to the homogeneous mixture obtained above. After stirring for 2 h under sealed condition, an initial gel mixture was obtained. The initial gel mixture was transferred into the stainless steel synthetic kettle, then heated to 190° C., dynamically crystallized for 12 h. The stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain a raw powder sample. 16.1 g of the raw powder sample was obtained (with mass loss of 16.0% after calcined at 600° C.) and the product yield was 75.1%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of sample were similar to Table 2, which showed that each corresponding peak had the same peak position, and the intensity of each corresponding peak was less than the sample obtained in Example 1, and the intensity of the strongest peak was about 80% of the sample obtained in Example 1. The elemental analysis of the surface composition and the bulk composition of the samples were detected with XPS and XRF, respectively, showing that the bulk composition was Al.sub.0.49P.sub.0.41Si.sub.0.10 and the ratio of Si.sub.surface/Si.sub.bulk was 2.15.

(16) The sample (with the rhombohedral morphology and the crystal size from 1 μm to 3 μm according to the SEM photo) was immobilized using epoxy resin and polished at a glazing machine. The composition analysis from the core to the shell was detected with SEM-EDX linear scanning of the crystal section near the crystal core. The result indicated that the atomic ratio of Si/Al near the core area of the crystal was about 0.15 and the atomic ratio of Si/Al near the surface area of the crystal was about 0.41.

COMPARATIVE EXAMPLE 3

(17) 16.4 g of phosphoric acid (85 wt %), 17.6 g of water and 10 g of pseudo-boehmite (72.5 wt %) were added into the synthetic kettle in sequence, stirred for 30 min to obtain a homogeneous mixture. 12.5 g of N,N,N′,N′-tetramethyl ethylenediamine, 2.3 g of tetraethoxysilane and 11.2 g of deionized water were homogeneously mixed by stirring, and added to the homogeneous mixture obtained above. After stirring for 2 h under sealed condition, an initial gel mixture was obtained. The initial gel mixture was transferred into the stainless steel synthetic kettle, then heated to 190° C., dynamically crystallized for 12 h. The stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain the sample which was not SAPO-34 molecular sieve according to the result of XRD analysis.

COMPARATIVE EXAMPLE 4 (Change of the Order of Ingredients Addation)

(18) The amount of ingredients and the crystallization condition were the same as Example 1, except that the order of ingredients addation was changed. The process of ingredients addation was as follows: the aluminum source and the organic amine were mixed homogeneously by stirring, and then the phosphorus source was added, stirred for 20 min under sealed condition, and then the silicon source and deionized water were added, stirred vigorously for 30 min under sealed condition to obtain a homogenous gel mixture. The gel mixture was transferred into the stainless steel synthetic kettle, then heated to 190° C., dynamically crystallized for 12 h. After finishing the crystallization, the stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain a raw powder sample. 18.5 g of the raw powder sample was obtained (with mass loss of 15.6% after calcined at 600° C.) and the product yield was 83.7%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of sample were similar to Table 2, which showed that each corresponding peak had the same peak position, and the intensity of each corresponding peak was less than the sample obtained in Example 1, and the intensity of the strongest peak was about 85% of the sample obtained in Example 1. The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, respectively, showing that the ratio of Si.sub.surface/Si.sub.bulk was 1.69.

COMPARATIVE EXAMPLE 5 (Change of the Order of Ingredients Addation)

(19) The amount of ingredients and the crystallization condition were the same as Example 4, except that the order of ingredients addation was changed. The process of ingredients addation was as follows: the aluminum source and the organic amine were mixed homogeneously by stirring, and then the phosphorus source was added, stirred for 20 min under sealed condition, and then the silicon source and deionized water were added, stirred vigorously for 30 min under sealed condition to obtain a homogenous gel mixture. The gel mixture was transferred into the stainless steel synthetic kettle, then heated to 190° C., dynamically crystallized for 12 h. After finishing the crystallization, the stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain a raw powder sample. 17.9 g of the raw powder sample was obtained (with mass loss of 15.1% after calcined at 600° C.) and the product yield was 81.6%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of sample were similar to Table 2, which showed that each corresponding peak had the same peak position and the slightly different peak intensity (<±10%). The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, respectively, showing that the ratio of Si.sub.surface/Si.sub.bulk was 1.79.

COMPARATIVE EXAMPLE 6 (Change of the Order of Ingredients Addation)

(20) The amount of ingredients and the crystallization condition were the same as Example 4, except that the order of ingredients addation was changed, and a small quantity of ethanol was added into the synthesis system, and an ageing process was used. The process of ingredients addation was as follows: the aluminum source and the organic amine were mixed homogeneously by stirring, and then the silicon source was added, stirred for 20 min under sealed condition, and then the phosphorus source, 1.0 g of ethanol and deionized water were added, stirred vigorously for 30 min under sealed condition, and then the mixture was aged by being stirred for 12 h at 40° C. to obtain a homogenous gel mixture. The gel mixture was transferred into the stainless steel synthetic kettle, then heated to 190° C., dynamically crystallized for 12 h. After finishing the crystallization, the stainless steel synthetic kettle was taken out from the oven and cooled. The solid product was centrifugal separated, washed to neutral using deionized water and dried at 100° C. in air to obtain a raw powder sample. 16.9 g of the raw powder sample was obtained (with mass loss of 14.7% after calcined at 600° C.) and the product yield was 77.4%. The sample was detected with XRD, indicating that the sample prepared was SAPO-34 molecular sieve. XRD data of sample were similar to Table 2, which showed that each corresponding peak had the same peak position and the slightly different peak intensity (≦±10%). The elemental analysis of the surface composition and the bulk composition of the sample were detected with XPS and XRF, respectively, showing that the ratio of Si.sub.surface/Si.sub.bulk was 2.15.

EXAMPLE 24

(21) The samples obtained in Example 18 and Comparative Example 1 were calcined at 600° C. for 4 hours in air, then pressed, crushed and sieved to 20-40 mesh. 1.0 g of this sample was weighted and loaded into a fixed bed reactor to carry out a methanol to olefins reaction evaluation. The sample was activated at 550° C. for 1 hour in nitrogen gas and reduced to 470° C. to perform a reaction. Methanol was carried by nitrogen gas with a flow rate of 40 ml/min and the Weight Hour Space Velocity of the methanol was 2.0 h.sup.−1. The reaction products were analyzed by an on-line gas chromatograph (Varian3800, FID detector, capillary column was PoraPLOT Q-HT). The results were shown in Table 3.

(22) TABLE-US-00003 TABLE 3 The reaction result of methanol to olefins on the sample Life Selectivity (mass %) * Sample (min) CH.sub.4 C.sub.2H.sub.4 C.sub.2H.sub.6 C.sub.3H.sub.6 C.sub.3H.sub.8 C.sub.4.sup.+ C.sub.5.sup.+ C.sub.2H.sub.4 + C.sub.3H.sub.6 Example 18 200 1.8 44.9 0.8 40.0 1.4 9.1 2.0 84.9 Comparative 120 2.3 43.8 1.0 38.0 2.0 10.8 2.1 81.8 Example 1 * The highest (ethylene + propylene) selectivity when methanol conversion was 100%.

EXAMPLE 25

(23) The samples obtained in Example 1 and Comparative Example 2 were calcined at 600° C. for 4 hours in air, then pressed, crushed and sieved to 20-40 mesh. 1.0 g of this sample was weighted and loaded into a fixed bed reactor to carry out ethanol dehydration reaction evaluation. The sample was activated at 550° C. for 1 hour in nitrogen gas and reduced to 260° C. to perform a reaction. Ethanol was carried by nitrogen gas with a flow rate of 40 ml/min and the Weight Hour Space Velocity of the ethanol was 2.0 h.sup.−1. The reaction products were analyzed by an on-line gas chromatograph (Varian3800, FID detector, capillary column was PoraPLOT Q-HT). The results indicated that on the sample obtained in Example 1, ethanol conversion was 95% and selectivity for ethylene was 99.5%. On the sample obtained in Comparative Example 2, ethanol conversion was 70% and selectivity for ethylene was 90%, and the product containing the hydrocarbon by-products, such as methane, and the like.

EXAMPLE 26

(24) The sample obtained in Example 1 was used for propylene adsorbent. The adsorption isotherm of the sample was detected by ASAP2020 of US Micromeritics. The adsorbed gases were propylene (99.99%), propane (99.99%). In order to avoid the influence of physical absorb water in molecular sieve, the sample was calcined at 600° C. for 4 hours in air before the adsorption isotherm detection. Then the sample was heated to 350° C. at the rate of 1° C./min in an extremely low vacuum (5×10.sup.−3 mmHg) and kept for 8 hours. The adsorbent temperature was 298K and controlled by thermostatic water bath (accuracy: ±0.05° C.). The result indicated that the adsorption capacities of propylene and propane were 1.95 and 1.0 mmol/g (at 101 kPa) respectively. The adsorption selectivity was propylene/propane=1.95.

(25) The sample after the adsorption was vacuumed at room temperature for 30 min by ASAP2020, and then detected again for the adsorption isotherm. The adsorption capacities of propylene and propane were 2.00 and 1.05 mmol/g (at 101 kPa) respectively. The result indicated that the sample had good regeneration performance which can be regenerated under very mild conditions.