Shape-selective methylation of naphthalene over SAPO-11, SAPO-5 and mordenite molecular sieves were carried out in a fixed-bed flow reactor under atmospheric pressure. Methanol and mesitylene were used as methylation and solvent agents. The experiment results showed that SAPO-11 exhibited higher stability, higher selectivity of 2,6-dimethylnaphthalene (2,6-DMN) and higher 2,6-/2,7-DMN ratio than SAPO-5 and mordenite molecular sieves. The catalytic performances for the methylation of naphthalene were mainly related to the pore structure of the catalysts. The comparison of the spent SAPO- 11 with fresh SAPO-11 suggested that structure collapse of the SAPO-11 by dealumination was occurred during the methylation of naphthalene with methanol, which may have been caused by high temperature steam from water produced in the reaction or by high temperature methanol vapor.
KINETICS AND CATALYSIS; REACTION ENGINEERING; AND MATERIALS SCIENCE • Braz. J. Chem. Eng. 34
(1)
• Jan-Mar 2017 • https://doi.org/10.1590/0104-6632.20170341s20160120 linkcopiar
SYNTHESIS OF 2,6-DIMETHYLNAPHTHALENE OVER SAPO-11, SAPO-5 AND MORDENITE MOLECULAR SIEVES
Autoria
person Xiaoxiao Wang *
schoolTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368Taiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368
person Zhenmin Liu
schoolTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368Taiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368
person Xianxian Wei
schoolTaiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cnTaiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cn
person Fang Guo
person Peng Li
schoolTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368Taiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368
person Shaoqing Guo *
schoolTaiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cnTaiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cn
person*To whom correspondence should be addressed
SCIMAGO INSTITUTIONS RANKINGS
Taiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368Taiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, School of Chemical and Biological Engineering, Taiyuan 030021, PR China. Phone: + (86) 03512307368
Taiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cnTaiyuan University of Science and TechnologyChinaChinaTaiyuan University of Science and Technology, College of Environment and Safety, Taiyuan 030024, PR China. Phone: +(86) 03512307368 *E-mail: guosq@sxicc.ac.cn
Figuras | Tabelas | Fórmulas
imageFigure 1 XRD Patterns of SAPO-11 sample and SAPO-5 sample. open_in_new
imageFigure 2 SEM images of SAPO-11 sample (a) and SAPO-5 sample (b). open_in_new
imageFigure 3 NH3-TPD profiles of samples SAPO-5 (a), SAPO-11(b), Mordenite (c). open_in_new
imageFigure 4 The conversion of naphthalene comparison of different molecular sieves. open_in_new
imageFigure 5 Effect of different molecular sieves on molar ratio of 2, 6- to 2, 7-DMN open_in_new
imageFigure 6 The 2,6-DMN yield over the investigated molecular sieves. open_in_new
imageFigure 7: XRD patterns of the fresh SAPO-11 (a) and the spent SAPO-11(b). open_in_new
imageFigure 8 SEM images of the fresh and the spent SAPO-11. open_in_new
imageFigure 9 N2 adsorption-desorption isotherms of the fresh (a) and the spent SAPO-11(b). open_in_new
imageFigure 10 Pore size distributions of the fresh and the spent SAPO-11. open_in_new
imageFigure 11 TG curve of weight loss of the fresh SAPO-11. open_in_new
imageFigure 12 TG curve of weight loss of the spent SAPO-11. open_in_new
imageFigure 13 NH3-TPD results of the fresh and the spent SAPO-11. open_in_new
table_chartTable 1
Physicochemical properties of different molecular sieves.
table_chartTable 2
Acidity values of different molecular sieves.
| Sample | weak acid sites | Medium strong acid sites | strong acid sites | ||||
|---|---|---|---|---|---|---|---|
| Peak temperature / ºC | The acid amount/ (mmol g-1) | Peak temperature/ ºC | The acid amount/ (mmol g-1) | Peak temperature/ ºC | The acid amount/ (mmol g-1) | The total acid amount/ (mmol g-1) | |
| SAPO-5 | 210 | 0.55 | 0 | 0 | 0 | 0 | 0.55 |
| SAPO-11 | 210 | 0.47 | 288 | 0.28 | 0 | 0 | 0.76 |
| Mordenite | 213 | 0.68 | 0 | 0 | 516 | 11.2 | 11.88 |
table_chartTable 3
Bronsted acid sites and Lewis acid sites of molecular sieves spectra of absorbed pyridinea.
| Samples | Bronsted acid sites | Lewis acid sites | Total acid sites | |||
|---|---|---|---|---|---|---|
| 200 (ºC) | 400 (ºC) | 200 (ºC) | 400 (ºC) | 200 (ºC) | 400 (ºC) | |
| Mordenite | 23.25 | 18.12 | 10.2 | 6.56 | 33.45 | 24.68 |
| SAPO-11 | 11.76 | 11.46 | 2.20 | 0.58 | 13.96 | 12.04 |
| SAPO-5 | 11.2 | 10.2 | 1.90 | 0.43 | 13.1 | 10.63 |
table_chartTable 4
Comparison of catalytic performance of different molecular sieves in the methylation of naphthalene.
| Mordenite | SAPO-11 | SAPO-5 | |
|---|---|---|---|
| Naphthalene onv(%) | 60.2 | 55.2 | 26.1 |
| Product distribution (mol%) | |||
| EN | 3.50 | 0 | 1.07 |
| MN | 40.1 | 43.7 | 51.8 |
| DMN | 36.3 | 52.8 | 39.7 |
| TMN | 20.1 | 3.5 | 7.43 |
| DMN distribution (mol%) | |||
| 2,6-DMN | 22.6 | 23.9 | 21.30 |
| 2,7-DMN | 20.5 | 16.4 | 21.4 |
| 1,7-DMN | 20.0 | 13.4 | 20.1 |
| 1,3-DMN | 6.0 | 7.93 | 6.81 |
| 1,6-DMN | 18.1 | 12.5 | 15.89 |
| 2,3-DMN | 5.6 | 8.33 | 2.90 |
| 1,4-DMN | 2.4 | 4.51 | 1.80 |
| 1,5-DMN | 1.7 | 9.43 | 9.8 |
| 1,2-DMN | 3.1 | 3.60 | 0 |
| 1,8-DMN | 0 | 0 | 0 |
| 2,6-/2,7-DMN | 1.10 | 1.46 | 0.99 |
| 2,6-DMN yield | 4.94 | 6.96 | 2.73 |
-
Reaction conditions: Temperature = 350 ºC, Pressure = 0.1MPa, WHSV= 0.19h-1, naphthalene:methanol:mesitylene = 1:5:3.5 (molar ratio), TOS = 1h. Product distribution includes the corresponding molar percentages of EN (ethylnaphthalene), MN (methylnaphthalene), DMN (dimethylnaphthalene) and TMN (trimethylnaphthalene) in the total product mixture.
table_chartTable 5
ICP results of the fresh and the spent SAPO-11.
| Sample | n(SiO2/Al2O3) |
|---|---|
| fresh SAPO-11 | 0.53 |
| spent SAPO-11 | 0.68 |
table_chartTable 6
BET Surface area and pore volume of the fresh and the spent SAPO-11.
| Sample | BET Surface area / (m2 g-1) | Pore volume / (cm3 g-1) |
|---|---|---|
| fresh SAPO-11 | 215 | 0.145 |
| spent SAPO-11 | 121 | 0.091 |
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