Theoretical Studies on the Structure and Adsorption Properties of Isomorphously Substituted FAU Zeolite†

doi:10.7503/cjcu20160449

Abstract

Abstract:

The adsorption of oxygenated chemicals(methanol, dimethyl ether, propionaldehyde) in channel structure of FAU type zeolite β cage, as well as the modification mechanism of Zn/Ca isomorphous substitution were investigated by means of density functional theory(DFT) calculations. The results indicate that methanol, dimethyl ether and propionaldehyde can chemisorb at the top site of the Al atom, while they can barely adsorb at the Si atom. For Zn-/Ca-doped β cage, Al³⁺ was substituted by Zn²⁺/Ca²⁺, a hole was formed on the adjacent Si atom due to the loss of one electron, therefore the adsorption of methanol, dimethyl ether and propionaldehyde were enhanced. However, the dopant atom itself doesn’t serve as adsorption site.

Key words: Density functional theory(DFT), FAU zeolite, Doping, Adsorption

TrendMD:

YANG Bingxing, YE Liping, GU Huijie, XU Huasheng, LUO Yong, LI Huiying. Theoretical Studies on the Structure and Adsorption Properties of Isomorphously Substituted FAU Zeolite^†[J]. Chem. J. Chinese Universities, 2016, 37(11): 2018.

Figures/Tables 11

Fig.1 Calculated structure of FAU zeolite(A), β cage(B) and the isosurface(50 e/nm3) of calculated spin charge densities(C) The Si, Al and O atoms are represented by balls in yellow, green and red, respectively.

Fig.2 Calculated structures of Al(A, B), Si(C, D), Al'(E, F) and Si'(G, H) atoms substituted by Zn(A, C, E, G) and Ca(B, D, F, H) atoms The Zn and Ca atoms are represented by balls in purple and blue, respectively.

Table 1 Calculated lengths of Al/Si/Zn/Ca-O bonds, rRMS of different substituted atoms and substitution energies of Zn/Ca doped β cage

Defect	Substitution atom	d(Al/Si/Zn/Ca—O)/nm	r_RMS/nm	E_sub/eV	Figure
Clean	Al	0.1701, 0.1698, 0.1701			1(B)
	Si	0.1641, 0.1647, 0.1643			1(B)
	Al'	0.1685, 0.1699, 0.1696			1(B)
	Si'	0.1646, 0.1629, 0.1641			1(B)
Zn doped	Al	0.1842, 0.1999, 0.1863	0.0213	4.89	2(A)
	Si	0.1888, 0.1860, 0.1929	0.0250	5.67	2(C)
	Al'	0.1975, 0.1852, 0.1859	0.0211	5.05	2(E)
	Si'	0.1900, 0.1833, 0.1909	0.0244	5.72	2(G)
Ca doped	Al	0.2133, 0.2112, 0.2254	0.0470	0.92	2(B)
	Si	0.2147, 0.2129, 0.2169	0.0505	1.86	2(D)
	Al'	0.2103, 0.2141, 0.2254	0.0477	1.00	2(F)
	Si'	0.2181, 0.2096, 0.2162	0.0509	1.90	2(H)

Fig.3 Calculated structures of methanol(A), dimethyl ether(B) and propionaldehyde adsorption(C) at Al site of β cage and isosurfaces(6 e/nm3)(D—F) of charge redistribution of (A—C), respectively The yellow and blue isosurfaces denote charge gain and miss, repectively. The C and H atoms are represented by balls in black and white, respectively.

Table 2 Calculated lengths of Al/Si—O bonds, rRMS of methanol, dimethyl ether and propionaldehyde adsorption at Al/Si site of β cage

Defect	Adsorption molecular	Before adsorption Al/Si—O/nm	After adsorption Al/Si—O/nm	r_RMS/nm	Figure
Clean	Ethanol	0.1701, 0.1698, 0.1701	0.1726, 0.1736, 0.1718	0.0028	3(A)
	Dimethylether		0.1727, 0.1728, 0.1707	0.0023	3(B)
	Propionaldehyde		0.1733, 0.1737, 0.1727	0.0033	3(C)
Zn doped	Ethanol	0.1550, 0.1590, 0.1589	0.1614, 0.1618, 0.1640	0.005	4(G)
	Dimethyl ether		0.1592, 0.1612, 0.1631	0.0037	4(H)
	Propionaldehyde		0.1619, 0.1625, 0.1665	0.0063	4(I)
Ca doped	Ethanol	0.1595, 0.1602, 0.1552	0.1620, 0.1622, 0.1557	0.0019	4(D)
	Dimethyl ether		0.1625, 0.1626, 0.1559	0.0023	4(E)
	Propionaldehyde		0.1629, 0.1630, 0.1579	0.003	4(F)

Table 3 Calculated adsorption energies of ethanol, dimethyl ether and propionaldehyde at Al and Si sites

Site	E_ads/eV
Site	Ethanol	Dimethyl ether	Propionaldehyde
Al	0.83	0.97	0.76
Si	0.54

Fig.4 Calculated structures of ethanol(A, D, G), dimethyl ether(B, E, H) and propionaldehyde(C, F, I) adsorption in Ca-doped(D—F) and Zn-doped(G—I) β cageThe insets denote the isosurfaces(6 e/nm3) of charge redistribution.

Site	E_ads/eV
Site	Ethanol	Dimethyl ether	Propionaldehyde
Zn
Si(Zn)	2.28	1.08	3.93
Ca	0.45	0.25	0.15
Si(Ca)	0.77	0.68	2.29

Fig.5 Local structures of clean(A), Ca-doped(B), Zn-doped(C) β cage

Table 5 Calculated Bader charge of different Si sites

Si number	Charge/e
Si number	Clean	Ca-doped	Zn-doped
1	0.83	0.76	0.00
2	0.82	0.00	0.76
3	0.82	0.78	0.78

References 34

[1]	夏思奇, 王鹏飞, 徐华胜, 胡杰, 吕待清. 精细化工, 2014, 31( 12), 1476- 1479
	Xia S., Q. , Wang P., F. , Xu H., S. , Hu, J. , Lv D., Q. , Fine Chem., 2014, 31( 12), 1476- 1479 (
[2]	Luiz K., C. , Juliana J., R. , Jose R., Z. , Geraldo, N. , Cristiano M., B. , Romulo S., A. , Carlos E., F. , Powder Techn., 2012, 229, 1- 6
[3]	Sheng X., L. , Zhou Y., M. , Duan Y., Z. , Xue M., W. , J. Porous Mat., 2011, 18( 6), 677- 683
[4]	Yan, B. , Mahmood, A. , Liang, Y. , Xu B., Q. , Catal. Today, 2016, 269( 1), 65- 73
[5]	张艳青, 郑华艳, 章日光, 李忠, 王宝俊, 赵秋勇. 高等学校化学学报, 2015, 36( 10), 1945- 1953
	Zhang Y., Q. , Zheng H., Y. , Zhang R., G. , Li, Z. , Wang B., J. , Zhao Q., Y. , Chem. J. Chinese Universities, 2015, 36( 10), 1945- 1953 (
[6]	Popovych N., O. , Kyriienko P., I. , Soloviev S., O. , Orlyk S., M. , Dzwigaj, S. , Microp. Mesop. Mater., 2016, 226( 15), 10- 18
[7]	Najar, H. , Zina M., S. , Ghorbel, A. , React Kinet. Mech. Catal., 2010, 100( 2), 385- 398
[8]	Lim W., T. , Seo S., M. , Lee O., S. , Wang L., Z. , Lu G., Q. , J. Incl. Phenom. Macrocycl. Chem., 2010, 67( 3), 261- 269
[9]	Li H., C. , Zhou D., H. , Tian D., X. , Shi, C. , Muller, U. , Feyen, M. , Yilmaz, B. , Gies, H. , Xiao F., S. , de Vos, D. , ChemPhysChem, 2014, 15( 8), 1700- 1707
[10]	Meeprasert, J. , Jungsuttiwong, S. , Namuangruk, S. , Microp. Mesop. Mater., 2013, 175, 99- 106
[11]	Ma, J. , Qiang L., S. , Wang J., F. , Tang X., B. , Tang D., Y. , J. Porous Mat., 2011, 18( 5), 607- 614
[12]	Wang, Q. , Wu Y., J. , Wang, J. , Lin, X. , Acta Phys. Chim. Sin., 2012, 28( 9), 2108- 2114
[13]	Hernandez-Morales, V. , Nava, R. , Acosta-Silva Y., J. , Pawelec, B. , Microp. Mesop. Mater., 2012, 160, 133- 142
[14]	Tao, L. , Li G., S. , Yin S., F. , Au C., T. , React Kinet. Mech. Catal., 2011, 103( 1), 191- 207
[15]	张瑞珍, 王翠, 邢普, 温少波, 王剑, 赵亮富, 李玉平. 高等学校化学学报, 2015, 36( 4), 725- 732
	Zhang R., Z. , Wang, C. , Xing, P. , Wen S., B. , Wang, J. , Zhao L., F. , Li Y., P. , Chem. J. Chinese Universities, 2015, 36( 4), 725- 732 (
[16]	Su X., F. , Wang G., L. , Bai X., F. , Wu, W. , Xiao L., F. , Fang Y., J. , Zhang J., W. , Chem. Eng. J., 2016, 293, 365- 375
[17]	Jin Y., J. , Asaoka, S. , Zhang S., D. , Li, P. , Zhao S., L. , Fuel Proc. Techn., 2013, 115, 34- 41
[18]	Omata, K. , Yamazaki, Y. , Watanabe, Y. , Kodama, K. , Yamada, M. , Ind. Eng. Chem. Res., 2009, 48( 13), 6256- 6261
[19]	王瑜, 吴伟, 李程, 杨杰, 周亚静. 石油学报, 2011, 27( 5), 682- 686
	Wang, Y. , Wu, W. , Li, C. , Yang, J. , Zhou Y., J. , Acta Petrolei Sin., 2011, 27( 5), 682- 686 (
[20]	Geraldo, E. , Stevie H., L. , Ana C., R. , Antonio S., A. , Valter, J. , J. Mater. Sci., 2010, 45( 4), 1117- 1122
[21]	Shamzhy, M. , Shvets, O. , Opanasenko, M. , Cejka, J. , J. Mater. Chem., 2012, 22( 31), 15793- 15803
[22]	Ahmed, S. , J. Porous Mat., 2012, 19( 1), 111- 117
[23]	Wang J., H. , Xie J., Y. , Zhou, Y. , Wang, J. , Microp. Mesop. Mater., 2013, 171, 87- 93
[24]	Yang C., G. , Qiu M., H. , Hu S., W. , Chen X., Q. , Zeng G., F. , Liu Z., Y. , Sun Y., H. , Microp. Mesop. Mater., 2016, 231, 110- 116
[25]	Zhou, Y. , Jin Y., H. , Wang, M. , Zhang, W. , Xie J., Y. , Gu, J. , Wen H., M. , Wang, J. , Peng L., M. , Chem. Eur. J., 2015, 21( 43), 15412- 15420
[26]	Kang L., H. , Zhang, T. , Liu Z., M. , Han K., L. , J. Phys. Chem. C, 2008, 112( 14), 5526- 5532
[27]	Kresse, G. , Furthmü, ller J. , Comp. Mater. Sci., 1996, 6, 15- 50
[28]	Kresse, G. , Furthmü, ller J. , Phys. Rev. B, 1996, 54( 16), 11169- 11186
[29]	Perdew J., P. , Burke, K. , Ernzerhof, M. , Phys. Rev. Lett., 1996, 77( 18), 3865- 3868
[30]	Kresse, G. , Joubert, D. , Phys. Rev. B, 1999, 59( 3), 1758- 1775
[31]	Blö, chl P. E. , Phys. Rev. B, 1994, 50( 24), 17953- 17979
[32]	Monkhorst H., J. , Pack J., D. , Phys. Rev. B, 1976, 13, 5188- 5192
[33]	Wang H., F. , Gong X., Q. , Guo Y., L. , Guo, Y. , Lu G., Z. , Hu, P. , J. Phys. Chem. C, 2009, 113( 23), 10229- 10232
[34]	Li H., Y. , Wang H., F. , Gong X., Q. , Guo Y., L. , Guo, Y. , Lu G., Z. , Hu, P. , Phys. Rev. B, 2009, 79( 19), 193401- 193405