Methanol diffusion in zeolite HY: a combined quasielastic neutron scattering and molecular dynamics simulation study

被引:37
作者
O'Malley, Alexander J. [1 ,2 ]
Sakai, Victoria Garcia [3 ]
Silverwood, Ian P. [3 ]
Dimitratos, Nikolaos [4 ]
Parker, Stewart F. [2 ,3 ]
Catlow, C. Richard A. [1 ,2 ,4 ]
机构
[1] UCL, Dept Chem, Mat Chem, Third Floor,Kathleen Lonsdale Bldg,Gower St, London WC1E 6BT, England
[2] Rutherford Appleton Lab, UK Catalysis Hub, Res Complex Harwell, Didcot OX11 0FA, Oxon, England
[3] STFC Rutherford Appleton Lab, ISIS Facil, Didcot OX11 0QX, Oxon, England
[4] Cardiff Univ, Sch Chem, Cardiff Catalysis Inst, Cardiff CF10 3AT, S Glam, Wales
基金
英国工程与自然科学研究理事会;
关键词
SIDE-CHAIN ALKYLATION; SODIUM-Y-ZEOLITE; MN-ZN CATALYSTS; ZSM-5; ZEOLITE; FORCE-FIELD; N-ALKANES; CONCENTRATION-DEPENDENCE; COMPUTER-SIMULATION; FAUJASITE SYSTEMS; SELF-DIFFUSIVITY;
D O I
10.1039/c6cp01151a
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The diffusion of methanol in zeolite HY is studied using tandem quasielastic neutron scattering (QENS) experiments and molecular dynamics (MD) simulations at 300-400 K. The experimental diffusion coefficients were measured in the range 2-5 x 10(-10) m(2) s(-1) and simulated diffusion coefficients calculated in the range of 1.6-3.2 x 10(-9) m(2) s(-1). Activation energies were measured as 8.8 and 6.9 kJ mol(-1) using QENS and MD respectively. Differences may be attributed predominantly to the experimental use of a dealuminated HY sample, containing significant defects such as strongly adsorbing silanol nests, compared to a perfect simulated crystal containing only evenly distributed Bronsted acid sites. Experimental and simulated diffusivities measured in this study are lower than those obtained from those previously calculated in siliceous faujasite, due to methanol H-bonding to Bronsted acid sites as observed in the MD simulations. However, both experimental and simulated diffusivities were significantly higher than those obtained in NaX, due to the higher concentration of extraframe work cations present in the previously studied structures.
引用
收藏
页码:17294 / 17302
页数:9
相关论文
共 83 条
[1]   A MOLECULAR MECHANICS FORCE-FIELD (MM3) FOR ALCOHOLS AND ETHERS [J].
ALLINGER, NL ;
RAHMAN, M ;
LII, JH .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1990, 112 (23) :8293-8307
[2]  
[Anonymous], 2008, HDB HETEROGENEOUS CA
[3]   TRANSPORT-THEORY FOR CATIONIC ZEOLITES - DIFFUSION OF BENZENE IN NA-Y [J].
AUERBACH, SM ;
HENSON, NJ ;
CHEETHAM, AK ;
METIU, HI .
JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (26) :10600-10608
[4]   Diffusion in zeolites via cage-to-cage kinetics: Modeling benzene diffusion in Na-Y [J].
Auerbach, SM ;
Metiu, HI .
JOURNAL OF CHEMICAL PHYSICS, 1996, 105 (09) :3753-3760
[5]   DAVE: A Comprehensive Software Suite for the Reduction, Visualization, and Analysis of Low Energy Neutron Spectroscopic Data [J].
Azuah, Richard Tumanjong ;
Kneller, Larry R. ;
Qiu, Yiming ;
Tregenna-Piggott, Philip L. W. ;
Brown, Craig M. ;
Copley, John R. D. ;
Dimeo, Robert M. .
JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, 2009, 114 (06) :341-358
[6]   MOLECULAR-DYNAMICS WITH COUPLING TO AN EXTERNAL BATH [J].
BERENDSEN, HJC ;
POSTMA, JPM ;
VANGUNSTEREN, WF ;
DINOLA, A ;
HAAK, JR .
JOURNAL OF CHEMICAL PHYSICS, 1984, 81 (08) :3684-3690
[7]   Nonequilibrium molecular dynamics of microwave-driven zeolite-guest systems: Loading dependence of athermal effects [J].
Blanco, C ;
Auerbach, SM .
JOURNAL OF PHYSICAL CHEMISTRY B, 2003, 107 (11) :2490-2499
[8]   DENSITY-FUNCTIONAL THEORY CALCULATIONS OF THE ACTIVATION OF METHANOL BY A BRONSTED ZEOLITIC PROTON [J].
BLASZKOWSKI, SR ;
VANSANTEN, RA .
JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (30) :11728-11738
[9]   Active sites in the alkylation of toluene with methanol:: a study by selective acid-base poisoning [J].
Borgna, A ;
Sepúlveda, J ;
Magni, SI ;
Apesteguía, CR .
APPLIED CATALYSIS A-GENERAL, 2004, 276 (1-2) :207-215
[10]   CONCENTRATION-DEPENDENCE OF SELF-DIFFUSIVITY OF METHANOL IN NAX ZEOLITE CRYSTALS [J].
BRANDANI, S ;
RUTHVEN, DM ;
KARGER, J .
ZEOLITES, 1995, 15 (06) :494-495