Mechanistic Study of Alcohol Dehydration on γ-Al2O3

被引:213
作者
Roy, Sounak [2 ]
Mpourmpakis, Giannis [2 ]
Hong, Do-Young [2 ,3 ]
Vlachos, Dionisios G. [2 ]
Bhan, A. [2 ,3 ]
Gorte, R. J. [1 ,2 ]
机构
[1] Univ Penn, Dept Chem & Biomol Engn, Philadelphia, PA 19104 USA
[2] Univ Delaware, CCEI, Newark, DE 19716 USA
[3] Univ Minnesota, Dept Chem Engn & Mat Sci, Minneapolis, MN 55455 USA
关键词
alcohol dehydration; alumina; acid sites; reaction mechanism; TPD-TGA; DFT; TEMPERATURE-PROGRAMMED DESORPTION; GAMMA-ALUMINA; CATALYTIC ALUMINAS; SURFACE; ADSORPTION; WATER; 2-BUTANOL; MODELS; SITES; PHASE;
D O I
10.1021/cs300176d
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 acid sites on gamma-Al2O3 were characterized using FTIR spectroscopy of adsorbed pyridine and temperature programmed desorption (TPD) of 2-propanamine, ethanol, 1-propanol, 2-propanol, and 2-methyl-2-propanol, together with density functional theory (DFT) calculations. Following room-temperature adsorption and evacuation, the surface coverages of the adsorbed alcohols were between 2 and 3.2 x 10(18) molecules/m(2). For each of the adsorbed alcohols, reaction to olefin and water products occurred in a narrow peak that indicated reaction is a first-order process with a well-defined activation energy, which in turn depended strongly on the particular alcohol. DFT calculations on an Al8O12 cluster are in excellent agreement with the experimental observations and show that the transition states for dehydration had carbenium-ion character. The carbenium ion stability in terms of proton affinity (of alkenes) matches well with the activation energy of the dehydration reaction. Adsorption of water on the gamma-Al2O3, followed by evacuation at 373 K, demonstrated that water simply blocks sites for the alcohols without affecting the reaction activation energy. There was no evidence for Bronsted sites on the gamma-Al2O3 based on FTIR of pyridine or TPD of 2-propanamine.
引用
收藏
页码:1846 / 1853
页数:8
相关论文
共 28 条
[1]   DENSITY-FUNCTIONAL THERMOCHEMISTRY .3. THE ROLE OF EXACT EXCHANGE [J].
BECKE, AD .
JOURNAL OF CHEMICAL PHYSICS, 1993, 98 (07) :5648-5652
[2]   Bond dissociation energies of organic molecules [J].
Blanksby, SJ ;
Ellison, GB .
ACCOUNTS OF CHEMICAL RESEARCH, 2003, 36 (04) :255-263
[3]   Temperature programmed desorption-FTIR investigation of C1-C5 primary alcohols adsorbed on γ-alumina [J].
Clayborne, PA ;
Nelson, TC ;
DeVore, TC .
APPLIED CATALYSIS A-GENERAL, 2004, 257 (02) :225-233
[4]   Nanoscale surface study and reactions mechanism of 2-butanol over the γ-alumina (1 0 0) surface and nanochannel: A DFT study [J].
Dabbagh, Hossein A. ;
Zamani, Mehdi ;
Davis, Burtron H. .
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, 2010, 333 (1-2) :54-68
[5]   DESIGN PARAMETERS FOR TEMPERATURE-PROGRAMMED DESORPTION FROM A PACKED-BED [J].
DEMMIN, RA ;
GORTE, RJ .
JOURNAL OF CATALYSIS, 1984, 90 (01) :32-39
[6]   Hydroxyl groups on γ-alumina surfaces:: A DFT study [J].
Digne, M ;
Sautet, P ;
Raybaud, P ;
Euzen, P ;
Toulhoat, H .
JOURNAL OF CATALYSIS, 2002, 211 (01) :1-5
[7]   Isopropanol adsorption on γ-Al2O3 surfaces: A computational study [J].
Feng, Gang ;
Huo, Chun-Fang ;
Deng, Chun-Mei ;
Huang, Long ;
Li, Yong-Wang ;
Wang, Jianguo ;
Jiao, Haijun .
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, 2009, 304 (1-2) :58-64
[8]  
Frisch M. J., 2016, Gaussian 03 Revision B.03
[9]   What do we know about the acidity of solid acids? [J].
Gorte, RJ .
CATALYSIS LETTERS, 1999, 62 (01) :1-13
[10]   HEATS OF ADSORPTION OF WATER ON ALPHA-ALUMINA AND GAMMA-ALUMINA [J].
HENDRIKS.BA ;
RUDHAM, R ;
PEARCE, DR .
JOURNAL OF CATALYSIS, 1972, 24 (01) :82-&