Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study

[img]PDF - Authorized users only
Language: English
101Kb
Title:Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study
Creators:
Sauer, Joachim
Schröder, Klaus-Peter
Termath, Volker
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 63, 9, pp. 1394-1408
Uncontrolled Keywords:<i>Ab initio</i> calculations, Silico-aluminophosphate catalysts, Aluminosilicate catalysts, Zeolites, DFT-B3LYP, Quantum chemistry, Ion pair shell model potential

Abstract

DFT-B3LYP calculations are performed on 4-ring models of aluminophosphates (AlPOs) and silico-aluminophosphates (SAPOs). The results are used to fit the parameters of ion pair shell model potential functions. The potentials obtained are tested in lattice energy minimizations for berlinite and the microporous materials AlPO-18, AlPO-40, AlPO-52, and VPI-5. Not only does the potential reproduce the observed structures (average error of the cell constants 1.3%), it also predicts vibrational frequencies over the whole frequency range equally well (maximum deviation 50 cm<sup>-1</sup>). The potential is used to predict the structures and properties of Bronsted acid sites in an aluminosilicate and a SAPO with the chabazite framework structure (HSSZ-13 and HSAPO-34). A new combined quantum mechanics-intermolecular potential function approach (QM-Pot) is used at the DFT level. Comparison is made with full periodic DFT calculations using plane wave basis sets. The deprotonation energies corrected for systematic errors of the methods used are 1 231-1 235 and 1 261-1 280 kJ/mol for HSSZ-13 and HSAPO-34, respectively. The same acid site has a lower acidity in a SAPO than in an aluminosilicate zeolite of the same structure. <p>

Title:Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study
Creators:
Sauer, Joachim
Schröder, Klaus-Peter
Termath, Volker
Uncontrolled Keywords:<i>Ab initio</i> calculations, Silico-aluminophosphate catalysts, Aluminosilicate catalysts, Zeolites, DFT-B3LYP, Quantum chemistry, Ion pair shell model potential
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:63
Number:9
Page Range:pp. 1394-1408
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19981394UNSPECIFIED
ID Code:1389
Item Type:Article
Deposited On:06 Feb 2009 17:09
Last Modified:06 Feb 2009 16:09

Citation

Sauer, Joachim; Schröder, Klaus-Peter; Termath, Volker (1998) Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study. Collection of Czechoslovak Chemical Communications, 63 (9). pp. 1394-1408. ISSN 0010-0765

Repository Staff Only: item control page