Locating Structure Directing Agent and Al inCHA: Combined Study of Structure Determination of X‐Ray Powder Diffraction and Classical Lattice Energy Calculation

Abstract

Locating the structure directing agent and Al in zeolite CHA has been performed using structure determination of X‐ray powder diffraction combined with General Utility Lattice Program (GULP) calculation. Trimethyladamantylammonium ion (TMAdaOH+) and benzyltrimethyl ammonium ion (BTMAOH+), respectively, have been found to fit in the pore, resulting in the formation of high silica zeolite CHA, which shows the superior catalytic performance in abatement of NOx using NH3 in the exhaust gas stream of mobile car. The intimate interaction between the corresponding structure directing agent (SDA) and the counter ion due to the Al substitution in the framework has been characterized using the lattice energy calculation. The difference in the lattice energy of the zeolite CHA prepared with TMAdaOH was large compared to that of the zeolite CHA prepared with BTMAOH, which can be attributed probably to the molecule's size. Thereby, the SDA in the zeolite pore has been located readily and the resulting information can be useful for increasing the understanding in the zeolite formation mechanism and designing novel zeolite.

Synthesis and Characterization of Silicoaluminophosphate CIT-16P and Its Transformation to SAPO-17

“…The configuration of the DiQ-C 4 OSDA molecules within the pore system of CIT-16P phase was determined by utilizing the parallel templating method in which the previously obtained framework was considered as a rigid body and the flexible OSDA molecule was placed in the pore randomly. − The same procedure was also used to identify the configuration of the organic molecules within the AFX phase, the major impurity. The Rietveld refinements on as-synthesized CIT-16P with a small amount of AFX impurity were performed successfully in the space group of P 3 for CIT-16P (Figure ).…”

Control of the oxidation state of copper in copper silicate SGU‐29 for efficient catalytic reduction

“…Zeolites have been widely used to synthesize heterogeneous catalysts because of their large surface area, high adsorption capacity, and excellent thermal/hydrothermal stability. Typically, they exhibit three‐dimensional microporous crystalline features that are composed of Al, Si, O, and cations in their regular framework 1–3 . In catalytic applications, these features significantly influence the chemical reactions occurring within the micropore or microchannel because of size‐selectivity and active acidic/basic sites in the framework.…”

“…Typically, they exhibit three-dimensional microporous crystalline features that are composed of Al, Si, O, and cations in their regular framework. [1][2][3] In catalytic applications, these features significantly influence the chemical reactions occurring within the micropore or microchannel because of size-selectivity and active acidic/basic sites in the framework. Introducing transition metals into the zeolite framework is a promising strategy for improving its catalytic performance by generating and increasing the number of active sites.…”