Zeolite Mixes Up Pore Sizes To Good Effect | Chemical & Engineering News
Volume 90 Issue 5 | p. 41 | Concentrates
Issue Date: January 30, 2012

Zeolite Mixes Up Pore Sizes To Good Effect

Material with 10- and 12-sided channels converts naptha to diesel fuel with minimal carbon fouling
Department: Science & Technology
Keywords: zeolites, diesel, fuel, naphtha
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ITQ-39 is shown with its channels outlined in blue; the 12-ring pores (holes) are coming out of the page, and the 10-ring pores are parallel to the page.
Credit: Nat. Chem.
Molecular model showing the channels of the aluminosilicate zeolite ITQ-39 with the 12-ring channels coming out of the page and the 10-ring channels in the plane of the page.
 
ITQ-39 is shown with its channels outlined in blue; the 12-ring pores (holes) are coming out of the page, and the 10-ring pores are parallel to the page.
Credit: Nat. Chem.

A complex zeolite with differently sized, interlocking pores shows promise for converting naphtha to diesel fuel while avoiding fouling by residual carbon that can sideline some catalysts (Nat. Chem., DOI: 10.1038/nchem.1253). Aluminosilicate zeolites with pores bounded by either 10 or 12 silicon or aluminum atoms are important petrochemical catalysts, raising interest in a material that combines the two pore sizes. A group led by Xiaodong Zou of Stockholm University and Avelino Corma of Polytechnic University of Valencia, in Spain, has synthesized just such a zeolite and solved its structure using electron crystallography of nanometer-sized crystals. Called ITQ-39, the material contains intersecting 10- and 12-ring channels that run perpendicular to each other. The diameters of the channels are about 6 Å and 7 Å, respectively. In tests of naphtha alkylation, ITQ-39 performed better than commercial zeolite catalysts.The researchers believe the 12-ring channels promote the formation and diffusion of alkylated products, whereas the 10-ring channels prevent coke deposits by precluding the formation of polyaromatic precursor molecules.

 
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