Characterization of Molecular Highways in Zeolites

In 2004, Javier Garcia-Martinez, Rive Technology, Monmouth Junction, NJ, USA, and University of Alicante, Spain, and colleagues developed a simple, surfactant-based, inexpensive technique to introduce precisely controlled mesoporosity into a wide range of zeolite crystals [1, 2], while maintaining the chemical and physical properties of the zeolites. The size of the pores is tuned using surfactants of different lengths and its volume is adjusted with the severity of the treatment. The zeolites are used in refineries as Fluid Catalytic Cracking (FCC) catalysts to produce liquid fuels at reduced yields of coke and unconverted feed [3].

Now the team has confirmed the presence of the intracrystalline and interconnected mesopores in surfactant-templated mesostructured zeolites by using a combination of advanced gas sorption techniques, electron tomography and rotation electron diffraction.
The majority of the highly interconnected mesopores is freely accessible and forms a network. The team called it “molecular highways” as it significantly enhances intracrystalline diffusion. The pore architecture and the connectivity of the mesopores are shown in the movie below.

Lab testing and two months long refinery trials in two separate North American refineries showed that the hierarchical structure leads to improved product selectivity for the mesostructured zeolite Y and fluid catalytic cracking (FCC) catalysts.
Moreover, the team believes that the “molecular highways” could also improve the performance of the catalysts or adsorbents in many processes that are currently limited by slow mass transport [4].

Evidence of Intracrystalline Mesostructured Porosity in Zeolites by Advanced Gas Sorption, Electron Tomography and Rotation Electron Diffraction,
Javier Garcia-Martinez, Changhong Xiao, Katie A. Cychosz, Kunhao Li, Wei Wan, Xiaodong Zou, Matthias Thommes,
ChemCatChem 2014.
DOI: 10.1002/cctc.201402499

[1] Improve Zeolites for Catalysis, ChemistryViews.org 2012.

[2] U. S. Patent, 7,589,041 B2, 2004.

[3] Hierarchical Zeolites Make it to the Refinery, ChemistryViews.org 2013.

[4] Kunhao Li, Julia Valla, Javier Garcia-Martinez, Realizing the Commercial Potential of Hierarchical Zeolites: New Opportunities in Catalytic Cracking, ChemCatChem 2014, 6(1), 46–66. DOI: 10.1002/cctc.201300345