Tailoring the physicochemical properties of zeolite catalysts

Abstract

The physicochemical properties of zeolite catalysts, such as crystal topology, composition, size, and morphology, can have a marked effect on their performance for a broad range of reactions, notably in catalyst activity, hydrothermal stability, shape selectivity, and/or lifetime. There are relatively few zeolite framework types employed as commercial catalysts. Contributing factors include the high cost of synthesis and the difficulty of tailoring crystal nucleation and growth to achieve the desired properties. There is an increasing amount of structure performance data in the literature and patents that can be used to guide the identification of effective zeolite “formulations”; however, the challenges for realizing these materials are generally twofold: (i) growth mechanisms are not well understood, which often prohibits the control of zeolite crystallization, and (ii) the impracticality of most design schemes hinders their economic feasibility and their potential for facile implementation. These aspects are often overlooked in the design of zeolite catalysts, yet they are essential for any plans aimed at eventual commercialization. In this review, we summarize our recent findings in the area of zeolite synthesis and characterization, focusing specifically on practical routes to control zeolite crystallization in the absence of costly organics, tailoring crystal habit through the use of versatile and recyclable zeolite growth modifiers, and pioneering techniques in zeolite surface science as a platform to expand our knowledge of crystal growth mechanisms. These concerted efforts in rational design bridge fundamental and applied research towards the development of zeolites with improved catalytic performance.