Retrospective: Zeolites in Environmental Applications

Automotive exhaust conditions present unique challenges for the design of effective catalysts. In addition to the need for catalytic activity over a wide temperature range, the catalyst must show durability towards extreme hydrothermal aging conditions. The use of zeolitic materials under such conditions is especially challenging due to the vulnerability of zeolites to steam aging. The BASF discovery of the Cu-CHA catalyst for selective catalytic reduction (SCR) of NOx demonstrated an effective balance between favorable active sites and zeolite framework durability. It also paved the way for the implementation of urea SCR as the key approach for NOx reduction in diesel vehicles. In addition to highlighting the development of Cu-CHA SCR catalyst, this presentation will primarily focus on various synthesis approaches for the crystallization of CHA zeolites.