A critical review of waste resources, synthesis, and applications for Zeolite LTA

Abstract

This review not only provided a summary of the state of the art with regards to commercially important zeolite LTA technology, but also identified strategies to further promote uptake of this material in industry. The hypothesis was that application of SWOT analysis principles would assimilate data regarding zeolite LTA in a manner which provided a concise and clear pathway for future development. Zeolite LTA synthesis innovation related to preparation of nano-zeolites, hierarchical materials, binderless zeolite granules, magnetized zeolites, loading of metals/metal oxides into the pore structure and introduction of heteroatoms. Waste resources included used glass, alum sludge from drinking water plants, fly ash from power stations, recycled aluminium, manufacturing waste, ash from organic material and various aluminosilicate rocks from the mining sector. In addition to traditional application of zeolite LTA for water softening opportunities; use of zeolite LTA for catalytic processes, membrane separation, alternate zeolite production, wastewater treatment, and anti-microbial purposes have been described. A key weakness identified was the lack of compelling economic models in relation to synthesis of zeolite LTA from waste resources or by new methods which produce hierarchical materials. Linked to the lack of economic studies was the limited information about process design of zeolite LTA manufacturing systems or industrial application of zeolite LTA. Key strategies developed included: (1) scaling-up of new synthesis methods to kg levels and beyond; (2) creation of process flow diagrams and piping and instrumentation diagrams; (3) detailed economic analysis of zeolite LTA synthesis from waste materials; (4) Utilization of methods to reduce the cost of zeolite manufacture such as ultrasonics, microwaves, “one pot” synthesis, continuous production and rapid synthesis; and (5) demonstration of zeolite LTA performance at pilot plant scale for the various applications identified. In conclusion, zeolite LTA has an expanded role to play in the area of zeolite science and this study has provided a roadmap to accelerate this development.