Synthetic zeolites are manufactured aluminosilicate minerals with a sponge-like structure, made up of tiny pores (frameworks) that make them useful as catalysts or ultrafine filters. They are commonly known as molecular sieves and can be designed to selectively adsorb molecules or ions dependant on their unique construction and have the ability to be regenerated over and over again for re-use (recycled).
Zeolites act much like a magnet that can hold cations, like heavy metal, ammonia, low level radioactive elements, toxins, petrochemicals, many different types of gases and a multitude of various solutions.
The selectivity properties of different synthetic zeolites enable them to be effective in wastewater treatment applications, water filters and as ion exchangers in many everyday dishwashing and laundry detergents.
Zeolites play an important role in a cleaner and safer environment.
- zeolites are an effective substitute for harmful phosphates in powder detergent, now banned in many parts of the world because of blue green algae toxicity in waterways
- as catalysts zeolites increase process efficiencies = decrease in energy consumption
- zeolites can act as solid acids and reduced the need for more corrosive liquid acids
- zeolites adsorbent capabilities see them widely used in water treatment i.e. heavy metal removal including those produced by nuclear fission
- as redox catalyst sorbents (zeolites) can help remove exhaust gases and CFC’s
Our proprietary mineral processing technology also presents as a commercial environmental management solution for suitable mine tailings/residues, by applying tail streams as feed for low cost production of high value zeolites.
Synthetic zeolites can be manufactured for specific applications in a range of industrial environments, the types that Zeotech has synthesized are:
Zeolite A is a sodium aluminosilicate and is utilized as a builder in tablets and detergent powders for the water softening in washing process. This type of zeolite is also known as Linde Type A (LTA), which belongs to the aluminosilicate molecular sieves family. Sodium ions present in zeolite A can be replaced with other cations, including potassium, lithium, and calcium. There are around 150 synthetic zeolites designed for the specific purposes. However, the most common type is zeolite type A, which include:
- 4A applications include a detergent builder and polyvinyl chloride (PVC) heat stabiliser. 4A molecular sieve with uniform pore size of 3 angstroms can be used for the deep drying of air, natural gas, alkaline, refrigerants and other gases and liquids.
- 3A is a molecular sieve that has a pore size that is 3 angstroms (3A), hence it will not adsorb any molecules larger than 3A. It is a very effective and reliable desiccant (drying agent) and is used in a wide variety of commercial applications, some of which include, natural gas drying, refrigerant drying, moisture removal in polyurethane plastic/paint, static drying of insulating glass units and is also applied in method of drying that is used by fuel ethanol producers.
- 5A is a molecular sieve that has a pore size that is 5 angstroms (5A). It cannot adsorb any molecules smaller than 5A and primary applications are separation of alkane types, co-adsorption of carbon dioxide and moisture, along with pressure swing adsorption (PSA) for gases.
Zeolite X belongs to Faujasite family which are used as catalysts and sorbents. There are several different types of zeolite X dependent on pore size. It is mainly used in the gas drying applications, however, it has a variety of industrial applications, including gas separation and adsorption, besides being utilized as a catalyst. Zeolite X ion exchange properties also make it effective in removing toxins from wastewater. One key type of zeolite X is:
- 13X has larger pore size than Type A zeolites (circa 10 angstroms) and is primarily used in types of air refining (ie removing carbon dioxide and water), removal of grease and solvents and in gas pressure swing adsorption.
Diverse applications of synthetic zeolites:
- Detergent builder
- PVC heat stabiliser
- Gas separation ie Air purification and industrial applications
- Water treatments ie heavy metal removal
- Moisture removal / drying, across a diverse range of substances
- Insulating glass units
- Animal feed supplements ie mycotoxin adsorbents
Most common applications of molecular sieves:
Air Separation & Industrial Gas industry (include oxygen & hydrogen production)
Molecular sieves can preferentially adsorb water vapour and impurities from industrial gas. (For example, upstream of cryogenic separation processes, thus preventing freezing and hydrate formation.) By removing various impurities, molecular sieves can also improve the quality of an industrial gas like synthesis gas.
Molecular sieve (MS) adsorbents used in the air separation and industrial gas industry (including oxygen & hydrogen production) are mainly MS4A, MS5A and MS13X.
Molecular sieves adsorbents are used for the drying and purification of feedstocks for refinery applications such as isomerisation, alkylation, and reforming. These processes often use catalysts, sensitive to impurities in the feed, which need to be protected by a feed purification step using molecular sieve adsorbents. In addition, the removal of other impurities with molecular sieve adsorbents can improve the quality of the final product.
Some examples are:
- Hydrocarbon gas drying with molecular sieves, prior to cryogenic extraction of LPG, to avoid ice and hydrate formation.
- Alkylation and isomerisation feed drying: Removal of water for catalyst protection and corrosion prevention using molecular sieve adsorbents.
- Non-regenerative removal of chloride by molecular sieves adsorbents to prevent contamination from isomerisation catalysts to avoid corrosion downstream the catalyst unit.
- Drying and purification of feed streams for Methyl tert-butyl ether (MTBE) and Butamer production.
- LPG sweetening and butane destenching.
The petrochemical industry uses molecular sieves to purify feedstocks and to dry and remove impurities from products such as ethylene and propylene. This protects catalysts in downstream conversion units and prevents freezing in cryogenic systems.
Some examples are:
- Drying in cracked gas in order to prevent freezing.
- Drying hydrogen gas for acetylene converters.
- Drying and purification of olefins. (removal of CO2 and oxygenates)
- Drying and removal of CO2 and oxygenates of ethylene and propylene.
- Dehydration and purification of a wide variety of solvents.
Natural gas applications
The natural gas industry has strict specifications and limits on impurities in hydrocarbon gas and condensates supplied to processing plants and downstream customers in order to prevent corrosion, hydrate formation and freezing in cryogenic equipment. When sulphur compounds and carbon dioxide levels are too high, they need to be removed to meet product specifications or avoid formation of solid CO2. Molecular sieve adsorbents are used to fulfill these requirements.
Some examples are:
- Drying natural gas prior to cryogenic processing or turbo expansion.
- Sweetening natural gas for removal of H2S and mercaptans to meet pipeline specifications.
- Drying sour natural gas with molecular sieve to meet transmission specifications to the sulphur removal unit.