Zeolite 13X molecular sieve 13X

Na2O . Al2O3 . m SiO2 . n H2O (m ≤ 2.35)

Also known as BASF 13X Molecular Sieve, BASF 13X

Zeolite 13X is a synthetic sodium aluminosilicate with the faujasite (FAU) framework and a nominal 10 Å pore size.

8 sources · Updated 2026-11-01 · CC BY 4.0

Evidence level

2 of 5

Lab-measured

Water capacity

> 26.5 % wt

Pore size

10 Å

Recipe, share of the weight

  • Na2O not statedSodium oxide
  • Al2O3 not statedAluminium oxide
  • SiO2 not statedSilicon dioxide
  • H2O not statedWater

Best for

Residual drying of gas streams where low dust in a packed bed matters (NASA's stated selection criterion).

Weakest at

Little numeric data in text: NASA's adsorption and dust results are in plots, and the BASF data sheet gives typical values only. CO2 performance fell after cyclic humid exposure in NASA's tests.

Risk at a glance

  • People None found. Nontoxic per BASF; no GHS hazard found
  • If it fails Moderate. Dust release in a packed bed
  • Corrosion Moderate. NASA's cyclic tests show 13X sorbents below their dry capacity, and the paper says 13X recovers most capacity at 204 °C.

Why it exists

Zeolite 13X is a synthetic sodium aluminosilicate sold as a molecular sieve. A molecular sieve is a material with pores of uniform size comparable to individual molecules (Wikipedia, Molecular sieve). A zeolite is a microporous crystalline aluminosilicate used as a commercial adsorbent (Wikipedia, Zeolite). The BASF 13X grade has a nominal pore size of 10 Å (1.0 nm). NASA's paper names 13X as the residual desiccant layer in the ISS Carbon Dioxide Removal Assembly, and it judged 13X the primary residual desiccant among the candidates it tested.

Where it's used

ISS carbon dioxide removal

NASA describes 13X zeolite as the residual desiccant layer of the ISS Carbon Dioxide Removal Assembly. The grade flown there is Grace MS 544 (Grade 544 13X in NASA's paper), not the BASF product in the data sheet.

Gas drying and oxygen enrichment

BASF lists drying of gases and liquids, removal of mercaptans, and non-cryogenic oxygen enrichment from air by pressure or vacuum swing adsorption as applications of its 13X grade.

Thermal energy storage

BASF says the product can be used as regenerative thermochemical energy storage for the generation of cold or heat.

Recipe

Na2O . Al2O3 . m SiO2 . n H2O (m ≤ 2.35)

Zeolite 13X is a sodium aluminosilicate with the general composition Na2O . Al2O3 . m SiO2 . n H2O, where m is at most 2.35 (BASF data sheet). Its framework is faujasite (FAU), built from sodalite cages (Wikipedia, Faujasite). The data sheet does not fix the water content n, and the synthesis route is not stated in our sources.

What 13X is made of
IngredientShare of the weightWhat it does
Sodium oxide Na2O not stated Sodium is the cation in the framework. The name 'Na-X' in Wikipedia's molecular sieve table marks the sodium form of the X-type zeolite.
Aluminium oxide Al2O3 not stated Alumina part of the framework, as printed in the chemical formula.
Silicon dioxide SiO2 not stated Silica part of the framework; the printed formula gives m SiO2 with m at most 2.35.
Water H2O not stated Water of hydration, printed as n H2O; the amount is not fixed in the data sheet.

Weight shares are as printed in the sources.

What it can do

Water capacity

> 26.5 % wt

measured

The data sheet gives a minimum water adsorption of 26.5 % wt at 55 % relative humidity and 20 °C for the activated sample.

Pore size

10 Å

measured

The nominal pore size is 10 Å (1.0 nm), per the BASF data sheet.

Bead strength

Crush strength is at least 25 N per bead for the 1.6 to 2.5 mm beads and at least 50 N per bead for the 2.5 to 5.0 mm beads.

Regeneration

BASF recommends regenerating with purge gas at 200 °C to 300 °C, and not above 450 °C.

How it compares

In NASA's standalone residual-desiccant tests, 13X zeolite was by a large order the best option for capturing water below detectable limits for the longest time. 4A zeolite came next at about half that effectiveness, and 3A zeolite broke through early despite a similar final capacity. In NASA's CO2 screening, every X-type zeolite under consideration gave higher CO2 capacity than RK-38, a 5A zeolite used in CDRA, after 204 °C activation. The paper says APGIII and VSA-10 have exceptional adsorption capacity but weaker pellet integrity, so NASA selected a 13X grade for its low dusting instead.

The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.

Benchmarks
Measurement13XAl2O3BaTiO3BeOCaTiO3RCFCeO2CoO and Co3O4CuO, Cu2OHfO2Fe2O3, Fe3O4LSMPZTMgONiONb2O5Al2Si4O10(OH)2Ln2O3SiOMgO-SiO2SnO2, ITOTiO2WO3V2O5Y2O3ZnOMg-PSZ, ATZ, ZTAYSZ
Capacity and energy
Water adsorption capacity> 26.5 % wt5no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Physical and electrical
Bulk density, compacted, small gradeManufacturer typical-properties table655 to 700 g/Lno datano datano datano datano datano datano datano datano datano datano datano data2.2 g/cm³no datano datano datano datano datano datano datano datano datano datano datano datano datano data
Bulk density, compacted, large gradeManufacturer typical-properties table655 to 700 g/Lno datano datano datano datano datano datano datano datano datano datano datano data2.2 g/cm³no datano datano datano datano datano datano datano datano datano datano datano datano datano data
Temperature behavior
Regeneration purge gas temperature, recommended range200 to 300 °C6no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Regeneration temperature, not to exceed< 450 °C7no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Other measurements
Pore size, nominalManufacturer typical-properties table10 Åno datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Bead size, small gradeManufacturer typical-properties table1.6 to 2.5 mmno datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Bead size, large gradeManufacturer typical-properties table2.5 to 5 mmno datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Attrition, small grade< 0.2 % wt1no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Attrition, large grade< 0.2 % wt2no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Crush strength, small grade> 25 N/bead3no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Crush strength, large grade> 50 N/bead4no datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data
Moisture content as deliveredManufacturer typical-properties table< 1 % wtno datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano datano data

Why choose it, and why not

Good for

  • Drying gas streams to very low water levels: NASA chose a 13X grade for residual drying in the ISS desiccant beds.
  • Low dust in a packed bed: NASA judged the 13X grades to carry the least overall dusting risk among the candidates it compared.

Watch out for

  • CO2 capacity falls after cyclic humid exposure: NASA's cyclic tests show the 13X zeolites below their dry isotherm values.
  • Dust is the main failure mode NASA screened for, and thermal-expansion mismatch in the pellet is a theorised cause.
  • No flight, vacuum or radiation data for the BASF grade were found in our sources.

NASA treats 13X as the primary residual desiccant for ISS-style CO2 removal beds. The BASF data sheet gives typical manufacturing values only, so confirm the grade and its test data before design.

Technical details

For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.

Other names and standards

The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.

Other names and standards
SystemCodes
Trade nameBASF 13X Molecular Sieve, BASF 13X

Notes

The method, full conditions and any caveat for the numbered rows above.

Notes for the numbered rows
#MeasurementMethodConditionsCaveat
1Attrition, small gradeManufacturer typical-properties table, printed as Max 0.2grade beads 1.6 to 2.5 mmtest not described in the data sheet—
2Attrition, large gradeManufacturer typical-properties table, printed as Max 0.2grade beads 2.5 to 5.0 mmtest not described in the data sheet—
3Crush strength, small gradeManufacturer typical-properties table, printed as Min 25grade beads 1.6 to 2.5 mmtest not described in the data sheet—
4Crush strength, large gradeManufacturer typical-properties table, printed as Min 50grade beads 2.5 to 5.0 mmtest not described in the data sheet—
5Water adsorption capacityManufacturer typical-properties table, printed as Min 26.5relative humidity 55 %temperature 20 °Csample activated, as the data sheet footnote states—
6Regeneration purge gas temperature, recommended rangeManufacturer recommendation printed in the regeneration paragraphpurpose warms the bed to this level during regenerationnote recommended operating range, not a measured limit—
7Regeneration temperature, not to exceedManufacturer recommendation printed in the regeneration paragraph, 'not exceeding 450 °C'purpose upper limit for the purge gas during regeneration—

Corrosion and compatibility

What happens when it meets other materials and environments.

Corrosion and compatibility
EnvironmentConcernWhat happens
Humid air and water vapour in a cyclic desiccant or CO2 bed moderate NASA's cyclic tests show 13X sorbents below their dry capacity, and the paper says 13X recovers most capacity at 204 °C.1
Thermal cycling of pelletized zeolite in a packed bed low NASA lists thermal-expansion mismatch in the pellet as a theorised cause of dusting, and judges the 13X grades to carry the least dusting risk.2
Hydrothermal conditions during regeneration not rated The data sheet asks users to avoid hydrothermal conditions during regeneration, and gives no test figure for them.3
Corrosion details
#EnvironmentDetailsTest conditions
1 Humid air and water vapour in a cyclic desiccant or CO2 bed NASA's paper reports that the three 13X zeolites in its screening settled at a reduced performance level in cyclic testing, compared with the dry isotherm values or with a 350 °C activation cycle. In a simulated cycle the paper says "13X zeolites can recover 90-95% of full CO2 removal capacity from a worst-case water exposure event" at a regeneration temperature of 204 °C. cycling simulated 4-BMS cycles with humid air exposureregeneration 204 °C for the simulated recovery case, 350 °C for the full activation case
2 Thermal cycling of pelletized zeolite in a packed bed NASA lists differing thermal-expansion coefficients between zeolite crystals and the binder as a theorised cause of pellet cracking, dusting and flaking. The paper also names bed-wide crushing from thermal expansion and contraction as a possible cause. The authors judged Grade 544 13X and BASF 13X to carry the least overall risk of dusting among the candidates they compared. test hydrothermal stability test stand, thermal cycling of packed bedsgrades 13X grades named in the paper
3 Hydrothermal conditions during regeneration BASF says the appearance of so-called hydrothermal conditions during regeneration should be avoided as far as possible. The data sheet does not quantify the loss of capacity or strength under these conditions. regeneration purge gas warms the bed to 200 °C to 300 °C, not exceeding 450 °C

Risks and side effects

Hazards to people, what happens when a cell overheats, and how the material is handled and stored.

For people

BASF calls the product nontoxic, but its own disclaimer asks users not to assume that toxicity data are given. The PubChem record used covers sodium aluminosilicate, a related substance, not the BASF grade.

The powder
BASF states the product is nontoxic. PubChem's record for sodium aluminosilicate reports no GHS hazard criteria for 97.4% (559 of 574) of company reports.
Dust
NASA ranks dust as the main selection risk for these beds. The data sheet gives no dust-handling guidance.

If the bed overheats

The sources we opened contain no runaway or fire test for 13X. Hydrothermal conditions during regeneration are the one warning BASF gives.

Regeneration
BASF advises avoiding hydrothermal conditions during regeneration as far as possible, and recommends 200 °C to 300 °C with a purge gas, not exceeding 450 °C.

Handling and storage

Packaging
The product ships in 216 L (135 kg) airtight steel drums, or in polypropylene-lined big bags of 650 or 800 kg net.
Thermal cycling
NASA lists thermal-expansion mismatch between zeolite crystals and binder as a theorised cause of pellet dusting.

Test details
The original wording and numbers from the sources, for readers who want them.

Failure risks

Failure risks
FailureTrigger and consequence
Dust release in a packed bedmoderate severityCrushing loads, thermal cycling and particle collisions in the voids of a packed bed (causes NASA lists)NASA states that dust can impair moving parts and seals, damage pumps and compressors, and clog filters, which raises pressure drop and can force a system shutdown. The paper reports no dusting problems for the flown Grade 544 13X on the ISS.
Lower CO2 capacity after cyclic humid exposuremoderate severityRepeated cycles with humid air, and regeneration below the full-activation temperatureIn NASA's cyclic tests the three 13X zeolites settled at a reduced CO2 performance level compared with dry isotherm values. The paper's simulated recovery figure depends on regeneration at 204 °C.

Handling and storage

  • BASF packs the product in 216 L (135 kg) airtight steel drums, or in polypropylene-lined big bags of 650 or 800 kg net.

Mitigations

  • Regenerate with purge gas at 200 °C to 300 °C and do not exceed 450 °C, as BASF recommends.
  • NASA selected a 13X grade after screening candidates on crush strength, attrition and hydrothermal stability, with minimised dusting as the main criterion.

Supply and geography

How common the raw materials are and where they come from.

Zeolites (natural), the mined analogue; synthetic 13X is not covered by the USGS data

USGS gives 1,300,000 t of world natural zeolite mine production in 2025e. No producer data for synthetic 13X was found in any source we opened.

Top producers (2025)
Slovakia 21.5%, Georgia 18.5%, Korea, Republic of 12.3%, China 11.5%
Recycling
USGS: zeolites used for desiccation, gas absorbance, wastewater treatment and water purification may be reused after reprocessing of the spent zeolites.

Alumina (aluminium oxide), an aluminium raw material; the 13X synthesis route is not stated in our sources

Top producers (2025)
China, Australia, Brazil

Updated