spore: profile
id: zeolite-13x
spore_version: 0.2
family: oxide-ceramics
name: Zeolite 13X molecular sieve
abbreviation: 13X
role: CO2 and water sorbent (residual desiccant)
category: ceramics
type: oxides
summary: |
  Zeolite 13X is a synthetic sodium aluminosilicate with the faujasite (FAU) framework and a nominal 10 Å pore size. The BASF product data sheet for its 13X grade gives beads of 1.6 to 5.0 mm, a compacted bulk density of 655 to 700 g/L and a minimum water adsorption of 26.5 % wt at 55 % relative humidity. NASA reports 13X as the residual desiccant layer of the ISS Carbon Dioxide Removal Assembly, but the grade flown there is Grace MS 544 (Grade 544 13X in NASA's paper), not the BASF product.
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.'
identity:
  formula: Na2O . Al2O3 . m SiO2 . n H2O (m ≤ 2.35)
  source: basf-13x
  where: Product Data Sheet, Chemical Formula row
  designations:
    - system: Trade name
      code: BASF 13X Molecular Sieve
      source: basf-13x
      where: Title block, first line
    - system: Trade name
      code: BASF 13X
      source: nasa-ices2017
      where: Table 2, Molecular Sieve rows, Sorbent Name column
tags:
  environments:
    - low-earth-orbit
  stresses:
    - thermal-cycling
    - dust-abrasion
  applications:
    - habitats-and-suits
    - thermal-control
properties:
  - benchmark: pore_size
    label: Pore size, nominal
    value: 10
    unit: Å
    scope: material
    conditions:
      printed: 10 Å (1.0 nm)
      product: BASF 13X Molecular Sieve, as delivered
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Product Data Sheet, Typical Properties table, Pore Size row
  - benchmark: bead_size
    label: Bead size, small grade
    value: 1.6
    value_high: 2.5
    bound: range
    unit: mm
    scope: material
    conditions:
      grade: beads 1.6 to 2.5 mm nominal, mesh range 8 x 12 as printed
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Typical Properties table, Beads size range row, first column
  - benchmark: bead_size
    label: Bead size, large grade
    value: 2.5
    value_high: 5
    bound: range
    unit: mm
    scope: material
    conditions:
      grade: beads 2.5 to 5.0 mm nominal, mesh range 4x8 as printed
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Typical Properties table, Beads size range row, second column
  - benchmark: bulk_density
    label: Bulk density, compacted, small grade
    value: 655
    value_high: 700
    bound: range
    unit: g/L
    scope: material
    conditions:
      state: compacted
      grade: beads 1.6 to 2.5 mm
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Typical Properties table, Bulk Density, compacted row, first column
  - benchmark: bulk_density
    label: Bulk density, compacted, large grade
    value: 655
    value_high: 700
    bound: range
    unit: g/L
    scope: material
    conditions:
      state: compacted
      grade: beads 2.5 to 5.0 mm
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Typical Properties table, Bulk Density, compacted row, second column
  - benchmark: attrition
    label: Attrition, small grade
    value: 0.2
    bound: upper
    unit: '% wt'
    scope: material
    conditions:
      grade: beads 1.6 to 2.5 mm
      test: not described in the data sheet
    method: Manufacturer typical-properties table, printed as Max 0.2
    status: ground
    source: basf-13x
    where: Typical Properties table, Attrition row, first column
  - benchmark: attrition
    label: Attrition, large grade
    value: 0.2
    bound: upper
    unit: '% wt'
    scope: material
    conditions:
      grade: beads 2.5 to 5.0 mm
      test: not described in the data sheet
    method: Manufacturer typical-properties table, printed as Max 0.2
    status: ground
    source: basf-13x
    where: Typical Properties table, Attrition row, second column
  - benchmark: crush_strength
    label: Crush strength, small grade
    value: 25
    bound: lower
    unit: N/bead
    scope: material
    conditions:
      grade: beads 1.6 to 2.5 mm
      test: not described in the data sheet
    method: Manufacturer typical-properties table, printed as Min 25
    status: ground
    source: basf-13x
    where: Typical Properties table, Crush Strength row, first column
  - benchmark: crush_strength
    label: Crush strength, large grade
    value: 50
    bound: lower
    unit: N/bead
    scope: material
    conditions:
      grade: beads 2.5 to 5.0 mm
      test: not described in the data sheet
    method: Manufacturer typical-properties table, printed as Min 50
    status: ground
    source: basf-13x
    where: Typical Properties table, Crush Strength row, second column
  - benchmark: moisture_content_as_delivered
    label: Moisture content as delivered
    value: 1
    bound: upper
    unit: '% wt'
    scope: material
    conditions:
      state: as delivered
      grade: both bead sizes, printed as Max 1.0
    method: Manufacturer typical-properties table
    status: ground
    source: basf-13x
    where: Typical Properties table, Moisture Content row
  - benchmark: water_adsorption_capacity
    label: Water adsorption capacity
    value: 26.5
    bound: lower
    unit: '% wt'
    scope: material
    conditions:
      relative_humidity: 55 %
      temperature: 20 °C
      sample: activated, as the data sheet footnote states
    method: Manufacturer typical-properties table, printed as Min 26.5
    status: ground
    source: basf-13x
    where: Typical Properties table, Water Adsorption Capacity row, and the footnote marked with an asterisk
  - benchmark: regeneration_temperature
    label: Regeneration purge gas temperature, recommended range
    value: 200
    value_high: 300
    bound: range
    unit: °C
    scope: material
    conditions:
      purpose: warms the bed to this level during regeneration
      note: recommended operating range, not a measured limit
    method: Manufacturer recommendation printed in the regeneration paragraph
    status: ground
    source: basf-13x
    where: Regeneration paragraph, page 1
  - benchmark: max_regeneration_temperature
    label: Regeneration temperature, not to exceed
    value: 450
    bound: upper
    unit: °C
    scope: material
    conditions:
      purpose: upper limit for the purge gas during regeneration
    method: Manufacturer recommendation printed in the regeneration paragraph, 'not exceeding 450 °C'
    status: ground
    source: basf-13x
    where: Regeneration paragraph, page 1
corrosion:
  - environment: Humid air and water vapour in a cyclic desiccant or CO2 bed
    headline: NASA's cyclic tests show 13X sorbents below their dry capacity, and the paper says 13X recovers most capacity at 204 °C.
    effect: 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.
    rating: moderate
    conditions:
      cycling: simulated 4-BMS cycles with humid air exposure
      regeneration: 204 °C for the simulated recovery case, 350 °C for the full activation case
    source: nasa-ices2017
    where: Results, section C (CO2 sorbent selection), text beside Figures 13 to 15, and Conclusions
  - environment: Thermal cycling of pelletized zeolite in a packed bed
    headline: 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.
    effect: 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.
    rating: low
    conditions:
      test: hydrothermal stability test stand, thermal cycling of packed beds
      grades: 13X grades named in the paper
    source: nasa-ices2017
    where: Section III.A, Hydrothermal Stability Test text, and Sorbent Structural Property Summary
  - environment: Hydrothermal conditions during regeneration
    headline: The data sheet asks users to avoid hydrothermal conditions during regeneration, and gives no test figure for them.
    effect: 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.
    rating: unknown
    conditions:
      regeneration: purge gas warms the bed to 200 °C to 300 °C, not exceeding 450 °C
    source: basf-13x
    where: Regeneration paragraph, page 1
risks:
  hazards:
    - text: BASF states that BASF 13X Molecular Sieve is nontoxic. The same data sheet warns that users should not assume that toxicity data and safety measures are indicated, or that other measures may not be required.
      ghs: []
      source: basf-13x
      where: Regeneration paragraph (nontoxic statement) and the disclaimer on the last page
    - text: PubChem's record for sodium aluminosilicate (CID 72941443), a related substance and not the BASF 13X grade, reports that it does not meet GHS hazard criteria for 97.4% (559 of 574) of company reports. Only 2.6% of companies provided GHS information.
      ghs: []
      source: pubchem-sodium-aluminosilicate
      where: Safety and Hazards, GHS Classification (CID 72941443)
  failure_risks:
    - mode: Dust release in a packed bed
      trigger: Crushing loads, thermal cycling and particle collisions in the voids of a packed bed (causes NASA lists)
      consequence: 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.
      severity: moderate
      source: nasa-ices2017
      where: Introduction (dust paragraph), and Conclusions
    - mode: Lower CO2 capacity after cyclic humid exposure
      trigger: Repeated cycles with humid air, and regeneration below the full-activation temperature
      consequence: In 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.
      severity: moderate
      source: nasa-ices2017
      where: Results, section C (CO2 sorbent selection)
  handling:
    - text: BASF packs the product in 216 L (135 kg) airtight steel drums, or in polypropylene-lined big bags of 650 or 800 kg net.
      source: basf-13x
      where: Packaging
  mitigations:
    - text: Regenerate with purge gas at 200 °C to 300 °C and do not exceed 450 °C, as BASF recommends.
      source: basf-13x
      where: Regeneration paragraph, page 1
    - text: NASA selected a 13X grade after screening candidates on crush strength, attrition and hydrothermal stability, with minimised dusting as the main criterion.
      source: nasa-ices2017
      where: Introduction, and Sorbent Structural Property Summary
uses:
  - application: habitats-and-suits
    device: Residual desiccant layer in the ISS Carbon Dioxide Removal Assembly (CDRA)
    example: NASA's paper says the desiccant beds contain layers of silica gels and 13X zeolite, and the grade flown on the ISS is Grace MS 544 (Grade 544 13X).
    source: nasa-ices2017
    where: Section I (Introduction), CDRA paragraph; Table 2
  - application: habitats-and-suits
    device: Pressure or vacuum swing adsorption plant for non-cryogenic oxygen enrichment from air
    example: BASF lists non-cryogenic oxygen enrichment from air using pressure (vacuum) swing adsorption (PSA/VPSA) as a field of application for BASF 13X.
    source: basf-13x
    where: Product applications, first page
  - application: thermal-control
    device: Regenerative thermochemical energy storage for cold or heat
    example: BASF says BASF 13X can be used as regenerative thermo-chemical energy storage for the generation of cold or heat, possibly with sun energy or exhaust heat.
    source: basf-13x
    where: Product applications, first page
supply:
  - subject: Zeolites (natural), the mined analogue; synthetic 13X is not covered by the USGS data
    abundance: 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.
    producers:
      - country: Slovakia
        share_percent: 21.5
        year: 2025
      - country: Georgia
        share_percent: 18.5
        year: 2025
      - country: Korea, Republic of
        share_percent: 12.3
        year: 2025
      - country: China
        share_percent: 11.5
        year: 2025
    critical_lists: []
    recycling: 'USGS: zeolites used for desiccation, gas absorbance, wastewater treatment and water purification may be reused after reprocessing of the spent zeolites.'
    substitutes: []
    source: usgs-zeolites-2026
    where: World Mine Production and Reserves table, 2025e column (shares calculated by Space Mushroom against the 1,300,000 t world total); Recycling
  - subject: Alumina (aluminium oxide), an aluminium raw material; the 13X synthesis route is not stated in our sources
    producers:
      - country: China
        year: 2025
      - country: Australia
        year: 2025
      - country: Brazil
        year: 2025
    critical_lists: []
    substitutes: []
    source: usgs-bauxite-alumina-2026
    where: 'Alumina production table, 2025e column: China 93,000 t, Australia 17,000 t, Brazil 11,000 t. The table total was not read reliably, so no shares are given.'
documents:
  - title: BASF 13X Molecular Sieve product data sheet (BASF-9391 rev 02/2024)
    type: datasheet
    url: https://download.basf.com/p1/8a8082048fa5910c018fc44de15565ae/en/13X_Molecular_Sieve_Datasheet_Technical_Data_Sheet_English.pdf
    year: 2024
  - title: Investigation of Desiccants and CO2 Sorbents for Exploration Systems 2016-2017 (ICES-2017-188)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20170008962/downloads/20170008962.pdf
    year: 2017
  - title: 'PubChem: Sodium aluminosilicate (CID 72941443), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/72941443
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Zeolites (Natural)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zeolites.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Bauxite and Alumina'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
    year: 2026
gaps:
  - 'No attrition, crush-strength, humidity-cycling or hydrothermal-stability numbers for the BASF grade were recorded: NASA''s values are printed in figures, not in the text we could read.'
  - No flight, vacuum, radiation or thermal-vacuum result for the BASF grade was found. NASA's ISS flight heritage refers to Grace MS 544 (Grade 544 13X), a different product.
  - No CAS number for zeolite 13X was confirmed in a source we opened; PubChem returned no record for the name 'zeolite 13X'.
  - No SDS or PubChem hazard record for 13X itself was found. The PubChem record used is for sodium aluminosilicate (CID 72941443), a related substance; the BASF data sheet gives only a 'nontoxic' statement.
  - 'The 13X synthesis route is not stated in any source we opened. Wikipedia describes the 4A route: aqueous sodium silicate and sodium aluminate combined at 80 °C and then activated at 400 °C.'
  - Producer shares for synthetic 13X were not found. The USGS zeolite data cover natural zeolites only, and the alumina table total was not read reliably, so no alumina shares are given.
  - Wikipedia's molecular sieve table gives 13X figures, but the column headings were not readable in the text we extracted, so none of those numbers were recorded.
  - CO2 capacity values for the BASF grade at 25 °C or 50 °C were not found in text; NASA's isotherm results are in figures.
  - RK-38 (a 5A zeolite CO2 sorbent in CDRA, Table 2 of NASA's paper) is used only as a comparison point here; its dust history is not a property of 13X.
  - Property names not in spores/property-canon.yaml (pore_size, bead_size, bulk_density, attrition, crush_strength, moisture_content_as_delivered, water_adsorption_capacity, regeneration_temperature, max_regeneration_temperature) were used as short snake_case names.
sources:
  basf-13x:
    title: BASF 13X Molecular Sieve, Product Data Sheet (BASF-9391 rev 02/2024)
    id: BASF-9391 rev 02/2024
    url: https://download.basf.com/p1/8a8082048fa5910c018fc44de15565ae/en/13X_Molecular_Sieve_Datasheet_Technical_Data_Sheet_English.pdf
    year: 2024
    kind: datasheet
    license: manufacturer data sheet, linked not reproduced
  nasa-ices2017:
    title: Investigation of Desiccants and CO2 Sorbents for Exploration Systems 2016-2017
    id: ICES-2017-188, 47th International Conference on Environmental Systems; NTRS 20170008962
    url: https://ntrs.nasa.gov/api/citations/20170008962/downloads/20170008962.pdf
    year: 2017
    kind: report
    license: public domain (NASA)
  usgs-zeolites-2026:
    title: Mineral Commodity Summaries 2026, Zeolites (Natural)
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zeolites.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-bauxite-alumina-2026:
    title: Mineral Commodity Summaries 2026, Bauxite and Alumina
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-sodium-aluminosilicate:
    title: PubChem compound record, Sodium aluminosilicate (CID 72941443)
    id: CID 72941443
    url: https://pubchem.ncbi.nlm.nih.gov/compound/72941443
    year: 2026
    kind: database
    license: public domain (NCBI)
  wiki-molecular-sieve:
    title: Molecular sieve, Wikipedia
    id: en.wikipedia.org/wiki/Molecular_sieve
    url: https://en.wikipedia.org/wiki/Molecular_sieve
    kind: web
    license: CC BY-SA 4.0 (Wikipedia text)
  wiki-zeolite:
    title: Zeolite, Wikipedia
    id: en.wikipedia.org/wiki/Zeolite
    url: https://en.wikipedia.org/wiki/Zeolite
    kind: web
    license: CC BY-SA 4.0 (Wikipedia text)
  wiki-faujasite:
    title: Faujasite, Wikipedia
    id: en.wikipedia.org/wiki/Faujasite
    url: https://en.wikipedia.org/wiki/Faujasite
    kind: web
    license: CC BY-SA 4.0 (Wikipedia text)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 0
  caveats: 2
  note: Written by an AI assistant on 2026-11-01 from the BASF datasheet, the NASA ICES-2017 paper, two USGS chapters, the PubChem record for a related substance and three Wikipedia pages. Values are the datasheet's typical values, not NASA test results.
story:
  why: 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.
  uses:
    - where: ISS carbon dioxide removal
      line: 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.
    - where: Gas drying and oxygen enrichment
      line: 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.
    - where: Thermal energy storage
      line: BASF says the product can be used as regenerative thermochemical energy storage for the generation of cold or heat.
  can_do:
    - label: Water capacity
      benchmark: water_adsorption_capacity
      line: The data sheet gives a minimum water adsorption of 26.5 % wt at 55 % relative humidity and 20 °C for the activated sample.
    - label: Pore size
      benchmark: pore_size
      line: The nominal pore size is 10 Å (1.0 nm), per the BASF data sheet.
    - label: Bead strength
      line: 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.
    - label: Regeneration
      line: BASF recommends regenerating with purge gas at 200 °C to 300 °C, and not above 450 °C.
  compare: 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.
  compare_rows:
    - label: Water adsorption capacity
      benchmark: water_adsorption_capacity
    - label: Crush strength
      benchmark: crush_strength
    - label: Bulk density
      benchmark: bulk_density
  handling:
    - The data sheet calls the product nontoxic, but also says users should not assume that toxicity data and safety measures are indicated.
    - 'Store and ship it in its airtight packaging: 216 L (135 kg) steel drums or 650 or 800 kg big bags.'
    - Regenerate with purge gas at 200 °C to 300 °C, and do not exceed 450 °C.
    - Avoid hydrothermal conditions during regeneration as far as possible, as BASF advises.
  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:
    - '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.
  verdict: 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.
  recipe:
    line: 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.
    parts:
      - name: Sodium oxide
        symbol: Na2O
        role: 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.
      - name: Aluminium oxide
        symbol: Al2O3
        role: Alumina part of the framework, as printed in the chemical formula.
      - name: Silicon dioxide
        symbol: SiO2
        role: Silica part of the framework; the printed formula gives m SiO2 with m at most 2.35.
      - name: Water
        symbol: H2O
        role: Water of hydration, printed as n H2O; the amount is not fixed in the data sheet.
  risk_groups:
    - title: For people
      level: 0
      verdict: Nontoxic per BASF; no GHS hazard found
      lead: 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.
      points:
        - label: The powder
          line: 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.
        - label: Dust
          line: NASA ranks dust as the main selection risk for these beds. The data sheet gives no dust-handling guidance.
    - title: If the bed overheats
      lead: The sources we opened contain no runaway or fire test for 13X. Hydrothermal conditions during regeneration are the one warning BASF gives.
      points:
        - label: Regeneration
          line: 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.
    - title: Handling and storage
      points:
        - label: Packaging
          line: The product ships in 216 L (135 kg) airtight steel drums, or in polypropylene-lined big bags of 650 or 800 kg net.
        - label: Thermal cycling
          line: NASA lists thermal-expansion mismatch between zeolite crystals and binder as a theorised cause of pellet dusting.