Potassium tert-butoxide from potassium and dry tert-butanol, semi-batch with alcohol strip and vacuum drying (1000 t/a)

A batch plant: molten potassium is dosed into excess dry tert-butanol (hydrogen to the flare), the alcohol is stripped, recycled and the solvate vacuum-dried; the azeotropic make-up from tert-butanol-1 is dried on a molecular sieve. Concept stage, 831.6 kg per batch every 6.586 h on a dedicated train, preliminary gate-to-gate LCI.

Calculation maturity: not assessedDesign maturity: Concept (research)Not independently reviewedOxygenatesReport a problem with this process
Research outputNot engineering advice and not an approved design: do not use it for construction, operation or safety decisions. What this means

The route is the classic one: potassium metal with dry tert-butanol in excess (Wikipedia, Potassium tert-butoxide; Organic Syntheses, Coll. Vol. 4, 132 and Coll. Vol. 5, 1060, where the molten metal disperses in the stirred alcohol and dissolves at a rate set by the stirring, the alcohol refluxing and hydrogen leaving), with the excess alcohol distilled off and the solid heated (Wikipedia; US 4 577 045 A dries its product at 160 C and 10 mbar). The KOH route with azeotropic water removal (US 4 577 045 A, US 5 053 560 A) and the amalgam route (US 6 150 569 A) are recorded as alternatives (DESIGN.md D-001). Per mol of potassium 8.6 mol of tert-butanol are charged (Organic Syntheses, Coll. Vol. 4, 132), so that the alkoxide stays dissolved at 16.6 wt% (US 4 577 045 A runs its solution at 10-18 wt%, ASSUMED to hold at 348 K). The make-up arrives as the azeotrope with 11.76 wt% water (US 5 053 560 A); tert-butanol-1 counts the alcohol contained and leaves out the drying past the azeotrope, so this plant dries it on a vapour-phase 3A molecular sieve (ASSUMED design, a specified split from scripts/makeup_drying.py) to 0.1 wt% water, which the potassium then takes to KOH. The modelled product is 99.47 wt% KOtBu, 0.23 wt% KOH and 0.30 wt% tert-butanol, an upper bound on the assay (the metal's sodium, moisture picked up in handling and any decomposition are not modelled; no open product specification was read). The modelled yield is 99.5 % on potassium (the rest is KOH) and 89.5 % on the tert-butanol bought: 5.7 % of it goes to the flare (with the hydrogen and the dryer's nitrogen bleed), 3.4 % with the purge, 1 % with the sieve's regeneration and 0.4 % with the product.

The batch is modelled with cheme-as-code 1.10.0: the reactor R101 is a semi-batch (reactor: semibatch) whose hydrogen leaves by a vent as it forms (batch.vent, core ADR 0054), saturated with the alcohol's vapour through a vent condenser at 308 K, on tempered water at 303/313 K so that no alcohol freezes on its tubes, whose condensate returns (vent vapour and condenser, core ADR 0062); the still is core's batch still with the charge's heat-up and the vessel's metal (core ADRs 0055, 0063), its reboiler and condenser duties written by the model (core ADRs 0059, 0061); the paddle dryer is core's dryer to a residual alcohol content (core ADR 0057); the alcohol loop converges at its tear (core ADR 0060). The recipe gives the cycle (6.586 h, R-101 the bottleneck, 1202 batches a year), sizes the vessels and checks R-101's jacket. Kinetics and heats of reaction are ASSUMED (no open data): the dispersed metal accumulates to 3.1 % and the cooling-failure temperature reaches 350.1 K against an MTT of 355.45 K (tert-butanol's boiling point), the gas released with the liquid's vapour 133.4 m3/h against an ASSUMED vent capacity of 200 m3/h (core ADR 0058); a ten times slower rate takes the MTSR to 366.9 K, above the MTT: the alcohol would boil in a cooling failure. The hydrogen and the potassium's reaction with water are the plant's main hazards (DESIGN.md D-011).

Capacity
1000 t/a dried potassium tert-butoxide: 1202 batches/a of 831.6 kg in 7920 h on a dedicated train (126.26 kg/h year average), ASSUMED (DESIGN.md D-002, D-003, D-013)
Operation
7,920 h/a
Location
generic fine-chemicals site with a potassium metal supply, a flare and wastewater treatment (not chosen)
Engineering gates
Concept and feasibility (no results yet)
Maintainers
Artur Schweidtmann
Design basis and assumptions (5)
  • Route: potassium metal with an excess of dry tert-butanol, the metal molten and dispersed, the hydrogen vented (Organic Syntheses Coll. Vol. 4, 132 and Coll. Vol. 5, 1060; Wikipedia; D-001); 8.6 mol of tert-butanol per mol of potassium in the charge (D-004).
  • ASSUMED kinetics and heats of reaction (no open data, D-005): an effective first-order rate in the dispersed metal, k = 3e-3 1/s at 348 K; -135 kJ/mol for the alkoxide and -138.8 kJ/mol for the water's reaction.
  • ASSUMED stripping to the 1:1 solvate in an ideal-liquid batch still and vacuum drying at 433 K to 0.3 wt% tert-butanol (D-007, D-008).
  • ASSUMED vapour-phase 3A molecular-sieve drying of the azeotropic make-up to 0.1 wt% water, 1 % of its alcohol lost to the regeneration (D-004).
  • All flows are year averages of the recipe (D-003); the duties of R101, its vent condenser and the still from the models (written by cheme process propagate), the dryer's from cheme's dryer model, the sieve unit's from scripts/makeup_drying.py, the others hand arithmetic from the stream table (D-009); accuracy +/-30 % not demonstrated.

From process/design-basis.yaml.

Engineering model

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Snapshot of a3c52e4, cheme-as-code 1.6.0.

What goes in and out

In

  • PotassiumFeedstockfeed:K: technical potassium metal (merchant), 0.348 kg/kg KOtBu, melted and dosed; no library process makes it (proxy KCl + Na recorded, D-012)
  • tert-Butanol (2-methylpropan-2-ol)Feedstockfeed:TBAF: the tert-butanol of the azeotrope grade (tert-butanol-1, kg of alcohol contained), 0.734 kg/kg KOtBu; dried on site past the azeotrope (A-001)
  • WaterFeedstockfeed:TBAW: the azeotrope grade's 11.76 wt% water, 0.098 kg/kg KOtBu, removed by the sieve unit
  • NitrogenFeedstockNitrogen (asu-1) for inerting, blankets, the potassium's pressing, the dryer's bleed and the vent header's purge, 95.7 kg per batch, 0.115 kg/kg KOtBu (ASSUMED)

Out

  • Potassium tert-butoxideMain productDried potassium tert-butoxide powder to packing under nitrogen; modelled 99.47 wt% KOtBu, 0.23 wt% KOH, 0.30 wt% tert-butanol, an upper bound on the assay (the metal's sodium, handling moisture and decomposition not modelled)
  • WastewaterWasteSieve regeneration condensate, 0.104 kg/kg KOtBu, water with about 7 wt% tert-butanol, to wastewater treatment

Utilities: Electricity (0.325 kWh/kg KOtBu: agitators of R-101 and C-101, the paddle dryer's drive and vacuum pump, and the sieve's regeneration heater and blower (0.154 kWh) (ASSUMED)), Steam (1.188 kWh (4.28 MJ)/kg KOtBu of LP steam: the still's reboiler (0.714 kWh, the charge's heat-up and the metal included), the sieve's evaporator (0.223 kWh), R-101's warm-up, the potassium melter and tank heating), Steam (0.357 kWh (1.29 MJ)/kg KOtBu of MP steam to the paddle dryer at 433 K (cheme's dryer model, the vessel's metal each batch included)), Cooling water (1.774 kWh/kg KOtBu removed by cooling water, through a closed tempered-water loop at 303/313 K that keeps every condenser wall above tert-butanol's freezing point (298.3 K, D-009): the heat of reaction and R-101's vent condenser (R101's model), the still's condenser, the dryer's vapour condenser and product cooling, the recycle cooler and the sieve's condensers)

Show in the process graph

Reactions

IdAs writtenReactionOther processes
KTBAK + (CH3)3COH → (CH3)3COK + 1/2 H2 · Potassium with tert-butanol to potassium tert-butoxide and hydrogen2K+2C4H10O2C4H9KO+H2
WATK + H2O → KOH + 1/2 H2 · Potassium with the water of the make-up to KOH and hydrogen2K+2H2O2KOH+H2

Each reaction's page has the conversion, heat of reaction, catalyst and sources this process states, next to those of other processes with the same reaction. All reactions

Life cycle assessment

–kg CO2-eqPreliminarypartial, 12 data gaps

Climate change per 1 kg Potassium tert-butoxide powder, cradle-to-gate

No factors. No contribution is characterised, so no factor stands behind any number.

Main contributors
    Method and data
    Goal
    Preliminary gate-to-gate life cycle inventory of potassium tert-butoxide made from molten potassium and an excess of dry tert-butanol in a semi-batch, the hydrogen flared, the excess alcohol stripped in a batch still and recycled, the solvate dried to the alcohol-free powder under vacuum, and the make-up tert-butanol dried past its azeotrope with water on a molecular sieve, at the concept stage: which raw materials, utilities and wastes the batch plant exchanges per kg of dried potassium tert-butoxide, as the foreground for a later cradle-to-gate study. No impact results: most backgrounds are not mapped yet (D-012).
    Functional unit
    1 kg Potassium tert-butoxide powder (1 kg potassium tert-butoxide)
    Boundary
    cradle-to-gate
    Characterisation
    Factors kept with the process · GWP100
    Data quality
    No factors
    Result
    partial screening carbon footprint · 12 data gaps
    ScenarioClimate change (kg CO2-eq)
    baselineno total (data gaps)

    Inventory per 1 kg Potassium tert-butoxide powder (13 flows)

    FlowPhaseDirectionQuantityUnitProvenance
    Potassium metal (merchant)operationinput0.3482kgassumed
    tert-Butanol, azeotrope grade, the alcohol contained (tert-butanol-1)operationinput0.7342kgassumed
    Water of the azeotrope grade (with the tert-butanol of tert-butanol-1)operationinput0.09785kgassumed
    Electric poweroperationinput0.3252kWhassumed
    LP steam 350 kPa(a) (R-101 heat-up, the still, the potassium melter, the sieve's evaporator, tank heating)operationinput1.188kWhassumed
    MP steam 1000 kPa(a) (the dryer DR-101)operationinput0.3573kWhassumed
    Potassium tert-butoxide powder to packing under nitrogenoperationoutput1kgcalculated
    Vent gas (hydrogen with tert-butanol vapour) to the site flareoperationoutput0.0509kgcalculated
    Alcohol purge to solvent incinerationoperationoutput0.02489kgcalculated
    Sieve regeneration condensate to wastewater treatmentoperationoutput0.1045kgassumed
    Tempered water return (closed loop on the site's cooling water)operationoutput1.774kWhassumed
    Nitrogen for inerting R-101, blanketing C-101 and the tanks, pressing the potassium, the dryer's bleed and vacuum breaks and the vent header's purgeoperationinput0.1151kgassumed
    Disposal: Nitrogen for inerting R-101, blanketing C-101 and the tanks, pressing the potassium, the dryer's bleed and vacuum breaks and the vent header's purge (through the vent header to the site flare, unchanged (D-012))operationoutput0.1151kgassumed

    Computed by ChemE-as-Code from lca/README.md, lca/dataset.yaml, lca/factors.yaml, lca/gaps.csv, lca/inventory.csv, lca/lca.yaml, lca/mappings.yaml, lca/results.csv, lca/results.md.

    In the open LCI database (cheme-as-code-atlas-preview-a3c52e4) as Potassium tert-butoxide powder to packing under nitrogen Preliminary.

    Download it for Brightway, openLCA and other tools.

    In the LCI database: system model, datasets and KPIs against the benchmarks

    In the LCI database

    Status
    Preliminary 4 unmapped exchanges. Some exchanges have no background mapping yet: they are exported unlinked and count no burden, so the inventory is incomplete.
    System model
    attributional, cut-off (methodology 1.1.0)
    Allocation
    mass (single-output, from default) · product:KOTBU 100 %
    Allocation findings
    none
    Change report
    Not available: this build has no change report against an earlier release.
    Dataset pages
    Potassium tert-butoxide powder to packing under nitrogen Preliminary

    KPI benchmark positions

    KPIValueReference rangePosition
    Potassium metal consumption per kg of potassium tert-butoxide
    No open source with a plant's potassium use per kg of potassium tert-butoxide found (searched 2026-11-06: Google Patents US 4 577 045 A, US 5 053 560 A and US 6 150 569 A read, the KOH and amalgam routes, the metal route only as prior art without figures; Organic Syntheses Coll. Vol. 4, 132 and Coll. Vol. 5, 1060 read, laboratory preparations used in situ without a yield of the isolated alkoxide; Wikipedia, Potassium tert-butoxide, the route without figures). The stoichiometric floor is 0.3484 kg/kg (K + tert-butanol -> KOtBu + 1/2 H2), a limit, not a range of real plants.
    		– kg/kgnot availablenot evaluated
    tert-Butanol consumption per kg of potassium tert-butoxide
    No open source with a plant's tert-butanol use per kg of potassium tert-butoxide found (searched 2026-11-06, the sources named under kotbu-specific-potassium; US 4 577 045 A says the alcohol is recycled almost completely, without a figure). The stoichiometric floor is 0.6606 kg/kg; the losses to the vent, the purge and the sieve's regeneration are this design's ASSUMED values (potassium-tert-butoxide-1, DESIGN.md D-006, D-007).
    		– kg/kgnot availablenot evaluated

    Maturity and review

    Design maturity Concept (claimed): An idea or first flowsheet; numbers are rough. Concept batch PFD with closed mass, component and element balances (cheme validate: 4 blocks, 15 steps). Every material stream is calculated by cheme process propagate from the feeds except the sieve unit's two outlets: the semi-batch R101 from its ASSUMED rate laws with the hydrogen vented, the vent's vapour and its condenser (core ADRs 0054, 0062), the still from Raoult's law on NIST Antoine constants, the dryer to an ASSUMED residual alcohol content, the alcohol recycle converged at its tear S19 (core ADR 0060); the sieve unit A001 is a specified split with its duties from scripts/makeup_drying.py (core has no adsorption model). The feeds are sized by hand for 1000 t/a (the outlets scale with them); the duties of R101, its vent condenser and the still are written by the models (core ADRs 0059, 0061, 0062), the dryer's by core's dryer model, the other duties are hand arithmetic from the stream table. The recipe takes the dosing, post-reaction, warm-up, distillation and drying times from the models (cheme process recipe, no cheme.recipe-basis or cheme.recipe-jacket finding). Thermal screening (cheme process reactor-hazards): R101 dT_ad 60.2 K, accumulation 3.1 %, MTSR 350.1 K against an MTT of 355.45 K; a cooling failure's gas release 133.4 m3/h with the liquid's vapour (38.4 m3/h of hydrogen) at the end of the dosing, the largest over the batch, against an ASSUMED vent capacity of 200 m3/h; no criticality class without a TD24 from calorimetry (never estimated): classes 1, 2 or 5 remain possible. The kinetics are assumed: at k/10 the MTSR is 366.9 K and at k/100 399.9 K, above the MTT, the content boiling (a design finding: the dosing interlocked with the hydrogen flow, emergency relief from calorimetry, DESIGN.md D-011). Preliminary gate-to-gate LCI with nitrogen as a per-batch consumable; the make-up tert-butanol linked to tert-butanol-1 (kg of alcohol contained), nitrogen to asu-1; potassium metal a gap with its proxy recorded; the hydrogen flared, no credit. Not reviewed. Needs cheme-as-code 1.10.0.

    Calculation maturity, from the checked evidenceNot assessed

    The process has no maturity report (cheme maturity, checks/maturity.json), so no calculation maturity is established.

    No level shownThe design maturity (Concept) is the manifest's claim, not evidence. A level appears here once the process's repository holds a current report from cheme maturity --write.

    Artifact completeness

    Which deliverables exist. They never raise a calculation maturity level: a drawing from unchecked numbers is still unchecked.

    Not reported without a maturity report.

    Independent review

    Not independently reviewed

    No independent engineering review yet. Automated checks passing is not a review.

    Set by people only. Reaching a calculation maturity level or passing automated checks is not an independent review or an approval.

    Where the evidence comes from
    Report
    processes/potassium-tert-butoxide-1/checks/maturity.json (not in the library)
    Design basis
    process/design-basis.yaml
    Method
    How ChemE-as-Code checks the levels (requirement by requirement)

    Open items

    0 open items · 0 closed

    New action itemNew engineering holdNew technical queryNew design changeAll issues

    Sources

    Engineering project
    Potassium tert-butoxide · cheme-as-code>=1.10
    Library version
    a3c52e4 (process last changed in a3c52e4)
    Drawings rendered by
    cheme 1.6.0 (pyDEXPI 2.1.0)
    Data
    Catalog record (JSON) · CC-BY-4.0
    Files
    View the files on GitHub · change history and authors

    References

    How to cite

    For the data, cite the Process Atlas paper; for the platform that builds and checks it, the ChemE-as-Code paper.

    Schweidtmann, A. M. & Weber, J. M. (2026, in preparation). Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title).

    For this process: "Potassium tert-butoxide from potassium and dry tert-butanol, semi-batch with alcohol strip and vacuum drying (1000 t/a)", ChemE-as-Code process library, version a3c52e4.

    BibTeX
    @unpublished{schweidtmann_process_atlas,
  author = {Schweidtmann, Artur M. and Weber, Jana M.},
  title = {{Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title)}},
  year = {2026},
  url = {https://atlas.cheme-as-code.org},
  note = {in preparation}
}

    Schweidtmann, A. M. (2026). ChemE-as-Code: An Open-Source Platform for Agentic AI in Chemical Engineering. arXiv:2611.07947. https://doi.org/10.48550/arXiv.2611.07947

    BibTeX
    @misc{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for Agentic AI in Chemical Engineering}},
  year = {2026},
  eprint = {2611.07947},
  archivePrefix = {arXiv},
  doi = {10.48550/arXiv.2611.07947},
  url = {https://arxiv.org/abs/2611.07947}
}