Acetaldehyde by the one-stage Wacker oxidation of ethylene (100 kt/a)

Ethylene and oxygen react in an aqueous PdCl2/CuCl2 catalyst solution in a boiling bubble column; the cycle gas is cooled, scrubbed with water and recycled with a purge, and the crude acetaldehyde is purified in two live-steam columns. Ethylene and oxygen are boundary feeds. Concept stage.

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

One-stage (Hoechst-Wacker) process: ethylene and 99.5 % oxygen are fed to a bubble-column reactor with the aqueous palladium/copper chloride catalyst at about 130 C and 400 kPa(a). The heat of reaction evaporates water; a precondenser returns it, a cooler condenses an acetaldehyde-rich aqueous condensate and a water scrubber recovers the rest of the acetaldehyde. The scrubbed cycle gas is recompressed and recycled; a small purge limits CO2, argon and ethane. Crude acetaldehyde (about 12 wt%) passes an extractive light-ends column (CO2, chloroethane, chloromethane) and the acetaldehyde column, which gives 99.9 wt% product overhead, a side draw of crotonaldehyde and chlorinated aldehydes, and waste water with the acetic acid at the bottom. A catalyst side stream is regenerated with direct steam.

All values are concept estimates (scripts/acet_balance.py of the engineering files): the ethylene fate follows the product distribution reported for the industrial process; water, steam and waste-water rates are scaled from the 13 t/h example of US 4,237,073; conversion per pass and the cycle-gas oxygen content are assumptions. See DESIGN.md for every assumption and gated step.

Capacity
100 kt/a acetaldehyde, 99.9 wt% (ASSUMED)
Operation
8,000 h/a
Location
generic (not chosen)
Engineering gates
Concept and feasibility (no results yet)
Maintainers
Artur Schweidtmann
Design basis and assumptions (8)
  • Route: one-stage Wacker process, ethylene and oxygen reacting together in an aqueous PdCl2/CuCl2/HCl catalyst solution in a bubble-column reactor at about 403 K and 400 kPa(a) (Wikipedia 'Wacker process', citing Ullmann's; US 4,237,073: 125-135 C, 3-4.5 bar abs) (D-001, D-005).
  • Ethylene fate per 100 mol fed: 95 acetaldehyde, 1.9 chlorinated aldehydes, 1.1 unconverted, 0.8 CO2, 0.7 acetic acid (Wikipedia, citing Ullmann's); our split of the remainder: crotonaldehyde 0.25, chloroethane 0.15, chloromethane 0.10; chlorinated aldehydes 1.6 plus 0.3 of acetaldehyde losses (D-004).
  • ASSUMED ethylene conversion per pass 35 % and 8 mol% O2 in the cycle gas (kept below the limiting oxygen concentration), not sourced (D-004, D-007).
  • Heat of reaction removed by evaporating water from the catalyst solution; the precondenser returns the water needed to close the reactor energy balance (D-005).
  • ASSUMED gas cooling to 318 K with 30 % of the acetaldehyde condensed; water scrubber to 0.05 mol% acetaldehyde in the cycle gas; CO2 and ethylene dissolved in the crude by Henry's law (NIST WebBook), chloroethane and chloromethane fully absorbed (D-007).
  • Distillation: an extractive light-ends column and an acetaldehyde column, both heated with live steam at the rates of US 4,237,073 scaled to 12.5 t/h; 0.2 % of the acetaldehyde lost to the light ends; waste water at the patent's 200 mg/kg organic chlorine and 360 mg/kg aldehyde; side draw 40 wt% heavy organics, 10 wt% acetaldehyde (D-008).
  • The catalyst inventory (Pd, Cu) and its losses are not quantified (no open source found): an open item of the LCI (D-010).
  • All flows and duties are concept estimates from scripts/acet_balance.py (D-006); accuracy not stated, roughly +/-30 % for duties.

From process/design-basis.yaml.

Engineering model

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Drawing of the process (preview)Open the engineering model

The interactive model (drawings, streams, 3D) is made for larger screens.

Snapshot of c3ab348, cheme-as-code 1.6.0.

What goes in and out

In

  • EthyleneFeedstockfeed:ETH: polymer-grade ethylene, 0.676 kg/kg acetaldehyde (boundary feed; e.g. a steam cracker such as ethylene-1)
  • Hydrogen chlorideFeedstockfeed:HCLA: hydrochloric acid 30 wt% (catalyst make-up), counted by mass of the solution
  • OxygenFeedstock99.5 mol% O2 at 600 kPa(a), 410 kg/t (boundary feed; e.g. processes/asu-1)
  • WaterFeedstockDemineralised water: reactor make-up and extraction water, 1.27 t/t
  • WaterFeedstockProcess water to the acetaldehyde scrubber, 5.96 t/t

Out

  • AcetaldehydeMain productAcetaldehyde 99.9 wt% to storage
  • WastewaterWasteColumn bottoms with acetic acid, residual aldehydes and organic chlorine, 8.7 t/t, to biological treatment
  • Carbon dioxideEmissionCycle-gas purge (CO2, ethylene, argon, ethane, O2) to a thermal oxidiser outside the boundary

Utilities: Electricity (Cycle-gas compressor and pumps (ASSUMED electric drives), 42.8 kWh/t), Steam (LP steam 450 kPa(a) injected live into the two columns, 1.31 t/t), Steam (MP steam 1000 kPa(a) injected into the catalyst regenerator, 0.115 t/t), Cooling water (25/35 C (ASSUMED))

Show in the process graph

Reactions

IdAs writtenReactionOther processes
R1C2H4 + 0.5 O2 → ACH2C2H4+O22C2H4O
R2C2H4 + O2 → ACOHC2H4+O2C2H4O2
R3C2H4 + 3 O2 → 2 CO2 + 2 H2OC2H4+3O22CO2+2H2O3 other processes
R4C2H4 + HCL + O2 → CAC + H2OC2H4+HCl+O2C2H3ClO+H2O
R5C2H4 + HCL → ETCLC2H4+HClC2H5Cl
R6C2H4 + HCL + 1.5 O2 → MECL + CO2 + H2O2C2H4+2HCl+3O22CH3Cl+2CO2+2H2O
R72 ACH → CROT + H2O2C2H4OC4H6O+H2O

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

Footprint not publishedThe process changed since the LCA was last run; its values return once it is run again. Method, functional unit and inventory are below.
Method and data
Goal
Preliminary gate-to-gate life cycle inventory of acetaldehyde (99.9 wt%) by the one-stage Wacker oxidation of ethylene at the concept stage, for the process library: the foreground exchanges per kg of product with their provenance, and the list of backgrounds still to link. Not an impact result: every background is a gap.
Functional unit
1 kg Acetaldehyde 99.9 wt% (1 kg acetaldehyde)
Boundary
gate-to-gate
Characterisation
Factors kept with the process · GWP100
Data quality
No factors
Result
partial screening carbon footprint · 13 data gaps

Inventory per 1 kg Acetaldehyde 99.9 wt% (14 flows)

FlowPhaseDirectionQuantityUnitProvenance
Ethylene, polymer grade (boundary feed; e.g. a steam cracker)operationinput0.6765kgassumed
Oxygen 99.5 mol% (boundary feed; e.g. from asu-1)operationinput0.4096kgassumed
Hydrochloric acid 30 wt% (catalyst make-up)operationinput0.05416kgassumed
Demineralised wateroperationinput1.269kgassumed
Process water to the scrubberoperationinput5.962kgassumed
MP steam 1000 kPa(a), direct (catalyst regenerator)operationinput0.1154kgassumed
LP steam 450 kPa(a), direct (live steam to the columns)operationinput1.308kgassumed
Electric poweroperationinput0.04277kWhassumed
Acetaldehyde 99.9 wt% to storageoperationoutput1kgcalculated
Cycle-gas purge to the thermal oxidiseroperationoutput0.0198kgcalculated
Light ends to the thermal oxidiseroperationoutput0.01636kgassumed
Crotonaldehyde and chlorinated aldehyde side draw to incinerationoperationoutput0.0713kgassumed
Waste water to biological treatmentoperationoutput8.687kgcalculated
Cooling water returnoperationoutput2.591kWhassumed

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-c3ab348) as Acetaldehyde 99.9 wt% to storage 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:PROD 100 %
Allocation findings
none
Change report
Not available: this build has no change report against an earlier release.
Dataset pages
Acetaldehyde 99.9 wt% to storage Preliminary

KPI benchmark positions: not available (no benchmarked KPI for this process's datasets).

Maturity and review

Design maturity Concept (claimed): An idea or first flowsheet; numbers are rough. Concept PFD with closed mass, component and element (reaction extent) balances in every block and step (cheme validate, cheme process streams). The reactor is a selectivity model calculated by cheme (per-pass conversion ASSUMED 35 %, selectivities from the reported ethylene fate); separator outlets, the cycle-gas loop and all duties are specified values of an independent script (scripts/acet_balance.py). Consumptions agree with the 1980 patent example (ethylene 677 vs 692 kg/t, oxygen 410 vs 408 kg/t, waste water 8.7 vs 8.7 m3/t). Energy closure is not evaluable in core. The preliminary gate-to-gate LCI in lca/ leaves every background unmapped (gaps). Not reviewed. Main products and feeds are listed under chemistry with their chemicals registry entries (issue #251).

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/acetaldehyde-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
Acetaldehyde (Wacker process) · cheme-as-code>=0.8
Library version
c3ab348 (process last changed in c3ab348)
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: "Acetaldehyde by the one-stage Wacker oxidation of ethylene (100 kt/a)", ChemE-as-Code process library, version c3ab348.

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, in preparation). ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title).

BibTeX
@unpublished{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title)}},
  year = {2026},
  url = {https://cheme-as-code.org},
  note = {in preparation}
}