Tetrahydrofuran from 1,4-butanediol (50 kt/a, cyclodehydration and pressure-swing distillation)

Acid-catalysed cyclodehydration of purchased 1,4-butanediol to THF by reactive distillation with homogeneous p-toluenesulfonic acid, then pressure-swing distillation of the THF/water azeotrope at 110 and 800 kPa(a) with condenser-reboiler integration. Concept stage, assumed basis, preliminary gate-to-gate LCI (foreground only).

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

1,4-Butanediol (BDO, a boundary feed) is dehydrated at 145 C and 130 kPa(a) in a stirred, steam-heated reactor with 2 wt% p-toluenesulfonic acid in the liquid, within the ranges of a published reactive-distillation patent (US 9284289 B2). A short rectifying column on the reactor holds BDO and heavies back; THF and the water of reaction leave overhead as an 80 wt% THF condensate. Heavies (lumped as the BDO dimer ether) are held at 30 wt% in the reactor liquid by a bleed to incineration, which also removes the acid. The condensate and the high-pressure column's distillate are separated in a low-pressure column (110 kPa(a)) into process water and a near-azeotropic distillate, which a high-pressure column (800 kPa(a)) splits into THF (99.95 wt%) and a recycle near the high-pressure azeotrope. The high-pressure condenser reboils the low-pressure column.

All values are concept estimates. The selectivity, bleed and column specifications are assumed; the stream and duty values come from an independent script whose property method (NRTL with the ChemSep THF/water parameters in thermo) is not qualified by ChemE-as-Code for this mixture yet. The same NRTL parameters predict two liquid phases in part of the low-pressure column's stripping range, while its reflux and duties come from a calculation that assumes one homogeneous liquid, so the LP column duties are unverified; see DESIGN.md of the engineering files for every assumption and gated step.

Capacity
50 kt/a THF (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 (6)
  • Route: liquid-phase cyclodehydration of BDO with a homogeneous sulfonic acid (p-toluenesulfonic acid, 2 wt% in the reactor liquid) by reactive distillation at 145 C and 130 kPa(a), within the ranges of US 9284289 B2 (80-250 C, preferred 120-180 C; 0.01-20 wt% acid; 2-8 wt% water in the reactor liquid) (D-001, D-004).
  • ASSUMED THF selectivity 0.995 kmol per kmol BDO converted, the rest to heavies lumped as the BDO dimer ether (DHBE); heavies held at 30 wt% in the reactor liquid by a bleed: plant BDO conversion 0.9906, THF yield 0.9857 mol/mol BDO fed (D-005). A sourced conversion/selectivity model is not available; no kinetics.
  • ASSUMED pressure-swing distillation: LP column 110 kPa(a), HP column 800 kPa(a); distillates 0.03 mol/mol on the feasible side of each NRTL azeotrope (x_THF 0.827 at 110 kPa(a), 0.651 at 800 kPa(a)); reflux 1.3 x minimum, at least 0.3 (D-007).
  • ASSUMED heat integration: the HP column condenser reboils the LP column (E-201), LP steam trims (D-009).
  • ASSUMED pump efficiency 0.6; reflux of the reactor rectifying column 0.5 (D-004, D-008).
  • All flows, temperatures and duties are concept estimates from an unqualified property method (thermo NRTL, ChemSep THF/water parameters, ideal gas, D-006); accuracy not stated.

From process/design-basis.yaml.

Engineering model

Loading the drawing…
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

Out

  • TetrahydrofuranMain productTHF to storage
  • WastewaterWasteProcess water with about 80 ppm(wt) THF to treatment (product:WW, 0.249 kg per kg THF)

Utilities: Steam (MP steam 1000 kPa(a), R-101 and HP column reboiler (feed:MPS); LP steam 450 kPa(a), LP column trim reboiler (feed:LPS)), Electricity (Pumps P-101 and P-201 (feed:POWER)), Cooling water (25/35 C (ASSUMED), product:CW)

Show in the process graph

Reactions

IdAs writtenReactionOther processes
CYCLOC4H10O2 → C4H8O + H2OC4H10O2C4H8O+H2O
ETHER2 C4H10O2 → C8H18O3 + H2O2C4H10O2C8H18O3+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

No footprint assessed yet; the process is part of the life-cycle inventory below.

In the open LCI database (cheme-as-code-atlas-preview-c3ab348) as Tetrahydrofuran, THF product 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 3 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
none (single-output, from study) · product:THFP 100 %
Allocation findings
none
Change report
Not available: this build has no change report against an earlier release.
Dataset pages
Tetrahydrofuran, THF product 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 balances (cheme validate, cheme process streams, cheme assess lca --balance: mass, C, H, O, S closed to 0.01 %) and an independent overall energy closure of 0.01 % (scripts/thf_balance.py). cheme maturity reaches no level: the feeds and the capacity are assumed (no sourced or owner-given feed), the reactor is a conversion model with an assumed selectivity, and the three columns are specified values from an independent NRTL script that core cannot qualify for THF/water (polar activity-coefficient benchmark, liquid-phase reactor energy). The LCI is a gate-to-gate foreground inventory with every background open (8 gaps): no impact result, and no LCA result passed to the catalog (lca.source none). 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/thf-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
Tetrahydrofuran (BDO dehydration) · 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: "Tetrahydrofuran from 1,4-butanediol (50 kt/a, cyclodehydration and pressure-swing distillation)", 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}
}