Aniline by adiabatic gas-phase hydrogenation of nitrobenzene (25 t/h)

Nitrobenzene is evaporated into a large hydrogen recycle and hydrogenated to aniline over a palladium/alumina fixed bed; the reaction heat raises MP steam, the condensate is decanted, the process water stripped and the crude aniline dried and distilled. Concept stage, assumed basis, preliminary gate-to-gate inventory.

Calculation maturity: not assessedDesign maturity: Concept (research)Not independently reviewedNitrogen organicsReport 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

Liquid nitrobenzene is sprayed into the preheated hydrogen recycle gas (60 mol H2 per mol nitrobenzene at the reactor inlet) and converted completely in one adiabatic Pd-V-Pb/alpha- alumina bed (513 to 729 K, 5 bar) at a selectivity of 99.7 % to aniline; benzene and diphenylamine stand for the low- and high-boiling by-products, with ammonia. The effluent raises MP steam, preheats the recycle gas and is condensed; the gas is recycled with a small purge, the condensate splits into a wet crude aniline and an aniline-saturated water. A dehydration column, a vacuum aniline column and a process water stripper give aniline at 99.95 wt% and a process water with 50 ppm aniline.

All values are concept estimates. The reactor conditions and selectivity follow open Bayer (now Covestro) patents; the separator, decanter and columns come from an independent script whose activity approximation is not qualified by ChemE-as-Code; see DESIGN.md of the engineering files for every assumption and gated step.

Capacity
25 t/h aniline, 210 kt/a (ASSUMED)
Operation
8,400 h/a
Location
generic (not chosen)
Engineering gates
Concept and feasibility (no results yet)
Maintainers
Artur Schweidtmann
Design basis and assumptions (7)
  • ASSUMED reactor: single adiabatic Pd-V-Pb/alpha-alumina fixed bed, inlet 513.15 K and 530 kPa(a); conditions inside the preferred ranges of US 2008/0234518 A1 (D-003).
  • ASSUMED complete nitrobenzene conversion and selectivity 0.997 to aniline (US 2008/0234518 A1, example 3); remaining 0.3 % split 0.2 % benzene, 0.1 % diphenylamine (D-004).
  • ASSUMED H2/NB 60 mol/mol at the reactor inlet (patent range 3-150, most preferred 50-90); N2 held at 5 mol% in the loop gas by the purge (D-005).
  • ASSUMED three-phase separator at 333.15 K, 410 kPa(a); decanter at 313.15 K with 5 wt% water in the organic and 3.6 wt% aniline in the aqueous phase (D-007).
  • ASSUMED columns: C-201 top 60 kPa(a), C-202 top 20 kPa(a) with reflux ratio 0.5, C-102 at 101.3 kPa(a) with 50 ppm(wt) aniline in the bottoms; 30 % reflux margin on the C-201 and C-102 condensers (D-008).
  • ASSUMED circulator isentropic efficiency 0.75; pumps and vacuum pump 150 kW lumped (D-009).
  • All separator, column and duty values are concept estimates of scripts/aniline_balance.py with an unqualified activity approximation (D-006, D-007); accuracy not stated.

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

  • NitrobenzeneFeedstockfeed:NBF: nitrobenzene from the nitration plant, 1.33 kg/kg aniline
  • HydrogenFeedstockMake-up hydrogen from hydrogen-1 (99.9 mol%, 2850 kPa(a))

Out

  • AnilineMain productAniline to storage
  • SteamCo-productMP steam 1500 kPa(a) raised from the reaction heat, net of the reboilers (product:MPSX)
  • WastewaterWasteStripped process water, 50 ppm(wt) aniline and about 0.1 wt% ammonia (ASSUMED)

Utilities: Electricity (Circulator K-101, pumps and vacuum pump (ASSUMED electric drives)), Cooling water (25/35 C (ASSUMED))

Show in the process graph

Reactions

IdAs writtenReactionOther processes
BZ_FORMC6H5NO2 + 4 H2 → C6H6 + NH3 + 2 H2OC6H5NO2+4H2C6H6+NH3+2H2O
DPA_FORM2 C6H5NO2 + 6 H2 → (C6H5)2NH + NH3 + 4 H2O2C6H5NO2+6H2C12H11N+NH3+4H2O
NB_HYDC6H5NO2 + 3 H2 → C6H5NH2 + 2 H2OC6H5NO2+3H2C6H7N+2H2O

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 Aniline to storage Preliminary; MP steam export (1500 kPa(a)), net of the reboilers 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
exergy (deviation, from study) · product:ANILINE 98.2 %, product:MPSX 1.8 %
Allocation findings
none
Change report
Not available: this build has no change report against an earlier release.
Dataset pages
Aniline to storage Preliminary · MP steam export (1500 kPa(a)), net of the reboilers 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). The reactor outlet is calculated by cheme from a sourced selectivity (US 2008/0234518 A1, example 3) and its adiabatic duty checks to within 1 kW; the capacity, feed state, by-product split, separator, decanter and column values are ASSUMED or come from scripts/aniline_balance.py, whose vapour-liquid-liquid model of aniline and water is not qualified. Energy closure of the separations is not evaluable in core. 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/aniline-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
Aniline (nitrobenzene hydrogenation) · 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: "Aniline by adiabatic gas-phase hydrogenation of nitrobenzene (25 t/h)", 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}
}