{ "authors": [], "basis": { "capacity": "1000 t/a distilled benzyl bromide: 1127 batches/a of 887.3 kg in 7920 h on a dedicated train (126.26 kg/h year average), ASSUMED (DESIGN.md D-002, D-003, D-013)", "location": "generic fine-chemicals site with bromine and toluene supplies (not chosen)", "operating_hours_per_year": 7920 }, "benchmarks": [ { "dataset": "benzyl-bromide-by-semi-batch-light-driven-side-chain-bromination-of-toluene-with-hbr-absorption-and-batch-distillation-1000-t-a", "expression": "feed:BR2 / product:BNBR", "family": "chlorinated-organics", "kpi": "bnbr-specific-bromine", "no_open_reference": "No open source with a plant's or a pilot's bromine use per kg of benzyl bromide found (searched 2026-11-06: Google Patents US 3 528 899 A read, a laboratory example with X-ray initiation at 1.2 mol of bromine per mol of toluene, about 90 % on toluene, no yield on bromine; PubChem CID 7498 (HSDB) names the route without figures; NIST WebBook has no plant data). Only the stoichiometric floor, 0.934 kg/kg, is known.", "problem": "1 to kg/kg needs core's foundation.units (pip install 'cheme-as-code[units]')", "reference": null, "status": "unchecked", "title": "Bromine consumption per kg of benzyl bromide", "unit": "kg/kg", "value": null }, { "dataset": "benzyl-bromide-by-semi-batch-light-driven-side-chain-bromination-of-toluene-with-hbr-absorption-and-batch-distillation-1000-t-a", "expression": "feed:TOL / product:BNBR", "family": "chlorinated-organics", "kpi": "bnbr-specific-toluene", "no_open_reference": "No open source with a plant's toluene use per kg of benzyl bromide found (searched 2026-11-06 as for bnbr-specific-bromine). US 3 528 899 A, Example I implies about 0.60 kg/kg (about 90 % of theory on toluene), one laboratory value under other initiation and excess bromine, not a range; the stoichiometric floor is 0.539 kg/kg.", "problem": "1 to kg/kg needs core's foundation.units (pip install 'cheme-as-code[units]')", "reference": null, "status": "unchecked", "title": "Toluene consumption per kg of benzyl bromide", "unit": "kg/kg", "value": null } ], "chemistry": { "inputs": [ { "chemical": "bromine", "grade": null, "inventory_key": "feed:BR2", "note": "Dry bromine (bromine-1), 1.034 kg/kg benzyl bromide (stoichiometric 0.934)", "role": "feedstock" }, { "chemical": "toluene", "grade": null, "inventory_key": "feed:TOL", "note": "Toluene make-up (btx-1), 0.614 kg/kg; 1.95 kg/kg of recovered toluene (91 wt% toluene, 9 wt% benzyl bromide) is recycled within the plant", "role": "feedstock" }, { "chemical": "water", "grade": null, "inventory_key": "feed:PW", "note": "Process water to the HBr absorber, 0.565 kg/kg", "role": "feedstock" }, { "chemical": "nitrogen", "grade": null, "inventory_key": "consumable:nitrogen", "note": "Nitrogen (asu-1) for inerting, breaking the vacuum and padding, 25 kg per batch, 28 g/kg (ASSUMED)", "role": "feedstock" } ], "outputs": [ { "chemical": "benzyl-bromide", "grade": null, "inventory_key": "product:BNBR", "note": "Distilled benzyl bromide to storage under nitrogen; modelled 99.85 wt%, an upper bound (ring-brominated and condensation by-products not modelled, DESIGN.md D-007)", "role": "main-product" }, { "chemical": "hydrogen-bromide", "grade": null, "inventory_key": "product:HBRACID", "note": "Hydrobromic acid 48 wt% (on HBr and water), 1.094 kg/kg (0.522 kg HBr), counted by mass of the acid; allocated by mass of its HBr, shares 0.6572/0.3428 (DESIGN.md D-012)", "role": "co-product" } ], "utilities": [ { "chemical": "electricity", "grade": null, "inventory_key": "feed:POWER", "note": "0.160 kWh/kg: the lamps of R-101 (0.118 kWh/kg), the agitators and the vacuum pump (ASSUMED)", "role": "utility" }, { "chemical": "steam", "grade": null, "inventory_key": "feed:LPS", "note": "0.431 kWh/kg of LP steam 450 kPa(a): R-101's heat-up and the still with its column (the reboilers from core's models, DESIGN.md D-009)", "role": "utility" }, { "chemical": "cooling-water", "grade": null, "inventory_key": "product:CW", "note": "0.666 kWh/kg removed: R-101's jacket and lamp wells, the reflux condenser, the absorber, the still's and the column's condensers and coolers", "role": "utility" }, { "chemical": "chilled-water", "grade": null, "inventory_key": "product:BRINE", "note": "0.046 kWh/kg removed by brine at 258 K: the vent condenser and the column's condenser and cooler during the forerun (the registry has chilled water, not brine: closest entry)", "role": "utility" } ] }, "description": "Bromine is dosed at a constant rate over 5 h into toluene (4 mol per mol of bromine, the\nrecycled toluene counted) at 363 K in a glass-lined photoreactor with immersion lamps, and the\nfree-radical chain brominates the side chain: C7H8 + Br2 -> C7H7Br + HBr, and in series\nC7H7Br + Br2 -> C7H6Br2 + HBr (the route PubChem's HSDB names for benzyl bromide, bromine and\ntoluene under light; US 3 528 899 A describes the dosing at the rate the bromine reacts). The\nHBr leaves the liquid as it forms, saturated with the content's vapour (about 0.9 mol per mol,\nmostly toluene), through a reflux condenser that returns the vapour to the reactor and a brine\nvent condenser whose condensate is recycled, and is absorbed in water to 48 wt% hydrobromic\nacid, 1.094 kg per kg of product (a co-product). The crude is stripped of most of its toluene\nat 15 kPa(a), then distilled at 2 kPa(a) in the same batch still through a packed column of\nabout 5 theoretical stages: a forerun (toluene with some benzyl bromide, reflux ratio 2) that\ngoes back with the stripped toluene to the next batch, 2 % of it purged, and the main cut\n(reflux ratio 0.5), 99.85 wt% benzyl bromide with 0.11 wt% toluene and 0.04 wt% benzal\nbromide in the model (an upper bound: ring-brominated toluenes and condensation products are\nnot modelled). The benzal bromide residue goes to incineration. Yields 90.2 % on the bromine\nand 87.7 % on the toluene make-up (US 3 528 899 A, Example I: about 90 % on toluene); both\nfollow from an ASSUMED ratio of the two rate constants.\n\nThe batch is modelled with cheme-as-code's semi-batch reactor with a gas vent that carries the\nliquid's vapour through a vent condenser (reactor: semibatch, batch.vent with vapour and\ncondenser, core ADRs 0050, 0054 and 0062), its batch still (still:, one Rayleigh stage for the\nstrip, ADR 0055) with a column for the forerun and the main cut (still.column, Diwekar's\nshortcut, ADR 0061) and the batch recipe (process/recipe.yaml, ADRs 0051, 0052 and 0057): the\ndosing, post-reaction and distillation times come from the models, the photoreactor is the\nbottleneck (cycle 7.03 h, 1127 batches a year), the recipe sizes it (4 m3) and checks its\njacket, and the flowsheet's flows are the recipe's year averages; the toluene recycle is\nconverged at its tear stream by cheme process propagate. The light-driven rate is an ASSUMED\neffective rate law (core has no photochemical rate): the bromine accumulates to 1.7 % at the\nend of the dosing and the cooling-failure temperature stays 20 K below the boiling point of\ntoluene; a 100 times slower reaction (weak or failed lamps) would exceed it. See DESIGN.md for\nevery assumption.\n", "design_basis": { "assumptions": [ "Route: bromine dosed into excess toluene under light, the HBr leaving as gas (PubChem CID 7498, HSDB; US 3 528 899 A, background and Example I); 4 mol of toluene per mol of bromine, 363 K, 5 h dosing, ASSUMED (D-001, D-004, D-005).", "ASSUMED effective rate laws for the light-driven chain (core has no photochemical rate law): k1 5.0e-4 m3/(kmol s) at 363 K, k2/k1 0.2; the lamps sized for an ASSUMED quantum yield of 20 (D-005); the 1.7 % accumulation follows from them.", "ASSUMED all HBr leaves the liquid as it forms (batch.vent fraction 1): none stays dissolved in the crude (D-005).", "Stills: the strip one Rayleigh stage, the forerun and the main cut through a packed column of 5 theoretical stages at reflux 2 and 0.5 (ASSUMED; Diwekar's shortcut in cheme), all on Raoult's law with NIST Antoine constants (an ideal liquid, ASSUMED), benzal bromide's vapour pressure ASSUMED from one measured point (D-007).", "The HBr leaves R-101 saturated with the content's vapour (Raoult, ASSUMED ideal liquid), condensed in E-102 at 303 K and E-103 at 268 K (D-008).", "All flows are year averages of the recipe (D-003); the duties and power concept estimates (scripts/balance.py, D-006, D-009); accuracy +/-30 % not demonstrated." ], "source": "process/design-basis.yaml" }, "engineering": { "description": "Benzyl bromide by light-driven semi-batch side-chain bromination of toluene with an HBr vent to 48 wt% acid, toluene strip and recycle, batch vacuum distillation, a batch plant, concept stage (issue ChemE-as-Code/process-library#139)", "name": "Benzyl bromide", "requires": "cheme-as-code>=1.10", "stage": "concept", "stages": [ { "id": "concept", "title": "Concept and feasibility" }, { "id": "basic", "title": "Basic engineering" }, { "id": "detail", "title": "Detail engineering" } ], "tool": "plantcode" }, "facets": { "feedstock_basis": [ "fossil", "mineral", "electricity" ], "product_classes": [ "chemicals" ], "region": "generic", "unit_operations": [ "reaction", "absorption", "distillation" ] }, "families": [ "chlorinated-organics" ], "gap_count": 3, "gates": null, "id": "benzyl-bromide-1", "issues": { "closed_count": 0, "list_url": "https://github.com/ChemE-as-Code/process-library/issues?q=is%3Aissue%20label%3A%22process%3Abenzyl-bromide-1%22", "new": { "action": "https://github.com/ChemE-as-Code/process-library/issues/new?template=1-action-item.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1", "change": "https://github.com/ChemE-as-Code/process-library/issues/new?template=4-design-change.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1", "hold": "https://github.com/ChemE-as-Code/process-library/issues/new?template=2-engineering-hold.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1", "process": "https://github.com/ChemE-as-Code/process-library/issues/new?template=6-process-development.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1", "tq": "https://github.com/ChemE-as-Code/process-library/issues/new?template=3-technical-query.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1", "tracker": "https://github.com/ChemE-as-Code/process-library/issues/new?template=7-process-tracker.yml&labels=process%3Abenzyl-bromide-1&process=benzyl-bromide-1" }, "open": [], "open_by_gate": {}, "open_count": 0, "private": false, "repository": "ChemE-as-Code/process-library" }, "keywords": [ "benzyl bromide", "toluene", "bromine", "side-chain bromination", "photobromination", "free-radical bromination", "benzal bromide", "hydrobromic acid", "semi-batch", "batch", "dosing", "gas evolution", "HBr off-gas", "batch distillation", "vacuum distillation", "solvent recycle", "thermal screening", "lachrymator", "fine chemicals" ], "lca": { "allocation": "shares", "backend": "factors", "boundary": "cradle-to-gate", "categories": [ { "id": "climate-change", "method": "GWP100", "title": "Climate change", "unit": "kg CO2-eq" } ], "contributions": [], "data_sources": [], "factors_status": "none", "functional_unit": { "amount": 1, "chemical": "benzyl-bromide", "grade": null, "label": "1 kg benzyl bromide", "product": "BNBR", "product_name": "Benzyl bromide", "product_title": "Benzyl bromide to storage", "unit": "kg" }, "goal": "Preliminary gate-to-gate life cycle inventory of benzyl bromide made by the light-driven semi-batch side-chain bromination of toluene with bromine, the HBr off-gas absorbed to 48 wt% hydrobromic acid, the toluene stripped and recycled and the product distilled under vacuum, at the concept stage: which raw materials, utilities and wastes the batch plant exchanges per kg of distilled benzyl bromide, as the foreground for a later cradle-to-gate study. No impact results: most backgrounds are not mapped yet (D-012).", "inventory": [ { "direction": "input", "key": "feed:TOL", "kind": "material", "phase": "operation", "provenance": "assumed", "quantity": 0.403249, "title": "Toluene make-up (btx-1)", "unit": "kg" }, { "direction": "input", "key": "feed:BR2", "kind": "material", "phase": "operation", "provenance": "assumed", "quantity": 0.679471, "title": "Bromine (bromine-1)", "unit": "kg" }, { "direction": "input", "key": "feed:PW", "kind": "material", "phase": "operation", "provenance": "assumed", "quantity": 0.371393, "title": "Process water (HBr absorber)", "unit": "kg" }, { "direction": "input", "key": "feed:POWER", "kind": "energy", "phase": "operation", "provenance": "assumed", "quantity": 0.104893, "title": "Electric power", "unit": "kWh" }, { "direction": "input", "key": "feed:LPS", "kind": "energy", "phase": "operation", "provenance": "assumed", "quantity": 0.283323, "title": "LP steam 450 kPa(a) (R-101 heat-up, still C-101)", "unit": "kWh" }, { "direction": "output", "key": "product:BNBR", "kind": "material", "phase": "operation", "provenance": "calculated", "quantity": 1.0, "title": "Benzyl bromide to storage", "unit": "kg" }, { "direction": "output", "key": "product:HBRACID", "kind": "material", "phase": "operation", "provenance": "calculated", "quantity": 1.09395, "title": "Hydrobromic acid 48 wt% (co-product)", "unit": "kg" }, { "direction": "output", "key": "product:RES", "kind": "material", "phase": "operation", "provenance": "calculated", "quantity": 0.0518275, "title": "Still residue (benzal bromide) to hazardous-waste incineration", "unit": "kg" }, { "direction": "output", "key": "product:PURGE", "kind": "material", "phase": "operation", "provenance": "calculated", "quantity": 0.0261448, "title": "Toluene purge to hazardous-waste incineration", "unit": "kg" }, { "direction": "output", "key": "product:CW", "kind": "energy", "phase": "operation", "provenance": "assumed", "quantity": 0.437959, "title": "Cooling water return", "unit": "kWh" }, { "direction": "output", "key": "product:BRINE", "kind": "energy", "phase": "operation", "provenance": "assumed", "quantity": 0.0304823, "title": "Chilled brine return (263 K)", "unit": "kWh" }, { "direction": "input", "key": "consumable:nitrogen", "kind": "material", "phase": "operation", "provenance": "assumed", "quantity": 0.0185185, "title": "Nitrogen for inerting R-101 and C-101, breaking the vacuum and padding the receivers", "unit": "kg" } ], "no_total": { "baseline": { "climate-change": { "gaps": 10, "reason": "every-contribution-a-gap" } } }, "not_computed": [ "climate-change" ], "pcf": [], "publishable": true, "result": { "classification": "partial", "gaps": 10, "label": "partial screening carbon footprint", "publication": "public" }, "sources": [ "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" ], "totals": { "baseline": {} }, "withheld_reason": null }, "lci_gaps": [ { "dataset": "benzyl-bromide-by-semi-batch-light-driven-side-chain-bromination-of-toluene-with-hbr-absorption-and-batch-distillation-1000-t-a", "key": "product:RES", "link": "technosphere", "type": "output" }, { "dataset": "benzyl-bromide-by-semi-batch-light-driven-side-chain-bromination-of-toluene-with-hbr-absorption-and-batch-distillation-1000-t-a", "key": "product:PURGE", "link": "technosphere", "type": "output" }, { "dataset": "benzyl-bromide-by-semi-batch-light-driven-side-chain-bromination-of-toluene-with-hbr-absorption-and-batch-distillation-1000-t-a", "key": "product:BRINE", "link": "technosphere", "type": "output" } ], "maintainers": [ { "name": "Artur Schweidtmann" } ], "maturity": "concept", "preliminary": true, "provenance": { "library_commit": "a3c52e472f42fbc8cdacfeacf5ef28703c004174", "previews": { "sheets": [ "BFD", "PFD" ], "source_commit": "a3c52e472f42fbc8cdacfeacf5ef28703c004174", "tool": "cheme 1.6.0 (pyDEXPI 2.1.0)" }, "previews_stale": false, "source_commit": "a3c52e472f42fbc8cdacfeacf5ef28703c004174" }, "publication": { "license": "CC-BY-4.0", "status": "public" }, "references": [ { "title": "Plander, E.; Zahalka, J.; Formacek, V. (1970) US 3 528 899 A, Method of brominating the side chain of an alkyl benzene (background: light-, heat- and peroxide-activated processes; Example I: bromine dosed into toluene at the rate it reacts, HBr withdrawn, product cut at 190-210 C, about 90 % on toluene)", "url": "https://patents.google.com/patent/US3528899A/en" }, { "title": "PubChem CID 7498, Benzyl bromide (identity; HSDB: methods of manufacturing, physical properties, reactivity and hazards)", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/7498" }, { "title": "NIST Chemistry WebBook, SRD 69: toluene, bromine, benzyl bromide, benzal bromide (Antoine constants, heats of vaporization, boiling points, formation enthalpies)", "url": "https://webbook.nist.gov/chemistry/" }, { "doi": "10.1002/9783527621606", "title": "Stoessel, F. (2008) Thermal Safety of Chemical Processes, Wiley-VCH (accumulation and MTSR of a semi-batch; method reference, not data)" } ], "repository": { "access": "public", "path": "processes/benzyl-bromide-1", "url": "https://github.com/ChemE-as-Code/process-library" }, "representations": [ { "bytes": 38769, "id": "BFD", "kind": "bfd", "preview": "artifacts/benzyl-bromide-1/BFD.svg", "source": "process/BFD.xml", "status": "preview", "title": "Block flow diagram" }, { "bytes": 125024, "id": "PFD", "kind": "pfd", "preview": "artifacts/benzyl-bromide-1/PFD.svg", "source": "process/PFD.xml", "status": "preview", "title": "Process flow diagram" }, { "id": "process-model", "kind": "process-model", "source": "process/flowsheet.yaml", "status": "viewer", "title": "Flowsheet and stream table" }, { "id": "equipment-list", "kind": "equipment-list", "source": "equipment/equipment-list.yaml", "status": "viewer", "title": "Equipment list" }, { "id": "lca", "kind": "lca", "source": "lca/lca.yaml", "status": "viewer", "title": "Life cycle assessment" } ], "summary": "A batch plant: bromine is dosed over 5 h into excess toluene at 363 K under lamps; the HBr is absorbed to 48 wt% acid, and the crude is stripped of its toluene (recycled) and distilled under vacuum through a packed column. Concept stage, 887.3 kg per batch every 7.03 h on a dedicated train, thermal screening with a rate-constant sensitivity, preliminary gate-to-gate LCI.", "title": "Benzyl bromide by light-driven semi-batch bromination of toluene, HBr absorption and batch distillation (1000 t/a)", "validation": { "notes": "Concept batch PFD with closed mass, component and element balances (cheme validate, cheme process streams: 3 blocks and 10 steps within tolerance). The semi-batch R101 with its HBr vent carrying the content's vapour through its vent condenser E-102 (from its ASSUMED effective rate laws, Raoult over an ideal liquid; core ADR 0062), the strip ST101 (one Rayleigh stage), the forerun ST102 and the main cut ST103 through the still's column (5 theoretical stages, reflux 2 and 0.5, ASSUMED; Diwekar's shortcut, ADR 0061; all on Raoult's law with NIST Antoine constants, the ideal liquid and benzal bromide's vapour pressure ASSUMED), the mixers, the splitter and the toluene recycle (converged at its tear stream S2, ADR 0060) are calculated by cheme process propagate, which also writes the model duties: E-102's (Q4), the stills' reboilers (Q7, Q9, Q14) and the column's condensers (Q10, Q11; ADRs 0059, 0061, 0062). scripts/balance.py gives the feeds for 1000 t/a, the brine vent condenser E-103 (a flash as core's vent condenser), the absorber water, the mixing and bubble-point temperatures and the other duties (no property package of core covers these liquids); the stills' charges' sensible heat, 2.84 kW less steam, is left out and recorded (DESIGN.md D-009). The recipe's year-average rate of the product agrees with the flowsheet (no cheme.recipe-basis finding); the recipe sizes R-101 (4 m3), its jacket check passes, and the stills' times come from their boil-up. Thermal screening (cheme process reactor-hazards): dT_ad 44.2 K, accumulation 1.66 %, MTSR 363.9 K against an MTT of 383.8 K (hazard.mtt: the boiling point of toluene); no criticality class without a TD24 (1 or 2 if the TD24 lies above the MTSR, 5 if below). With k/10 the MTSR is 370.3 K, with k/100 396.1 K, above the MTT, where the content boils (DESIGN.md D-011). At the MTSR the gas leaves with the content's vapour at 59.6 m3/h, and at most 72.8 m3/h for a cooling failure earlier in the dosing, within R-101's off-gas capacity of 90 m3/h (ASSUMED: 1.2 times the largest, rounded up to the next 5 m3/h); at k/10 102.3 m3/h exceeds it, and the blocked-vent case (about 0.24 MPa in the head space in the design case, 2.3 MPa at k/10) needs a relief device (open findings, DESIGN.md D-014). Preliminary gate-to-gate LCI with the per-batch nitrogen; the bromine linked to bromine-1, the toluene to btx-1, the nitrogen to asu-1, the other backgrounds gaps; the hydrobromic acid a co-product by mass of its HBr (shares 0.6572/0.3428). cheme maturity reaches no level (assumed feeds, kinetics and separations); the claim `maturity: concept` is the lowest value of the schema, not an evidenced level. Not reviewed. Needs cheme-as-code 1.10.0.", "status": "unreviewed" }, "viewer": { "commit": "a3c52e472f42fbc8cdacfeacf5ef28703c004174", "dirty": false, "sheets": [ "process/BFD.xml", "process/PFD.xml" ], "skipped": [], "snapshot": "snapshots/benzyl-bromide-1/", "stale": false, "tool": "cheme-as-code 1.6.0", "views": [ "checks" ] } }