Methyl acetate esterification via reactive distillation — a NRTL process flowsheet
Acetic acid and methanol esterify over the reactive stages of a column into methyl acetate and water — a genuine quadruple-azeotrope system where reactive distillation intensifies what would otherwise need several conventional columns. Reactive Distillation Design and Control, Luyben & Yu, Wiley (2006), pp. 147-164.
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- Rigorous NRTL thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: RD.
- Focus areas: Reactive distillation, Esterification, Process intensification.
- Thermodynamics
- NRTL
- Components
- acetic_acid, methanol, methyl_acetate, water
- Unit operations
- RD
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Read the step-by-step guideReproduce this exact result from Python — the real client.get_example() → run_and_wait() path, not a mockup.
from flowsim.sdk import FlowSimClient
client = FlowSimClient()
example = client.get_example("methyl-acetate-reactive-distillation")
sim = client.create_simulation(example["title"], example["flowsheet"])
result = client.run_and_wait(sim["id"])
print(result["status"]) # "converged"
streams = client.streams(sim["id"])Related models
DME synthesis via reactive distillation
Methanol dehydrates to dimethyl ether over the reactive stages of a column — reaction and separation in one shell, pulling DME overhead while unconverted methanol and water leave the bottoms (Peng-Robinson EoS avoids the missing UNIFAC group-decomposition for ethers that blocks this under an activity-coefficient package). The conversion is 78%, not 80%: with the distillate drawing 40% of the feed, an 80% conversion makes exactly the 4 mol/s of DME the distillate takes, so it would demand a perfectly pure DME overhead and DME-free bottoms, a split no finite column makes. The stages near the condenser hold almost no methanol, so the reaction runs where the methanol is, on the feed and stripping trays.
TAME synthesis via reactive distillation
Tert-Amyl Methyl Ether (TAME) is etherified from a cracked C₅ cut's reactive isoamylenes (2-methyl-1-butene / 2-methyl-2-butene) and methanol over the reactive stages of a column, pulling unreacted light C5s overhead while methanol-free TAME leaves the bottoms — reaction and separation in one shell, the same reactive-distillation pattern as the DME etherification example. The distillate draws 53% of the feed: etherification turns two molecules into one, so at 90% conversion the column has 6.21 mol/s to send out, of which the light C5s and unreacted methanol are 4.32. Luyben, Ind. Eng. Chem. Res. 2005, 44, 5715.
Butyl acetate synthesis via reactive distillation
Methyl acetate transesterifies with n-butanol over the reactive stages of a column into butyl acetate (a common paint/coatings solvent) and methanol, which is pulled overhead as it forms while high-boiling butyl acetate collects in the bottoms. The light reactant (methyl acetate) enters low in the reactive zone and rises through it, the heavy one (n-butanol) enters high and falls through it, so the two meet on the trays between: fed the other way round each leaves by its nearer end before it meets the other, and the column converts under a third of the methyl acetate. Luyben et al., Ind. Eng. Chem. Res. 2011, 50, 1247.
Patent benchmark: methyl lactate synthesis (CN104628563A)
Real patent replication, not an invented process: CN104628563A's acid-catalyzed lactate-ester route — lactic acid esterified with excess methanol, then purified by vacuum distillation — reproduced here as a continuous flowsheet. The patent's own worked methyl-lactate example reports 98.8% esterification conversion and 99.6% product purity at 120 degC/3h. This flowsheet's reactor conversion is set directly to the patent's reported 98.8% (not fitted); the vacuum column (0.2 atm, matching the patent's vacuum-distillation purification step) then splits the methanol and reaction water off the ester completely — zero methyl lactate leaves overhead — and delivers 97.8 mol% methyl lactate in the bottoms at 389.9 K. The property method is the whole story here, exactly as it was on the sulfolane extractive column. Written on Peng-Robinson, this example did not converge at all: every pair in a methanol / water / lactic-acid / methyl-lactate mixture is hydrogen-bonding, which van der Waals mixing cannot represent, and the column returned a partial profile carrying 2.60 mol/s of methyl lactate out of a column fed 1.98 — 32% more product than the reactor made, a 0.26 component-balance residual. (That wrong profile is where this example's previously-published 98.75% purity was read from; the number was retracted at the test level and is now corrected here.) A plain activity model cannot be used either, for a data reason rather than a physics one: neither lactic acid nor methyl lactate carries a regressed ideal-gas-Cp correlation, and the gamma-phi enthalpy path raises on that where a cubic quietly falls back to a corresponding-states estimate. PSRK is a cubic whose mixing is driven by UNIFAC, so it has both — and it converges to a 2.7e-06 component-balance residual, with methyl lactate and lactic acid each leaving in exactly the amount the reactor made.
Batch campaign: a batch step inside a continuous flowsheet
Fine chemicals and pharma run batches, but a flowsheet is written in mol/s. These two unit ops reconcile that: they integrate the real batch physics over the batch, then report the products as the RATE that campaign delivers, so a batch step sits inside a continuous flowsheet the way a plant actually runs one. The batch reactor esterifies ethanol with acetic acid to ethyl acetate and water. It reaches 63.2% conversion and stops, and that number is not a specification — it is the equilibrium. The reaction is reversible with an equilibrium constant of 4 (the forward and reverse pre-exponentials are given as 5.0e4 and 1.25e4), and solving K = x(0.10+x)/(0.45-x)^2 = 4 for an equimolar charge carrying 10% water gives an extent of 0.285, which is 63.3% of the acid. Fischer esterification really does plateau there; a model that ran to completion would be describing a different reaction. Turnaround time costs throughput exactly as reaction time does. Two hours of reaction plus one hour of turnaround is a 3-hour cycle and 2922 batches a year, and the reactor is only reacting for 67% of the time it is occupied. That fraction is the number that decides whether you need a second reactor, and it is invisible to a steady-state model. The batch still then takes the crude and recovers the ethyl acetate — the distillate comes off essentially pure, from a pot that started at 28.5 mol% ester — on its own longer 4-hour cycle, so the two units run at genuinely different campaign rates. Bounded: the flowsheet sees each unit's CYCLE AVERAGE, not the transient. A real plant has a surge tank between these two smoothing the pulses, and neither the concentration profile during the batch nor the still's changing overhead composition is visible downstream.
Bio-acrylic: glycerol to acrylic acid and butyl acrylate
Biodiesel glycerol (5 mol% in water, the dilute crude a transesterification plant actually sells) is vaporised and dehydrated over an acid catalyst at 553 K to acrolein, oxidised with air at 573 K to acrylic acid, quenched, dewatered in a vacuum column, and esterified with n-butanol to n-butyl acrylate: the two-step route from a renewable C₃ to the acrylic monomer, written out so its water, oxygen and carbon bookkeeping can be checked end to end. Each reaction is a conversion reactor with an exact element balance: dehydration (glycerol → acrolein + 2 H₂O), the competing C-C cleavage that every gas-phase dehydration catalyst shows (glycerol → acetaldehyde + CO + H₂ + H₂O), selective oxidation (acrolein + 1/2 O₂ → acrylic acid), over-oxidation (acrolein + 3/2 O₂ → acetic acid + CO₂), and esterification (acrylic acid + n-butanol → n-butyl acrylate + H₂O). A knock-out flash after dehydration rejects most of the water before the oxidiser; the quench liquid goes to a 0.15 atm acrylic-acid column (vacuum because acrylic acid polymerises when hot, which is also why its inhibitor profile is the question the column-inhibition analysis answers on this column); a caustic wash takes the unreacted acids out of the ester before a 0.2 atm butyl-acrylate column. What the flowsheet shows is where the water goes: 102 mol/s of it arrive with 5 mol/s of glycerol, the dehydration makes two more per acrolein, and nearly all of it has to be removed before the acid is concentrated, which is the energy cost that decides whether a bio-acrylic plant is viable. Solved: the vacuum column delivers a crude acid of 87 mol% acrylic acid (11% water, 2% acetic) and loses about 7% of the acid overhead with the water; the ester column delivers 94 mol% n-butyl acrylate, the balance unreacted butanol.