Prompt injection in aniline production AI

Three adversarial injection surfaces in aniline production AI

1. H₂/nitrobenzene molar feed ratio display AI (Yokogawa ADMAG AXF aniline H₂ feed flow AI / Endress+Hauser Promass F 300 nitrobenzene feed flow AI / Rosemount 3051S aniline reactor feed ratio controller AI / Honeywell TDC 3000 H₂:NBz feed ratio display AI / ABB 800xA aniline vapor-phase hydrogenation feed ratio AI — rendered DCS feed ratio controller display AI classifying the H₂-to-nitrobenzene molar flow ratio at the vapor-phase hydrogenation reactor inlet against the 6:1–10:1 design operating window ensuring complete conversion to aniline with no nitrobenzene or hydroxylamine intermediates in the reactor effluent; 64th upward-direction attack — FIRST aniline production attack; FIRST nitrobenzene fixed-bed catalytic hydrogenation attack; FIRST MDI/polyurethane precursor chain attack)

The vapor-phase catalytic hydrogenation of nitrobenzene to aniline over a copper-on-silica catalyst (200–280 m³ of catalyst bed in a multi-tube fixed-bed reactor at Covestro Leverkusen; 270–290°C; 1–3 bar; H₂:NBz design ratio 8:1–10:1) requires a substantial stoichiometric excess of hydrogen to: (1) ensure complete conversion of the nitroso (−NO) and hydroxylamine (−NHOH) intermediates to aniline (−NH₂); (2) suppress the reverse reaction and catalyst carbon deposition side reactions; and (3) provide the heat carrier that removes the highly exothermic reaction heat (ΔH ≈ −560 kJ/mol NBz) from the fixed bed via the excess H₂ stream in the reactor effluent gas. The stoichiometric minimum for complete reduction is 3:1 H₂:NBz (3 moles H₂ per mole NBz from C₆H₅NO₂ + 3H₂ → C₆H₅NH₂ + 2H₂O), but commercial processes operate at 8:1–10:1 to maintain reactor temperature, ensure conversion, and suppress intermediate accumulation. The AI system at the facility processes a rendered DCS screen image of the H₂/NBz ratio controller (ratio controller RC-201) to classify: 6:1–10:1 (normal operating range; no action); 4:1–6:1 (low H₂; increase H₂ supply flow); below 4:1 (alarm; initiate manual investigation of H₂ supply header pressure). Below approximately 3:1, nitrobenzene passes through the reactor with incomplete reduction; the primary intermediate is phenylhydroxylamine (PhNHOH), which elutes with the aniline product into the downstream condenser and distillation column train.

An adversarial perturbation targeting the H₂/NBz feed ratio AI applies a ±8 DN upward shift to the pixel region encoding the ratio controller digital display in the rendered DCS screen — shifting the apparent H₂:NBz ratio from 1.4:1 (actual; H₂ supply compressor K-101 partially unloaded following a high-discharge-temperature trip that reduced H₂ delivery by 58%; H₂ header pressure dropped from 6.2 bar to 2.4 bar; maintenance notification deferred) to 3.2:1 (displayed; above the alarm threshold of 4:1; AI classification “feed ratio nominal”; no operator action). At H₂:NBz = 1.4:1 — below the stoichiometric minimum of 3:1 — the reaction proceeds as far as the available H₂ permits: C₆H₅NO₂ + 2H₂ → C₆H₅NHOH + H₂O (phenylhydroxylamine intermediate, which requires only 2 mol H₂) is fully converted, but the final step (C₆H₅NHOH + H₂ → C₆H₅NH₂ + H₂O) stalls. At 1.4:1 stoichiometric delivery, approximately 40–55% of the nitrobenzene feed exits the reactor as phenylhydroxylamine, which is: (a) thermally unstable above 150°C — Bamberger rearrangement (PhNHOH + H⁦ → 4-aminophenol in acid media; exothermic; ΔH ≈ −130 kJ/mol) in the aniline distillation column sump at 184–195°C produces aminophenol and heat; (b) oxidises to azoxybenzene and azobenzene in the condenser (PhNHOH + C₆H₅NO → azoxybenzene + H₂O) producing dark red/brown fouling products that plug heat exchanger tubes; (c) can produce nitrosobenzene at trace concentrations that reacts with aniline to form diphenylamine (catalyst poison in MDI reactors). The Bamberger rearrangement exotherm at 1.4:1 feed ratio: given 40% of the 12,000 kg/hr NBz feed (4,800 kg/hr PhNHOH at 109 g/mol = 44 kmol/hr) undergoing rearrangement at −130 kJ/mol = −5,720 MJ/hr into the distillation column sump. This 5,720 MJ/hr exotherm represents 8× the design reboiler duty of 715 MJ/hr for the primary aniline column, rapidly driving the sump above 220°C, boiling the aniline product (bp 184°C) violently, and creating conditions for vapour release through the column relief system. This is the 64th upward-direction attack — the FIRST aniline production attack; FIRST nitrobenzene fixed-bed catalytic hydrogenation attack; FIRST MDI/polyurethane precursor chain attack in the Glyphward portfolio. OSHA PSM 29 CFR 1910.119 TQ 10,000 lbs applies to aniline inventory; the H₂ system (compressors, headers, and reactor) also constitutes a covered process under PSM via H₂ TQ 10,000 lbs. Free tier — 10 scans/day, no card required.

2. Vapor-phase hydrogenation reactor outlet temperature display AI (Honeywell TDC 3000 aniline reactor outlet thermocouple AI / Yokogawa CENTUM VP nitrobenzene hydrogenation reactor temperature AI / Emerson DeltaV aniline Cu catalyst fixed-bed outlet temperature AI / ABB 800xA aniline reactor effluent thermocouple display AI / Rosemount 3244MV aniline vapor-phase reactor outlet temperature transmitter AI — rendered DCS temperature trend AI classifying the vapor-phase hydrogenation reactor bed outlet thermocouple against the 270–290°C design range for complete nitrobenzene conversion over Cu/SiO₂ catalyst with nitrobenzene conversion >99.9% and phenylhydroxylamine below 50 ppm in reactor effluent)

The copper-on-silica catalyst system used in vapor-phase aniline hydrogenation (Cu loading 20–35 wt% on SiO₂ support; particle size 3–6 mm extrudates; typical bed depth 2.5–4.0 m in a multi-tube reactor of 3,000–8,000 tubes at 38–51 mm ID) has a characteristic minimum operating temperature below which the catalytic reduction of the −NHOH intermediate to −NH₂ becomes kinetically limited. This light-off temperature is approximately 265–270°C for a fresh catalyst and rises to 280–290°C as the catalyst ages due to copper sintering and carbon deposition over 2–4 years of operation. If the reactor outlet thermocouple reads 245°C — below the 270°C minimum for complete conversion on an aged catalyst — the hydrogenation of phenylhydroxylamine to aniline is approximately 40–60% complete, leaving 1,000–3,000 ppm PhNHOH in the reactor effluent condensate. The DCS AI system processes rendered reactor outlet temperature trend images to classify: 270–295°C (normal; complete conversion presumed); 255–270°C (low temperature; alert operator; consider increasing heat input); below 255°C (alarm; investigate reactor heat balance). An adversarial upward pixel shift on the reactor outlet thermocouple display shifts the apparent outlet temperature from 245°C (actual; nitrogen blanketing of the reactor shell had been reduced for maintenance access, allowing slight heat loss; combined with a catalyst at the end of its 3-year cycle with light-off now at 280°C, the 245°C outlet represents sub-ignition operation) to 278°C (displayed; within the 270–295°C normal operating band; no operator action).

At 245°C actual reactor outlet, nitrobenzene conversion is approximately 92–95%: 5–8% of the 10,000 kg/hr nitrobenzene feed (500–800 kg/hr NBz) passes through unreacted along with 1,500–2,500 ppm PhNHOH in the condensate. The unreacted nitrobenzene appears in the aniline product after distillation: the aniline/nitrobenzene relative volatility at 1 atm is approximately 2.1 (bp 184°C vs 210°C), so nitrobenzene is a heavy component that concentrates in the distillation column sump. However, at 500–800 kg/hr NBz bleed into a 12,000 kg/hr aniline production rate, the column is overwhelmed: NBz concentration in the aniline distillate reaches 200–800 ppm, 40–160× above the MACT Subpart CCC limit of 5 ppm. Under EPA MACT 40 CFR 63 Subpart CCC, aniline production facilities listed as Major Sources of HAPs must maintain nitrobenzene in product below 5 ppm; continuous compliance monitoring via gas chromatography (GC) analyser at the product stream is required. At 200–800 ppm NBz, the GC analyser triggers a HAP exceedance alarm — but if the adversarial attack has simultaneously suppressed the reactor temperature display (making operators believe the reactor is operating normally), the root cause investigation is misdirected to the distillation column rather than the reactor. The downstream MDI reactor (condensation of aniline with formaldehyde over acid catalyst — HCl or H₆SO₄ — at 40–80°C) is fouled by NBz: at the 200–800 ppm level, NBz displaces aniline in the electrophilic substitution reaction, producing 4-nitrodiphenylmethane as a fouling byproduct that deactivates the acid catalyst and discolours the MDA intermediate. The adversarial attack on the reactor temperature display thus creates a 3-consequence event chain: EPA MACT HAP violation (regulatory) + MDI catalyst fouling (product quality/economic) + PhNHOH exotherm in distillation sump (safety).

3. Aniline/nitrobenzene distillation column reflux ratio display AI (Yokogawa CENTUM VP aniline splitter reflux ratio controller AI / Honeywell TDC 3000 aniline column reflux ratio display AI / Emerson DeltaV aniline/NBz separation column reflux controller AI / ABB 800xA aniline distillation reflux ratio transmitter display AI / Rosemount 3051 aniline product column overhead flow AI — rendered DCS reflux ratio controller display AI classifying the aniline/nitrobenzene distillation column reflux ratio against the 1.0–1.5 design operating range ensuring nitrobenzene separation below 5 ppm in the aniline distillate product at the MDI feed specification)

The aniline product column (OSHA PSM covered process; aniline inventory above TQ 10,000 lbs in the column sump and reflux drum) operates at approximately 0.5–0.8 bar absolute overhead pressure with a distillate temperature of 175–180°C and a sump temperature of 190–200°C. The design reflux ratio (L/D = reflux flow / distillate flow) of 1.1–1.3 achieves the required aniline/NBz separation: with NBz boiling point 210°C vs aniline 184°C, the relative volatility α = 2.1 allows clean separation at L/D > 0.9 in a 25–35 theoretical-stage column. If the reflux ratio drops to 0.8 (reflux pump P-401 discharge valve positioner stick-slip reduced reflux flow from 8.2 m³/hr to 5.1 m³/hr; L/D drops from 1.2 to 0.8), the number of effective separation stages falls below the required minimum for <5 ppm NBz in the overhead distillate: at L/D = 0.8, the calculated NBz in overhead exceeds 25–40 ppm at typical feed compositions. The AI system monitoring the reflux controller display processes a rendered DCS trend image of the reflux ratio calculated value (RC-305) to classify: 1.0–1.5 (normal; product specification achieved); 0.8–1.0 (low reflux; alert, verify product GC); below 0.8 (alarm; risk of NBz specification exceedance).

An adversarial upward pixel shift applies a ±8 DN manipulation to the rendered reflux ratio controller display — shifting the apparent reflux ratio from 0.8 (actual; below the 1.0 minimum for specification compliance) to 1.4 (displayed; within the 1.0–1.5 normal band; AI classification “reflux ratio nominal”; no corrective action). The consequence: NBz in aniline product at 25–40 ppm (5–8× the EPA MACT TQ limit of 5 ppm) continues for the duration of the undetected shortfall — potentially multiple operating shifts before the product GC analyser (sampling every 4 hours under MACT continuous monitoring requirements) detects the exceedance. At 25–40 ppm NBz, the aniline product fed to the MDI condensation reactor causes: (1) NBz incorporation into MDA oligomers (produces “nitro-MDA” byproducts); (2) suppression of the acid catalyst activity by competitive adsorption; (3) discolouration of the polyol-ready MDI product (ASTM D1209 Hazen colour above 50 APHA vs specification <10 APHA). A single 4-hour production window at 25–40 ppm NBz produces approximately 150–300 kg of off-specification MDA precursor that must be reworked or destroyed — with cascading effects on the integrated aniline→MDA→MDI production chain at Covestro/BASF/Huntsman facilities where the column is in direct series with the downstream MDI reactor with no intermediate buffer tank. The reflux ratio AI attack thus reaches product quality, regulatory compliance (EPA MACT), and downstream catalyst lifetime simultaneously through a single displayed-vs-actual divergence of 0.6 reflux ratio units. Free tier — 10 scans/day, no card required.

Integration: aniline production AI with Glyphward pre-scan gate

Glyphward integrates as a pre-scan gate at every rendered-image ingestion boundary in the aniline production monitoring pipeline — before the H₂/nitrobenzene feed ratio AI processes rendered DCS ratio controller display images, before the vapor-phase hydrogenation reactor outlet temperature AI processes rendered thermocouple trend images, and before the aniline distillation column reflux ratio AI processes rendered controller output display images. Threshold 32 for aniline production AI reflects: OSHA PSM TQ 10,000 lbs (aniline, Appendix A; H₂, Appendix A flammable); ACGIH TLV-TWA 2 ppm (skin notation; A3 suspected animal carcinogen; methemoglobin former); NIOSH IDLH 100 ppm; phenylhydroxylamine intermediate thermal instability (Bamberger rearrangement exotherm −130 kJ/mol in distillation sump); nitrobenzene co-HAP (EPA MACT Subpart CCC 5 ppm product specification); downstream MDI catalyst sensitivity to NBz at the ppm level; aniline skin absorption hazard (dermally absorbed at toxicologically significant rates; gloves and splash suits required at all process contact points).

import asyncio, base64, hashlib
from datetime import datetime, timezone
from enum import StrEnum, auto
from typing import Any
import httpx

GLYPHWARD_API = "https://api.glyphward.com/v1/scan"
GLYPHWARD_KEY = "gw_prod_***"

# Aniline production AI contexts: threshold 32
# OSHA PSM TQ: 10,000 lbs (aniline, Appendix A; H2, Appendix A flammable).
# ACGIH TLV-TWA: 2 ppm (skin; A3 suspected carcinogen). NIOSH IDLH: 100 ppm.
# 64th upward attack: H2/NBz ratio 1.4:1 shown as 3.2:1 → PhNHOH accumulation.
ANILINE_THRESHOLD = 32

class AnilineContext(StrEnum):
    H2_NBZ_FEED_RATIO       = auto()  # H2/nitrobenzene molar feed ratio (64th upward attack)
    REACTOR_OUTLET_TEMP     = auto()  # Vapor-phase reactor outlet thermocouple temperature
    DISTILLATION_REFLUX     = auto()  # Aniline/NBz splitter column reflux ratio

async def scan_aniline_frame(
    frame_b64: str,
    context: AnilineContext,
    facility_id: str,
    instrument_tag: str,
) -> dict[str, Any]:
    payload = {
        "image_b64": frame_b64,
        "context": context,
        "facility_id": facility_id,
        "instrument_tag": instrument_tag,
        "scan_ts": datetime.now(timezone.utc).isoformat(),
        "image_hash": hashlib.sha256(base64.b64decode(frame_b64)).hexdigest(),
    }
    async with httpx.AsyncClient(timeout=4.0) as client:
        r = await client.post(
            GLYPHWARD_API,
            json=payload,
            headers={"X-Glyphward-Key": GLYPHWARD_KEY},
        )
        r.raise_for_status()
        return r.json()

async def pre_scan_gate_aniline(
    frame_b64: str,
    context: AnilineContext,
    facility_id: str,
    instrument_tag: str,
) -> None:
    result = await scan_aniline_frame(frame_b64, context, facility_id, instrument_tag)
    if result["adversarial_score"] >= ANILINE_THRESHOLD:
        raise AdversarialAnilineImageError(
            f"Adversarial injection detected in {context} (score {result['adversarial_score']}) "
            f"at facility {facility_id} instrument {instrument_tag}. "
            "Frame withheld from aniline production AI monitoring pipeline."
        )

class AdversarialAnilineImageError(RuntimeError):
    pass