TAME Storage — tert-Amyl Methyl Ether Tank Selection for Refinery Gasoline Oxygenate

TAME Storage — tert-Amyl Methyl Ether Tank Selection for Refinery Gasoline Oxygenate Service

Tert-amyl methyl ether (TAME; 2-methoxy-2-methylbutane; C₆H₁₄O; CAS 994-05-8) is a refinery-produced gasoline oxygenate used to boost gasoline-pool octane + provide reformulated-gasoline (RFG) oxygen content. It is a clear, colorless, ether-like-smelling volatile liquid with density 0.770 g/cm³, boiling point 86.3°C, flash point −11°C, autoignition 415°C, and freezing point −80°C. TAME has Research Octane Number (RON) ~105 and Motor Octane Number (MON) ~95 with blending RVP ~1.5 psi (substantially lower than MTBE's 8 psi blending RVP, which is the operational advantage post-summer-RVP regulations). Worldwide TAME production peaked at ~3 million metric tons annually during the early-2000s gasoline-oxygenate transition window; current production is in the 1.5–2 million MT range as global gasoline oxygenate demand consolidates around ethanol blending in the US + EU.

Production technology: TAME is produced by acid-catalyzed etherification of methanol + reactive C5 isoamylenes (2-methyl-1-butene + 2-methyl-2-butene) over sulfonic-acid ion-exchange resin (Amberlyst 15, Purolite CT-275, Lewatit K-2620) in fixed-bed reactors at 60–90°C and 5–10 bar. The reactive isoamylenes are recovered from FCC (fluid catalytic cracking) C5 olefin cuts at refineries; tertiary amylenes (~30% of refinery C5 olefins) react preferentially while secondary amylenes (1-pentene, cis/trans-2-pentene) and pentanes pass through unconverted. Honeywell UOP (CDTAME catalytic distillation) + Axens (Octamax / TAMisom) + Sulzer (CDTECH) license the dominant reactor + separation technology, with both fixed-bed and reactive-distillation reactor configurations in commercial use. Largest historical TAME producers: Lyondell-Equistar (now LyondellBasell, Houston TX), Sunoco refineries (legacy, now Energy Transfer / Phillips 66 / others), Neste Engineering (Finland) for European refinery-revamp service, multiple US refineries (Marathon, Phillips 66, Valero) with on-site TAME units feeding the gasoline pool.

Regulatory citations: OSHA has no specific PEL for TAME; the OSHA general-duty clause + facility-specific exposure limits apply; ACGIH TLV-TWA 20 ppm with skin notation (set 2008 based on rodent neurotoxicity + reproductive endpoints); NIOSH no REL but recommends engineering controls + best-practice industrial hygiene; EPA HAP NOT listed (TAME was specifically NOT added to the CAA Section 112(b) list when MTBE was added in the 1990s); 40 CFR 80 RFG oxygenate compliance for gasoline blending; NFPA 30 Class IB flammable liquid (flash point −11°C); DOT UN 2398 Methyl tert-Amyl Ether, Class 3 (flammable liquid), Packing Group II; EPA TSCA active inventory; SARA Title III EPCRA Section 313 NOT listed (in contrast to MTBE which was listed during the 1990s groundwater-contamination response).

1. Material Compatibility Matrix

TAME shares ether-class compatibility with MTBE + ETBE: aggressive solvent toward many elastomers + plasticizer-extracting toward PVC. Carbon-steel API 650 tanks dominate bulk storage for refinery + terminal applications. HDPE / XLPE rotomolded tanks are NOT acceptable for primary TAME service due to permeation + swelling. Standard refinery practice keeps TAME in the same tank-system class as MTBE + ETBE.

Industrial spec: API 650 carbon-steel welded vertical tank with internal floating roof (IFR), nitrogen-blanketed vapor space, primary + secondary IFR seals, vapor-recovery on tank-fill operations, 316L stainless on TAME-reactor effluent transit + downstream gasoline-blender feed line. OneSource scope at refinery + terminal sites is the water-side + ancillary chemistry tank infrastructure adjacent to gasoline-blending tank-farms.

2. Real-World Industrial Use Cases

Refinery Gasoline Oxygenate (Dominant ~95% Use). TAME is blended into the refinery gasoline pool at 5–15% volumetric concentration to provide oxygen content (~13.8% wt oxygen vs MTBE 18.2% wt + ethanol 34.7% wt) and octane boost (RON 105 vs typical naphtha-pool ~88–92 RON). The lower blending RVP (1.5 psi vs MTBE 8 psi) is operationally important during summer RVP-restricted gasoline (RVP 7.0–9.0 psi seasonal limits per CAA Section 211(h) reformulated-gasoline + CARB CaRFG) — TAME does not push the blended-gasoline RVP up the way MTBE did, allowing higher butane-blending margins. Major US refinery-on-site TAME units historically: BP-Amoco (Whiting IN), Marathon (Detroit MI, Robinson IL), Phillips 66 (Sweeny TX, Borger TX), Lyondell-Equistar (Houston TX), Sunoco (Toledo OH, Marcus Hook PA legacy), Valero (Texas City TX, Three Rivers TX, Memphis TN). Many TAME units were idled or revamped to other service post-2008 ethanol-blending displacement of TAME demand.

Octane Boost in Niche Refinery Operations. Refineries without ethanol-blending logistics access (geographically isolated, contractually constrained, or with specific premium-gasoline grade differentiation strategy) have continued TAME use as a high-octane blendstock. Some specialty fuel applications (aviation-gasoline alternative, race-fuel formulations, high-performance off-road fuel) also use TAME as a high-octane blend component. The market is small relative to 1990s peak.

Specialty Solvent (Sub-1% Use). Pure TAME serves as a specialty solvent in coatings + cleaning + agricultural-formulation diluent applications. The fraction is small relative to refinery gasoline-blendstock use but creates a niche distributor-level supply chain.

Comparison vs MTBE + ETBE. MTBE was banned in California 2003 + several other US states 2003-2007 due to groundwater-contamination concerns (high water solubility 4.8 g/100 mL + persistent + low odor threshold creating taste-and-odor complaints at <15 ppb in drinking water). ETBE substitutes for MTBE in EU markets (lower water solubility + ethanol-derived feedstock counts toward biofuel mandate). TAME is generally considered a partial MTBE replacement at refineries that retain on-site etherification capacity but lack geographic + economic incentive to switch to ETBE. The TAME water-solubility profile (~1.15 g/100 mL) is intermediate between MTBE (4.8) + ETBE (1.2) + standard hydrocarbon gasoline components (<0.01), reducing but not eliminating the groundwater-contamination concern from leaking USTs.

3. Regulatory Hazard Communication

OSHA / ACGIH / NIOSH Exposure Limits. No OSHA-specific PEL for TAME. ACGIH TLV-TWA 20 ppm with skin notation, set 2008 based on rodent neurotoxicity (high-dose CNS depression), liver effects, and limited reproductive evidence. NIOSH has not issued a TAME REL but recommends best-practice engineering controls + industrial hygiene at refinery + chemical-manufacturing scale. The 20-ppm ACGIH TLV is substantially tighter than the historic 100 ppm MTBE benchmark, reflecting TAME's incremental neurotoxicity findings. Refinery + terminal exposure-monitoring programs typically design to the 20-ppm ACGIH TLV.

IARC Not Classified. TAME has not been evaluated by IARC. The 2009 NTP 2-year inhalation bioassay on TAME found rodent kidney + liver effects but did not establish carcinogenicity. Regulatory framing remains non-cancer occupational toxicity.

EPA HAP Status. TAME is NOT listed Hazardous Air Pollutant under CAA Section 112(b). This is operationally important — refinery + terminal handling does NOT trigger 40 CFR 63 NESHAP MACT requirements specifically driven by TAME content (in contrast to MTBE which became HAP-listed via the 1990 CAA amendments + state implementation).

40 CFR 80 RFG Oxygenate Compliance. When blended into RFG gasoline, TAME must meet EPA RFG Phase II oxygen + RVP + fuel-property requirements. Ethanol-blended gasoline (E10) has largely displaced TAME-blended gasoline in most US markets; geographic + contractual exceptions remain.

NFPA 30 Class IB Flammable Liquid. TAME flash point of −11°C / 12°F places it NFPA Class IB (same class as MTBE + benzene + ethanol). Storage requires API 650 IFR or floating-roof + vapor-recovery, secondary containment 110% largest tank, NFPA 30 spacing, Class I Division 1 hazardous-area within 3–5 ft of vents + pump cabinets per NFPA 70 Article 500.

DOT and Shipping. UN 2398 Methyl tert-Amyl Ether, Hazard Class 3 (flammable liquid), Packing Group II. Rail-car: DOT-111A. Truck: MC-307 / DOT-407. Marine: IMO Type II/III chemical tankers.

Reportable Quantities + Right-to-Know. CERCLA RQ no specific TAME RQ (defaults to generic statutory 1-lb for unlisted hazardous substances if a specific listing is later assigned). EPCRA Section 313 TRI NOT listed. State-level UST-leak + groundwater-monitoring rules vary; California has specific TAME drinking-water action levels following the MTBE-ban-era oxygenate-tracking rules.

4. Storage System Specification

Bulk Tank Construction. Industry-standard TAME bulk storage at refineries + gasoline-blending terminals is API 650 carbon-steel welded vertical tank, 25,000–100,000 bbl capacity (1.0–4.2 million gallons), internal floating roof construction (vapor-loss + emissions reduction), nitrogen-blanketed vapor space, primary + secondary IFR seals, pressure-vacuum vent + flame arrestor, manual + automatic high-level shutoffs per API 2350, foam fire-suppression to NFPA 11. Heating not required.

Vapor Recovery. 40 CFR 63 EEEE Organic Liquids Distribution MACT for terminal-handling vapor controls + 40 CFR 60 Subpart Kb for new bulk-storage tanks. Standard configurations: regenerative thermal oxidizer (RTO), regenerative carbon adsorption with steam-stripped product recovery, refrigerated condenser + carbon polish. Vapor-balance loops on truck/rail loading return displaced vapor to source tank.

Secondary Containment + UST Considerations. NFPA 30 + EPA SPCC: 110% largest tank capacity for above-ground TAME storage. 1 gallon per hour sensitivity. Post-MTBE-contamination experience drove tighter UST monitoring rules nationally.

Pump Selection. API 610 + API 682 centrifugal pumps with double mechanical seals + seal-flush plan. Magnetically-coupled or canned-motor pumps for fugitive-emissions reduction. Carbon steel acceptable for most TAME service; 316L stainless for high-purity etherification-reactor feed.

Closed-Loop Sampling + Online Analysis. API MPMS Chapter 8 closed-loop. Online GC analyzers for TAME purity + isoamylene-conversion + methanol-residual trending. TAME-product spec from etherification reactor typically >90% TAME with unconverted methanol + isoamylenes + tertiary-amyl alcohol comprising the balance.

OneSource Scope. API 650 referrals for primary TAME + gasoline-blending storage to fabricators (Caldwell Tanks, CB&I, Ferguson Group). Ancillary scope is OneSource direct.

5. Field Handling Reality

The Vapor-Pressure Reality. TAME vapor pressure at 25°C is 9.7 kPa (73 mm Hg) — lower than MTBE's 33 kPa but still high enough to produce significant breathing-zone exposure at open valves + manual gauging. The flash point of −11°C means tank vapor space is normally above the lower flammable limit; ignition-source control + nitrogen-blanket + flame-arrestor design is the engineering response.

The Ether-Solvent Reality. TAME's ether functionality drives more aggressive material attack than MTBE in some elastomers + extracts plasticizers from PVC. Refinery + terminal piping specifications must use FKM seals + verified-compatible gaskets. Switching a MTBE tank to TAME service requires elastomer + gasket review; switching back from TAME to ETBE or other ether is similarly material-checked.

Spill Response. TAME spills are flammable + groundwater-mobile. Site response: evacuate upwind 100 m, eliminate ignition sources, foam blanket large pools (AFFF / AR-AFFF per NFPA 11), recover via vacuum truck for hazardous-waste disposal. Do NOT flush to drain or stormwater; TAME is groundwater-mobile + slow-degrading and can create monitoring + remediation liability if released to soil + groundwater. EPA RCRA D001 (ignitability) for spent product.

Tank Entry / Cleaning. OSHA 29 CFR 1910.146 permit-required confined-space. Pre-entry purge to <20 ppm TAME ACGIH TLV AND <10% LEL AND >19.5% O₂. Continuous monitoring during entry. Air-supplied respiratory protection above ACGIH TLV.

UST Leak Reality. TAME-blended gasoline at retail + terminal USTs has the same groundwater-mobility profile that drove MTBE bans, although less severe. EPA + state UST programs require leak detection + interstitial monitoring + secondary containment to prevent the failure-mode that created multibillion-dollar MTBE remediation liabilities in the 1990s-2000s.

LDAR Compliance. 40 CFR 60 Subpart VVa applies to TAME etherification-reactor process units. Refinery-fugitive-emissions programs include TAME components alongside other process-unit LDAR scope. Quarterly Method 21 monitoring; standard 500 ppm gas-service / 2,000 ppm light-liquid leak threshold.

Related Chemistries in the Alcohol & Oxygenate Cluster

Related chemistries in the alcohol & oxygenate cluster (alcohols + ethers + ketones + aromatic-hydrocarbon refinery cuts + ether-oxygenate fuel components + branched-paraffin reference fuel chemistry):

• Methyl Tert-Butyl Ether (MTBE) — Ether-oxygenate sister chemistry
• Ethyl Tert-Butyl Ether (ETBE) — Ether-oxygenate sister chemistry
• Methanol — Ether-precursor companion chemistry
• Ethanol — Oxygenate companion chemistry
• Isobutylene — Etherification-feed companion chemistry

Related Hub Pillars

For broader chemistry context, see the OneSource Plastics high-traffic chemical-compatibility hub pillars:

• Sulfuric Acid (H₂SO₄)
• Sodium Hydroxide (NaOH / caustic soda)