Methyl tert-butyl ether (MTBE), CAS 1634-04-4, is manufactured across Chinese C4 processing sites by the liquid-phase addition of methanol to isobutylene over sulfonic acid ion exchange resin. The molecule has a normal boiling point of 55.2 °C, a molecular weight of 88.15 g/mol, a density of approximately 0.740 g/cm³ at 20 °C, and a closed-cup flash point near -28 °C. These properties place the product under UN 2398, Class 3, Packing Group II for transport. In China, merchant supply is concentrated in integrated refining and C4 processing complexes in Shandong, East China, and South China, where product is sold either into gasoline oxygenate blending or into downstream high-purity isobutylene production. Export specifications are not defined by a single national product standard for all grades; supplier COAs and refinery purchase specifications govern methanol, water, C4 hydrocarbon, and color limits according to the intended end use.

MTBE Supplier in China: Grades, Packaging and Export Terms

Chinese export grades in merchant trade are differentiated by purity and retained methanol rather than by separate product families. A supplier’s standard export COA commonly specifies MTBE purity not less than 99.5 wt%, methanol not more than 0.05–0.1 wt%, water not more than 0.05 wt%, C4 hydrocarbons not more than 0.1 wt%, and distillation final boiling point near 55.5 °C. Higher-purity lots intended for downstream synthesis may specify methanol below 0.03 wt% and require supplemental stabilizer or nitrogen-sealed sampling. Packaging classes include 150 kg steel drums, 1,000 L composite IBC for qualified domestic and short-sea movements, and 24,000–26,000 L ISO tank containers for oceangoing lots. Export terms are normally quoted FOB Shanghai/Ningbo or CFR/CIF to Rotterdam, Singapore, or Pengerang, with LC at sight or TT against transport documents. These commercial parameters are supported by technical documentation rather than marketing-driven product labels.

What Limits Methanol and Water Content in Contractual COAs?

Methanol retention matters in gasoline blending because methanol increases water affinity and can encourage phase separation when oxygenated gasoline contacts dissolved water or condensed tank water. Chinese MTBE units generally operate with methanol-to-isobutylene molar ratios of 1.05:1 to 1.10:1 in the etherification reactor. Residual methanol in the product is then removed by azeotropic distillation or water extraction; failure of the methanol recovery column reboiler at reduced steam pressure can raise batch methanol from 0.02 wt% to over 0.15 wt%. Water content is controlled because moisture hydrolyzes sulfonic acid catalyst in downstream MTBE cracking and contributes to corrosion in carbon steel storage tanks. Test methods used for export COA include ASTM D5441 for gas chromatography composition, ASTM E203 for Karl Fischer water, ASTM D4052 for density, ASTM D86 for distillation, and ASTM D1209 for platinum-cobalt color. Some refinery purchasers additionally require copper strip corrosion under ASTM D130 to detect trace sulfur or acid species that are not captured by routine GC.

In drummed export operations, MTBE is loaded into internally coated carbon steel drums with gaskets of fluoroelastomer or PTFE to resist ether swelling. Drum filling is limited to 95% ullage at 15 °C, and closures are pressure-tested after filling. Marine loads are segregated from peroxides and strong oxidizers under the IMDG Code. For ISO tank quantities, the liquid is loaded via bottom or top connections under nitrogen padding. MTBE vapor forms explosive mixtures in air between approximately 1.6 vol% and 8.4 vol%. Static bonding and flow velocity control below 1 m/s are used during initial fill to limit electrostatic accumulation. Long-term storage in air should be avoided because ethers can develop trace peroxides; nitrogen blanketing or closed-loop vapor recovery is applied at terminal import tanks.

Marine Packaging Configurations for UN 2398 Flammable Liquid

For ocean transport, the product is declared as methyl tert-butyl ether, UN 2398, Class 3, Packing Group II, with EmS F-E, S-D and marine pollutant reporting depending on the receiving jurisdiction. Closed steel drums of 200 L capacity provide net weights near 148 kg based on density 0.74 g/cm³. ISO tank containers are specified with stainless steel or lined carbon steel shells, top or bottom discharge, and pressure-relief devices set to prevent vapor-space overheating. Before loading, tanks are inspected for residual water, rust, and previous cargo incompatibility. A nitrogen pad of 0.2–0.3 bar gauge may be applied to reduce atmospheric oxygen ingression and volatile organic emission during transit. Samples are drawn after loading through ballast or top sample ports; shore tank and vessel composite samples are retained for demurrage and quality disputes. Packaging configurations must also satisfy IMDG Code segregation: MTBE is separated from oxidizing substances and kept clear of sources of ignition, but no formal segregation from many other flammable liquids is required. The proper shipping name is accompanied by the Class 3 label and marine pollutant marking where applicable.

When Incoterms 2020 Shift Risk for Bulk Export Lots

FOB terms at Shanghai, Ningbo, or Lianyungang transfer risk when the product is loaded on board the vessel. CFR and CIF terms keep seller responsibility for main carriage to the discharge port, with CIF adding marine insurance. DAP terms place delivery and import clearance costs on the importer except where specifically negotiated. Bulk export contracts generally define quantity by shore tank gauging or vessel ullage survey at the load port, with measurement tolerances of ±0.5% and independent inspection by SGS, Intertek, or CCIC. Documents required for payment under letter of credit include commercial invoice, packing list, bill of lading, certificate of quantity, certificate of quality, certificate of origin, SDS under EU 2020/878 or GB/T 16483, and GHS label. For EU-bound shipments, the SDS must include registration and use restrictions under REACH Regulation (EC) No 1907/2006 and classification under CLP Regulation (EC) No 1272/2008. Chinese export customs require HS code 2909.19 and compliance with GB 30000.7-2013 for flammable liquids.

High-Purity MTBE in Isobutylene Cracking and Solvent Systems

High-purity MTBE is used as feedstock for back-cracking to high-purity isobutylene over silica-alumina or acidic catalysts at temperatures near 180–300 °C and pressures designed to maintain vapor-phase operation. Methanol levels above 0.1 wt% in feed can form dimethyl ether as a byproduct, reducing isobutylene yield and complicating downstream distillation. In solvent applications, MTBE’s low atmospheric boiling point and low water solubility make it useful for extraction of polar and moderately nonpolar compounds, but its peroxide-forming potential requires storage with limited oxygen exposure. Production-scale handling therefore includes nitrogen padding on feed tanks and regular peroxide screening before thermal processing, because accumulated peroxides can decompose during distillation and create a localized pressure excursion.

Storage terminals in China that handle MTBE for gasoline blending in-line avoid floating-roof tanks without secondary vapor treatment because of high vapor pressure. The liquid is preferably stored in fixed-roof tanks with internal nitrogen blankets or connected to vapor recovery. Seal materials in loading pumps and valves are selected from fluoroelastomer or PTFE grades because ether contact can produce volume swell in EPDM and natural rubber. Batch-to-batch variance in Chinese export lots is generally lowest at continuous catalytic distillation units with on-line GC feedback; older water-wash units may show wider methanol swings after reboiler cleaning cycles. At terminals where MTBE is received for gasoline blending, in-line analyzers measure density, vapor pressure, and methanol response after the injection point. Dosing is typically adjusted by mass flow according to the final gasoline oxygen limit and RVP target; Chinese supply contracts may specify oxygenate content by ASTM D4815 and vapor pressure by ASTM D4953 or equivalent GB methods. Blending tanks are slotted rather than fixed-roof only when vapor recovery is installed because MTBE vapor can accumulate near the liquid surface and create a flammable mixture. These operational boundaries are documented in terminal operating procedures and are not treated as optional handling preferences.