Technical Standards

The gasoline specifications sets an annual average of 30 ppm sulfur, with a per-batch limit of 80 ppm sulfur. Diesel sulfur is required to meet 15 ppm sulfur limits for all imports and sales in the border region, three major metropolitan areas and 11 specified corridors. Diesel produced within the country and sold outside of the specified regions may still comply with a 500-ppm limit until December 31, 2018, at which point all diesel sold within the country must meet the 15-ppm sulfur limit.

Gasoline

Values for gasoline that impact emissions vary depending on the region, with the most stringent specifications for the Mexico City Metropolitan Region.

Table 1. Select gasoline specifications by region

The standard sets minimum limits for octane in premium and regular gasoline. While fuel providers often market higher-octane fuels, these values match the typical minimum values in the United States.

Table 2. Minimum octane limits for gasoline

MTBE, ETBE and TAME are allowed to be added as oxygenates at levels of up to 2.7% of the oxygen mass in the gasoline. Ethanol is prohibited in the Mexico City, Guadalajara and Monterrey Metropolitan Areas. In the rest of the country it can be added to make up up to 5.8% by volume of the finished fuel. There are no waivers for vapor pressure limits due for ethanol use.

Vapor pressure impacts the evaporative emissions from vehicles, service stations and during refueling. The specifications for vapor pressure and volatility vary depending on the altitude and climate of the region. Specific volatility classes are defined in the regulation.

Table 3. Specifications for vapor pressure and distillation temperature by volatility class

And vapor lock protections are defined for each volatility class.

Table 4. Specification for protection against vapor lock

For each region and season or month, a specification is set for the fuel to meet certain volatility classes and vapor lock protections, defined in Table 5.

Table 5. Seasonal requirements for each region

[1] Includes the states of Veracruz, Campeche, Puebla, Tabasco, Yucatán, Quintana Roo, Aguascalientes, Jalisco, Guanajuato, Michoacán, Zacatecas, Morelos, Tlaxcala, Estado de México, Hidalgo, Querétaro, Baja California, Baja California Sur, Sonora, Sinaloa, Nayarit, Colima, Guerrero Oaxaca, and Chiapas.

[2] Includes the states of Nuevo León, Chihuahua, Durango, Coahuila, Tamaulipas, and San Luis Potosí

Diesel

Diesel sulfur specifications are defined in Table 6.

Table 6. Implementation timeline for sulfur reduction in diesel fuel

Other parameters of importance to vehicle manufacturers, some with limited impact on emissions, include cetane, aromatics and lubricity (Table 7). Because desulfurization processes tend to result in improved cetane levels, the actual fuel quality has far exceeded equivalent limits in the US and is expected to exceed the minimum specification in Mexico without additional effort by refiners. Desulfurization has the opposite impact on lubricity, but the fuel specification in the U.S. matches the proposal here.

Table 7. Select diesel specifications for on-road, agricultural and marine diesel

Intermediate Fuel Oil (IFO)

The IFO sulfur specifications meet current International Maritime Organization (IMO) standards for use in international shipping. Mexico is working towards the ratification of the IMO MARPOL Annex VI agreement which establishes more stringent provisions for air quality protection and is planning to seek Emission Control Area (ECA) designation under MARPOL Annex VI (once ratified). ECAs require more stringent regulations for fuel sulfur content and NOx emissions compared to those established by IMO. If implemented, intermediate fuel oil (IFO) used within the ECA should not exceed 0.1% sulfur, although fuel of that quality will not necessarily need to be sold within Mexico.

Table 8. Maximum sulfur limits for IFO