Evaporative fuel vapor emission control systems

An evaporative emission control canister system including one or more canisters comprising:

• at least one fuel-side adsorbent volume;
• and
• at least one vent-side low retentivity particulate adsorbent volume comprising a particulate adsorbent having microscopic pores with a diameter of less than about 100 nm, macroscopic pores having a diameter of about 100-100,000 nm, and a ratio of the volume of the macroscopic pores to the volume of the microscopic pores that is greater than about 150%,
• wherein the at least one vent-side low retentivity particulate adsorbent volume has a butane retentivity of less than 0.5 g/dL.

An evaporative emission control canister system including one or more canisters comprising:

• at least one fuel-side adsorbent volume;
• and
• at least one vent-side low retentivity particulate adsorbent volume comprising a particulate adsorbent having microscopic pores with a diameter of less than about 100 nm, macroscopic pores having a diameter of about 100-100,000 nm, a ratio of the volume of the macroscopic pores to the volume of the microscopic pores that is greater than about 200%, and
• wherein the at least one vent-side particulate adsorbent volume has a butane retentivity of less than 1 g/dL.