Emission control system

A process for controlling the emission of noxious materials in exhaust gases from an internal combustion engine upon starting the engine wherein the exhaust gases are initially cool and then become hot, said exhaust gases containing noxious materials selected from the group consisting of volatile organic compounds, NOx, CO, carbonaceous particulate matter and mixtures thereof, said process comprising:

• (a) passing cool exhaust gases through a gas permeable solid material containing an adsorbent and a heterogeneous catalyst, said adsorbent capable of adsorbing the noxious materials below a certain temperature and said catalyst capable of converting the noxious materials into innocuous materials when heated above a certain temperature, said catalyst initially below the temperature at which it is effective in converting the noxious materials, said noxious materials adsorbed by the adsorbent;
• and
• (b) continuing to pass the exhaust gases through the gas permeable solid material as the exhaust gases become heated while reversing the flow of the gases through the gas permeable solid material in a continuing series of cycles to ignite at least some portion of the catalyst to the temperature at which the catalyst is effective in converting the noxious materials before all of the adsorbent has been heated to the point that the noxious materials desorb, said noxious materials converted by the catalyst,
• whereby emissions are initially controlled by the adsorbent while the catalyst is being heated and thereafter are controlled by the catalyst.