Methods and apparatus to treat exhaust streams are disclosed. A disclosed example treatment device to treat a carbon monoxide-containing exhaust stream includes a conversion device to convert carbon monoxide to carbon dioxide, where the energy released in the conversion is used to supply thermal energy and/or electrical energy. The example treatment device also includes a cleaning device to clean the exhaust gas stream to be provided to the conversion device, where the cleaning device is provided upstream in an inlet of the conversion device.

A cerium-zirconium-aluminum-based composite material, a cGPF catalyst and a preparation method thereof are provided. The cerium-zirconium-aluminum-based composite material adopts a stepwise precipitation method, firstly preparing an aluminum-based pre-treated material, then coprecipitating the aluminum-based pre-treated material with zirconium and cerium sol, and finally roasting at high temperature to obtain the cerium-zirconium-aluminum-based composite material. The cerium-zirconium-aluminum-based composite material has better compactness and higher density, and when it is used in cGPF catalyst, it occupies a smaller volume of pores on the catalyst carrier, such that cGPF catalyst has lower back pressure and better ash accumulation resistance, which is beneficial to large-scale application of cGPF catalyst.