the present disclosure may include a device for testing catalysts , and a method for controlling the flow rate and temperature parameters during the process . the device may separate mass flow control through heating elements from the mass flow through the sample , as well as separate banks for mixing oxidizing elements , carbon dioxide , and diluent gas as well as reducing agents , nitric oxide , and diluent gas . the device disclosed here may also use mass control units of a sufficiently high speed so as to allow the desired testing conditions .