There is no catalyst associated with a Diesel Particulate Filter.  A DPF is a ceramic matrix which accumulates particulates/soot at temperatures below soot ignition temperature.   During regeneration, when DPF achieves and maintains at least 500 degrees Fahrenheit, the temperature of a hot kitchen oven, accumulated soot incinerates during a few minutes.
Operator Manuals for DPF equipped compact tractors do a poor job of explaining DPFs and a poor job of explaining regeneration cycles.  For instance, two manuals  i have viewed do not  inform that soot accumulates faster during low weather temperatures, none inform time required for DPF to attain 500 degrees fahrenheit, the ignition temperature for diesel soot and none address faster soot accumulation at higher altitudes.  It seems to me a DPF temperature readout on electronic instrument panels would address many DPF complaints, as would more descriptive  technical writing.
As off-road diesel engines increase in displacement and  horsepower emission treatment becomes increasingly complex.  DPFs as a final particulate treatment are primarily associated with diesel engines <75-horespower.