That is not true methane, propylene, hydrogen can be easily produced and they have temperature >2800C while burning of coal can produce combustion gases as hot

That is not true methane, propylene, hydrogen can be easily produced and they have temperature >2800C while burning of coal can produce combustion gases as hot as 2,500 °C (4,500 °F). https://www.thoughtco.com/flame-temperatures-table-607307 https://www.thoughtco.com/flame-temperatures-table-607307