Kinetic study on CO2 gasification of brown coal and biomass chars: reaction order

•Higher CO2 partial pressure leads to higher gasification reaction rate.•Reaction orders for coal and biomass chars pyrolyzed at high temperature are high.•At low gasification temperature, reaction order for biomass is higher than coal.•At high gasification temperature, reaction orders for biomass and coal are similar.•Reasons for above behaviors are related to catalytic effect and pore distribution.