Effect of high temperature on nanopores in cokes

Small Angle Neutron Scattering and Ultra Small Angle Neutron Scattering were used to study the effect of annealing at temperatures of 1400 and 1600 degrees C, in an inert atmosphere, on the pore size distribution of three cokes prepared from Australian coals. The pore size range investigated was 1 nm to 2 mu m. It was found that annealing substantially changed the size distribution of these pores in similar ways for all three cokes examined, despite the difference in rank and maceral composition of the starting coals. The pore sizes at which the greatest percentage changes in numbers occurred on heating was around 10 nm, with an increase in the number of both open and closed pores, by up to a factor of four after annealing at 1600 degrees C. For pores in the size range 100 nm to 2 mu m, the number of closed pores decreased slightly and the number of open pores increased substantially; new open pores were created. The percentage increase in pore numbers introduced by annealing decreased with increasing pore size above 100 nm, but even at 2 mu m pore radius, some samples showed a 50 % increase in total pore numbers. Annealing at greater temperature or longer time had a greater effect on pore numbers.

Automated summary

Small Angle Neutron Scattering and Ultra Small Angle Neutron Scattering were used to investigate the changes in pore size distribution of three cokes prepared from Australian coals after annealing at temperatures of 1400 and 1600 degrees C. The study found that annealing caused substantial changes in pore size distribution, with the greatest percentage increase occurring around 10 nm pore size. The number of open pores increased significantly, while the number of closed pores decreased slightly for pores in the size range of 100 nm to 2 mu m. The effect of annealing on pore numbers decreased with increasing pore size above 100 nm.