The catalytic behavior of alkaline earth carbonates of Mg, Ca, Sr and Ba on the gasification of carbon were investigated under high pressures of CO
2 by using a thermobalance, fixed bed flow reactor system and temperature-programmed X-ray diffraction. The carbon material used was prepared from phenol formaldehyde resin. It was mixed with respective carbonate of 0 .5 atomic % in a mortar grinder for 1 hour.
It was found from nonisothermal thermogravimetric measurements that the gasification of the pure carbon showed an increase in conversion with increasing CO
2 pressure, and the rate of gasification was proportional to the square root of CO
2 pressure. Addition of four carbonates, Ca, Sr and Ba, except Mg, had appreciable catalytic actions, but their rate constants were not so much large increased with the increase of CO
2 pressure. For MgCO
3, little catalytic effect was observed only between 750°C and 800°C at 49.5 atm of CO
2 in the flow reactor system.
According to the temperature-programmed X-ray diffraction, high catalytic activities were obtained when the carbonates coexist with their oxides. Such results will confirm the cyclic catalytic mechanism of oxide-carbonate, previously stated.
View full abstract