Evolution of pore surface area during noncatalytic gas-solid reactions. 1. Model development

Study of Activation of Coal Char

“…This may be verified by comparing the ordinate scales of Figures 1, 3 Focusing for the moment on the representation of data involving normalization by m 0 (Figures 1, 3, and 5), it appears that over a wide range of burn-off, the rates in NO and CO 2 are quite constant with burn-off, whereas the rate in O 2 increases and decreases dramatically. This is emphasized by the comparison in Figure 7, which illustrates the change in rate with conversion in The behavior seen in the case of oxygen is often reported in the literature [9][10][11][12][13]. The general interpretation is that the surface area for reaction initially increases with burn-off, and then is lost as a result of pore coalescence.…”

Study of Activation of Coal Char

“…Much combustion literature suggests that char reactivities should be expressed on a surface area basis [2], although small char micropores might not be fully utilized during oxidation or gasification [e.g., [3][4][5][6][7][8]. Many models have been proposed to describe development of char surface areas with burn-off [9][10][11][12][13][14][15], but many features need further clarification -e.g., different patterns of porosity development are observed in the same char, in different gases, even when rates of reaction are set to be identical [7,16]. While this study cannot fully answer the question of the extent of internal microporosity utilization, some results clearly indicate that opening up of this porosity does impact observed kinetics in a chemical control regime.…”

Intrinsic char reactivity of plastic waste (PET) during CO2 gasification

“…When narrow micropores participate in the reaction, they initially become larger due to the fact that the reaction occurs on the pore surface, and this results in an increase in the surface area. However, as these pores get even bigger, they coalesce with neighbouring pores, with the result that the pore surface area decreases [32]. And at the same time, an increase in the surface area of higher micropore sizes occurs, leading to an increase in BET surface area (Table 1), again due to pore coalescence.…”