Figure 4
Schematic diagram of kinetic model simulating gas generation from gas-solid equilibrium. A and B are reservoirs charged with native gas, (Cx) is in A and [Cx] is in B (reaction 8). Reservoir C resides in B. Open catalytic sites [···] reside in C and B, unspecified in diagram. Gas passes reversibly between reservoirs as indicated by first-order kinetics (k1 = 0.07) and by second-order kinetics (k-1 = 0.007) for generation of [Cx]. Gas passes to the surface from A by first-order kinetics controlled by rate constant k2 (0.2). Catalytic gas is generated in C from [Cn] at a constant rate controlled by second-order rate constant k (0.0004), considered irreversible in this simulation. Generated gas passes directly into B. Each reservoir is filled with an initial quantity of gas, assumed non-depletable in C (100), and depletable by first-order kinetics in A ((Cx) = 200) and B ([Cx] = 200). The initial value of [···] was assumed 5, with all concentrations unitless. Reaction 8 was simulated by iterating kinetic steps by first or second-order changes until concentrations of [···], [Cx], and (Cx) were constant (steady-state). For example, the concentration of [Cx] at iteration ii was: [Cx] ii = [Cx] i + (k*[ ] i *[Cn]) + (k-1*(Cx) i *[···] i )-(k1*[Cx] i ). All concentrations were similarly calculated at each iteration.