狭缝孔内水煤气变换反应平衡的蒙特卡罗模拟

Monte Carlo simulation of the equilibrium of the water gas shift reaction in slit pores

采用反应蒙特卡罗(RCMC)方法模拟了狭缝孔内水煤气变换反应的化学平衡。模拟中,CO和H2描述成球形LJ分子,H2O和CO2的分子势能分别采用TIP4P和EPM2模型计算。孔壁分子与LJ点位之间的相互作用采用Steele的10-4-3模型计算。采用经典热力学方法得到主体相的平衡组成,并与RCMC的计算结果比较。两者的一致表明可以通过RCMC方法来计算预测狭缝孔内的化学平衡组成。进一步探讨了压力、温度、孔宽以及进料气摩尔组成等因素对孔内化学平衡的影响。计算表明,尽管孔内H2摩尔分数低于主体相,但是在压力为1MPa、温度723·15K、孔宽H=3·652nm和进料水汽比n(H2O)∶n(CO)=1∶1条件下,可以得到较大的孔内H2产量。

The equilibrium of the water gas shift reaction in slit pores has been simulated by the Reactive Canonical Monte Carlo （RCMC） method. In our simulations, CO and H2 are both described as spherical Lennard-Jones molecules, whilst H2O and CO2 are described by the TIP4P and EPM2 models respectively, and the Steele 10-4- 3 potential is used to represent the interaction between a Lennard-Jones site and a solid wall. The close agreement of chemical equilibrium compositions in the bulk phase obtained by the RCMC method with those from thermodynamic prediction suggests that the RCMC method can be used to predict the chemical compositions in the pore region. The effects of different factors such as pressure, temperature, pore width and feed molar ratio on the chemical equilibria occurring inside the pores are discussed in detail. Our calculations demonstrate that a high yield of H2 can be obtained in the pore region under the following conditions： 1 MPa, 723.15 K, pore width H = 3.652 nm and feed molar ratio of n （H20） ： n （CO） = 1 ： 1 ; the yield is lower than that in the bulk phase however.