对于真空绝热压力容器来说,如何获得并且能够长期维持满足要求的夹层真空度,主要在于吸附剂的吸附性能和微观结构。为此,采用巨正则系综的蒙特卡罗方法,结合13X分子筛在298 K下吸附CO2的实验数据,优化了模拟力场参数。通过模拟308 K下的CO2吸附和298 K下的N2吸附并与实验数据进行对比,验证了优化的力场参数的准确性和可靠性,表明该力场参数在不同温度和吸附质的条件下能够较准确的模拟13X分子筛的吸附行为。最后使用优化调整后的力场参数模拟13X分子筛在77K温度下的N2吸附等温线,同时采用ASAP2020物理吸附仪对13X分子筛样品进行微观结构测试。对比模拟与实验的吸附等温线,发现压力在0~70 k Pa内两者比较接近,并计算了其比表面积,模拟所得分子筛比表面积为455.52m2/g,与实验值的相对误差为4.3%,表明利用模拟的方法可以获得吸附剂的比表面积。研究结果将会极大地促进真空绝热压力容器的快速发展。
The adsorption ofgases by 13X molecular sieve via numerical simulation. First, the adsorption of CO2 was mathematically modeled and numerically simulated in Grand Canonical Monte Carlo (GCMC) method with the force field in 13X zeolites being optimized by analyzing the measured CO2 sorption data at 298 K. Second, the ad- sorption of CO2 at 308 K and N2 at 298 K was simulated, measured and compared. The consistency between the sim- ulated and measured results shows that the optimized force field was accurate and reliable. Finally, the adsorption i- sotherm of N2 at 77 K was simulated. The simulated N2 adsorption isotherm was found to agree fairly well with that measured by ASAP2020 physisorption meter in 0 ~ 7 kPa range. In addition, the specific area of 13X zeolites was calculated to be 455.52 m2/g in Brauner-Emmet-Teller method, with a discrepancy of 4.3% from the measured one.