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用Monte carlo方法计算设定硅铝比下八面沸石中五种结构单元Si(nAl)(n=0,1,2,3,4)的数量分布,与~(29)SiMASNMR实验结果直接比较,有令人满意的吻合. 八面沸石中四种类型铝离子Al(mAl)(m=0,1,2,3)的数量分布关系到八面沸石酸性质.在低铝浓度情况下,Monte Carlo计算结果与基于二项分布统计假设的计算结果相近;在高铝浓度(低硅铝比)情况下,Monte Carlo方法较只适于高度稀释前提的二项分布假设为优。在Monte Carlo模拟八面沸石脱铝过程的研究中,基于一级动力学把连续的脱铝过程用离散、可列状态的马尔科夫链作近似,其优点是考虑了过程因素从而更逼近真实;同时又计算了脱铝过程亚稳态的铝-铝次邻分布{Al(mAl)}和硅-铝近邻分布{Si(nAl)}.前者涉及脱铝八面沸石的酸性质;后者可通过~(29)SiMAsNMR实验观测。Monte Carlo模拟把二者联系起来,从而开拓了用~(29)SiMASNMR实验推断铝-铝次邻分布的途径.
The Monte Carlo method was used to calculate the quantitative distribution of Si (nAl) (n = 0, 1, 2, 3, 4) in the faujasite zeolite with Si / , With satisfactory agreement.The quantitative distribution of the four types of aluminum ions, Al (mAl) in faujasites (m = 0, 1, 2, 3) is related to the acid nature of the faujasite zeolite.In the case of low aluminum concentrations, Monte Carlo calculation results are similar to those based on binomial distribution statistical assumptions. Monte Carlo method is better than the binomial distribution hypothesis that is only suitable for highly diluted conditions at high Al concentration (low Si / Al ratio). In Monte Carlo simulation of the faujasite dealuminization process, based on the first-order kinetics, the continuous dealumination process is approximated by discrete and demarcated Markov chains, which has the advantage of taking into account the process factors and thus closer to the real And the metastable Al {Al (mAl)} and the Si-Al neighbor distribution {Si (nAl)} during the dealumination are also calculated. The former deals with the acidity of the dealuminated faujasite and the latter It can be observed by ~ (29) SiMAs NMR experiment. The Monte Carlo simulation links the two and opens up the way to deduce the aluminum-aluminum sub-distribution using the ~ (29) SiMASNMR experiment.