Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (2): 20220459.doi: 10.7503/cjcu20220459

• Physical Chemistry • Previous Articles     Next Articles

Transfer Learning Modeling for Predicting the Methane and Hydrogen Delivery Capacity of Metal-organic Frameworks

CHEN Shaochen1, CHENG Min1, WANG Shihui1, WU Jinkui1, LUO Lei1, XUE Xiaoyu1, JI Xu1, ZHANG Changchun2, ZHOU Li1()   

  1. 1.School of Chemical Engineering,Sichuan University,Chengdu 610065,China
    2.Sichuan Mingtaishun CNC Cutting Tools Co. ,Ltd. ,Suining 629201,China
  • Received:2022-07-06 Online:2023-02-10 Published:2022-09-29
  • Contact: ZHOU Li E-mail:chezli@scu.edu.cn
  • Supported by:
    the Young Scientists Fund of the National Natural Science Foundation of China(22108178)

Abstract:

As critical energy resources, methane and hydrogen have been limited in large-scale applications due to their difficulty in storing at low pressure. Metal-organic frameworks(MOFs) are promising materials for gas delivery due to their highly tunable nanoporous structures. At present, machine learning(ML) has been used to assist in the screening of high-performing MOFs, but the traditional ML modeling needs to pay a high cost to obtain a large amount of data, when the amount of data is insufficient, the availability of ML will be greatly reduced. In this paper, based on deep neural network(DNN) and transfer learning(TL), TL models are established using a small amount of data to accurately predict the methane and hydrogen delivery capacity of a large number of MOFs to reduce modeling costs and quickly respond to the changing delivery standards. Before TL modeling, six geometric descriptors of 12020 MOFs based on experimental synthesis are calculated, covering the largest cavity diameter, pore limiting diameter, density, accessible volumetric surface area, accessible mass surface area, void fractions, and grand canonical Monte Carlo simulation is used to calculate the delivery capacity data of methane and hydrogen by these MOFs. The first step of TL modeling is to train a DNN[Source task(ST) model] with a coefficient of determination(R2) of 0.973 using methane delivery capacity data from 8414 MOFs at 298 K/65 bar—298 K/5.8 bar(1 bar=0.1 MPa). Since then, partial parameters of the ST model are frozen, and data of 100 MOFs delivering methane at 233 K/65 bar—358 K/5.8 bar(Task 1, T1) and 100 MOFs delivering hydrogen at 198 K/100 bar—298 K/5 bar(Task 2, T2) are used, the ST model is fine-tuned twice to obtain two TL models, and the 11820 data in T1 and T2 are predicted, with R2 of 0.968 and 0.945, respectively, which are higher than other five traditional ML models. In addition, TL models have high precision and high stability in predicting small data sets and do not produce bad prediction results. Finally, the permutation feature importance is used to measure the importance of descriptors. For the three models of different tasks(ST, T1, and T2), accessible mass surface area(AMSA), accessible volumetric surface area(AVSA), and void fraction(VF) are the most important descriptors for these models, and there is a large amount of shared “knowledge” between the models. On this basis, the relationship between important descriptors and delivery capacity is shown. It provides an efficient research method for future researches on other advanced nanoporous materials to deliver methane and hydrogen.

Key words: Metal-organic framework, Methane and hydrogen, Delivery capacity, Deep neural network, Transfer learning, Permutation feature importance

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