Experimental and Theoretical Studies of Gas Adsorption in Cu₃(BTC)₂:  An Effective Activation Procedure

Abstract

We have improved the activation process for CuBTC [Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylate] by extracting the N,N-dimethylformamide-solvated crystals with methanol; we identify material activated in this way as CuBTC−MeOH. This improvement allowed the activation to be performed at a much lower temperature, thus greatly mitigating the danger of reducing the copper ions. A review of the literature for H2 adsorption in CuBTC shows that the preparation and activation process has a significant impact on the adsorption capacity, surface area, and pore volume. CuBTC−MeOH exhibits a larger pore volume and H2 adsorption amount than any previously reported results for CuBTC. We have performed atomically detailed modeling to complement experimentally measured isotherms. Quantum effects for hydrogen adsorption in CuBTC were found to be important at 77 K. Simulations that include quantum effects are in good agreement with the experimentally measured capacity for H2 at 77 K and high pressure. However, simulations underpredict the amount adsorbed at low pressures. We have compared the adsorption isotherms from simulations with experiments for H2 adsorption at 77, 87, 175, and 298 K; nitrogen adsorption at 253 and 298 K; and argon adsorption at 298 and 356 K. Reasonable agreement was obtained in all cases.

Recent advances on simulation and theory of hydrogen storage in metal–organic frameworks and covalent organic frameworks

“…Liu et al 79 synthesized a new MOF material, [Zn(bdc)(ted) 0.5 ] (bdc = benzenedicarboxylate, ted = triethylenediamine), and showed good agreement between experimental and simulational H 2 uptake isotherms at 77 and 298 K where they used the UFF 63 and DREIDING 69 together with the quantum effect correction. 70 However, they (Liu et al) 80 also applied the same simulational technique to the Cu-BTC 72 MOF (the activation process of the sample was experimentally improved in the work) and showed a slight disagreement between simulations and experiments for the H 2 adsorption isotherm at 77 K. And Noguchi et al 81 synthesized a new Cu-based MOF [Cu(4,4 0 -bipyridine) 2 (CF 3 SO 3 ) 2 ] n of one-dimensional pore networks. They measured H 2 and D 2 adsorption isotherms of the MOF at 40 and 70 K and then compared them with GCMC simulated isotherms where the OPLS-AA was used.…”

Nanosized Cu-MOFs induced by graphene oxide and enhanced gas storage capacity

“…29, 30 The H 2 storage a H 2 uptake at 77 K and 42 atm; CO 2 uptake at 273 K and 1 atm; average particle sizes of Cu-BTC nanocrystals are measured according to the TEM images of composites, as shown in Fig. S5.…”

Enhanced Adsorption Selectivity of Hydrogen/Methane Mixtures in Metal−Organic Frameworks with Interpenetration: A Molecular Simulation Study

“…6,7 In the latter additional small pores and adsorption sites are formed by the interpenetration of frameworks, leading to MOFs with multipores of different sizes that may exhibit enhanced gas adsorption and separation properties. [7][8][9][10][11][12][13] Currently, most theoretical [14][15][16][17][18][19][20][21][22][23] and experimental [24][25][26] investigations focus on noninterpenetrated MOFs and far less attention has been paid on these interpenetrated structures. Extensive studies have been carried out on the adsorption and diffusion of pure gases in MOFs, [1][2][3][4][5][6][8][9][10][14][15][16][17][18][24][25][26][27][28][29] but far less attention has been given to the separation of gas mixtures.…”

“…[7][8][9][10][11][12][13] Currently, most theoretical [14][15][16][17][18][19][20][21][22][23] and experimental [24][25][26] investigations focus on noninterpenetrated MOFs and far less attention has been paid on these interpenetrated structures. Extensive studies have been carried out on the adsorption and diffusion of pure gases in MOFs, [1][2][3][4][5][6][8][9][10][14][15][16][17][18][24][25][26][27][28][29] but far less attention has been given to the separation of gas mixtures. 7,[11][12][13][19][20][21][22][23] Among the available separation studies, Chen and co-workers performed experimental separations of light gas mixtures in several interpenetrated MOFs that exhibit high selectivity.…”