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

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.