Preparation, Characterization and Surface Free Energy of Nickel-Doped Silica Organic-Inorganic Hybrid Membrane for H-2/CO2 Separation

摘要

Nickel-doped silica organic-inorganic hybrid (Ni/SiO2) membranes based on tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) were prepared via a sol-gel process for H-2/CO2 separation. The influence of calcination temperature and Ni-doping amount on the microstructure and surface free energy of Ni/SiO2 materials was investigated. The permeance of H-2 and CO2 and vapor stability of the membranes were tested. For the Ni/SiO2 membrane, the optimal calcination temperature should be 350 degrees C and Ni/TEOS molar ratio is 0.1. After calcination at 350 degrees C, nickel element exists in form of Ni-O-Si structure and crystalline NiO with small grain size. At this temperature, the water contact angle of Ni/SiO2 film achieved a maximum of (96.1 +/- 0.4)degrees and the surface free energy reached the minimum. The H-2 and CO2 permeance of freshly-prepared the Ni/SiO2 membrane was 7.86 x 10(-6) and 1.50 x 10(-6) mol m(-2) Pa-1 s(-1), respectively, at 25 degrees C and a pressure difference of 0.4 MPa. Compared with the pure SiO2 membrane, the H-2 permeance and H-2/CO2 selectivity of Ni/SiO2 membrane increased by 20.9% and 15.9%, respectively. After aging in the moist condition for 7 d, the H-2 permeance of Ni/SiO2 membrane was reduced by 6.9% and the H-2/CO2 selectivity increased by 4.7%. The Ni/SiO2 membrane showed higher H-2 permeance, H-2/CO2 selectivity and vapor stability than pure SiO2 membrane .