An investigation of hydrogen separation by a palladium membrane: Gas composition effect and high temperature water gas shift reaction

• Main Authors: Chien-NanLin, 林健男
• Other Authors: Wei-Hsin Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/4tbm37

碩士 === 國立成功大學 === 航空太空工程學系 === 104 === This study is divided into two parts. The first part is investigte the permeances of two palladium (Pd) membranes in pure H2, binary, and ternary gas mixtures. Three membrane temperatures of 320, 350, and 380 °C and five H2 partial pressure differences of 1, 2, 3, 4, and 5 atm are considered. With 10 % of gas impurities in H2, the profiles of dimensionless permeance suggest that H2 permeation rate is lessened by approximately 50 % to 90 %, and the permeance reduced by the gas impurities is ranked as: CO〉CO2〉N2. By introducing a parameter of permeance resistance, which is the reciprocal of permeance, the permeance resistance and thereby H2 permeation rate in a ternary gas mixture can be predicted from the summation of individual permeance resistances in binary gas mixtures. At least 75 % and up to 100 % of H2 in the gas mixtures can be recovered in the membrane system, and the maximum H2 recovery is always exhibited at the H2 partial pressure difference of 2 or 3 atm. In the Arrhenius-type equation describing the relationship of permeance and temperature, the activation energy is between approximately 2 and 18 kJ mole-1. In general, the permeances of the membranes in gas mixtures, especially in ternary gas mixtures, are more sensitive to temperature when compared to those in pure H2. In the second part, WGSR at different temperatures (350 °C, 400 °C, 450 °C) and different pressures (1 atm, 5 atm, 9 atm) are investigated. The Fe-Cr catalysis is used in the reaction, and the steam CO ratio is from 2 to 4. From the results of experiment, the CO conversion is from 30 to 65%. approximately WGSR at high pressures causes methanation and coking, it will retard hydrogen production and hydrogen through the palladium membrane.