Pd composite membrane was prepared by electroless plating on ceramic tubes. The hydrogen permeation properties of CO_2/H_2 mixture on ultrathin Pd composite membrane(2 μm) were studied. The effects of feed gas velocity

temperature and pressure on the hydrogen permeation property were analyzed

and the carbon deposition in CO_2/H_2 separation was characterized. The results show that

at temperatures below 623 K

CO2 adsorption is the main factor affecting the hydrogen transmission

while over 723 K

the CO

H_2O and carbon deposition are the main factors. The higher the feed gas flow rate is

the weaker the CO_2/H_2 reaction is. When the flow rate is above 2 000 m L/min

the conversion rate of CO_2/H_2 is very low. The suitable CO_2/H_2 separation temperature range is 623～723 K. The reaction of CO_2/H_2 above 723 K is intense

while the hydrogen penetration of palladium film below 623 K is too low. The higher the feedstock side pressure

the higher the CO_2/H_2 conversion rate. The surface carbon

palladium carbide

carbon aggregation and graphite carbon were generated on the palladium membrane after the CO_2/H_2 separation experiment.