Study On The Catalytic Hydrogen Production Performance Of Metallic Nickel Hollow Fiber Membrane Reactor

With the development of modern industry,hydrogen(H2)plays an important role in chemical production.It is not only an important by-product in some chemical production processes,a raw material for preparation processes such as ammonia synthesis,methanol,hydrocracking,etc.,hydrogen energy is also an ideal secondary energy source.Hydrogen in nature exists mainly in the form of compounds.Therefore,hydrogen is need produced by reacting hydrogen-containing compounds.Hydrogen production from methane steam reforming is one of the industrially mature hydrogen production processes.Up to now,there are still some shortcomings in the preparation and purification of hydrogen,so it is still necessary to continuously explore and improve it.In the work here in,Ni hollow fibers(HF)having a closed end are first fabricated and assembled into a membrane module,and pure H2 separation is performed by applying a vacuum to the permeate side.The separation behavior of the HF module was studied experimentally and theoretically.The results show that the amount of H2 recovery can be significantly improved by changing the operating conditions.The more hydrogen in the mixed gas,the more hydrogen is recovered;In addition,the hydrogen recovery rate is also improved as the temperature of the test process increases,and the hydrogen purity is also more stable;Furthermore,the hydrogen recovery rate can be increased by increasing the temperature but increasing the feed flow rate and feed concentration will reduce the hydrogen recovery rate.In the vacuum mode of operation,there is little difference in H2 recovery efficiency,regardless of whether the feed gas stream is controlled in a countercurrent operation or in a recycle operation.In the case where CO2 is present in the hydrogen mixture feed,a slight negative impact of the rWGS reaction must be considered as it will consume some of the hydrogen and ultimately reduce the driving force for hydrogen permeation.Increasing the feed/cavity pressure ratio(ps/pv)is beneficial to improve hydrogen recovery,reduce membrane area and permeation temperature;In addition,the theoretical model agrees well with the experimental results.This work provides important insights into the development of high quality membrane H2 separation systems.The Ni/?-Al2O3 catalyst with high catalytic efficiency,good anti-sintering ability and strong stability was successfully prepared by y-Al2O3 as the carrier by the whole impregnation method.The catalysts were assembled with the metal nickel hollow fiber membrane sealed at one end to become a reactor.Firstly,the basic performance characterization and testing of the catalyst were carried out.The performance of the metal nickel hollow fiber membrane reactor for hydrogen production from methane steam reforming was studied.The experimental results show that when the self-made nickel-based catalyst was added,the overall conversion of methane was about 4.8 times,and the initial reaction temperature was significantly reduced by 100 ?.The catalyst is basically stable in the 10-hour stability test;At the same time,when the metal nickel hollow fiber membrane sealed at one end with a membrane area of 447.26 mm2 was used for separation,the methane conversion rate,the hydrogen yield,and the hydrogen recovery amount increased.Compared with the fixed bed reactor,the maximum conversion of methane can reach 67.59%,which is 1.45 times higher than the vacuum applied without vacuum pump.The maximum hydrogen production in the shell side can reach 12.28 cm3 min-1,and the maximum recovery of hydrogen on the permeate side can reach 3.5 cm3 min-1.The research has the advantages of no secondary separation,shortened process flow,improved product purity and reduced hydrogen production cost in the hydrogen production process.