Study On New Technology For Hydrogen Production From The Autothermal Conversion Of Natural Gas

Natural gas will play a growing role as carbon-source for the world's supply of fuel and chemicals.at present ,conventional steam reforming technology of natural gas is widely used in industry for the production of hydrogen. For the limit of reaction ,the technology shows higher energy consumption,capital investment and production cost. Compared to this technology ,the partial oxidation of methane to synthesis gas (POM) exhibits lower energy consumption, fast reaction rate. However POM is an exothermic reation which can be operated at a great space velocity. The POM reaction zone is concentrated on the entrance of the catalyst-bed. Such will result in hot-spot temperature and unreasonable heat distribution in the catalyst-bed, and further a series of problems for POM reaction systems as follows: Gas-phase reaction occurs in front of catalyst-bed, and further decrease the safety of operational system; Catalyst deactivation and the loss of active component in the catalyst at higher temperature (hot-spot temperature); Energy-consumption of reaction system increases because of the unreasonable distribution of reaction heat; Stricter requirement of reactor materials for higher hot-spot temperature.To solve the above problems existed in autothermal reaction systems, reactor design and catalyst preparation have been studied in this thesis. the reactor with oxygen distributor was designed, and reaction performance and temperature distribution of catalyst bed were tested, the results exhibit it has more reasonable temperature distribution of catalyst bed in the reactor with oxygen distributor. the state of oxygen distribution in the reactor has been investigated by adjusting the structure of oxygen distributor, the ratio of oxygen distribution and the structure of reactor. Ni-based catalysts were prepared and their catalytic performances were tested, the results were given as: 8%Ni-2%La2O3-MgAl2O4 catalyst exhibits the best reaction performance: 97% methane conversion can be obtained for CH4-Air-H2O system under the reaction conditions of 830℃,0.8MPa. Finally, we investigated the autothermal reaction stability of selected Ni-based catalyst in our designed reactor with oxygen distributor.1000 h experimental results show that the reaction performance keeps stable and no carbon deposition was observed during 1000 h reaction. Such results provide the valuable basic data for the further scale-up test of autothermal reaction in our designed reactor.