摘要:
The invention relates to catalysts for the methanation of carbon monoxide, which comprise metal-doped nickel oxide of the composition (in mol %) (M1)a(M2)bNicOxwhere a=0.1 to 5 mol %, b=3 to 20 mol % and c=100−(a+b) mol % and M1 comprises at least one metal of transition group VII or VIII of the PTE (=Periodic Table of the Elements) and M2 comprises at least one metal of transition group III or IV of the PTE. The catalysts can be used as pure catalysts or as supported catalysts, if appropriate applied as coatings to an inert support body. They display high conversion and high selectivity and are used in methanation processes of CO in hydrogen-containing gas mixtures, in particular in reformates for operation of fuel cells. The catalysts of the invention can be prepared by precipitation, impregnation, sol-gel methods, sintering processes or by powder synthesis.
摘要:
The invention relates to a process and an apparatus for producing hydrogen-containing fuel gases for fuel cells by catalytic reforming of hydrocarbons and subsequent gas purification. The process is characterized in that the catalytic reforming comprises two successive stages of which the first stage comprises autothermal reforming and the second stage comprises low-temperature steam reforming at temperatures below 650° C. In the first stage (autothermal reforming, ATR stage), a feed mixture of hydrocarbons, oxygen and water or water vapour is reacted over a catalyst in an autothermal reforming reaction to convert it incompletely into a hydrogen-rich gas mixture. The mixture which still contains residual amounts of hydrocarbons is then reacted in a subsequent steam reforming stage (second stage, SR stage) to give a hydrogen-rich fuel gas. A fuel gas which has a temperature at the reactor outlet of 400-650° C. and contains a very high proportion of hydrogen is obtained. Owing to the low outlet temperatures, the fuel gas can be passed directly to a gas purification stage without use of additional heat exchangers. In addition to the improvement in the reformer efficiency, a more compact and cheaper reformer design is made possible by the invention. Process and apparatus are used for producing hydrogen or hydrogen-containing fuel gases for fuel cells, in particular for mobile and stationary applications.
摘要:
A ceramic microreactor for carrying out reactions having a large heat of reaction which has at least three interior spaces, with at least one interior space having internal buffers whose shape, number and positioning ensure homogeneous flow, is described. The microreactor is built up as a monolith from at least seven plate-shaped layers of inert ceramic material, preferably aluminium oxide, which form an upper heating/cooling space, a central reaction space and a lower heating/cooling space. One interior space has a coating of a catalyst comprising noble metal. The shape, number and positioning of the internal buffers is determined by means of flow simulation calculations; the internal buffers preferably have a lozenge shape. The microreactor displays very good selectivity in reactions having a large heat of reaction, in particular in heterogeneous gas-phase reactions, and is used in particular for hydrogen production and/or hydrogen purification in fuel cell technology.