Abstract:
The present invention relates to a catalyst for the conversion of oxygenates to olefins, wherein the catalyst comprises one or more zeolites of the MFI, MEL and/or MWW structure type and particles of one or more metal oxides, the one or more zeolites of the MFI, MEL and/or MWW structure type comprising one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba and combinations of two or more thereof, wherein the catalyst displays a water uptake of 9.0 wt.-% or less, as well as to a process for the production thereof and to its use, in particular in a process for converting oxygenates to olefins.
Abstract:
The invention relates to a nickel hexaaluminate-comprising catalyst for reforming hydrocarbons, preferably methane, in the presence of carbon dioxide, which comprises hexaaluminate in a proportion in the range from 65 to 95% by weight, preferably from 70 to 90% by weight, and a crystalline, oxidic secondary phase selected from the group consisting of LaAlO3, SrAl2O4 and BaAl2O4 in the range from 5 to 35% by weight, preferably from 10 to 30% by weight. The BET surface area of the catalyst is ≧5 m2/g, preferably ≧10 m2/g. The molar nickel content of the catalyst is ≦3 mol %, preferably ≦2.5 mol % and more preferably ≦2 mol %. The interlayer cations are preferably Ba and/or Sr. The process for producing the catalyst comprises the steps: (i) production of a mixture of metal salts, preferably nitrate salts of Ni and also Sr and/or La, and a nanoparticulate aluminum source, (ii) molding and (iii) calcination. The catalyst of the invention is brought into contact with hydrocarbons, preferably methane, and CO2 in a reforming process, preferably at a temperature of >800° C. The catalyst is also distinguished by structural and preferred properties of the nickel, namely that the nickel particles mostly have a tetragonal form and the particles have a size of ≦50 nm, preferably ≦40 nm and particularly preferably ≦30 nm, and are present finely dispersed as grown-on hexaaluminate particles. The catalyst has only a very low tendency for carbonaceous deposits to be formed.