Catalysts having catalytic material applied directly to thermally-grown alumina and catalytic methods using same; improved methods of oxidative dehydrogenation
The invention describes catalysts, methods of making catalysts, methods of making a microchannel reactor, and methods of conducting chemical reactions. It has been discovered that superior performance can be obtained from a catalyst formed by directly depositing a catalytic material onto a (low surface area) thermally-grown alumina layer. Improved methods of conducting oxidative dehydrogenations are also described.
1. A microchannel reactor, comprising a reaction microchannel;
wherein said reaction microchannel is an interior microchannel;
the reaction microchannel comprising a metal substrate;
an aluminide layer disposed on the metal substrate;
a dense alumina layer disposed on the aluminide layer; and
catalyst metal particles directly disposed on the alumina layer.
2. The microchannel reactor of claim 1 wherein at least 30% of the mass of the catalyst metal is in the form of particles having a size of 3 μm or more.
3. The microchannel reactor of claim 1 wherein the metal substrate comprises a microchannel wall.
4. The microchannel reactor of claim 3 wherein the aluminide layer is nickel aluminide.
5. The microchannel reactor of claim 4 wherein the catalyst metal particles comprise Pt and Sn in a Pt/Sn atomic ratio in the range of 1 to 4.
6. The microchannel reactor of claim 1 wherein the metal aluminide is nickel aluminide.
7. The microchannel reactor of claim 6 wherein the nickel aluminide comprises 20 mass % or Ni and 10 mass % or greater Al with the sum of Ni and Al being 80 mass % or more.
8. The microchannel reactor of claim 1 wherein the catalyst metal particles comprise Pd, Rh, or Pt.
9. The microchannel reactor of claim 3 wherein the microchannel wall comprises steel.
10. The microchannel reactor of claim 3 wherein the microchannel wall comprises a Ni-based superalloy.
11. The microchannel reactor of claim 1 comprising at least 10 heat exchangers interleaved with at least 10 reaction microchannels.
12. The microchannel reactor of claim 1 wherein the reaction microchannel is a contiguous microchannel wherein the microchannel walls surrounding the microchannel have no more than 5% openings, by area.
13. The microchannel reactor of claim 1 wherein the substrate is not an expanded metal sheet.
14. The microchannel reactor of claim 1 wherein the substrate comprises a finned substrate.
15. The microchannel reactor of claim 1 wherein the catalyst metal particles comprise at least one metal selected from the group consisting of Pt, Pd, Rh, Ni, Co, Ag, Au, Ir, and Ru.