Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Reexamination Certificate
1999-08-17
2002-12-03
Langel, Wayne A. (Department: 1754)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
C208S143000, C208S209000, C252S373000, C423S418200, C423S437200, C423S648100, C423S651000, C423S652000, C423S656000, C423S659000, C568S924000, C570S101000, C570S123000, C585S250000, C585S654000, C431S007000
Reexamination Certificate
active
06488838
ABSTRACT:
FIELD OF THE INVENTION
The present invention is a chemical reactor and method for gas phase reactant catalytic reactions.
As used herein, the term “molecular diffusion” is used in its classic sense of the transfer of mass based upon Brownian motion between adjacent layers of fluid in laminar, transition, or turbulent flow, and includes transfer of mass between adjacent layers of fluid that are stagnant.
As used herein, the term “Knudsen diffusion” means Knudsen flow, or free molecule flow, wherein the mean free path of the molecules is long compared to a characteristic dimension of the flow field, for example the pore size of a material through which the molecules are diffusing.
BACKGROUND OF THE INVENTION
Many catalytic reactions begin with gas phase reactants, for example steam reforming, partial oxidation, water gas shift and others. However, equipment, specifically reactor volume is generally large because of mass and heat transfer limitations. Conventional reactors are operated with a gas hourly space velocity from about 1,000 to about 10,000 hr
−1
. In other words, residence time is greater than 1 second because of the heat and mass transfer limitations.
These problems have been recognized and research is considering microchannel reactors because the microchannels have been shown to offer less resistance to heat and mass transfer thus creating the opportunity for dramatic reductions in process hardware volume. Several types of microchannel reactors have been described in the literature.
Franz et al., 1998 and Lowe et al., 1998 report applying a coating of the active catalyst (such as Pt, Ag, or other noble metal) directly to the microchannel wall. This approach has the disadvantage that the only usable surface area is that of the microchannel wall.
Weissmeier and Honicke, 1998a-b report creating a porous interface directly from the microchannel wall material onto which the catalyst is deposited. An aluminum wall was anodized to create the porous alumina interface that had an average pore diameter in the nanometer size range (permitting only Knudsen diffusion) and a thickness in the range of tens of microns. Disadvantages of this approach include that it is only applicable for aluminum, and limited surface area. The anodized walls formed a two-dimensional array of 700 identical microchannels.
Tonkovich/Zilka et al., 1998 reported packing catalytic powders directly within an array of parallel microchannels as a packed microbed. A disadvantage was a tendency to create relatively large pressure drops by forcing the fluid to flow through the packed microbed.
Tonkovich/Jimenez et al., 1998 reported placing a palladium catalyst supported on a metallic nickel foam within a cavity (more than an order of magnitude larger than a microchannel) and then sending the effluent to an array of microchannels to exchange heat. Again, a disadvantage was large pressure drop through the metal foam.
Hence, there is a need for a chemical reactor for catalytic reactions with fast kinetics that has a small reactor volume with a low pressure drop.
BACKGROUND REFERENCES
Franz, A. J., Quiram, D., Srinivasan, R., Hsing, I-M., Firebaugh, S. L., Jensen, K. F., and M. A. Schmidt, 1998, New Operating Regimes and Applications Feasible with Microreactors, Proceedings of the Second International Conference on Microreaction Technology, New Orleans, La., p 33-38.
Lowe, H., Ehrfeld, W., Gebauer, K., Golbig, K., Hausner, O., Haverkamp, V., Hessel, V., and Richter, Th., 1998, Microreactor Concepts for Heterogeneous Gas Phase Reactions, Proceedings of the Second International Conference of Microreaction Technology, March 1998, New Orleans, La., p. 63-74.
Tonkovich, A. Y., Zilka, J. L., Powell, M. R., and C. J. Call, 1998, The Catalytic Partial Oxidation of Methane in a Microchannel Chemical Reactor, Proceedings of the Second International Conference of Microreaction Technology, March 1998, New Orleans, La., p.45-53.
Tonkovich, A. Y., Jimenez, D. M., Zilka, J. L., LaMont, M., Wang, Y., and R. S. Wegeng, 1998, Microchannel Chemical Reactors for Fuel Processing, Proceedings of the Second International Conference of Microreaction Technology, March 1998, New Orleans, La., p.186-195.
Weissmeier, G., and Honicke, D., 1998a, Strategy for the Development of Micro Channel Reactors for Heterogeneously Catalyzed Reactions, Proceedings of the Second International Conference on Microreaction Technology, New Orleans, La., p. 24-32.
Weissmeier, G., and Honicke, D., 1998b, Microreaction Technology: Development of a microchannel reactor and its application in heterogeneously catalyzed hydrogenation, Proceedings of the Second International Conference on Microreaction Technology, New Orleans, La., p.152-153.
SUMMARY OF THE INVENTION
The present invention is a chemical reactor and method for catalytic chemical reactions having gas phase reactants. The chemical reactor has at least one reactor microchannel defining a bulk flow path through which at least one reactant passes, and at least one product, and a catalyst material wherein at least one reactant contacts the catalyst material and reacts to form at least one product. The improvement, according to the present invention is:
the catalyst material is in a porous structure having a porosity that permits molecular diffusion therein. The porous structure further has a length, a width and a thickness, the porous structure defining at least a portion of at least one wall of the at least one microchannel.
It is an object of the present invention to provide a chemical reactor for gas phase reactant catalytic reactions.
It is an object of the present invention to provide a method for gas phase reactant catalytic reactions.
A significant advantage of the present invention is the reduced pressure drop because the flow through the bulk flow path passes and contacts the porous structure but is not required to flow through the porous structure. Sufficient reaction still occurs because of the net flux through molecular diffusion into (gas phase reactant(s)) and out of (product(s)) the porous structure. Gas hourly space velocity is unexpectedly greater than 10,000 hr
−1
corresponding to residence time less than 1 second.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.
REFERENCES:
patent: 5366719 (1994-11-01), Van Wingerden et al.
patent: 5674301 (1997-10-01), Sakai
patent: 0 869 842 (1998-10-01), None
patent: 0 689 842 (2001-10-01), None
patent: 6111838 (1994-04-01), None
patent: WO 98/38147 (1998-09-01), None
Fitzgerald Sean P.
Marco Jennifer L.
Roberts Gary L.
Tonkovich Anna Lee Y.
Vanderwiel David P.
Battelle (Memorial Institute)
Langel Wayne A.
May Stephen R.
Rosenberg Frank S.
LandOfFree
Chemical reactor and method for gas phase reactant catalytic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chemical reactor and method for gas phase reactant catalytic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical reactor and method for gas phase reactant catalytic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2983793