The Dow Chemical Company

Neal N Hughes

John R Moyer

Peter A Doty

A filter useful for separating contaminants from fluids includes a fused single crystal acicular ceramic support having a discriminating layer thereon, such as a sintered, porous alpha-alumina membrane, on at least part of the support. The support is preferably composed of a non-stoichiometric acicular mullite of about 76 percent by weight Al.sub.2 O.sub.3 and about 24 percent by weight SiO.sub.2. The support can be any one of a variety of shapes, but is conveniently elongated in form and preferably includes a plurality of parallel channels through it. The support may be in either a dead-end or cross-flow configuration. In the dead-end configuration, half of the channel holes at each end are plugged in a checkerboard arrangement with the holes open at one end and plugged at the other end. In the cross-flow configuration, all channels are connected by a series of shallow slits cut in the filter, and no end plugs are used.

Filter including a porous discriminating layer on a fused single crystal

A cross-flow structure useful for filtering a fluid, for exchanging one or more constituents between two fluids, or for exchanging heat between two fluids, includes a body having porous partition walls defining at least one open channel extending entirely through it, and a portion of collecting fluid exiting the body through the porous partition walls, rather than through the open channel(s). The body is composed of a fused, interlocked, single crystal acicular ceramic material, preferably a non-stoichiometric acicular mullite of about 76 percent by weight Al.sub.2 O.sub.3 and about 24 percent by weight SiO.sub.2. The portion for collecting fluid exiting from the porous walls is preferably an impermeable coating, such as a glaze, substantially covering the exterior of the body, except for the areas where fluid enters the open channel(s) and exits the porous walls.

Structure for filter or heat exchanger, composed of a fused single

A regenerable exhaust gas filter element for diesel engines includes an interlaced network of mullite crystals grown together forming a rigid porous body. Soot carried by exhaust gas from a diesel engine flowing through the filter is trapped in the porous body and thereafter burned off to regenerate the element. A network of mullite crystals in accordance with the invention is automatically interlaced and fused with one another to form the porous body of the filter element.

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Midland, MI, United States of America

Neal N Hughes