Exxon Research and Engineering Company

John P DeLuca

Gary Brice McVicker

Lawrence L Murrell

Edward T Maas, Jr

Kenneth Kamholz

Lawrence B Ebert

Norman H Sweed

UO.sub.2 for nuclear fuel is made from UF.sub.6. The method involves injecting UF.sub.6, with or without a nitrogen carrier, into a solution containing 1) an inert reaction medium, 2) water, 3) a Lewis base. The precipitate from the above reaction is then reduced in H.sub.2 at a temperature below 750.degree. C. to give ceramic grade UO.sub.2.

Process for conversion of UF.sub.6 to UO.sub.2

A one-piece, integral, high strength, combined heat exchanger-reactor comprising a monolithic honeycomb structure wherein the channels thereof are divided into two or more groups; group one carrying one fluid and group two carrying another fluid which differs from the first in composition and/or temperature and/or pressure and/or direction of flow, the main design feature of the combined heat exchanger-reactor (CHER) being that group one channels extend outward parallel to the channel axis and perpendicular to the cross-section of the honeycomb and each channel of this group one being in thermal contact through common walls with channels of group two while each channel of group one is separated from other channels of group one by the intervening voids formed by the presence of the channels of group two. The extended ends of the channels of group one extending from one or both ends of the honeycomb are manifolded at one or both ends so as to form a separation of the entrances and/or exits of the extended group one channels from the recessed group two channels thereby permitting the entry and/or exit of fluid in group one channels while preventing entry of the same fluid into the group two channels thereby permitting the independent passage of different fluids through the different channel one and channel two systems, the common wall which exists between channels of the different groups allowing heat conduction from the fluid in one group of channels to the fluid in the other group of channels. In this manner, very precise concentration and/or temperature control may be maintained over the fluids and/or catalysts which exist in the different channel groups, enabling one to perform complex reactions, either self-induced or catalytic, in the reactor with greatly enhanced yields and/or selectively due to the refined temperature and/or concentration control which is made possible by the present invention.

Combined heat exchanger reactor

A method is disclosed for the selective separation and sequestering of plutonium from uranium which comprises contacting a gas stream containing uranium hexafluoride [at a partial pressure of 26 torr or less] and plutonium hexafluoride at any pressure with graphite whereby PuF.sub.6 is selectively intercalated into the graphite while UF.sub.6 is left unreacted in the gas stream. Preferably, the contacting of UF.sub.6 and PuF.sub.6 with graphite is conducted in the presence of excess fluorine. In another embodiment the graphite is first reacted with a chemical oxidant. Such pretreatment of the graphite renders it inert to UF.sub.6 intercalation at partial pressures over 26 torr, the pressure above which UF.sub.6 normally intercalates with graphite. Such pretreatment will have less effect on PuF.sub.6 intercalation into the prereacted graphite compound and therefore will permit the separation of UF.sub.6 -PuF.sub.6 by differential intercalation into the prereacted graphite compound to be conducted at higher partial pressures of UF.sub.6.

Separation of uranium hexafluoride from plutonium hexafluoride by means

The instant invention relates to high surface area multilayered oxide supports coated with ruthenium of the type Ru-MgO-MgAl.sub.2 O.sub.4 -MgAl.sub.2 O.sub.4 +Mg.sub.2 SiO.sub.4 -Core. The system comprises ruthenium on a critical amount of free MgO, i.e., at least 2 wt. % minimum, on pre-reacted Al.sub.2 O.sub.3 which itself is on a monolithic ceramic substrate. This combination demonstrates the desirable, and previously unachievable characteristic of resistance to ruthenium volatilization and agglomeration, coupled with high catalytic activity. The high surface area oxides (MgO+Al.sub.2 O.sub.3) are strongly bonded to and reacted with the monolithic core substructure so as to possess physical strength. Ruthenium catalyst systems prepared utilizing the supported support (multilayered mixed oxides) method disclosed by the instant invention are useful for the treatment of waste gases, particularly exhaust gases from internal combustion engines and stationary sources and the removal of oxides of nitrogen therefrom.

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New Providence, NJ, United States of America

John P DeLuca