Key benefits of this technology include:

 

·         Reduced reaction by-product - Small volumes and short path lengths inherent to the advanced microreactor translate into more uniform processing conditions often resulting in less by-product formation.

·         Improved safety - Chemicals that are dangerous to handle, ship, and store in large quantities, e.g., HCN, can be produced on-site using a microreactor to produce only as needed. Also, fast reactions that could accelerate uncontrollably in conventional reactors and lead to possible explosions can be run safely in a microreactor due to the small dimensions of the flow channels that prohibit a flame from propagating.

·         Improved reaction kinetic data - Better reaction kinetic data can be obtained in the microreactor permitting better and faster optimization of conventional production reactors.  Controls including electronic sensors and actuators can be incorporated into the microreactor structure to provide a complete chemical processing system.

·         Reduced Capital Costs - Capital costs for a microreactor will be much lower than for a traditional pilot plant, and the time required to build microreactors will be less.  The cost and time to commercialize a process using microreactors as production units can also be reduced by the practice of scale-out, i.e., by duplicating the prototype unit so as to have a system of microreactors running in parallel.

This innovative technology is part of a large technology base developed by DuPont. The specific patent abstracts relating to this technology are replicated below.

A complete chemical reactor system is contained in an integral structure. This structure is assembled from a number of laminae, wafer-like discs, that are fabricated to accommodate the requirements of the process.

Unit operations, such as heating, cooling, mixing, separation can be achieved by suitable laminae configuration. The surface of adjacent laminae are formed such that when they are stacked, a pathway, or multiple pathways are formed so that chemicals can be introduced as appropriate, unit operations performed and reactions conducted. The laminae are joined together, by one of several techniques depending on the requirements of the process and the material used to fabricate the laminae, to provide a leak proof integral structure.

Various chemical reaction types may be conducted in the microreactor, e.g., multi-phase, catalytic, non-catalytic, electrochemical, photochemical, gas-phase, and high-pressure reactions.

The laminae can be fabricated of materials from groups III, IV and V of the Periodic Table, such as silicon; ceramics such as silicon carbide, tungsten carbide, alumina; glasses, such as fused quartz, pure silica glass and borosilicate glass; polymers, such as polystyrene, polyester, poly ethylene, polytetrafluoroethylene; composite polymers such as fiber reinforced polymers and ceramics; and metals.

The laminae can be formed by one or more techniques such as chemical etching, electrochemical machining, laser machining, diamond point machining, electro-discharge machining, electroforming, selective plating, chemical vapor deposition, photoforming welding, molding, casting, stamping.
Various sensors can be incorporated in the structure, such as pressure, temperature and flow.

Very precise reaction kinetic data can be obtained from the microreactor which can be used to optimize conventional reactors.

Because the flow paths have very small dimensions, typically 10 to 5000 micrometers, very precise control and homogeneity of reaction conditions are achieved. This plus the fact that very little material is present in the reactor permits the safe operation of reactions that can be dangerous to operate in conventional reaction systems.

While the scale of the microreactors is small, many reactions can be run at more favorable conditions, resulting in faster reaction rates, and are thus commercially viable for production at rates of up to several million #/yr. As an example, using the scale-out principle, a bank of 20 microreactors each 4 inches in diameter by 1/4 inch high could produce 3 million #/yr of anhydrous HCN.

SUMMARY OF THE INVENTION

There is disclosed and claimed herein an integral structure for chemical processing and manufacture comprising a plurality of laminae joined together with at least one inlet port and at least one outlet port formed therein for the receipt and discharge of chemicals. The laminae have at least one three-dimensionally tortuous channel formed therethrough for accommodating chemicals to be processed. The channel, which desirably measures from about 10 to about 5000 micrometers in cross section, connects to the inlet and outlet ports. The laminae comprise a material selected to be compatible with the specific chemical process. Means to perform at least one unit operation are positioned to effect a desired control so that the chemicals are processed.

Exemplary of materials suitable for high temperature oxidation reactions, such as the oxidation of hydrochloric acid (HCl) to produce chlorine (Cl) and water (H2 O), are materials from groups III, IV, and V of the Periodic Table, such as silicon. Exemplary of materials found to be suitable for fluorination reactions, such as the fluorination of CF3 CH2 Cl to produce CF3 CH2 F, include ceramics, such as silicon carbide, tungsten carbide, alumina and sapphire. Exemplary of materials suitable for photoreactions, such as the photochlorination of dichlorodimethylsilane (DCDMS) are glass materials, such as fused quartz, pure silica glass and borosilicate glass. Exemplary of materials found to be suitable for bioreactions, such as the proteolytic enzymatic conversion of proteins to other substances are polymers, such as polystyrene, polyester, polyamide, and polytetrafluoroethlyene polymers. Exemplary of materials suitable for high pressure process conditions are composite materials, such as fiber reinforced polymers and ceramics. Exemplary of materials suitable for less demanding process conditions are metals.

In a preferred embodiment of the integral structure the laminae are arranged to accommodate a plurality of unit operations. In addition, the channel is precisely oriented between adjacent laminae. These channels may be continuous or discontinuous along said laminae thereof. Discontinuous channels are continuously aligned between adjacent laminae sufficient to form a continuous pathway therethrough.

The integral structure of the invention may be prepared according to the following process, comprising:

(a) first processing a plurality of laminae each having a top portion and a bottom portion and a desired thickness, sufficient to form desired pathways thereon or therethrough.

(b) The laminae are stacked and bonded together in precise alignment to include at least one inlet port and at least one outlet port formed therein for the receipt and discharge of chemicals. The pathways form at least one three-dimensionally tortuous channel therethrough for accommodating chemicals to be processed. This channel, which desirably measures from about 10 to about 5000 micrometers in cross section, connects to the inlet and outlet ports. The laminae comprise a material selected to be compatible with the specific chemical process.

(c) Finally, one or more means to perform at least one unit operation are positioned to effect a desired control so that the chemicals are processed.

The processing of the laminae to form pathways may be performed by a procedure selected from the group of: subtractive processes, comprising chemical etching (such as used to process wafers of semiconductor material), electrochemical machining (ECM), electrical discharge machining (EDM), laser ablation, drilling and cutting, abrasive grinding and single diamond point cutting (such as used to fabricate ceramic parts); additive processes, comprising deposition processes, such as electroforming, selective plating, chemical vapor deposition, stereo lithographic photoforming, and welding; and forming processes, such as molding, casting, and stamping. Wear resistant coatings, in the form of thin films, may be optionally deposited on the processed laminae before bonding.

In the process for preparing the integral structure, the pathways on facing surfaces of adjacent laminae form passages through the structure in the plane of the laminae having the desired cross-sectional areas. These planar passages are connected with each other and with passages orthogonal to the plane of the laminae which pass through one or more laminae to form passages having the desired overall three-dimensional tortuous shapes. The term "three-dimensional tortuous," as used herein, intended to include the characteristic that the passages may be bifurcated, branched, intersecting or reentrant, and may be of constant or varying cross-sectional shape and size to achieve the desired flow characteristics of chemicals to be passed therethrough.

The above-described apparatus may be used in a method for chemical processing and manufacture. The method comprises:

(a) introducing one or more chemicals to be processed into the inlet port of the above-described structure.

(b) directing the one or more chemicals to traverse at least one tortuous channel that is specially adapted to receive the one or more chemicals.

(c) coordinating the traversal of the one or more chemicals through the tortuous channel with means that perform at least one of the following unit operations to the one or more chemicals:
A--mixing,
B--heat exchanging,
C--separating,
D--reacting catalytically,
E--reacting noncatalytically,
F--reacting photochemically, and
G--reacting electrochemically.

(d) withdrawing one or more processed chemicals from the outlet port. This processing is characterized by coordination of the design of the tortuous channel with the unit operations effected upon the one or more chemicals being processed.

Each of these unit operations may be performed individually or in conjunction with other unit operations in the same or in different apparatus. The structures of this invention are specially suited for continuous or semi-continuous operations.