Multiautoclave for combinatorial synthesis of zeolites and...

Details Multiautoclave for combinatorial synthesis of zeolites and... Multiautoclave for combinatorial synthesis of zeolites and...

1999-07-16

2004-11-23

Tilt, Terrence R. (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Control element responsive to a sensed operating condition

C422S091000, C422S105000

Reexamination Certificate

active

06821486

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a pressure and temperature reactor vessel, especially a multi-autoclave and to details concerning the design of this equipment.
BACKGROUND OF THE INVENTION
Many materials, such as e.g. zeolites, are prepared by so-called hydrothermal synthesis at temperatures ranging from 100° C. to 200° C. requiring crystallization times of one hour or more. For syntheses being carried out at temperatures that are higher than the solvent's boiling point, it is necessary to use pressure vessels, and these have to be suitable for the temperature and pressure used during the operation. The pressure vessel has to be designed so that the handling of it does not represent any unnecessary hazard, provided it is used according to working instructions.
Zeolite syntheses are usually performed in strongly alkaline media, often at pH>14, and the reaction mixture will often contain toxic chemicals, such as e.g. fluoride. Conventionally, syntheses that may be performed at temperatures lower than 110° C. are carried out in polymer bottles, often Teflon, while reactions at higher temperatures require steel autoclaves, perhaps lined with Teflon. The price of an autoclave of this type with the required safety details are typically of the order of NOK 10,000 or higher. Furthermore, such an autoclave will weigh from 1 kilogram and upwards, and all these elements represent limitations regarding the number of syntheses that may be performed in most laboratories in the course of one year.
Zeolite synthesis is often carried out by keeping the synthesis mixture at around 100° C. for at least 6 hours. At these moderate temperatures sealed chambers are necessary in order to avoid drying out of the synthesis mixture.
As an example of conventional zeolite synthesis, Zeolite Y can be prepared according to U.S. Pat. No. 3,130,007, Example 1, by dissolving 5 g sodium aluminate containing 30 weight percent Na
2
O and 44 weight percent Al
2
O
3
and 22 g sodium hydroxide containing 77.5 weight percent Na
2
O in 89.5 ml distilled water. This solution was added to 124.2 g of an aqueous colloidal silica solution with 29.5 weight percent SiO2, so that the resulting mixture had a composition corresponding to 13.9 Na
2
O: Al
2
O
3
: 28.2 SiO
2
:471 H
2
O, and the mixture was homogenized by stirring. The mixture was enclosed in a sealed glass vessel, placed in a water bath and heated at 100° C. for 21 hours, after which the product was recovered by filtering, washed and dried. Common to all the synthesis procedures mentioned and for all other known synthesis procedures for preparation of zeolites on a laboratory scale with the purpose of discovering new zeolites or to optimize existing zeolites, is that these are performed in a cumbersome and expensive manner by having to separately prepare each reaction mixture, which typically consists of 4-7 reagents, and by adding the reagents one by one.
In many other examples the synthesis of zeolites and other molsieves need temperatures well above 100° C., so that steel pressure vessels or the like are required.
Furthermore, each reaction mixture is typically prepared in batches of 5 to 100 g and crystallized in expensive and heavy autoclaves with internal volumes often in the range of 25 to 250 ml and with weights of up to 8 kg per autoclave, causing considerable expense due to a large consumption of often expensive reagents and due to the fact that the handling of the heavy autoclaves often makes it impossible to handle more than one autoclave at the time, and finally that the size of the autoclaves limits the number of autoclaves that may be placed in each oven or heating unit The combination of all these elements are, according to known technology, making each zeolite synthesis a very resource intensive process, and there is a great need for greater efficiency, rationalization, downscaling and automation. Simple calculations have shown that by combining the different variables which are involved in zeolite synthesis with narrow enough intervals in reagent concentrations, temperatures, reaction time, etc. to cover any phase formation based on known examples, it is feasible to make up 10
18
recipes. With today's synthesis capacity, which on a global basis hardly exceeds 100,000 syntheses per annum, it would take 10,000,000,000,000 years to carry out all these syntheses in which each and every one in theory has potential for the preparation of a new zeolite or other microporous material. The expenses involved in performing these syntheses according to known technology would obviously be formidable, and there is thus a great need for new and more cost efficient methods for zeolite synthesis.
In recent years new, automated methods for systematic preparation of new compounds, so-called “combinatorial techniques”, have been developed, but equipment which may be used for liquid phase synthesis at temperatures above approximately 100° C. has til now not been disclosed, because this requires that the synthesis takes place in a hermetically sealed vessel at elevated pressures. WO 95/12608-A1 for instance, discloses an apparatus and a method for a) synthesis of several molecules on substrates, comprising distribution of the substrates in the reaction chambers, b) combination of the first addition of these molecules with different reagents in each of the reaction chambers, c) moving the substrates through tubing to separate mixing chambers where the substrates are mixed, d) redistribution of the substrates by transporting them through tubing back to the reaction chambers, and e) combination of a second portion of a different composition with the first portions of molecules in the different reaction chambers in order to prepare new mixtures. This publication describes only a system for mixing and distribution of different molecules and not a system for hermetical sealing of the reaction chambers which would make it possible to operate at high temperatures, and this system would thus not be suitable for the synthesis of zeolites. In WO 96/11878 there is a description of extensive use of a combinatorial arrangement for synthesis of new materials, including zeolite synthesis at 100° C. Even though this patent application presents a detailed description of instrumentation and equipment developed for different purposes, autoclave systems required for performing the syntheses under the prevailing physical conditions (elevated pressure and temperatures exceeding 100° C.) are not described.
The prior art teaches autoclaves with several chambers for special purposes, and there is for instance in U.S. Pat. No. 5,505,916 a description of a metal cassette which can be opened and closed like a suitcase, and which has an interior with compartments intended for placement of the different instruments used by dentists, where these may be sterilized by autoclaving. Furthermore, large autoclaves intended for instance for the growth of crystals, are known, and examples are described in U.S. Pat. No. 5,322,591, U.S. Pat. No. 5,312,506 and U.S. Pat. No. 5,476,635, but the purpose of these and similar autoclaves is to make it possible to carry out large-scale syntheses, for which there is a great need when a synthetic procedure has been established and scale-up is desired, or when the purpose is to grow single crystals as large as possible. The autoclave described in the earlier mentioned U.S. Pat. No. 5,312,506 is designed to withstand temperatures up to 1500° C. for growth of crystals from metal melts. Another feature in connection with work with autoclaves is energy savings, and this is addressed in EP 0.434.890 A1, with description of a system for insulation of the autoclave walls and for the design of such insulating layers in the walls, which could be useful for large-scale autoclaving, but is of no relevance when working with small laboratory autoclaves which are heated in ovens.
Furthermore, there is a series of known equipment intended for synthesis of proteins and biopolymers, where the design comprises sheets with a large number of chambers in

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