Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-10-25
2001-09-18
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C568S617000, C568S618000, C568S619000, C568S678000, C568S679000
Reexamination Certificate
active
06291714
ABSTRACT:
The present invention relates to a process for effecting gas-liquid reactions which occur with a liquid-in-gas dispersion mechanism.
In particular, the present invention relates to a continuous process for the production of polyadducts of alkylene oxides, by a poly addition reaction on a chain initiator which has at least one active hydrogen.
These products, particularly the polyadducts of ethylene and propylene oxides, are used mainly as non-ionic surfactants and polyether-polyols.
Non-ionic surfactants are very widely used as wetting agents, dispersants, stabilisers, emulsifying agents and anti-emulsifying, anti-foaming and foaming agents and, in general, as auxiliary chemicals and functional fluids in the textile, paper, cellulose, pharmaceutical, food, cosmetic, paint, resin, mineral extraction and processing, advanced recovery and extraction of petroleum industries. In particular the use should be mentioned of non-ionic surfactants based on natural or synthetic fatty alcohols, as primary components in the formulation of household and industrial detergents and also of polyether-polyols as the main intermediates in the production of polyurethanes (rigid, semi-rigid, flexible foams, elastomers, adhesives, sealants, etc).
Italian Patent No. 1 226 405 describes a method for the production of polymerisation products of alkylene oxides starting from alkylene oxides, ethylene and/or propylene oxides being most commonly used, and compounds having an active or mobile hydrogen atom with suitable catalysts. The method of this patent uses a two-section reactor of which the upper is termed the gas-liquid reactor and the lower is an accumulation reservoir, disposed essentially horizontally. The gas-liquid reaction takes place in the upper section, the chain initiator being supplied from a plurality of spray heads on a central distributor while the lower body acts as a receiver and for recycling through a pump and an external heat exchanger, the reaction product coming from the upper section being resupplied to the latter to continue the polymerisation reaction.
The process described in the aforesaid patent, however, has several disadvantages. First of all, since it is dealing with a semi-continuous process, the productivity per unit time is considerably restricted by the need to discharge the contents of the reactor periodically.
As internal distributors are provided, the surface-volume ratio of the reactor used in this process is very high, thus increasing the probability of secondary reactions. The presence of internal distributors also creates dead spaces within the reactor which makes it difficult to drain and clean the reactor, thus increasing problems in changing production.
It should also be mentioned that the flow under gravity of the reaction product which collects in the upper horizontal section and is then ducted down into the lower one induces retrodiffusion and overexposure to the oxide atmosphere.
U.S. Pat. No. 4,261,922 describes a continuous process for obtaining polymerisation products of alkylene oxides starting from 1,2-alkylene oxides and a compound containing hydroxyl groups selected from the group comprising water and mono-, di-, tri- and poly-aliphatic alcohols. This process is carried out with the use of a coil reactor having a length of at least 1.2 m immersed in a suitable heat-exchange fluid. A mixture of the hydroxyl compound and an alkaline catalyst is introduced continuously into the reactor and is brought into contact with the 1,2-alkylene oxide metered from a plurality of devices located along the entire length of the reactor. In order to optimise the reaction kinetics, the metering devices are located at intervals such as to ensure the optimum concentration of unreacted oxide at every point.
The processes carried out in such a reactor, however, have the great disadvantage of being extremely rigid, as it allows absolutely no variations in the reaction parameters, such as, the temperature, the type of chain initiator, etc. Every time there is, in fact, a variation, it is necessary to readjust the positions of the metering devices along the entire coil, as a result of the change in the concentration of unreacted oxide that occurs exactly because of this variation. It should also be mentioned that, whenever the rate of the polymerisation reaction in the initiation phase differs from that during the propagation phase, the metering devices cannot be positioned at regular intervals along the reactor; a change in the process parameters thus requires the separate readjustment of every one of them.
The problem at the basis of the invention is thus to provide a process for the production of polyadducts of alkylene oxides which can be used with any chain initiator, catalyst and alkylene oxide and which is also able to overcome the aforesaid problems.
SUMMARY OF THE INVENTION
The problem is solved according to the invention by a continuous process for the production of polyadducts of alkylene oxide on a chain initiator which has at least one active hydrogen, characterised in that it comprises the steps of;
a) providing n reaction units, where n is a whole number from 2 to 100, each constituted by a tubular reactor which is substantially vertical and has an upper part and a lower part, and a heat exchanger downstream of the tubular reactor, the tubular reactor having at least one first supply device for supplying the alkylene oxide, at least one second supply device and an outlet aperture, the devices being located on the inner surface of the upper part of tubular reactor;
b) supplying the reactor of a first of the n reaction units with the chain initiator, preheated to a predetermined temperature, through the at least one second supply device and with the alkylene oxide through the at least one first supply device;
c) reacting the chain initiator with the alkylene oxide to obtain a first liquid mixture containing an intermediate product;
d) cooling the first liquid mixture by means of the heat exchanger;
e) supplying the reactor of a second of the n reaction units with the first liquid mixture by means of the at least one second supply device and with the alkylene oxide by means of the at least one first supply device;
f) reacting the first liquid mixture with the oxide to obtain a second liquid mixture;
g) repeating the steps d), e) and f) in each of the remaining n-2 reaction units to obtain an nth liquid mixture containing the desired product;
i) cooling and discharging the nth liquid mixture containing the desired product.
The expression “tubular” is intended to include any type of elongate body with a section of any shape and dimensions. This expression further includes reactors with two different diameters, with a conical end and mushroom reactors.
The chain initiators which may be used for the process of the present invention are compounds having at least one active hydrogen, according to the final product it is desired to obtain; examples of such chain initiators may be found among the alkylphenols, such as octylphenol, nonylphenol, dodecylphenol, dinonylphenol, tristyrylphenol; natural and synthetic fatty alcohols and mixtures thereof, such as decyl alcohol, tridecyl alcohol, oleyl alcohol, oleylacetyl alcohol, cetylstearyl alcohol, lanolin, cholesterol, acetylene diol; fatty amines and hydrogenated amines, such as laurylamine, oleylamine, cocoamine, tallow amine and soya amine, tallow iminopropylenamine, abietylamine; fatty amides, such as laurylamide, stearyl amide, fatty amides derived from coconut oil, soya and tallow; fatty acids such as coconut, lauric, tallow, stearic, palmitic, oleic, myristic, linoleic, abietic and naphthenic acids; sorbitan esters such as the monolaurate, monopalmitate, monostearate, mono-oleate, monoabietate, dilaurate, tristearate, trioleate, pentalaurate, hexaoleate, hexastearate; monoglycerides and monostearates of, for example, of coconut and glycerol; pentaerythritol esters, such as the monolaurate, mono-oleate and of lanolin; ethylene glycols, such as mono-, di-, tri-ethylene glycols and polyethylene glycols; propylene glyc
Davis Brian J.
Linde Aktiengesellschaft
Millen White Zelano & Branigan P.C.
Richter Johann
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