Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1991-01-02
1992-12-15
Lone, Werren B.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568420, C07C 4704, C07C 4585
Patent
active
051718944
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for producing stabilized solutions of formaldehyde with methanol.
2. Description of the Related Art
Such solutions are commonly used in reactions of formaldehyde with other products, in which it is of interest to have less water than if a conventional formaldehyde-in-water solution were used and where, furthermore, the presence of methanol is desired, for example, to act as solvent for the end product obtained.
Spanish patent 447,890 discloses a process for the preparation of urea formaldehyde glues and resins, based on the preparation of said glues and or resins from methanol, by preparing a concentrated aqueous formaldehyde solution which is reacted with urea.
The process described in the above patent is characterized by the combination of the following steps: polymerized formaldehyde solution which retains the methanol and formaldehyde contained in the gases; aqueous formaldehyde solution and methanol are obtained separately; recovered and the formaldehyde is fixed; the distilled condensate obtained in step e); with urea under certain pH and temperature conditions to obtain urea-formaldehyde glues or resins.
The above described steps are effected continuously and, in a preferred embodiment, atmospheric air is aspirated at a pressure of 760 mm Hg with an appropriate compressor. The air is blown at a constant flow rate to a saturator and, therein, the air is bubbled through methanol, which is held at 50.5.degree. C. by means of a heating device. In turn, the methanol is supplied to the saturator from a reservoir at a constant rate thanks to an adequate regulation by way of a valve.
Thereafter, the mixture leaving the saturator, also at a constant methanol rate, is fed over a silver metal based catalyst held at a temperature of about 500.degree. C. such that it converts about 60% of the methanol into formaldehyde, in a conventional reaction, the corresponding hydrogen, part of which is oxidized in water by the air oxygen, being released. At the same time, a small amount of carbon dioxide is formed and practically all the air oxygen is converted during the reaction.
The gas mixture from the catalyzer is thereafter fed to the base of a scrubber receiving at the head thereof the condensates removed at the scrubber base, which are circulated by a pump and cooled by a cooler.
In the process of Spanish patent 447,890, the thus collected mixture is fed by a pump through the above mentioned remaining steps up to the preparation of the urea-formaldehyde glues and resins.
SUMMARY OF THE INVENTION
According to the present invention, the mixture cited in the foregoing paragraph forms the starting material for the preparation of said stabilized formaldehyde and methanol solutions. In the Examples given hereinafter, this mixture is referred to as: mixture from the scrubber base.
In other words, the present method is characterized in that the starting material is a liquid mixture comprising a formaldehyde concentration of from 48 to 55 wt %, a methanol concentration of from 20 to 30 wt % and an amount of water of from 32 to 15 wt %, said liquid mixture being tapped from an installation for the continuous preparation of urea-formaldehyde glues and resins, immediately after having subjected the methanol to catalytic oxidation in air, to condensation of the gases from said catalytic oxidation and to separation of the condensates from the uncondensed gases.
According to a further feature of the invention, said liquid mixture is tapped continuously and the liquid mixture is stabilized by the continuous supply of water and a base, using the heat from the liquid mixture itself and from prior heating of said water.
Preferably, according to the invention, the respective flow rates of said continuous supplies may be represented by magnitudes proportional to the following numbers: from 900 to 1100 for said liquid mixture; from 30 to 50 for said hot water and from 1 to 2 for said base.
According to a first embodiment of the invention, said l
Lone Werren B.
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