Formaldehyde production process

FIELD: industrial organic synthesis.

SUBSTANCE: formaldehyde is produced via oxidative dehydrogenation of methanol with air oxygen at high temperature on silver-containing in fixed-bed reactor enclosing gas stream distributor followed by absorption of resultant reaction gases to form methanolic formalin, which is further rectified. Gas stream distributor utilized is inert filling composed of geometrically shaped members 3-10 mm in diameter placed on grid mounted upstream of catalyst in the form of a bed 50 to 500 mm thick.

EFFECT: increased conversion and selectivity of process.

1 dwg, 4 ex

 

The invention relates to the field of petrochemical industry, specifically to processes for the preparation of formaldehyde by oxidative dehydrogenation of methanol that is used as a monomer in the production of resins and plastics, as well as raw materials for the synthesis of isoprene, polyhydric alcohols, explosives, additives to oils, medical industry and other

The known process of preparation of formaldehyde by oxidative conversion of methanol with air gelatomaltitolo the catalyst at a high temperature in a reactor with a fixed bed of catalyst and with a vertical shell-and-tube heat exchanger with the subsequent absorption of the gaseous products of reaction with the formation of formalin (Reference oil. Leningrad: Chemistry, 1978, vol 2, str, 203, RIS).

The disadvantage of the described method of producing formaldehyde is increased energy consumption and air, and also restrictions on the capacity of the installation.

There is also known a method of producing formaldehyde by oxidative conversion of methanol with air in the catalyst of silver on the pumice at high temperatures in the reactor with a fixed bed of catalyst and with a vertical shell-and-tube heat exchanger with the subsequent absorption of the gaseous products of reaction with the formation of the product (methanol) formalin and further rectification (the Reference oil is imica. Leningrad: Chemistry, 1978, vol 2, str-201, RIS).

The disadvantage of this method of producing formaldehyde is a high expense ratio for raw materials and increased formation of side reaction products associated with less-uniform distribution of the vapor mixture in the reactor volume and on the surface of the catalyst.

Many devices for uniform flow distribution after its entrance into the working chamber of installing a gas distribution grid (Yejdilek. "Handbook of hydraulic resistance", M, "engineering", 1975, str-477).

When starting the system in conditions of high temperatures occur local overheating of such switchgear, which leads to deformation of the grids and the loss of the ability of the uniform distribution are fed into the reaction apparatus of the stream.

Closest to the present invention is a method of producing formaldehyde by oxidation of methanol with oxygen on the catalyst of silver on the pumice" (Tuvastatav, Alikely. "Technology of synthetic rubbers", M, "Chemistry", 1980, p.75-77). Methanol, diluted with water up to 60-70%concentration, is evaporated in a stream of air at 68-80°C, superheated to a temperature of 100-120°and is directed to the oxidation in the contact device. Steam-air mixture flows first into the tapered portion of the apparatus for Firawn is of the gas velocity over the cross section of the apparatus, and then traverses the catalyst bed, located on the inert nozzle, which is placed on the grid. The oxidation of methanol is carried out at a temperature of 600-750°C. the resulting oxidation of the contact gas enters the refrigerator, mounted directly under the net with the catalyst. Contact the gas is cooled to 100-130°C. the Absorption of formaldehyde from the contact gas is performed in two sequential absorbers, in which gas and water are moving countercurrent. From the absorber formalin containing 37% formaldehyde and 10% methanol, is fed to obespecheniya by rectification method.

The disadvantage of the described method of producing formaldehyde is not sufficiently uniform distribution of the steam-air mixture in the cross section of the reactor and the surface of the catalyst layer and, as a consequence, the low conversion of methanol and selectivity of the process of oxidative dehydrogenation of methanol.

The objective of the invention is to increase the conversion and selectivity of the production of formaldehyde on the silver-containing catalyst.

The problem is solved using the method of producing formaldehyde by oxidative dehydrogenation of methanol with oxygen at high temperature in silver-containing catalyst in a reactor with a fixed bed of catalyst, with the dispenser containing a series of gas flow, with the subsequent absorption of the reaction gases with the formation of methanol formalin and further rectification, at the same time as the distributor of the gas stream is an inert nozzle of the elements geometric shapes, covered with a grid installed before the catalyst layer, and the layer thickness of the lens is 50-500 mm

The diameter of the elements of the lens is 3-10 mm

Distinctive feature of the proposed method of producing formaldehyde is that as the distributor of the gas stream in the reactor an inert nozzle of the elements of a geometric shape having a diameter of 3-10 mm, covered on the grill, which is established before the catalyst bed, while the thickness of the lens is 50-500 mm

The proposed switchgear in the reactor oxidative dehydrogenation of methanol oxygen allows to achieve uniform distribution of the gas flow - steam-air mixture fed to the reactor, the reactor volume and the surface layer of the catalyst at any load. In addition, the layer of inert nozzle prevents deformation of the lattice in the high temperature process that has a positive effect on the uniformity of the air-steam mixture in the reactor and the surface of the catalyst layer.

The elements of the density and can be made of such material, as aluminium oxide, aluminium silicate, aluminium oxide, ceramics, and any geometrical shape, such as spheres, cylinders, rings, etc.

The proposed method formaldehyde can be obtained, for example, silver-containing catalysts, such as silver on the carrier, crystal silver, silver mesh.

The proposed method of producing formaldehyde is as follows as shown in the drawing the diagram.

In the evaporator 1 is served fresh and return (circulating) methanol, water and air. In a stream of air at a temperature of 68-72°With the evaporation of water-methanol mixture. Steam-air mixture passing through the superheater 2, with a temperature of 110-130°into the reactor 3, passes through the valve 4, is evenly distributed over the volume of the reactor and the surface of the catalyst layer 5. The distributor is a layer of inert packing thickness of 50-500 mm, covered on the grill. The elements of the nozzles have a diameter of 3-10 mm In the reactor containing the catalyst at a temperature 645-680°is the oxidative dehydrogenation of methanol.

Next, the reaction mixture flows in a vertical shell and tube heat exchanger 6 containing tube with reinforced their pipes are made as one unit with the reactor. In the heat exchanger, the reaction mixture is cooled to a temperature 120-35° With and enters the absorber 7, where the absorption of formaldehyde and unreacted methanol water. Kubovy product of the absorber is given to methanol formaldehyde from formaldehyde content up to 40 wt.%. and methanol to 10% wt. From the top of absorber disposed of inert gases and hydrogen.

Formaldehyde is fed into the distillation column 8 on obespecheniya. Kubovy product of the column 8 is given bezmetallny formaldehyde from formaldehyde content 41-44% wt. The distillate of the column is taken methanol, which is returned to the step oxidative dehydrogenation.

The implementation of the method illustrated by the following examples.

Example 1

In the evaporator serves fresh methanol at a rate of 6000 kg/hour, return (circulating) methanol in the amount of 980 kg/h, water (3,000 kg/h and the air of 10500 kg/hour. In a stream of air at a temperature of 68-70°With a water-methanol mixture evaporates. From the evaporator vapor mixture enters the superheater, where the temperature of 110-115°enters the reactor, passes through the gas flow distributor, which contributes to its uniform distribution in the reactor volume and on the surface of the catalyst layer. The distributor is a layer of inert nozzle 50 mm thick, covered on the grill. The elements of the nozzle is made in the form of balls with a diameter of 3-4 mV the reactor at a temperature of 645-680° Is the oxidative dehydrogenation of methanol. Next, the reaction mixture flows in a vertical shell and tube heat exchanger is designed as one piece with the reactor oxidative dehydrogenation of methanol. In the heat exchanger, the reaction mixture is cooled and the temperature of 120-135°enters the absorber, where the formaldehyde and unreacted methanol is absorbed by the water. Kubovy product of the absorber is given to methanol formaldehyde from formaldehyde content of 40 wt.%. and methanol 8% wt. the number 11963 kg/hour. From the top of absorber disposed inert gases containing carbon monoxide 0,6% vol., carbon dioxide is 4.3%. and hydrogen 21% vol.

Next formaldehyde enters the distillation column to obespecheniya. Kubovy product of the column is given bezmetallny formaldehyde from formaldehyde content 43,6% wt., the distillate of the column is taken methanol, which is returned to the step oxidative dehydrogenation.

The selectivity to formaldehyde is 90,38%, the conversion of methanol - 82%.

Example 2

Formaldehyde receive in the same way as described in example 1, but the gas flow distributor is a layer of inert nozzle 100 mm thick, covered on the grill. The elements of the nozzle is made in the form of balls with a diameter of 5-6 mm

In the evaporator serves fresh methanol in the amount of 000 kg/h, return methanol 1450 kg/h, water 4520 kg/h and the air 15500 kg/hour.

Kubovy product of the absorber is given to methanol formaldehyde from formaldehyde content of 39.5% wt. and methanol and 8.5% wt. the number 18000 kg/h.

From the top of absorber discharged gases containing carbon monoxide 0,6% vol., carbon dioxide 4.4 vol.% and hydrogen 21% vol.

Next formaldehyde enters the distillation column to obespecheniya. Kubovy product of the column is given bezmetallny formaldehyde from formaldehyde content of 43.3% wt., the distillate is collected methanol, which is returned to the step oxidative dehydrogenation.

The selectivity to formaldehyde is 90,13%, the conversion of methanol and 82.2%.

Example 3

The gas flow distributor is a layer of inert nozzles thickness of 500 mm, covered on the grill. The elements of the nozzle is made in the form of balls with a diameter of 8-10 mm

In the evaporator serves fresh methanol in the amount of 5800 kg/hour, return (circulating) methanol in the amount of 1100 kg/h, water (3,000 kg/h and the air of 10500 kg/hour.

In a stream of air at a temperature of 70-72°With a water-methanol mixture evaporates. Steam-air mixture enters the superheater and a temperature of 120-130°into the reactor, where in the presence of a catalyst at a temperature of 650-680°is ocil the positive dehydrogenation of methanol. Next, the reaction mixture flows in a vertical shell and tube heat exchanger is designed as one piece with the reactor oxidative dehydrogenation of methanol. In the heat exchanger, the reaction mixture is cooled and the temperature of 115-120°enters the absorber, where the formaldehyde and unreacted methanol is absorbed by the water. Kubovy product of the absorber is given to methanol formaldehyde from formaldehyde content of 38 wt.%. and methanol 10 wt.%. the number 11690 kg/hour. From the top of absorber disposed inert gases containing carbon monoxide 0,6% vol., carbon dioxide is 4.3%. and hydrogen 20% vol.

Next formaldehyde enters the distillation column to obespecheniya. Kubovy product of the column is given bezmetallny formaldehyde from formaldehyde content of 42.3% wt., the distillate of the column is taken methanol, returned to the stage oxidative dehydrogenation.

The selectivity to formaldehyde is 90%, the conversion of methanol 80%.

Example 4

Formaldehyde receive in the same way as described in example 1, but the catalyst was covered with a layer of inert nozzle, which is placed on the grid.

Kubovy product of the absorber is given to methanol formaldehyde from formaldehyde content of 37.5% by weight. and methanol to 10.5 wt.%.

From the top of absorber discharged gases containing carbon monoxide 1,3% vol., dioxide of plastics technology : turning & the Yes of 4.7%. and hydrogen 21% vol.

Next formaldehyde enters the distillation column to obespecheniya. Kubovy product of the column is given bezmetallny formaldehyde from formaldehyde content 41,3% wt., the distillate is collected methanol, which is returned to the step oxidative dehydrogenation.

The selectivity to formaldehyde is 88,73%, the conversion of methanol to 75.2%.

As seen from the above examples, the use of the distributor of the gas stream in the reactor oxidative dehydrogenation of methanol inert nozzles of the elements of a geometric shape with a thickness of 50-500 mm, covered on the grate installed before the catalyst bed, allows to achieve high conversion and selectivity of the process.

The method of producing formaldehyde by oxidative dehydrogenation of methanol with oxygen at high temperature in silver-containing catalyst in a reactor with a fixed bed catalyst containing the distributor of the gas stream, with subsequent absorption of the reaction gases with the formation of methanol formalin and further by distillation, characterized in that as the distributor of the gas stream is an inert nozzle of the elements of a geometric shape having a diameter of 3-10 mm, covered on the grate installed before with the OEM catalyst, the thickness of the layer of the lens is 50-500 mm



 

Same patents:

The invention relates to a method for formaldehyde

The invention relates to a method of heterogeneous exothermic synthesis of formaldehyde with an excess amount of oxygen, in particular in the synthesis reactors that have multiple connected in series adiabatic catalytic layers, comprising the following stages: feeding gaseous reactants containing methanol and an excess amount of oxygen in the first catalytic layer; passing these gaseous reactants through the catalyst layers, accompanied by partial oxidation of methanol
The invention relates to chemical technology and can be used in the production of formalin in the chemical, petrochemical and woodworking industry

The invention relates to a continuous method of obtaining aqueous solutions of formaldehyde, in particular solutions having a concentration in the range from 53 to 57 wt.%, the method includes the following stages:

(a) the air supply and methanol in the evaporator, in which the methanol is evaporated, the formation of gas-phase mixture of methanol and air;

(b) interaction of gas-phase mixture of methanol and air over the catalyst at elevated temperature to obtain a reaction mixture containing formaldehyde formed by partial conversion of methanol and water vapors and noncondensable gases;

(c) passing the reaction mixture through at least one adsorption column where the above-mentioned mixture is absorbed in the aqueous solution flowing in the opposite direction;

(d) separation of the aqueous and non-condensable gases in the absorption columns;

(e) cooling and washing of non-condensable gases that carry small amounts of methanol and formaldehyde; and

(f) the fractional distillation of an aqueous solution with the appropriate Department of methanol
The invention relates to catalysts for oxidative dehydrogenation of methanol to formaldehyde
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical and other industries
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical, etc

The invention relates to the field of chemical technology of organic synthesis, particularly, to a method of producing formaldehyde by oxidative dehydrogenation of methanol with the use of reflexive methanol

The invention relates to the chemical industry, in particular to methods of regeneration of silver catalysts for the preparation of formaldehyde from methanol

The invention relates to the technology of organic synthesis, and in particular to an improved process for the preparation of formalin used in chemical industry, medicine and agriculture

The invention relates to an improved method of dewatering solution of formaldehyde containing formaldehyde, water and methanol, including the distillation of the specified solution of formaldehyde in the presence of exciting water connection with obtaining the formaldehyde-containing product that contains significantly less water than the original solution, and use a solution of formaldehyde containing methanol at a molar ratio of methanol to formaldehyde 0.3 to 1.5:1, obtaining the formaldehyde-containing product in the form of a complex with methanol

The invention relates to an improved method for the removal of formaldehyde or its adducts of organic liquid mixtures obtained in the production of methyl methacrylate containing at least a carboxylic acid or an ester of carboxylic acid and formaldehyde or its adducts, which forms a two-phase mixture of water, comprising at least one extraction liquid organic mixture in the system liquid-liquid using water as the extractant with getting the flow of the organic phase and flow of the aqueous phase, and the flow of the organic phase contains significantly reduced the concentration of formaldehyde or its adducts compared with the liquid organic mixture

The invention relates to a method of obtaining from semiformal Monomeric formaldehyde high purity, used as a monomer in the production of high molecular polyacetylenic resins, as well as in the synthesis of numerous organic compounds based on it
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical and other industries
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical, etc
The invention relates to the petrochemical industry, in particular to catalysts for the preparation of formaldehyde by the oxidation of natural and associated petroleum gas

FIELD: industrial organic synthesis.

SUBSTANCE: formaldehyde is produced via oxidative dehydrogenation of methanol with air oxygen at high temperature on silver-containing in fixed-bed reactor enclosing gas stream distributor followed by absorption of resultant reaction gases to form methanolic formalin, which is further rectified. Gas stream distributor utilized is inert filling composed of geometrically shaped members 3-10 mm in diameter placed on grid mounted upstream of catalyst in the form of a bed 50 to 500 mm thick.

EFFECT: increased conversion and selectivity of process.

1 dwg, 4 ex

Up!