SU662544A1 - Method of obtaining formaldehyde - Google Patents

Description

(54) METHOD FOR OBTAINING FORMALDEHYDE

i.

The invention relates to a method for producing formaldehyde, which is used in the manufacture of plastics.

A known method of producing formaldehyde by the oxidative dehydrogenation of methanol in the presence of a silver catalyst on an inert support — porous corundum modified with oxides of titanium, magnesium, calcium, and silicon (silver content in the catalyst is 5–30%) at temperatures of 680–720 C 1.

The disadvantage of this method is the high cost and scarcity of silver and} high process temperature.

The closest to the described invention to the technical essence and the achieved result is. A method of producing formaldehyde by gas-phase oxidative dehydrogenation of methanol in the presence of a copper-containing catalyst at a superficial temperature of 2.

According to a known method, the process is carried out on an iron-oxide catalyst, with the temperature varying over the catalyst bed from 260 to 440 ° C.

The disadvantage of this method is that the productivity of the process is not high enough, being 0.95 kg / l of catalyst per hour, and also the reaction temperature is relatively high.

The aim of the invention is to develop a method for producing methanol, which allows increasing the producer of the Hoc-fb process and reducing its temperature.

This goal is achieved by the described method of producing formaldehyde by oxidative dehydrogenation of methanol in the presence of a copper-containing catalyst, according to which the process is carried out using NaX zeolite, 38-64% of Na ions, replaced by ionate, Cu, at a temperature of 240-250 C,

The proposed method allows to increase the process efficiency up to 1.6 kg / l of catalyst per hour, as well as to reduce the reaction temperature to 24026 ° С, which leads to a decrease in energy costs.

The essence of the invention is that methanol is subjected to oxidative dehydrogenation in the presence of a zeolite kit of an isator at a temperature of 240-260 s, and methanol mixed with air through a quartz reactor filled with crushed quartz and a layer of catalyst. The catalyst is prepared by the ion-exchange method by treating the synthetic zeolite KAH with a solution of copper-ammonium KOMiineKca at rL 10, PR and m 1 1. 10 g of the punched water of the original NaX zeolite is poured over 100 m bivalent copper, an equivalent amount of ammonium hydroxide is added) and held dynamically at the catch for 5 minutes, filtered and dried at room temperature; Chatham again poured 100 ml of copper-ammonia solution Lex and shaken. After such a 7-fold treatment, the zeolite is washed to pH 9, dried at room temperature, and at 120 ° C, molded into granules of 1-0.5 mm in size and calcined at 450 ° C in air flow for 6 hours. Phase composition of the obtained sample,% 5 SiOa 43.68; Deg Oe 26.65 Fe2.03 0.12; Nag O 22.03, CuO -7.52, i.e., the degree of substitution of sodium ions on Cu is 55%. As a result of 5-fold treatment of the zeolite with a copper-ammonium complex, a sample with a degree of substitution of 38% is obtained, and 10-fold treatment gives the ability to roll a zeolite with a degree of substitution of 64%. Within the specified limits of change in the composition of the catalyst, its activity remained constant,. The reaction vapor-air mixture, taken at an oxygen: methanol ratio of 2.7: 1, at a rate of 400 ml / min (volume velocity 1526 h) is fed into a quartz flow reactor, in which 0.3000 g of catalyst is placed over a layer of crushed quartz 38% prepared according to make-up artist 1, Before experiments, the zeolite is kept in a stream of dry air at a temperature of 2 hours, the reaction products are analyzed by GLC,. . Amount of methanol missed in 0.5 h at 250 ° Comparative 144 mmol m; composition of products, mmol: CHgO 112, CO2, 26.5, total conversion of alcohol 93.4, yield of formaldehyde according to the fed methyl alcohol 77.5%, carbon dioxide 15.8%, selectivity 83.8%, Productivity 1, .55 kg / l of catalyst per hour. Example 2, under the conditions of Example -1, using a catalyst with a degree of substitution of 64%, carried out a series of experiments with a temperature change from 240 to 260 ° C. The results are shown in the table.