WO2014003525A1 - Method for producing hydrogen cyanide - Google Patents

Description

 METHOD FOR PRODUCING CYANIDE HYDROGEN

The invention relates to a method for producing hydrogen cyanide (hydrocyanic acid) HCN, for the production of cyanide compounds, in particular sodium cyanide NaCN.

 The essence of the invention is the production of hydrogen cyanide and its subsequent processing into sodium cyanide, from exhaust waste gases, metallurgical and other enterprises of the Republic of Kazakhstan.

 The purpose of the invention: the integrated use of mineral raw materials is the disposal of industrial waste by the enterprise of the Republic of Kazakhstan.

DESCRIPTION OF THE INVENTION

The invention relates to a technology for processing exhaust gas, metallurgical and other enterprises of the Republic of Kazakhstan and can be used in the production of hydrogen cyanide and cyanide compounds.

Numerous patents are known from various countries, especially the United States, which describe a method for producing hydrogen cyanide from a gaseous mixture of carbon monoxide CO and ammonia NH _{3 by} heating in the presence of catalysts at high temperature depending on the chosen catalyst 500 - 750 ° C, according to the endothermic reaction:

CO + H3 + Pcal - + HCN + H ₂ 0

The reaction was investigated in detail by P.V. Zimakov (1929) in the USSR, abroad Bradig and his collaborators in 1920-1930. on numerous catalysts prepared from aluminum oxides A1 ₂ 0 ₃ , chromium Cr ₂ Oz, calcium CaO, magnesium MgO, silicon SiO ₂ , thorium TiO ₂ , titanium Ti ₂ , cerium Ce ₂ O ₃ , zirconium ZrO ₂ and rare earth metals. Installed:

1. At 750 ° C, a large excess of carbon monoxide CO from 5: 1 to 20: 1 in volume and contact time of about OD sec on an aluminum oxide catalyst Al ₂ O ₃ with the addition of cerium oxide Ce ₂ O ₃ the maximum degree of ammonia conversion to hydrogen cyanide 65%.

2. With an 8-12-fold excess of carbon monoxide CO, 650-750 ° C and 10 g35 atm on a promoted carbon monoxide Al ₂ O ₃ catalyst (increased activity) with the addition of chromium oxide Cr ₂ O ₃ calcium oxides CaO or magnesium MgO, 97 - 100% conversion of ammonia NH ₃ to HCN was achieved.

3. With separate heating, carbon monoxide CO to 1200 ° C and ammonia NH ₃ to 600 ° C, taken in a volume ratio of CO: NH ₃ = 95: 5, a decrease in the loss of carbon monoxide CO to 0.2%, and ammonia NH ₃ -2%

The reaction was carried out in a two-stage apparatus with gas recirculation.

(S. S. Bobkov, S. K. Smirnov “Hydrocyanic acid” Publishing house “Chemistry” Moscow, 1970 pp. 90-91). (US patents US 1,387,170 - 1921; 1, 584,137- 1926; 1, 598,707-1926; 1,610,035-1926; 1,634,735-1927g; 1.934.610-1933; 2.475, 822-1949; 2,584,080-1952; 2,596,421 -1952g; 2,596,507-1952; 2,906,604-1959).

 The disadvantage of these methods for producing hydrogen cyanide from carbon monoxide and ammonia is the cumbersomeness of auxiliary equipment for heating large volumes of gases and to maintain the temperature of the reaction in the reactor itself, as well as a significant consumption of steam and electricity, which, despite the high use of ammonia, was economically unjustified and currently has not found industrial application.

Also known:

 - reducing the heating by electrical resistance of the chamber from chamotte tubes filled with pumice, charcoal, etc., the best yield was obtained by using a heated platinum spiral, platinized asbestos or a spark obtained by an ordinary induction coil;

 the assertion that a quiet discharge and high voltage current favor the formation of complex cyanide compounds; - mentions, if a mixture of carbon monoxide and ammonia is exposed to a weak electric discharge or to a high voltage current, then ammonium cyanate with the elimination of hydrogen is formed.

CO + NH ₃ HMH4CNO + H ₂

(G. Ehler “Technology of cyanide compounds” translation from German ONTI State NKTP Scientific and Technical Publishing House of Ukraine Kharkov 1934 Kiev. Pp. 145-146)

 The disadvantage of these methods of producing hydrogen cyanide from carbon monoxide and ammonia is, as the author himself claimed, that they did not find technical use in technology.

 Closest to the proposed invention in technical essence is a method for producing hydrocyanic acid (hydrogen cyanide) from carbon monoxide and ammonia in a reactor - US patent US N <> 2,906,604, patented September 29, 1959. The reactor consists of a three-zone gas path connected in series. Each zone also consists of three zones connected in series by a common gas path in order: - a gas heating zone - a tube or channel type heat exchanger, a mixing zone - gas accumulation - a mixing chamber and a contact (reaction) zone of the catalysts — catalyst bed. All heat exchangers are equipped with a thermocouple, which are connected to temperature controllers to regulate the temperature.

The method for producing hydrogen cyanide (hydrocyanic acid) according to US Pat. No. 2,906,604, is that carbon monoxide is fed into the first zone heat exchanger with an initial temperature of about 550 ° C and distributed over the numerous channels of the first heat exchanger to 700 - 1000 ° C , then the heated carbon monoxide enters the 1st mixing chamber, accumulates and mixes with ammonia incoming - through the inlet to the 1st mixing chamber with an initial temperature of 350 ° C, in such an amount that the volume ratio corresponded to CO: ΝΗ ₃ = 5: 1, gas mixtures of carbon monoxide and ammonia pass through the catalyst bed of the 1st zone, where there is a reaction of the formation of gaseous hydrogen cyanide and water vapor with the absorption of (endothermic) heat, then it enters the heat exchanger of the 2nd zone, it is also heated here to restore heat loss not less than the temperature specified in the first zone, then it passes to the chamber mixing zone 2, where 0.5 parts with ammonia are accumulated and mixed, the fresh gas coming through the inlet into the second mixing chamber with an initial temperature of 350 ° C, the gas mixture then passes through the catalyst layer of the second zone, where the reaction of the formation of gaseous hydrogen cyanide and water vapor from the absorption of (endothermic) heat, after which it enters the heat exchanger of the 3rd zone, it is heated here to restore heat loss not less than the temperature indicated in the first zone, then the mixture passes into the chamber of the third zone, where 0.5 parts with ammonia accumulates and mixes, the fresh gas coming through the inlet into the third chamber with an initial temperature of 350 ° C, the gas mixture then passes through the catalyst bed of the third zone, where the reaction also takes place the formation of gaseous hydrogen cyanide and water vapor with the absorption of (endothermic) heat and then into the outlet pipe of the reactor. The disadvantage of this method is:

 - the use of catalysts in the form of grains in layers, which creates dust, thereby reducing the rate of formation of the final product of hydrogen cyanide,

- the use of indirect heating of the reaction gas mixture in front of the next catalyst layers in a channel heat exchanger (tubular heat exchanger) of the type of heating, to restore the necessary heat loss on the endothermic reaction of hydrogen cyanide formation after each catalyst layer, thereby creating cumbersome indirect heating equipment even in the synthesis reactor itself ( feeding to the reactor preheated carbon monoxide 550 ° C, additional heating of carbon monoxide to 700-1000 ° C and mixing upayuschim with preheated to 350 ° C with gaseous ammonia in the reactor before passing the first layer, obtaining a mixture gas consisting of 5 parts and 1 part CO ΝΗ _3, said mixture gas had a temperature of about 650 - 660 ° C and below,

 - decomposition of ammonia is not excluded, despite the use of metal tubes of aluminum tubes instead of ceramic tubes

 - the lack of direct heating of the catalysts, which will create the passivity of the catalysts themselves, together the heat absorption of the reaction mixture is forced to give up, part of the heat for heating to activate the catalysts.

s The aim of the invention is to solve the problem of creating a highly efficient method for the production of hydrogen cyanide from carbon monoxide and ammonia, cheapen and simplify the existing technological scheme, use compact synthesis of the reactor and catalyst differing in the manufacturing method and the principle of exposure to the reaction mixture of gases of self-stimulating purposes, the use of simple energy-saving heating and cooling circulating closed systems with an inert heating agent, to the complex use of mineral raw materials, recycling waste gas containing CO and other metallurgical plant RK.

The essence of the present invention is that with the selection of exhaust industrial gases containing at least 25% carbon monoxide from the exhaust duct, purifying them from unnecessary impurities and carrying out enrichment processes, bringing carbon monoxide at least 95%, accumulate in a gas tank in sufficient volume as feedstock providing the conduct of a continuous technological process for the production of hydrogen cyanide without stopping. Our synthesis reactor, the production of hydrocyanic acid, works on the principle that an electric air heater, in contrast, has an additional outer jacket, thanks to which it is always heated at least 300 ° C and our catalysts are installed, which are made using special powder metallurgy technology in the form of round electrodes that are designed and operate as a heating element. The catalysts in the reactor are arranged vertically and horizontally along a certain step, form a multilayer network without contact, the catalyst electrode is heated by electric currents, due to which the catalysts emit heat and radiant energy are especially noticeable in a gaseous medium. After carrying out the obligatory pre-launch preparatory work according to the technological regulations, the entire technological system of the gas path of the hydrogen cyanide production is flushed with an inert gas, in particular pure nitrogen gas, to a residual oxygen content of no more than 1% at the end point of the path. The hydrogen cyanide production technology consists of the following operating modes: “start-up mode”, “mode-operation” and “mode-stop”. During the “start-up mode”, preparatory work is carried out, the technological system is launched and the equipment is manufactured and commissioned for the “operation mode”

According to the start-up mode, the reactor is started with inert gas in the closed reactor-smoke exhaust reactor circulating mode, the catalyst heating system is turned on, and at the same time the circulation agent is fed from the general inert gas heating system through the outer jacket of the reactor. Upon reaching a temperature of 500 ° C in the inside of the reactor and a temperature of 300 ° C of circulating inert gas external reactor barrel, the reactor is considered ready for start-up operating mode. The reactor is fully automated with regulating and controlling devices that operate in automatic and manual mode. In the reactor, technological parameters for maintaining the technological mode according to the regulation are: V— nm ³ / hr gas volume, T - ° С, gas temperature in three places, at the beginning, middle and tail part, Р - MPa, gas pressure, Q -% . concentration (composition) of gases (СО, NH3, HCN, С0 ₂ , Н ₂ , 0 ₂ , N ₂ ) /. An alloy of a tubular catalyst (TEN) consists of a mixture of electrode masses, iron oxides (III), aluminum, magnesium, silicon and thorium dioxide.

 The method of producing hydrogen cyanide consists in the fact that the carbon monoxide and ammonia entering the mixing pipe of the reactor are mixed due to incoming flowing horizontally directed against each other, the mixture is heated to 300 ° C from the temperature of the jacket of the reactor and falls into the initial internal chamber of the reactor in operating mode is heated being in direct contact with the catalysts due to the heat and radiant energy of the released self-heating catalysts (Tenov), the formation or decomposition of ammonia, from Deposition from the technological mode or other side effects is monitored according to the readings of the devices, if detected automatically or manually, it is controlled and immediately eliminated, the output of hydrogen cyanide reaches up to 99%, the loss of carbon monoxide is not more than 0.1%, and ammonia is not more than 0.9 %, the production flowchart operates in the non-waste technology mode, the reactor flow diagram rests on fig. one.

The implementation of this method of producing hydrogen cyanide is carried out by the utilization of gas wastes from metallurgical and other enterprises containing carbon monoxide of at least 25%.

The following examples illustrate the practice of the invention.

Example 1. An electrothermoreactor (operating temperature of internal circulating inert gas t = 500 ° C) brought into operation according to the technological schedule, 20 m ³ / h, gaseous carbon monoxide and 2 m ³ / h ammonia were fed through a mixer nozzle, the beginning of counting This experiment was started after complete displacement of the inert gas from the system according to analysis and instrument, while the temperature inside the reactor in the inlet was 500 ° С, in the middle 520 ° С and in the outlet part 550 ° С, providing in automatic mode with about deviation of ± 10 ° C, the automatic control by reducing the load current and the increase in self-heating catalyst (heaters). After an hour of operation, the production of the finished product of hydrogen cyanide was 2.4 kg, the remaining data are entered into table J4e i. Example 2. As in the first example, only with a change in the supply of ammonia by 5 m / h and the temperature in the reactor everywhere the same was kept up to 500 ° C. After an hour of work, the production of the finished product of hydrogen cyanide was 6.03 kg, the remaining data are entered in the Nsl table.

Example 3. As in the first example, only by changing the ammonia supply by 10 m / h and the temperature in the reactor everywhere the same was kept up to 500 ° C. After an hour of work, the production of the finished product of hydrogen cyanide was 12.05 kg, the remaining data are entered into the Nel table.

Example 4. In the same way as in the first example, only by changing the ammonia supply by 15 m ³ / h and the temperature in the reactor everywhere the same was kept up to 500 ° C.

 After an hour of operation, the production of the finished product of hydrogen cyanide was 18.25 kg, the remaining data are entered in the JSfel table.

Example 5. As in the first example, only by changing the ammonia supply by 20 m ³ / h and the temperature in the reactor were kept the same everywhere up to 500 ° C. After an hour of operation, the production of the finished product of hydrogen cyanide was 15.08 kg, the remaining data are entered into table N ° l.

Table 1

From the above examples it is seen that the use of the proposed method for producing hydrogen cyanide from waste gas waste from metallurgical and other enterprises of the Republic of Kazakhstan containing carbon dioxide CO ₂ and carbon monoxide CO of at least 25%, which will fully satisfy the needs of the republic for cyanide compounds in particular sodium cyanide and allows to create a production of hydrogen cyanide with subsequent processing into sodium cyanide from domestic raw materials with a quality not inferior to the best samples of foreign countries and ilizirovat waste metallurgical and other industrial enterprises RK

b

Claims

CLAIM  1. The method of producing hydrogen cyanide by the interaction of carbon monoxide and ammonia in the gas phase in the presence of a catalyst mainly consisting of alumina in the form of powders or grains, characterized in that instead, catalysts made in the form of metal alloys are used using powder metallurgy technology in the form of thin round tubes, arranged in the synthesis reactor in the form of vertical and horizontal rows, form cascades of grids without contact, the alloy of tubular catalysts consists of a mixture of: electrode s, oxides of iron (III); alumina; magnesium oxide; silicon oxides and thorium dioxide.  2. The method according to claims 1, characterized in that each row of the catalysts is connected in series, heated by alternating current inside an arranged spiral and is in heated states depending on the dependence of a given load of 500-1000 ° C with an exciting effect.  3. Method 1-2, characterized in that the synthesis reactor itself is in a heated state of at least 300 ° C through a heating jacket, where a heating agent constantly circulates in a closed mode.  4. Method 1-3, wherein the carbon monoxide reactor and ammonia are fed in an unheated state.  5. The method according to claims 1 to 4, characterized in that the synthesis process in the contact reactor carries out at least 70% hydrogen cyanide, which is maintained by reverse circulation, while the feed ratio of the feedstock is CO: 1CHnz = 1.7: 1.