DE1077198B - Process and device for the production of hydrogen cyanide or cyano compounds - Google Patents

Description

Process and device for the production of hydrocyanic acid or cyano compounds In patents not previously published in print, the production of hydrocyanic acid is mentioned or cyano compounds described in such a way, that one hydrocarbons, optionally nitrogen-containing hydrocarbons, preferably methane or methane-forming mixtures after conversion to methane and removal of water or or and carbonic acid with Ammonia in whole or in part according to the reaction known per se to form hydrogen cyanide and Hydrogen converts, hydrocyanic acid removed and discharged from the reaction system hydrogen-containing gas mixture, optionally after separation, contained therein Ammonia, used in whole or in part for the synthesis of hydrocyanic acid. C H4 is converted with N H3 to H C \ T and three times the amount of H2, H C N removed from the gas mixture, the ratio H2: N2 if necessary to the for the N H3 synthesis set, -the NH3-Synthe.se carried out the required Amount of NH3 recirculated and the rest recovered as such. In In this way, elementary \ T2 is used as a starting material, and yet become exploited the advantages of the reaction of CH4 with NH3 for the formation of HCN.

The conversion is CH4 + NH3 = HCN + 3 H2, provided no or only accordingly there is little oxygen present, which together with the H2 provides heat with water formation, an endothermic process. So it must be supplied heat of reaction, which through Heat is supplied to the gas mixture.

The present invention relates to a method for the implementation of gaseous hydrocarbons, possibly still containing elemental nitrogen, preferably methane, with ammonia to produce hydrocyanic acid and hydrogen, removal of hydrocyanic acid and \ rendering the remaining hydrogen-containing gas mixture usable during implementation the hydrogen cyanide synthesis in the cycle for methane or. Ammonia formation or as Heating gas in which coatings are used as catalysts that are applied by applying of solutions or dispersions of metal compounds on the walls of the reaction space and subsequent conversion into a catalytically active state have arisen; characterized in that resulting from the application of solutions or dispersions, converted into a catalytically active oxidic or oxidic and metallic state Coatings are used.

According to the invention, the use of such catalyst coatings has proven successful proved to be particularly suitable by applying solutions or dispersions and conversion, optionally via intermediate stages, into catalytically active oxidic ones or an oxidic and metallic state. To do this, turn z. B. coatings are used that consist of solutions or dispersions of the one hand compounds of aluminum and on the other hand of platinum or platinum metals, in particular z. B. platinum-ruthenium or platinum-rhodium, and subsequent transfer of the compounds of the aluminum in the oxidic state, the platinum metals in the metallic state are.

According to the present invention, excellent catalysts consist of Mixtures of aluminum oxide with copper or platinum or other metals of the platinum group or mixtures or alloys of such metals and are made up of solutions or dispersions of compounds of aluminum and at least one of the aforementioned additional Metals were formed, e.g. B. in a well-known manner by repeated applications on the tubes and vaporizing, heating and optionally passing air or non-oxidizing gases, such as N2, NH3, N2, over the coatings.

Catalysts that contain osmium have also proven to be advantageous or its alloys or mixtures with other platinum metals, preferably with Platinum, with possibly other components, in particular copper and / or rhenium, may be present.

As was further found, walls are more ale 03 than sillimanite (A12 03 # S'02) included, even without covering or impregnation or the like with others Catalysts already below 1200 ° C for catalytic H C N formation suitable. As cladding or support tubes or walls for other catalysts are Walls of such composition have excellent properties and allow with a minimum of additional catalyst substance, e.g. B. Pt metals to get along. According to the invention, therefore, by applying solutions or dispersions A1203-rich walls composed in this way were created in catalytically active ones oxidic or, preferably, oxidic and metallic state coatings used.

Another step is for the H C N-Bzldung walls or to use pipes that are not completely gas-tight, but have been impregnated, Covering, coatings or the like or or and by deposits during operation are made sufficiently tight. In particular, by applying the above Coatings or sealed by catalytic impregnation of the walls. Leave with it use materials that would otherwise be eliminated due to excessive permeability would, but especially with regard to the H C N generation, other advantages, z. B. the durability, fire resistance, catalytic suitability, thermal properties etc., own.

The management and use of the starting gases can be used for the purpose of recovery the heat or for the production of individual starting products in different ways. In particular, it is expedient that precisely in this process the starting gases be preheated prior to implementation, advantageously the waste heat of the hydrocyanic acid Reaction mixtures and / or the heating gases in whole or in part for preheating the reaction gases to be used.

Gas separation processes or systems known per se can also be used will. An embodiment of the invention is that in the present Process at least once from the gas mixtures freed from hydrocyanic acid and / or or from the residual or end gas of the ammonia synthesis Tdethane pure or in enriched form Partial streams is separated, with methane for hydrogen cyanide synthesis and at the same time hydrogen-containing mixtures coming from this gas separation plant for ammonia and / or are recycled to methane synthesis, while carbon oxide or carbon oxide Mixtures for methane synthesis or after conversion to hydrogen for ammonia synthesis to be led back.

The prussic acid can be separated off from the reaction mixture by liquefaction or absorbing or leaching, e.g. B. with cold water, alkaline solutions etc., take place. Washing out with organic solvents is ideal, especially with esters or alcohols, from which the hydrocyanic acid is preferably among Utilization of the waste heat or is driven off undiluted by heat exchange and if appropriate, is then liquefied, the solvents for the hydrocyanic acid be circulated, using cooling, especially deep freezing, in absorption. For example, methyl alcohol or ethyl acetate are used; Polyhydric alcohols and esters are also suitable.

The walls or pipes are not on when generating hydrogen cyanide a certain type of heating is bound (combustion gases, heating gases, surface combustion, Painting, electrical heating, etc.). Essential for electrical energy supply Embodiments consist in that: the catalytic H C N formation from C H4 and Gas mixtures containing N H3 on electrically heated metallic catalysts in Form of nets or or and wire meshes or the like. Takes place.

If the hydrogen formed during the H C N formation by combustion in the heating chamber to cover the heat demand for H C N formation in whole or in part is used, there is an advantageous embodiment: that the hydrogen-containing Gas mixture as obtained from the reaction gases after removal of the hydrocyanic acid is completely or partially by combustion with oxygen-nitrogen mixtures, such as air, preferably air enriched to about 60%, is used as heating gas and the nitrogen-containing combustion gases after their heat content has been used up for the purpose of generating ammonia used for carrying out the hydrogen cyanide synthesis be wholly or partially recycled to the ammonia synthesis.

Mixtures with methane-containing residues or residues can also be used as starting gases. End gases of ammonia synthesis into consideration. In another particular embodiment only so much of the hydrogen obtained from the reaction mixture is used for the synthesis of ammonia required hydrogen-nitrogen ratio set and converted to ammonia, as is required for recirculation, but not according to the invention Amount of hydrogen used for the synthesis of ammonia for hydrogenation with the formation of methane-containing Residual gases are used with the use of the same for carrying out the hydrogen cyanide synthesis.

If with nitrogen-containing technical starting gases and if necessary elemental nitrogen added during the process is worked and insofar as the amount of N2 exceeds the consumption for the ammonia synthesis or an ammonia synthesis does not take place, it is by draining part of the preferably remove hydrogen cyanide from the nitrogen cycle, in particular in such a way that the amount of gas discharged is not used for ammonia synthesis contains nitrogen used and at the same time the recycled gas so. a lot of hydrogen and optionally carbon oxide, that with it .the technical starting gases are suitable for methane synthesis without additional hydrogen. An essential embodiment of the present process is characterized in that in the reaction chamber Introduced hydrocyanic acid formation mixtures there immediately on surfaces whose temperature is above 800 ° C and preferably corresponds to the reaction temperature, wherein expediently all surfaces with which the gases come into contact in the reaction chamber, consist of catalyst substance or are covered or coated with it.

It was found that by this way of working the dreaded Pre-decomposition or C-deposition or side reactions to a negligible Level decrease or completely eliminated in the case of the best catalysts described which is surprising. So you can z. B. the gases through insert pipes smaller Diameter so far into the reaction chambers that the insert tubes gases flowing with a short dwell time on entry into the actual reaction tubes or spaces immediately meet catalyst surfaces, their temperature corresponds to the reaction temperature; the gases are also sufficient when leaving the hot walls immediately, z. B.: by insert pipes, removed and also at the outlet This avoids decomposition. It is preferably worked so that the walls : the lines in front of the inlet pipes and after the outlet pipes or Apparatus essential, d. H. by more than 100 or several 100 ° C, colder than the catalyst surfaces of the reaction spaces. Especially at the gas outlet, where in general the sensible heat of the reaction gases wholly or partially for steam generation, gas preheating, Heat exchange, etc. is exploited, are preferably utilizing the waste heat Cooled walls of apparatus (e.g. steam boilers, heat exchangers) and pipelines. In addition, walls or coatings or the like can be used outside the reaction space where no decomposition is to be feared, e.g. B. phosphor bronze, in particular on the gas inlet side.

In an older patent that was not previously published in print it has been described that carbon deposits are deposited by suitable measures can be avoided during the formation of the catalysts, but was not recognized that, especially when working on a larger scale, such carbon deposits are not permanently avoided during the introduction of the gases into the reaction spaces, if the present invention is not used.

Those in the older patent, which was not previously published in print described device for the production of hydrogen cyanide z. B. from ammonia and methane consists of a heating chamber or the like. mutually outstanding, if applicable extended or composite or or and provided with catalyst substance Pipe, or pipe bundle, means for holding on outside the boiler room of the pipe or pipes only on one side, but on the other side in the Way movable arrangements that by thermal and operational exposure Occurring expansions, distortions or the like. Without impairing the durability Resistances can occur. The or (the pipes are provided with movable gas supply lines on the side that is not firmly clamped, in addition, sealant that has the required Do not obstruct the freedom of movement of the pipe or pipes. Outside the boiler room and or or the furnace walls are cooling devices with passages for the reaction tubes.

According to the invention, at least one of the leadthrough walls of the heating chamber outside through cooled metal plates or chambers with openings for passage the reaction tubes covered. For example, in the case of vertically hanging pipes both the upper and the lower bushing wall covered accordingly, and the reaction tubes are in or on one side of the cooled metal plate attached, in particular clamped or hooked in at the top or the like. Otherwise, are they are then not fixed, but hang z. B. free down.

Another measure according to the invention consists in such pipes to at least partially relieve the hanging or supporting weight, whatever is basically arbitrary, z. B. by appropriate counterweights, support devices od..dgl., but in particular by spring tension.

The starting gases can be fed through small-diameter plug-in pipes into the reaction chambers, pipes or the like. In and / or out of the reaction chambers escape the H C N formation. According to the invention this is done in such a way that only this Insertion tubes penetrate the walls of the heating chamber and / or the cooling device or are suspended in it, so that the actual reaction tube or: the reaction tubes, chambers or the like at the ends provided with insert tubes protrude from the boiler room. This ensures that the in these plug-in pipes gases flowing with a short dwell time on entry into the actual reaction tubes or rooms immediately meet catalyst surfaces of sufficient temperature.

Claims (7)

PATENT CLAIMS: 1. Process for converting gaseous, possibly hydrocarbons still containing elemental nitrogen, preferably methane, with ammonia to hydrocyanic acid and hydrogen, removal of hydrocyanic acid and utilization of the remaining hydrogen-containing gas mixture when carrying out the hydrogen cyanide synthesis in the cycle for methane or ammonia formation or as heating gases, in which as Catalysts are used by applying solutions or coatings Dispersions of metal compounds on the walls of the reaction space and subsequent Conversion into a catalytically active state have arisen, characterized in that that resulting from the application of solutions or dispersions, in catalytic Effective oxidic or oxidic and metallic state transferred coatings be used. 2. The method according to claim 1, characterized by using Catalysts, which are made from mixtures of aluminum oxide with copper or platinum or other platinum group metals or mixtures or alloys of such metals and consist of solutions or dispersions of compounds of aluminum and at least one of the aforementioned additional metals have been formed. 3. The method according to claim 1 or 2, characterized in that for the in catalytically osmium or osmium coatings in an effective oxidic and metallic state its alloys or mixtures with other platinum metals, preferably with platinum, are used, with other components, in particular copper, if necessary and / or rhenium, may be present. 4. Method according to one of the preceding Claims, characterized in that by applying solutions or dispersions on walls that contain more A1202 than sillimanite (A120.-S'02) and coatings converted into an oxidic or an oxidic and metallic state be used. 5. The method according to any one of the preceding claims, characterized characterized: that the catalytic hydrogen cyanide formation is carried out in tubes or chambers wind, which are not completely gas-tight in themselves, but catalytically by applied effective coatings have become gas-tight. 6. Method according to one of the preceding Claims, characterized in that the starting gases are preheated prior to conversion be, advantageously the waste heat of the hydric acid Reaction mixtures and / or the heating gases are wholly or partially used to preheat the reaction gases will. 7. The method according to any one of the preceding claims, characterized in, that at least once from the gas mixtures freed from hydrogen cyanide and / or pure or enriched methane from the residual or end gas of ammonia synthesis Partial streams is separated, with methane for hydrogen cyanide synthesis and at the same time Hydrogen-containing mixtures coming from the gas separation plant for ammonia and or or can be returned to methane synthesis, while carbon oxide or carbon oxide Mixtures for methane synthesis or after conversion to hydrogen for ammonia synthesis to be led back. B. The method according to any one of the preceding claims, characterized characterized in that the removal of the hydrocyanic acid from the reaction mixture by Wash out with organic solvents, e.g. B. with esters or alcohols, from which the hydrocyanic acid is preferably made using the waste heat or by heat exchange is driven off undiluted, and optionally then liquefied, wherein the solvents for the hydrocyanic acid are circulated using of cooling, especially deep-freezing, during absorption. 9. Procedure after a of the preceding claims, characterized in that the hydrogen-containing Gas mixture wholly or partially by combustion with oxygen-nitrogen mixtures n, such as air, preferably air enriched to about 600% oxygen, as heating gas is used and the nitrogen-containing combustion gases after exhaustion their heat content for the purpose of generating for carrying out the hydrogen cyanide synthesis ammonia used wholly or partially recycled to the ammonia synthesis will. 10. The method according to any one of the preceding claims, characterized in, that the starting gases are mixtures of ammonia with methane-containing, residual or end gases the synthesis of ammonia. 11. Method according to one of the preceding Claims, wherein only so much hydrogen recovered from the reaction mixture on the hydrogen-nitrogen ratio required for ammonia synthesis is set and is converted to ammonia, as required for recycling, characterized in that the amount of hydrogen not used for ammonia synthesis is used for hydrogenation with the formation of residual gases containing methane same for carrying out the hydrogen cyanide synthesis. 12. Method according to one of the preceding claims, characterized in that with nitrogen-containing technical Starting gases and any elementary elements added during the process Nitrogen is worked and, insofar as the N2 amount is used, the consumption for ammonia synthesis exceeds or ammonia synthesis does not take place, nitrogen by venting a part of the gas preferably freed from hydrogen cyanide is removed from the circuit is, especially in .der way that the amount of gas discharged -den not for ammonia synthesis used contains nitrogen, and at the same time the recycled gas contains as much hydrogen and optionally has carbon oxide, so that the technical starting gases without Additional hydrogen are suitable for methane synthesis. 13. Method according to one of the preceding claims, characterized in that hydrocyanic acid forming mixtures with the help of plug-in pipes, in which they flow with a short dwell time, so far are introduced into the reaction tubes so that they immediately hit surfaces there, whose temperature is above 800 ° C and preferably the reaction temperature corresponds, with all surfaces with which the gases in the reaction space come into contact come, consist of catalyst substance or are covered or coated with it. 14. Device for performing the method according to claims 1 to 13 with a heating chamber with protruding tubes or tube bundles that are only on one side held and movably arranged on the other side and with gas supply lines are connected to cooling devices located outside the heating chamber, which Have passages for the reaction tubes, characterized in that the cooling devices are designed so that they externally cover at least one of the bushing walls, the tubes optionally on one side on or in a cooled metal cover are attached. 15. The device according to claim 14, characterized in that the Reaction tubes are relieved of weight, preferably by spring tension. 16. Device according to claim 14 or 15 with plug-in tubes pushed into the reaction tubes smaller diameter, characterized in that these plug-in tubes are arranged in this way are that only the plug-in tubes the walls of the heating chamber and / or the cooling device penetrate or are suspended in this. Legacy Patents Considered: German patents No. 969 768, 954 870, 919 769.