IL25566A - Process for the production of hydrogen cyanide - Google Patents

Description

Process for production of hydrogen 24325 The present Invention relates to a process for the production of hydrogen More it relates to a for the production of hydrogen cyanide by the high temperature gas phase reaction of ammonia with nitrogen and in the presence of a such as metallic platinum or its Even more particularly the present invention relates to an improvement in the basic process for carryijig out this catalytic reaction by the use of the components of the gaseous mixture in particular molar and by the suitable of said The industrial synthesis of from methane and air is The heat necessary for the endothermic reactioni is afforded by the contemporaneous of oxygen and In general the process is carried out in the of catalysts at ranging 900 to and large quantities of air and by introducing into the reactor a gaseous which has been at a temperature of about The gases which leave the catalytic zone contain not only but also nitrogen and carbon well as methane and BO that a very dilute is obtained considerable technical difficulties during its The conversions and the yields of realized by conducting these processes according to prior art are not very together with drawback of the dilution of the their use not very Other processes for the of ECU therein gaseous such as carbon mixtures of particular are to high temperatures and thereupon are made to in the tional presence of even by according to of low yields and conversions of low concentrations of the outlet gases are According to still other relatively high temperatures are thus rise to technological both in order to avoid the decomposition of the this latter must be separately at lower temperatures the other components of the gaseous and because heaters made of expensive materials have to be used to avoid corrosion and poisoning of the catalyst by entrained corrosion the employment of high temperatures requires very precise and regulation which further complicates the technology of the It the principal object of present invention to provide improved process for the of A further object of the present is that of providing a process for the production of from oxygen and which process is characterized by high conversions and the many advantages afforded by the process of the present invention for the produc of are the high concentration of in the gases which of a considerable increase in the output capacity of the the apparatus size remaining the a reduction in the consumption of energy per of produced as well as the after absorption of and of unconverted of a combustible as mixture of high heating Still a further advantage is provided by the fact that the process the present invention c an be carried out industrially in simple and easily operated The objects and advantages are according to the process the present invention by preparing a mixture of nitrogen and at and passing it into contact with catalyst comprising platinum group metals their preferably in net at a temperature lying in the range of from preferably from said mixture having a composition ponding to the molar ratios comprised in the range defined by the following above and not more than 6 and not less than 2 from 6 and not less than It has been found that when a gaseous mixture of nitrogen and oxygen with a composition comprised within the above defined is preheated to within the temperature there are obtained very high conversions and yields of and very high concentrations of in the produced without any concomitant technological The preferred temperature range at which the gaseous mixture is preheated in order to obtain beat and concentrations is between and Particularly good results are obtained by using gaseous mixtures having compositions such that the molar ratios are within the following As regards the catalyst particularly good results are obtained by operating in the presence of nets of platinum and for According to our copending application serial filed the excellent conversions and yields of as well as very high concentrations of in resultant are obtained by reacting a mixture of nitrogen and oxygen of a composition at high temperatures on nets made of metals of the platinum group and their particularly of platinum its It equally good or better results can be obtained by using mixtures having the compositions defined in the present specification which may be somewhat different than those of Application and by preheating these mixtures within the ranee of preferably of the reacting according to the process of the present does not involve very high so that all the components of the gaseous mixture can be together since by operating according to the present the decomposition of the ammonia in the stage is quite the relatively low temperatures involved allow the use of made of inexpensive example stainless as they are not particularly exposed to the temperatures of the gaseous according to the present invention not be very strictly controlled as they are relatively they do sot adversely affect temperature of the catalytic of the gaseous according to the present invention can be carried out by any suitable heat necessary for this can be recovered from the gas which is a of the according to the present it possible to obtain high yields of and conversions to and high concentrations of with simple and inex ensive The molar ratios required for carrying 2 out the process of the present invention obtained by adding a very small quantity of oxygen ean be done with minimal technical by adding the into the air feed line or to the mixture fed to the It a further advantage of the process of the present invention that it can be operated in conditions of maximum safety with regard to the inflammability of the gaseous In 1 is illustrated the upper part of an experimental ternary whose vertices the mixture of oxygen methane and that the points on the sides of the triangle represent binary mixtures of these and those inside the triangle represent ternary mixtures of In this diagram are represented gaseous mixtures different values of the molar ratio If one considers the mixtures of nitrogen and where the molar ratio is to that of then the corresponding points of inflammability at room temperature lie on the line through points A and and the area defined below this line represents the zone of for a mixture of the composition represented by point of the compositions used in the known industrial processes for the production of HON and eorresponiing to following percentages air the distance of this point from line is such that within the zone The critical variations of the individual flow rates which might cause the corresponding mixture to enter the zone of inflammability are about for for methane and for The line of inflammability corresponding to mixtures of nitrogen and oxygen wherein the ratio is equal to by is represented in the diagram by the line passing through points for room temperature and by line passing through points f the temperature of A gaseous mixture represented by point comprised in the ranges of the molar ratios according to present refers and to which the reported Example has practically the same margin of safety against inflammability as that of the point In the critical variations of the individual flow rates air and pure oxygen which are necessary to bring the gaseous mixture into the zone of have approximately the following for the enriched for for ammonia and for It thus turns out that the advantages obtained by the process for producing the present and in particular the high yields of and conversions to and the high concentrations of are effected under safety conditions which are equal or better than those of the less advanta eous known This makes the roces according to present invention quite attractive from an industrial point of the of the of the present invention is still further enhanced by the fact that it is preferably carried out with linear velocities of the gases through the catalyst nets equal to or higher than very much than rati of propagation in the gaseous mixtures under In order to further illustrate the present invention and the advantages the following specific Examples are it being understood that these are merely illustrative and not 6 gaseous mixtures containing air and oxygen were converted to in the presence of 8 nets an alloy of weight pla inum and having a weave corresponding to 80 mesh and a wire thickness of The linear velocity of the gases in the was and the catalyst temperature was in the range of from 1120 to The preheating temperatures and the compositions of the gaseous mixtures are recorded in the following Table together with the conversion yields and concentrations obtained in the respective Examples 1 and 5 used air which had not been enriched with As can be the Examples 5 and carried out according to the process of the present give greater and yields well as of hydrocyanic aeid than those obtained in Example 1 according to prior art The results obtained by Examples 2 and in the conditions conventional are ased for mixture compositions lying in the meed according to the present invention in the mixtures of composition at about give better resulte than the ones obtained by Example 1 but poorer than those of Examples embodiments of this invention may employ apparently widely different conditions without departing from the spirit and scope it is to be understood that the invention is not to be limited to the specific embodiments except as claimed in the appended Thus for instead of gaseous mixtures containin at least of in particular natural can be used with equally good insufficientOCRQuality

Claims (1)

1. CLAIMS A method for the preparation of hydrogen cyanide comprising preheating a mixture of nitrogen oxygen at a temperature from to and then passing this mixture over a consisting platinum group metals their in the of at temperatures of from to the ratios of the respective components of the gaseous mixture g as above and not more than The method of Claim wherein the preheating is effected at temperatures of from to The method of Claim wherein the molar ratios are as The method of Claim wherein the is ffected at temperatures of from to the method of Claim wher the catalyst is platinum and or ita method of Claim the is effected at temperature of to The Claim wherein the molar ratios as from to method of Claim wherein the preheating is effected at temperature of from to For the Applicants insufficientOCRQuality