IL26557A - Process of selective hydrogenation of hydrocarbon mixtures - Google Patents

Description

IMPROVED PROCESS OF OP HYDROCARBON MIXTURES Invention relates to a selective genation process of a mixture of normally liquid hydrocarbons containing hydrocarbon gum generators and less than 50 by of in which hydrogen is placed into contact with said mixture in the presence of a catalyst containing nickel andor metallic at a temperature of between 50 and characterized in that carbon monoxide added at the rate of to parts per million parts by volume of By hydrocarbon gum generators are meant alkenylaromatle hydrocarbons are present in certain refinery cuts such as gasolines resulting from steam cracking or said outs having a boiling range between approximately 20 and under 76 cm of The selective hydrogenation has the of converting the aforementioned hydrocarbon gum generators into monoolefinic hydrocarbons alkylaromatie without appreciable hydrogenation Of other unsaturated hydrocarbons present aromatic or alkylaromatie In other it concerns obtaining a stable gasoline of long induction without diminishing the that is to say its octane It is pointed out that a stable gasoline is characterized by a long induction time such as defined in method To effect this selective metallic nickel or metallic when used possess mediocre selectivity in relation to the transformation cannot he is and this is to improve the selectivity by the addition of a containing These compounds may be if to the charge or to the or be naturally present in the gas or in the which is the for with certain gasolines resulting from cracking when the charge does not contain compounds or contains a very low amount for example less than 50 and in particular less than 30 ppm by it is not ly desirable to add sulphurous compounds since this apart from being may harm the quality of the treated a part or the total having undergone a first stage of to eliminate alkenylaromatle is passed to a second stage of hydrodesulphuratlon and hydrogenatlon which decomposes the compounds dissolved in the gasoline and hydrogenates the olefins in a manner which produces a charge which is for the extraction of aromatic It is evident that there is little benefit in adding compounds prior to the first stage since they have to he eliminated later y a very laborious process to produce cuts for petrochemical must free of The present invention remedies the above de iciencies of the known processes relates to a process of selective hydrogenation of a ly liquid hydrocarbon mixture containing hydrocarbon gum generators as herein defined and less than 50 ppm by weight of in which mixture is contacted with hydrogen in the presence of a catalyst containing metallic nickel metallic at a temperature comprised between 50 and characterized in that carbon monoxide is added at a rate of to 1000 parts pe million parts by volume of Carbon monoxide the selectivity of nickel and cobalt at a higher degree compounds and possesses the advantage of being removed easily from the reaction product since the former is gaseous and the latter monoxide is moreover available cheaply and in large is already known that carbon monoxide is poisonous to the catalysts and consequently its use is avoided in most of the hydrogenation has now been discovered that carbon monoxide improves the selectivity of the nickel and cobalt catalysts respect to the hydrogenation of diole provided thatthis agent is utilized in This surprising It has been found that the content of carbon necessary to obtain good selectivity in the action of the should be very It nrast be comprised between and 1000 ppm by relative to Higher content is not advantageous since it would inactivate the catalyst and would not then be possible to hydrogenate the gum generator compounds Lower content does not confer a satisfactory selectivity to the A content of 50 to ppm constitutes the e catalyst may be dispersed in the charge disposed in a movable or fluid constituted of metallic nickel or either or mixed with catalyst for metal compounds of group VI of the Periodic Table and more particularly supports may also be for example eilica or In the case of use of a the content of nickel cobalt in the catalyst ously from 2 to by weight of the The preparation of the catalyst is made according to methods known in the not be described To put the process into it is preferable that at least a part of the charge remains the liquid For this the total pressure must be maintained at a sufficiently high at least equal to 10 and preferably comprised between JO and SO The spatial velocity of liquid of comprised between and and preferably between 1 and whilst the rate of gaseous hydrogen relative t the rate of the liquid charge is comprised for example between 50 and 500 the last two values not being The reaction temperature is comprised between 50 and preferably between and The hydrogen can be used pure or diluted with inert for example with saturated lower the presence of sulphur compounds avoided in the hydrogenating gas which will therefore advantageously contain less than 50 preferably less than 5 ppm by weight of sulphur The following which are illustrate the present EXAMPLE 1 This example relates to the selective hydrogenation of a conjugated diolefin such as by means of The liquid charge contains isoprene benzene 90 Benzene is used as a the presence of a selective benzene should resist the The catalyst is constituted by nickel by deposited on an activated The operating conditions are ae follows Temperature 100 to 20dG Pressure bars Spatial velocity 2 Molar ratio charge Three runs II III were carried The conditions and results of which are given in the following table In run the liquid charge and hydrogen did not any inhibitor in run the liquid charge contained 300 ppm by weight of sulphur in form of thiophene hydrogen was and in run the charge did not contain but the hydrogen contained 300 ppm by volume of carbon It is observed that the in the absence of an does hot possess a good selectivity since on the one hand complete hydrogena of intermediate olefins occurs and on the other hand a large part of the benzene is also the addition of inhibitor compounds permits selectivity to be which is explained by a minimum formation of saturated hydrocarbon It is noticed that the carbon monoxide selectivity distinctly higher than that of EXAMPLE 2 The starting material was a gasoline resulting from cracking a heavy oil the presence of This gasoline was characterized as Chemical composition Paraffins naphthenes 27 Aromatics tetraline styrene 5k Dioleflns Characteristics A S T M distillation Initial point C Pinal point i C Density at Sulphur 5 ppm by weight Operative conditions s Pressure bars T C as charge 250 catalyst is the same as in the two first The carbon oxide content in the hydrogen is 600 ppm The results are summarised in table t The gum is measured directly on the crude gasoline leaving reaetor and not after divers measurements indicated are obtained according to the known standardsj the maleio anhydride index is measured according to a Method observed that a Very stable product obtained high induction period as there being a very slight loss in elear The antioxidan butyl EXAMPLE Example 2 was repeated several times at a ature of instead of at various concentrations of carbon monoxide The obtained are assembled in the following table s of the octane the usually tolerated drop of the clear octane number being one Conversely with a very large quantity of carbon the gasoline obtained has no longer the desired the induction period for example being much too short minutes bein the minimum admissible the potential gum content is also too 3 repeated at a temperature of about In this ease it la noted that the carbon monoxide tolerance is even the tolerable limit for the period being for approximately of carbon monoxide in the insufficientOCRQuality

Claims (1)

\ 26557/2 Claims

1. Process of selective hydrogenation of a normally liquid hydrocarbon mixture containing hydrocarbon gum generators as herein defined and less than 50 ppm by weight of sulphur, in which said mixture is contacted with hydrogen in the presence of a catalyst containin metallic nickel and/or metallic cobalt, at a temperature comprised between 50 and! 2500·» characterized in that carbon monoxide is added at a rate of 10 to 1000 parts per million parts by volume of hydrogen* 2· Process according to claim , character* ized in that the proportion of carbon monoxide is comprised between 50 and 600 parts per million parts by volume of hydrogen. 3· Process according to claim 1 * characterized in that at least a part of the hydrocarbon mixture is in a liquid phase in the course of th hydrogenation* k. Process according to claim 1 , characterized in that the hydrogenation temperature is comprised between 120 and 80*0* 5· Process for the selective hydrogenation of hydrocarbon mixtures substantially as described in the herein Examples* Attorney or Applicants