IL22624A - A process for the preparation of ethylene oxide - Google Patents

Description

PATENTS AND DESIGNS ORDINANCE SPECIFICATION A process for the preparation of ethylene oxide a corporation organized and existing under the laws of the State of of 2 Park York New do hereby declare the nature of this invention and in what manner the same is to be to be particularly described and ascertained in and by the following invention relates to processes for the preparation of ethylene oxide by the partial oxidation of ethylene by means of gaseous oxygen in the presence of a silver containing and more particularly such a process wherein one reaction zone is used with pure oxygen to is and an inert gas or ballast is added to the eed in controlled manner to provide good system pressure The invention relates especially to such process wherein the concentration of the ethylene employed as is in the art to inhibit the activity of catalyst centers favoring formation of carbon dioxide and in the reaction mixture is from to about 100 pp per based on the total gaseous the reaction the centration of ethylene is in the range of 1 to the concentration of carbon dioxide is in the range of to the concentration of oxygen is in the range of 1 to the concentration methane or ethane or other ballast gas is in the range of to and the reactor pressure and flow rate are each within the range of to 50 to 650 and 50 to 1500 standard cubic feet hour per tube with tube diameter in the range of to and each tube length in the range of 5 to The term ballast gas as used in this specification means a gas both inert and non condensible under the reaction The preparation of ethylene oxide by the partial oxidation ethylene by means Of air in the presence of a silver containing catalyst is well includin the use of concentrated ox en with the reactor was sufficiently impure to require a considerable purge from the With improved raw material a purer feed is now but when used in the usual manner with scrubbing to remove reaction products or there extreme difficulty in pressure and this results in lowered The art is confronted the problem of Improving the yield or ductivity such a plant using the purer feed materials now In ethylene oxide processes there are two sources of yield It is known in the art that two basic reactions one the reaction of ethylene with molecular oxygen to form ethylene oxid the desired the other the reaction of ethylene with molecular oxygen to form carbon dioxide and which s an undesirable side Selectivity is defined as the ratio of the ethylene which reacts to form oxide to the total ethylene which that selectivity equals outlet oxide concentration minus oxide concentration divided by inlet ethylene minue outle ethylene Thus one source of yield loss a poor selectivity when the ethylene giving mainly carbon dioxide and In a recycle in order to keep inert materials from building up one must purge varying quantities of material from the system depending on the quantities o inerts A certain portion of the feed ethylene carried away purging these Henc another yield loss can be Incomplete utilization of the ethylene or poor overall The overall conversion related to the conversion pe pass the reactor and the amount of material recycled as well as the centration of ethylene in the purge from the With very pure this loss can be one must also remove carbon dioxide from the by ubbing the recycling stream to remove carbon dioxide aots as an inhibitor in the and suppresses the reaction of to form both ethylene oxide and When there can be such reduction total gas content as to control the very and a loss According to one is using pure oxygen as the oxidizing a controlled amount of inert ballast gas is added to there are certain critical reaction conditions required in the r that is there a critical inhibitor concentration iven trations of carbon dioxide ballast ethylene and oxygen in the The critical condition ia also function of the particular reactor pressure and contact time and tube diameter This control of carbon and ballast gas concentration results in marked improvement in the process yield and reactor productivity with decrease in catalyst as well as good system pressure For this pure oxygen containing to oxygen is reacted with 95 pur ethylene ove a silver catalyst and the invention can be practiced using catalyst in either carbon steel tubes or stainless steel tubes such for example or 410 stainless Materials of construction have no effect on results To practice this invention one must keep the carbon dioxide centration to the inlet of the reactor below and preferably in the range of 3 to by scrubbing out carbon dioxide from the recycle gases One add an inert ballast gas in a controlled manner to provide sufficient purge to control the system pressure The discoveries associated with the invention and relating to solution of the above and the objects achieved in accordance with nvention as set forth herein include the provision a process for producing ethylene oxide by the partial oxidation of high purit ethylene by means of a high purity oxygen the presence of a silver including the which comprises operating So aorban r a rotobaoa ttb oaab o or otortoro or or floor roto of foot par pot toba bod at ppd 300 o to oo o o ppfeotipptp t P of too appao o rooppl to pprobbad robtb orotpr to p rot of to to op tod to ordor to too to opotooo A too poo to tbo dlorrtdo aob to loan to ood bollPPt poo ot afboaa a p to of ood dlobtorldo pro to mtotprp to popptdo tbo oborpo to aba aa to tP tbo ot p low to o of to For tbo to ood ρ d a oar bo of I la rapoatod 10 insufficientOCRQuality

Claims (1)

1. CLAIMS In a process or producing ethylene oxide by the partial oxidation of high purity ethylene by of high purity oxygen in the presence of a silver containing the improvement which comprises operating with one reaction zone with purging and recycling and using a feed to this zone having a concentration of ethylene of 7 to a concentration of oxygen of 1 to a concentration of carbon dioxide of to a concentration of halogenated inhibitor herein of to 100 a concentration of ballast gas herein to a reactor temperature of to a reactor pressure of 50 to 650 a flow rate of 0 to 500 standard cubic feet per hour per ted zone with a zone average diameter of to a zone length o 5 to 40 the particular combination of conditions being controlled to provide a selectivity of 65 to a conversion of 10 to and an ethylene oxide concentration in the exit gas of to the system purge being to based on the volume of ethylene A process according to Claim 1 wherein oxygen and ethylene of 95 to purity are used and their purities are so selected that their mixture contains of inert A process according to Claim wherein the impurity is mostly A process according to Claim 1 wherein oxygen and ethylene of 95 to purity are used and their mixture contains less than and just sufficient inert gas i3 added thereto to provide a mixture having of A process according to Claim wherein the inert gas used is A process according to Claim wherein oxygen of purity and ethylene of purity are used and 3 to 4 of inert gas are added to the of oxygen and A process according to Claim wherein oxygen of purity and ethylene of purity are used and 1 to of iner gas are added to the mixture of and A process according to Claim wherein oxygen of purity and ethylene of purity are used and 2 to of inert gas are added to the mixture of oxygen and A process according to Claim wherein a purge of based on the ethylene is A process producing ethylene substantiall as described herein with reference to th For the Applicants insufficientOCRQuality