ENGINEERING RESEARCH INSTITUTE UNIVERSITY OF MICHIGAN ANN ARBOR GAMMA IRRADIATED CATALYTIC DEHYtDROGENATION OF BUTENE-2 TO BUTADIENE-1,3 J. Go LEWJIS H. A. 0ZHLGREN Project 2581 THE DOW CHEMICAL COMPANY MIDLAND, MICHIGAN July, 1957

PREFACE This report is presented as a result of investigations and evaluations of the dehydrogenation of butene-2 to butadiene 1-3 as affected by gamma irradiation. The work upon which this report is based was undertaken at the request of Alden W. Hanson, Director, Nuclear and Basic Research Laboratories. L. R. Drake, Assistant Director, Nuclear and Basic Research Laboratories, and D. E. Harmer, of the Nuclear and Basic Research Laboratories of The Dow Chemical Company have been of great assistance to the authors in completing the work described in this report. The authors wish to acknowledge gratefully the cooperation of the Phoenix Memorial Laboratory in making available space and radiation facilities for the completion of this work. Particular appreciation is due H. J. Gomberg, Assistant Director, Michigan Memorial Phoenix Project, and A. H. Emmons and W. Dunbar of the Phoenix Memorial Laboratory staff. Alan Christman and Roberto Trevino, graduate engineering students at the University of Michigan contributed greatly to the construction of the equipment and the completion of the experimental work reported herein. Alfred Anderson, Robert Dunn, and John Payne, engineering students at the University, assisted in the construction of experimental equipment and facilities.

TABLE OF CONTENTS Page PREFACE i ABSTRACT iii 1.0 INTRODUCTION 1 2.0 EXPERIMENTAL PROGRAM 2 3.0 EXPERIMENTAL EQUIPMENT 4 3.1 General Design Criteria 4 3.2 Reactor Vessel 10 3.3 Influence of Radiation Source Upon Reactor Design 10 3.4 Reactor Heaters 14 3.5 Measurement of Reaction Temperatures 15 3.6 Butene Metering System 15 3.7 Product-Handling System 17 3.8 Some Start-Up Considerations 18 4.0 RESULTS OF EXPERIMENTAL WORK 19 5.0 SUMMARY ATID CONCLUSIONS 26 6.0 BIBLIOGRAPHY 27 -ii

ABSTRACT Equipment was constructed for the conduct of the catalytic dehydrogenation of butene-2 over Dow Type B catalyst as influenced by gamma irradiation from MTR fuel elements and cobalt-60. The equipment after construction and test operation was installed in the Phoenix Memorial Laboratory for operation under irradiation conditions. Equipment design and construction was conducted so that the entire pilot plant facility could be moved from the site of construction to the site required for irradiation in order to fulfill space and facility requirements during the construction and test operation period. Results of catalytic dehydrogenation runs, both with and without irradiation, are presented for the range of temperatures of 575 to 650 ~C; space velocities in the vicinity of 300 standard volumes of butene feed per volume of catalyst per hour; steam ratios of 20 to 21 parts of steam per part of butene; and for a cycle time of one hour, comprising 28 minutes of dehydrogenation, 2 minutes of purge steaming, 28 minutes of burnoff, and concluding with 2 minutes of purge steaming. Some indicatioans were available from the data that irradiation accelerated the deterioration of the Dow Type B dehydrogenation catalyst. These indications cannot be confirmed at this writing, however. No significant difference was observed in the conversions or selectivities of dehydrogenation of butene-2 to butadiene 1-3 as affected by the presence or absence of gamma radiation for the doses and dose rates studied. -iii

1.0 INTRODUCTION In September of 1956, the Engineering Research Institute, University of Michigan, was contacted by the Nuclear and Basic Research Laboratories of The Dow Chemical Company relative to the conduct of sponsored research work. Discussions among the personnel of the two organizations resulted in The Dow Chemical Company's sponsoring a research contract with the Engineering Research Institute. Subsequently, among the many reactions which were of mutual interest to the two organizations, the Engineering Research Institute was directed to concentrate efforts upon the study of the catalytic dehydrogenation of butene-2 to butadiene 1-3 over Dow Type B catalyst, as affected by gamma irradiation. Complete experimental facilities for this particular reaction were not available at the University of Michigan and efforts were immediately concentrated upon the design and construction of a suitable pilot plant embodying all of the necessary special requirements. Because of the great interest in irradiation work at the University of lMichigan, space is at a premium in the immediate vicinity of the irradiation facilities. Consequently, it was decided to construct the pilot plant at the North Main Street, Ann Arbor, facilities of the Engineering Research Institute and to move the entire pilot plant to the Phoenix Memorial Laboratory upon completion of construction. The program of construction was substantially completed by the end of January, 1957. Test operations without radiation were completed and the pilot plant moved to the Phoenix Memorial Laboratory in March, 1957. The experimental program of butene dehydrogenation in the presence of radiation was completed at the end of June, 1957. The portable pilot plant and supporting spare parts and small tools were returned to The Dow Chemical Company at the conclusion of the experimental work. -1

2.0 EXPERIMENTAL PROGRAM The Dow Chemical Company have for many years conducted research on the catalytic dehydrogenation of butenes to butadiene 1-3, which is required as a raw material in the production of synthetic rubber. The Dow Chemical Company are presently engaged in the manufacture of a highly selective catalyst, the Dow Type B catalyst, for conducting the dehydrogenation of butene-2 to butadiene 1-3. As a consequence of the interest which The Dow Chemical Company have in the butadiene production program, it was decided that the Engineering Research Institute should concentrate its studies in the field of radiation effects upon chemical reactions upon the irradiation of the catalytic dehydrogenation of butene over Dow Type B catalyst under conditions which were similar to those used in Dow's standard test #5 for evaluating manufactured lots of the Dow Type B catalyst. The standard test #5 of The Dow Chemical Company is used to evaluate the activity and service life of lots of Dow Type B catalyst. the experimental pilot plant constructed at the University of Michigan was therefore designed to operate under temperatures, space velocities, steam to hydrocarbon ratios, and production and burnoff cycle times similar to those employed in the standard test #5. Consequently, the experimental conditions of operation for studying the butene dehydrogenation were rather firmly established prior to the initiation of any experimental work. The unique feature of the experimental program is that the catalytic dehydrogenation was conducted under industrial conditions during irradiation. In particular irradiated reaction studies were conducted under continuous flow conditions at temperatures ranging from 575 to 6500C, employing a catalytic bed with continuous charging of raw materials and continuous withdrawal of product. The method employed for analysis of product gases was that of gas phase chromatography using a wet-screened celite carrier and 2-5 hexanedione as stationary phase (2). This method provided indications of air, methane, carbon monoxide, carbon dioxide, lower hydrocarbons, butane, butene-l, trans-butene-2, cis-butene-2, and butadiene-l-3. Phillips pure grade mixed butene-2 was the only charge stock employed. Dow Type B catalyst, Lot 36, was used as furnished by D. E. Harmer. Distilled water was used throughout these investigations for conversion to required diluent steam. Initial efforts upon completion of the pilot plant were devoted to checking the performance of the catalytic dehydrogenation in the absence of radiation. These efforts were undertaken to establish baselines of comparison for evaluating the performance of the pilot plant with those -2

data available from previous experimental investigations of The Dow Chemical Company. After some six weeks of intermittent operation in the absence of radiation, it was mutually agreed by The Dow Chemical Company and the University of Michigan that the pilot plant displayed consistent performance and irradiation work should be started. The irradiation program at the Phoenix Memorial Laboratory was somewhat more flexible in regard to the application of radiation than were the process conditions of operation. In general, the effort was to run the standard test #5, modified in certain respects, first without radiation and then with radiation, and to observe any differences which might be apparent due to the radiation. Some unexpected effects were observed, such as, in certain cases, rapid coking of the catalyst. Initial runs at the Phoenix Memorial Laboratory were with 4 MTR fuel elements only, and later runs employed the 3,000 curie cobalt-60 source in addition to the 4 MTR fuel elements. Various combinations of variables were tried with and without radiation, either for considerable periods under each condition or under alternating radiation and no radiation conditions. Various indications of the experimental data were followed as they appeared in the attempt to derive generalizations of the effect of radiation upon the reaction under study. -3

3.0 EXPERIMENTAL EQUIPMENT 3.1 General Design Criteria The experimental equipment required for the butene dehydrogenation work studied under this contract was constructed at the University of Michigan. The Dow Chemical Company lent to the University of Michigan for the purposes of the study several vital pieces of equipment, including a Brown 8-Point Temperature Recorder, two Milton Roy pumps, and a gas chromatography unit for continual analysis of the product gas streams. In Figures 1, 2, and 3 appear photographs of the pilot plant as construction had been concluded at the construction shops at the University of Michigan. As can be seen from the photographs, the pilot plant employed certain features of design which were necessary due to the unique requirements of this particular program of investigation. The necessity of constructing the pilot plant at one location and then moving the entire facility bodily to another location for the radiation work was imposed by space requirements in the vicinity of the radiation source. The requirement of portability dictated lightness and rigidity, compactness, and accessibility of the experimental equipment. From these requirements arose the use of the Dexion slotted galvanized steel angle for the construction of the control panel and reactor support. The placement of all the control equipment upon one panel occupying one plane only was dictated by space requirements adjacent to the radiation source. This point can be further appreciated by referring to Figure 4, a photograph of the control panel in place in the space available on the west side of a gamma radiation room in the Phoenix Memorial Laboratory. About one foot was left clear behind the panel for access and about three feet in front of the panel for operation. It was decided to construct the control panel in an open style, that is, without any panel board covering the rack, in order to permit ready access to the equipment for inspection, replacement, or repair. The layout of equipment on the control panel was governed by the grouping of related operations and accessibility of components. In addition, all of the process, instrument, and power lines were required to leave the right end of the panel and pass through a highly restricted chute with an offset through the wall of the radiation cave. This chute, although open throughout, provided the required radiation shielding due to the offset angles in its construction, so that no direct radiation or intolerable amounts of scattered radiation could pass through the chute. The requirement of grouping all lines and passing them through one common opening necessitated an extreme compactness in the wiring, piping and tubing layouts. The passage of all power wiring adjacent to the thermocouple wiring was believed to be sufficient basis for running all thermocouple wiring through a braided, tinned-copper shielding which was grounded at both end's to minimize the effects of alternating current pickup upon the thermocouple performance. The reactor rack in its final location is shown in Figure 5 in location over the storage well for the radiation source. The reactor

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was in competition with many other experiments for utilization of the source, which rises out of the well and. surround~s the reactor, as shown in the figure. Consequently, it was necessary to move the reactor rack from the well whenever the source was not being used. in ord~er that others might use the space. As a means of circumventing this difficulty and. also maintaining an ord~erly appearance and. accessibility to all parts of the irrad~iation room., all of the process lines, instrument and. power wiring were run on one beam cantilevered. from the reactor rack as shown and. terminating in the entire group of lines which drop d~irectly d~own into the opening of the access chute through the shield~ing wall. A flow d~iagram of the experimental unit is shown in Figure 6. The flow d~iagram was entirely conventional and. follows closely the type of related. units presently employed. by the Gas Laboratory of The Dow Chemical Company. Figure 7 shows the power wiring d~iagram for the pilot plant and. Figure 8 shows the thermocouple wiring d~iagram for the pilot plant. No special d~ifficulties were encountered. when the pilot plant was moved. from the North Main Street shops to the Phoenix Memorial Laboratory. No joints were found. to have leaked. d~uring the transportation of the pilot plant. However, it was necessary to make connections to the new utility sources in the Phoenix Memorial Laboratory and. to add. some lengths of tubing line to pass through the shield~ing chute. 3.2 Reactor Vessel Limitations of time and. unavailability of special 4-i46 weld~ing rod. led. to the ad~option of a reactor d~esign which could. be fabricated. quickly and. cheaply in ord~er to avoid. d~elaying the commnencement of investigative work. The reactor consisted. of a piece of 3/4u" ips 446 pipe which was turned. d~own to l.OO" o-utsid~e d~iameter on each end.. This proced~ure permitted. closing each end. of the reactor by means of compression-type tubing fittings. The fittings employed. were of carbon steel, cad~mium plated. as manufactured. by the Weatherhead. Company and. bore the trad~e name, Ermeto. The. bottom fitting -was located. 5" below the bottom heating wind~ing and. the top fitting was located. 13"' above the top heating wind~ing. The reactor -was left bare between the termination of the heating wind~ings and. the fittings on each end. in ord~er to provid~e the maximum amount of cooling and. prevent the overheating of the end. fittings. During operation the top or inlet fitting, -was never observed. to rise above 1000C and. the bottom fitting d~id. not rise above 225 0Co Both of these temperatures were well within the operating limits of the materials of construction. 3.3 Influence of Radiation Source Upon Reactor Desg The d~esign and. construction of the reactor to operate at a temperature of'r — 50C at1 -* _ —q,__I __ I loain ihnoe t -1/ inches _ — -_L 1- __ ---- ofalmiu ca.3

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possible rupturing or parting of the seams of the aluminum clad~ding surrounding the cobalt rod~s. This problem was met by surround~ing the reactor, together with the associated. power wiring, quench cooler, and. measuring and. control thermocouples, by means of the 4~" diameter sheet aluminum housing. This housing fitted. with about 1/1111 clearance on all sid~es within the rack holding the rad~iation source. Consequently,, the reactor had. to be centered. accurately over the location at which the fuel elements would. rise from the source when operated. by remote control. It was believed. necessary to red~uce the temperature of the prod~ucts as they left the reactor as rapid~ly as possible in ord~er to avoid. und~esirable second~ary reactions of the prod~ucts. This was accomplished. by passing a stream of air through aj~acket surround~ing the outlet tube from the reactor. This cooler was then located. immed~iately ad~jacent to the reactor insid~e the aluminum sheet housing d~escribed. above. The air, as it exited. from the bottom of the quench cooler, was allowed. to pass upward. around. the outsid~e of the reactor, helping to red~uce the temperature of the exterior of the reactor insulation, the measuring and. control thermo-~ couples., and. power wiring lead~s passing into the reactor insulation from the outsid~e. 3.4i Reactor Heaters In ad~dition to preventing the overheating of the gamma source d~ue to the close proximity of the high temperature reactor operation, it was necessary to d~esign and. construct the reactor in such a way that it would. maintain a uniform temperature throughout its length by means of heating elements which would. absorb minim-um, amount of gamma radiation from the source. The heater d~esign employed. is shown in Figure 7, Power Wiring Diagram in schematic form. The actual heater wind~ings -were mad~e of 20 gauge chromel A-wire insulated. with asbestos, jacketed. on the outsid~e with 302 -stainless braid.. This wire was wrapped. over a copper sheet which had. previously been vr~apped. around. the ~446 pipe reactor. The copper sheet -was of some assistance in maintaining uniform temperature along the length of the reactor. The use of the self-insulated. heating wire permitted. much lower d~ead. times in response to controller signals from the temperature controller than would. be possible when using a layer of insulating material wrapped. upon the reactor and. also around. the outsid~e of the heating elements. This d~esign also absorbed. a minimum of gamma rad~iation. A similar d~esign of heaters was employed. for the steam generator required. to vaporize the d~istilled. water charged. from the control rack and. used. as a diluent and. heat transfer med~iumn within the reaction bed.. The initial installation of heating elements worked. quite well. Temperatures were controlled. automatically wil thin + 10C,. employing

the catalyst badly. High temperatures were applied to the wind~ings in order to raise the temperature of the reaction,, which was evid-ently being lowered by the water gas reaction. Under these conditions, several of the heating elements burned out. These were replaced without the copper sheet over the reactor and under the heating wires. These heaters did not perform very well. Close temperature control and uniform temperature control among the various heaters was not possible. This assenmbly was re-wound., employing an additional copper sheet under the windings. This assembly was employed for the rema~inder of the experimental work and appeared to work reasonably well. Good temperature control was possible., using the system as designed if the. reaction was behaving in such a way that large endothermic or exothermic effects were not observed. 3.5 Measurement of Reaction Timeratures The measuring thermocouples were placed inside. an SAE 4130 steel tube, heliarc welded closed at the bottom. It -was decided to try the double glass-wrapped silicon-impregnated thermocouple wire for this application within the thermo.-well although the manufacturer of this wire does not recommend its use above. a temperature of 9000F. It was found that the thermocouples standardized using the freezing points of Bureau of Standards samples of pure metals in graphite containers as reference points -would operate wvell so long as they were not subjected. to mechanical disturbance. If the thermocouples were withdrawn from the thermqwell after being heated to 650 C or were subjected to undue jarring or distur~bance, such as when changing catalyst, then it was necessary to replace the entire set of thermocouples. An improved design of thermocouples could have been employed. However,- within the limitations of the time and ma~npower available it was not~ deemed desirable to divert effort to this end. It was desired to read about 16 temperature points,, whereas only 8 positions were available in the Brow-n recorder. It ~was decided to record continually the 7 points within the reactor thermowell. The four control couples -were hooked directly to the Wheelco and constituted no problem., because they did not compete for a recorder space with the other points measured. However, the remaining points were connected to point'#8 in the Brown recorder through a Leeds and N~orthrup 11-posiltion rotary double pole thermocouple selector switch. Thus, it was possible to stop the recorder on point #8,, read the other nine points as desired, and then start the recorder chart to continue the automatic logging. 3.6 Butene Metering System. The metering of the butene into the system under controlled conditions

under high pressure. Consequently, the entire pilot plant was designed to run at a pressure of 400 psig, the probable limiting pressure due to creep considerations of the 446 reactor at 650~C for 10,000 hours of operation. For pressure operation, 1/4" stainless steel AISI 304 lines were employed. These lines were too small to permit flow of the required quantities of gases for operation at atmospheric pressure without back pressures of the order of about 3 to 5 lbs/sqo in. gauge. Consequently, a wet test meter could not be employed under these pressures for metering the feed gas at 1 atmosphere. One of the early methods of attempting to meter butene was the use of a Brooks rotameter. This rotameter had the proper characteristics with regard to flow range for metering butene in liquid form. It was initially believed that the combination of the sight glass for measuring integral quantities of butene liquid charged together with the instantaneous reading on the liquid butene rotameter would be adequate to provide control of the system~ It was found, however, that particles of paint and other foreign matter continually dissolved out of the system and caused the float to stick in the rotameter. In addition, the rotameter has a vent at the bottom of the sight glass which allowed the pressure-space of the rotameter to fill with liquid butene during operation. A further difficulty encountered because of the low pressure of operation was that the liquid butene flashed to the vapor form upon passing through the metering valve into the lower pressure of the reaction system. A steady flow of the butene could not be maintained under flashing flow conditions. A system was then devised to meter the butene in the liquid state inside a Penberthy 4 section gauge glass under nitrogen pressure. The liquid butene was charged to a vaporizer, which admitted the vaporized butene through a solenoid valve into an orifice constructed of a hypodermic needle and read by means of a masnometer. This system was not satisfactory because of liquid-level-surging in the gauge glass. It was then decided to pump the liquid butene through a Milton Roy pump. The pump was connected to the contacts on the Eagle signal timer governing the burnoff operationso The liquid butene discharged from the pump went to a vaporizer. From the vaporizer it went through a solenoid valve to a pressure regulator. The vapor was discharged from the pressure regulator at about 6 lbs/sqoin. gauge. The butene vapor then passed through a rotameter, into the orifice described above, through a metering valve, and finally to a second part of the vaporizer. The second part of the vaporizer re-heated the vapor for charging to the system. The last system described represents a compromise between a design of the overall unit for high pressure operation and its utilization for atmospheric operation. If one were to employ the system for hig pressure oeration1 it would be necessary to put in more high -16

pressure components, such as a high pressure alloy steel regulator and gauge glass and a better drevice than the orifice and manometer employed. Perhaps one could use a gauge capable of withstanding high static pressure but reading inches of water directly in a bourdon type element over an orifice placed in the line. However, operation of the equipment at high pressure was not easily possible under this setup. The principal reason for this was the desire to conduct the atmospheric runs first. In addition, it would have been necessary to supply high pressure air to the system, and such a source of air was not readily available. Campressed air was not available from existing utilities provisions on the North Main Street site during startup operations ofr the initial six weeks. Consequently, a small DeVilbiss paint spray compressor was purchased in order to supply air during this period. The Phoenix Memorial Laboratory had building air supply which was used for experiments in that location. It is believed that the unit could be run more advantageously at 1 atmosphere pressure if the sizes of the lines were reviewed and increased where necessary to values which would permit backpressures within the limits of the type of metering equipment it would be desired to use. 3.7 Product-Handling System The let-down pot which received product from the reactor was a single section Penberthy alloy steel gauge glass. Gas was removed from the top of this gauge glass and sent through the trap and drier to a gas chromatography unit, where samples were taken and analyzed periodically. The remaining gas was vented through a system comprising provision for cold traps, provision for a gas sampling bulb, backflow traps water saturator, wet test meter, and a vent line which terminated in the roof in a flame arrestor and vent hood. Water was removed from the bottom of the separation pot through a manifold. This manifold included a solenoid valve for regulation of the water level within the let-down pot. However, the solenoid valve caused large surges in current whenever activated. These surges caused blips to appear on the gas chromatography chart whenever the valve was activated. Consequently, the valve was not employed during the majority of the operations because it was not desired to divert the necessary man-power to the alteration of the system. If desired, however, a valve such as a Skinner low pressure solenoid could be hooked directly to the level controller, possibly even without the use of an intermediate relay. Such a system would reduce the starting current from a solenoid valve. The valve employed was designed to open under 3,000 lbs/sq.in. pressure and consequently, had much heavier solenoids than were required for the job. The level regulator proper was a capacitance brid~ge known as a Therocap relay. This d~evice operated. on the signal of variable capacitance between a probe inserted into the bottom of the separation pot and the -17

pot itself. Fluid. within the pot influenced. this capacitance and. gave an ind~ex of liquid. level. The probe -was 1/4? copper tube, silver.-sold~ered. shut on the top end. and. surround~ed. by a 3/8" teflon rod.. Upon startup the capacitance between the probe and. the separation pot was so great that it was not possible to balance the instrument. In ord~er to red-uce the capacitance between probe and. ground., a small capacitor was inserted. in the series'in the line between the probe and. the capacitance brid~ge. The unit operated. quite satisfactorily then, except for the excessive starting current in the solenoid. valve as d~escribed. above. 3.8 Some Start-Up Consid~erations Before raw materials were charged. to the unit,, all parts were blown free with air in ord~er to remove scale, d~irt and. other gross contamnination. After removal of the large particulate contamination occurring as a result of construction, the entire system was flushed. with several gallons of acetone. The acetone removed. quantities of oil, grease, and. other foreign matter. The cleaning with acetone was continued. throughout the entire system until the acetone came out of the system as clean as it was charged.. Upon the conclusion of this cleaning operation, it was found. necessary to replace the seats in all of the Skinner solenoid. valves. These seats viere evid~ently of butyl rubber. The rubber may have belen attacked. by acetone to a much greater extent than it would. be normally by the liquid. butene. In any event,, neoprene plugs were cut and. used. to replace the butyl rubber inserts with which the valves were shipped..

4-i. 0 RESULTS OF EXPERIMENT1AL WORK The results of the experimental work are summarized. in Table I. Data and. calculated. results are presented.'in chronological ord~er of runs. It can be seen that the controls of temperature and. space velocity are subject to variation. Conversions varied. over a rather wid~e range., from low values approximating 5% to high values on the ord~er of 45%. Generally, conversions were in the range of 15-30%. Selectivities were usually in excess of 90%. Lower selectivities were,, almost without exception,, ind~icative of catalyst failure. The pressure of'operation was generally in the range of 3~-5 psig. These pressures are somewhat higher than those normally used. by Dow and. -were a consequence of the use of lines sized. for higher pressure operation and. hence, too small to pass desired. flow rates at atmospheric pressure. In all, six charges of catalyst we-re placed. in the reactor. Each charge was introd~uced. in ord~er to replace a batch which had. begun to function unsatisfactorily. Malfunctioning of the catalyst was ind~icated. in each case by greatly red~uced. conversions and. selectivities. The sixth charge of catalyst was still functioning satisfactorily at the conclusion of experimental work. Discharged. batches of catalyst were black in color near the bottom of the bed.. Flow of reactants was d~ownward. through the reactor. Usually the top of the bed. was nearly normal in color when:removed.. Incomplete burn-off of carbon was suspected. as a strongly contributing variable in causing catalyst to behave poorly. During the last few runs the burn-off gases were tested. for carbon d~ioxid~e by barium hyd~roxid~e solution. Generally a noticeable turbid~ity occurred. in about one to two minutes at the end. of the burn-off period.. Orsat analysis of the same stream using potassium hyd~roxid~e solution ind~icated. a maximum concentration of about 1% of carbon d~ioxid~e near the beginning of the burn-off Iperiod.. A record. of batches of catalyst used. and. irrad~iation to which these batches were subjected. is provided. in Table IIL The rate of catalyst failure reported. in Table II is consid~ered. to be excessive. As ind~icated. above, tests were cond~ucted. to assess the ad~equacy of burn-off proced~ures as one suspected. element in rate of catalyst failure. In ad~dition, analyses were mad~e of the AISI 4130 thermocouple well in the reactor. Nickel content of this thermowell was found. (i) by D. E. Harmer to be 0.1 + 0.01%, a level regard~ed. as too low to accelerate catalyst failure. No analysis was mad~e of the reactor vessel, which was AIsi 446 3/4" IPS sched~ule 80 pipe, purchased. from Rolled. Alloy, Inc.,, Detro -- I — t, -L Michigan.

TABLE I 1957 Pressure Hp20 %%o Date & Run Temp. 12 C4 3,V,'C4 Dose Rate* Conversion Select. March 25 -(First day of operation in Phoenix Laboratory) 325-lB -,,575 6. o 10.0 - - No Rad. n,2 5.0 _'10010 March 28.328-lB 653-658 4.0 4.0 272 18.6 No Raci. 37.0 95.0 — 328-2B 646 3.5 3.5 259 19.5 No Bad. 3.2.0 95.0 328-3B 650 - 267 19.0 No Bad. 33.0 95.0 328-4B 650 3.5 4.0 267 19.0 No Rad. 36.0 95.0 March 29 32941B 650 3.5 4.0 281 17.9 No Bad. 32.0 IV95.0 329-.2B 646 3.5 4.0 277 18.1 No Rad. 34.0 n 95.0 329-3B 647 3.5 4.0 294 17.1 No Rad. 35.0 u95.0 329-4B 646 3.5 4.0 277 18.1. No Rad. 34.0, 95.0 329-5B 645 3.5 4.2 300 16.7 No Rad. 35.0 -~95.0 April 1 401-lB 642-652 3.5 4.0 266 18.2 No Bad. 41.0 93.0 4ol-2B 650-655 3.3 4.o 255 18.7 No Rad. 38.0 93.0 4ol-3B 648-652 3.0 4.o 266 18.0 No Bad. 35.5 94.0 4ol-4B 648-651 3.0 4.o 261 18.2 No Bad. 35.0 94.0 401-5B 645-~652 3.0 4.o 260 18.9 No Bad. 35.0 94.0 April 2 402-lB 646-653 3.5 4.0 262 18.6 No Bad. 33.0 94.0 402-2B 644-65o 3.0 4.o 262 18.7 No Bad. 39.2 93.5 402-3B 642-649 3.0 4.o.255 20.2 No Bad. 41.0 94.0 402-5B 645-651 3.2 4.0 275 18.2 No Bad. 4o.4 92.0o NOTE: The runs were made with the source up, but reactor not over the well. April 3 403-lB 645-655 3.6 4.o 262 19.6 No Bad. 30.7 94.5 403-2B 648-654 3.5 4.o 270 18.9 No Bad. 37.7 86.0 4o3-3BB 634-645 3.2 4.0 262 19.6 6o 47.2 85.o April 4 4o4-lBR 3.5 4.o 263 19.5 6o Data 4o4-2BR 4.0 4.o 262 19.6 6o Unavailable 4o4-3BR - - 261 19.6 6o April 5 405-lB 6oo-65o S.0 S.0 240 21.3 No Bad. -0405r-2 625K Z -675C 4.5 4.5 28C n7 1 7. NoAT BaD. 16.849.

TABL I(Continued) 1957 Pressure H120 %% ~of Date & Run Teap. H20 C4 S.V. TT7 Dose Rate Conversion Select. May 2 502-lB 575-625 5.0 6.o 311 19.7 No Rad. 12.4 100.0 502-3B 550-575 -- -- 296 20.6 No RacI. 10.5 100.0 502-5B 580 4.7 4.8 288 21.2 No Raci. 9.9 100.0 502-7B 550-580 4.2 4.8 296- 20.6 No Bad.. 9.9 100.0 502-8B 570-580 4.5 5.0 278 22.0 No Raci. 10.0 100.0 502-9B 574-576 4.5 5.0 278 22.0 No Bad.. 7.9 100.0 Ma y 3 503-lB 550-575 4.5 4.5 294 21.0 No Bad.. 7.2 100.0 503 —2B 550-560 4.5 4.5 269 22.8 No Bad.. 7.5 100.0 May 6 506-lB 575-585 4.2 4.5 296 21.1 No Rad.. 9.7 100.0 5o6-3B 565-570 4.0 4.5 291 21.4 No Rad.. 8.6 100.0 506-5B 575 -0- -- 295 21.2 No Rad.. 8.9 100.0 506-6BR -,55o-6oo 4.2 4.6 302 20.6 6o -o0 - 506-8BR 57'5 4.o 4.5 300 20.7 6o 8.9 100.0 May 7 5 4 - 6 00 507-1BR 560-575 4..5 -- - o9.9 100 507..3BR 575-580 5.1 5.0 281 22.3 6o ( 5.0 100.0 507-5BIR 575-585 5.0 5.4 316 19.8 6o ( 5.0 100.0 507-6BR 575..585 —, - 313 20.0 6o ( 5.0 100.0 507..8BR 565-570 5.0 5.2 335 18.7 6o 6.5 100.0 507-9BR 565-570 5.0 5.2 335~ r 18.7 6o 10.0 100.0 May 8 508-1BR 59o-.6oo 4.5 5.0 280 22.4 6o 9.2 100.0 508-3BB 595-602 4.5 5.0O 327 19.2 6o -11.7 100.0 5o8-4BB 595-6oo 4.5 5.0.327 19.2 6o 12.2 100.0 May 9 509-1BR 593-7 4.3 5.6 325 19.3 6o 7.0 100.0 509-2BR 591-2 5.0 5.7 325, 19.3 6o 10.0 100.0 5oq-4BR 594 5.0 5.7 312 20.1 6o 11.4 100.0 509-6BR 598-603 4.5 5.7 305 20.4 6o 11.6 1oO.o 509-7B 596 5.0 5.6 310 20.2 No Baa. 11.5 100.0 May 10 510-1B 616-626 4.6 5.8 325 19.1 No Bad.. 9.4 100.0 510-3B% I' 621 S.I 71 5.7 298o -tn 19.8 No- Ra. 12. 100.0t ln

TABLE I (Continued) 1957 Pressure H20 lo %'of' Date & Run -Temp. H20 C)4 S.V.- r~ Pose Rate Conversion Select. May 13 513-1BR 616-19 4.o 5.5 291 21.4 6o 5.85 89.0 513-3BR 611-13 4.0 5.5 313 19.8 6o 13.6 100.0 513-5BR 615-19 4.o 5.7 320 19.5 6o 14.o 100.0 513-7B 650 4.0 5.7 317 19.7 No Radi. 16.5 100.0 513-9B, 647 4.5 5.7 320 19.5 No Raci. 16.6 100.0 May 14 514-lB 648.9 4.5 5.7 300 20.9 No Rad. 10.8 100.0 514.-3B 642 4.5 5.7 300 20.9 No Raci. 15.8 100.0 514-5B 645-6 4.2 5.7 328 19.0 No Rad. 16.7 100.0 51.4-7BR 646 4.2 5.7 318 20.0 6o 16.o 100.0 514.-9BR 5.0 5.7 Chart off' rollers 100.0 May 15 515-1BR 645-50 4.5 5.4 280 22.3 6o 9.3 100.0 515-3BR 649 5.0 5.7 334 18.8 6o 15.4 ioo.o 515-5BR 645-54 5.0 5.6 310 20.0 6o 12.5 100.0 May 16 516-lBR 645-55 4.2 5.6 290 21.0 6o 11.2 100.0 516-2BR 647-8 4.2 5.6 294 20.6 6o 12.3 100.0 516_4BR 648-9 4.2 5.6 318 19.4 6o 13.2 100.0 516-6BR 648-SoU 4.8 5.8 325 19.8 6o 13.0 100.0 516-8BR 645-6 5.0 5.8 325 19.8 6o 11.6 100.0 May 17 517-1BR 639-40 4.5 5.8 293 21.8 6o 9.4 100.0 517-3BR 638-45 4.s 5.8 304 20.4 60 12.4 100.0 517,5B 642-7 4.6 5.7 313 19.8 No Raci. 13.1 100.0 517-7B 645.6 4.4 5.7 310 20.1 No Radi. 12.9 100.0 517-83 645.6 4.5 5.7 327 19.1 No Raci. 13.8 100.0 May 20 520-lB 648-5o 4.5 5.0 278 22.8 No Raci. 20.0 100.0 520-3B 643-7 5.5 5.0 297 21.1 No Rad. 18.3 100.0 52o-43 645-8 4.8 5.1 310 20.3 No Radi. 17.0 100.0 520_4BT 650 4.8 5.1 310 20.3 No Rad.. 18.0 100.0 May 23 523-13, 54o-6o 4.5 6.o 266 23.2 No Radi. 27.1 97.4 523-3B 555-6o 4.5 6.5 311 20.0 No Rad.. 27.9 97.8 523-5B 545-50 4.5 6.5 295 21.8 No Rad.. 28.0 96.0 523-7B 620-25 3.0 6.5 295 21.8 No Ra d.. 28.4 97.0 523p-8B SSORS3 3.0 6. 300n 20.8 No Raci-T 3. 7 97.0

TABLE I (Continued) 1957 Pressure H20 % of Date & Run Temp. H20 C4 S.V.- -C Dose Rate Conversion Select., May 29 529-lB 520..70 - 315 19.9 No Rad. 12.5 6i-o 529-2B 565-95 -~30 1. oRd 405.0 June 5 605-2B 350-560 5.0 11.5 320 19.6 No Raci. 10.9 -0605-3B 550-605 5.0 10.5 310 20.2 No Raai. 18.0 -0.June. 11 611-1B 630o-64o 5.5 5.7 400 15.6 No Raci. 24.66 94.5 611-3B 64o-66o 5.2 5.4 265 25.2 No Rad.. 34.05 96.8 611-5BE, 570-660 5.5 6.5 291 21.7 300 31.2 92.5 611-6BE 665-695 6.o 6.5 365 17.3 300 36.3 93.5 June 12 612-1BR 570.-660 6.2 6.2 1 66 -~3 8. o 300 38.4 32.4 612-3BR 612-628 5.5 6.3 370 17.0 300 30.5 31.1 612-5BR 61o-65o 5.0 -- 425 14.8 300 50.0 -0612-6BR 630-655 3.2 6.9 386 16.3 300 19.1 62.0 June 13 612-1B 620-663 6.o 7.6 280 22.4 No Raci. 42.2 91.0 613-3B 635-650 6.o 6.o 361 17.3 No Raa.. 31.3 95.2 June 14 614-2B 641-645 4.1 6.o 308 20.5 No Rad.. 23.33 97.2 614-4BR 647-655 4.5 6.1 357 17.7 300 31.45 97.8 614-6BR 652-661 -- -- 374 16.9 300 32.25 97.0 614-7BR 646-654l' 5.2 6.6 323 19.6 304.5 98.0 614-9BR 645-652 4.5 6.4 308 20.5 300 29.0 -%100.0 614-11BR 65o-655 5.0 6.4 287 22.0 300 32.0 KLOO0.0 614-13BR 645-65o 4.1 6.4 294 21.5 300 22.3 ~-J00.0 June 17 617h1BR 615-625 -,5.0 -- 227 27.8 300 \14.1 617-3BR 646-653 ~-5.0 ~- 333 18.9 300 22.66 95.5 617-5iBR 646-655 5.0 5.8 335 18.8 300 23.16 95.8 617-7BR 651-657 5.0 6.2 338 18.6 300 20.0 98.0 June 1 8 618-lBR 620-30 5.5 6.o 240 26.2 300 14.o5 97.4 618-3BR 643-48 6.o 6.3 217 29.1 300 19.7' 97.4 618-5BR 64o-45 -- -- 248 25.4 300 19.36 97.7 618-,n -7BmR% -'.r 64-So% 4.5r -' 6.1 298 - 21. 300 19.8f' 07 97.7

TABLE I (Continued) 1957 Pressure 1120 %% of Date & Run Temp. H20 C4 S.V. -L4 Dose Rate Conversion Select. June 19 619-1BR 655-6o 3.5 6.o 300 21.0 300 16.o 98.5 June 2 0 62po-1BR 645-49 5.5 7.0 238 26.5 300 13.7 - 62o-2BR 64s5i5 4.5 6.8 304 20.7 300 18.0 62o-4BR 647r-49 4.8 6.9 288 21.8 300 19.3 620-5BR 640-50 -- - 300 20 300 21.0 620o.6B 646.49 4.5 6.9 325 19.4 No Rad~. 17.4 62o-8B 637-40 4.5 7.0 311 20.2 No Raci. 16.3 June 21 621-1BR 648-52,,4.5- 304 20.7 300 < 10.0 621-3B 655-57 4.5 -~315 20.0 No Rad.. 15.5 1%d00.0 621-5BR 647-53 4.5 -- 307 20.5 300 16.2 621-7B 648-52 4.5 ~- 316 19.9 No Raci. 16.9 621-9BR 644.47 4.2 6.9 317 19.8 300 15.7 621-loB 635-40 5.0 6.9 390 16.2 No Racd. 14.8 621-12BR 645-47 4.5 6.9 295 21.3 300 15.2 621-13B 64o-48 5.0 6.9 311 20.2 No Rad.. 16.2

TAB3LE ITI CONLDITIONS OF CATALYST USE Max. Rep in Air, Batch No. Pate Charged. Date Discharged. Hours of Rad~iation Thousand~s During With Reactor Runs Cold. 1 2.-7-57 4-9..57 2 4-lo-574225 3 t-22..5r7' 5%23-57 4 5-24-57 665 5 6-7..5y1 6-12-~57 8.25 None 2,500 None, 6 6413-57 Not Removed. 34 49- 10,000 15,1000 * Accurate log of cold. reactor irrad~iation kept only for batches 5 and. 6.

5.0 SUJNMARY AND CONCLUSIONS An experimental program was cond~ucted. comprising the -construction and. operation of required. pilot plant equipment to-investigate the d~ehy — d~rogenation of butene-.2 over Dow Ty-pe B catalyst in the presence of gamma rad~iation. Measurements of conversion and, selectivity to butad~iene-1.,3 were made.e, using gas chromatography as the analytical method.. Experimental cond~itions approximated. those of the usual ind~ustrial process for butad~iene-l,3 manufacture. Temperatures were 575.-6500C;* pressures ~were 3-5 psig; space velocities were 26O014OO standard. volumes of butene-2 per hour per volume of catalyst; steam to butene-2 ratios were 14.8 to 29.1; and. maximum rad~iation d~ose rates were 60,000 or 300,*000 rep per hour in air. Conversions were observed. to vary between 5.9 and. 51.8% of the butene charged.. Usual conversions were in the range of lO0.30%. Selectivities were generally in excess of 95%. Lower selectivities were generally accompanied. by low conversions,, poor temperature controlI on occasion by other operating abnormalities, and. were consid~ered. to provid~e sufficient reason to replace the catalyst. Preliminary ind~ications were that exposure to rad~iation accelerated. loss of catalyst activity. Howeverj, later work d~id. not support this view. On the basis of the data available from the experiments cond~ucted. und~er this program,, no effect of gamma irrad~iation could. be d~etected. upon the d~ehyd~rogenation of butene-.2 to butad~iene -1,3 over Dow Type B catalyst.

BIBLIOGRAPHY IvLS.-55.36, January 26, 1956.