USEFUL, LESS CHLORINATED ALKANES

The present invention relates generally to processes for converting chlorinated alkenes, and especially chlorinated alkenes produced as byproducts or waste products of useful chemical manufacturing processes, to useful or salable less chlorinated alkanes

United States Patents No 4,818,368 to Kalnes et al , 4,895,995 to James, Jr et al , 4,899,001 to Kalnes et al , and 5,013,424 to James, Jr et al are exemplary of the known art in broadly describing processes for the hydrogenation of halogenated hydrocarbons in the

• o presence of metal or mixed metal catalysts involving combinations of Group VIB and Group Vlll metals "Hydrogenation" in these patents is contemplated as including dehalogenation and olefin saturation in addition to other processes, such as desulfuπzation, denitπfication, oxygenate conversion and hydrocracking

Applicants' inventive processes provide for the catalytic conversion of chlorinated

₁ 5 alkenes, and especially chlorinated alkenes produced as byproducts or waste products in other chemical manufacturing processes, to reaction products including their corresponding, less- chlonnaied and useful or salable alkanes in commercially substantial proportions (that is, at yields (defined as the product of the conversion and the selectivity to a given alkane, on a hydrogen chloride- and hydrogen-free basis) of at least 10 percent, but more preferably at least

20 20 percent and most preferably at least 30 percent), in which a chlorinated alkene feedstock is reacted with hydrogen in the presence of a supported catalyst including a selected Group IB metal or metals in an elemental or compound form with a selected Group Vlll metal or metals, also in an elemental or compound form The desired alkane product(s) are then conventionally separated from other materials in the product stream, and may be further processed in a

25 conventional, known manner to be placed in condi tion for an appropriate use or for sale

"Less chlorinated", it should be noted, embraces still-chlorinated alkanes as well as alkanes having no remaining chlorine atoms associated therewith

Preferred catalysts for use in the present invention will consist essentially of one or more Group IB metals in elemental or compound form with one or more Group Vlll metals in

30 elemental or compound form on a support More highly preferred catalysts for these processes include only Group IB and Group Vlll metals on a support

Preferably platinum in elemental or compound form and gold or silver (with gold being generally preferred to silver) in elemental or compound form are included in the catalyst as Group Vlll and Group IB constituent materials, respectively More preferably, the Group Vlll

35 and Group IB metals will consist substantially entirely of platinum and gold or silver in their elemental or compound forms, and a most preferred catalyst will employ only platinum and gold or silver in their elemental or compound forms as the Group Vlll and Group IB metals Especially preferred is a supported bimetallic catalyst of gold and platinum

1 e proportions and amounts of the Group Vlll and Group IB metals in these preferred catalysts may vary depending on the particular alkene or alkenes involved, but in general terms, a selected Group IB metal (e g ,gold) can be from 0 01 to 20 percent by weight (on an elemental basis) of the catalyst, with a selected Group Vlll metal (e g .platinum) comprising from 0 01 to 5 0 percent by weight (also on an elemental basis) of the catalyst

More preferably, the Group IB metal will be from 0 05 to 15 percent by weight of the catalyst (on an elemental basis) and the Group Vlll metal from 0 03 to 3 0 percent by weight of the catalyst Most preferably, the Group IB metal can be from 0 1 to 10 percent by weight of the catalyst (on an elemental basis) and the Group Vlll metal from 0 05 to 1 0 percent by weight

10 of the catalyst

The support in each of these various catalysts can be any known, conventional support, but is preferably silica or carbon, with carbon being more preferred The carbon is preferably a high surface area carbon, for example, carbon having a specific surface area in an unimpregnated condition of 200 m^ g or more, especially 400 m /g or more, and most

! 5 especially 600 m ² /g or more An example of a commercially-available carbon which is considered to be of use in the present invention is a coal-based carbon produced by Calgon Carbon Corporation underthe designation "BPLF3" , and may generally be characterized as having a speci fic surface area of 1 100 m2/g to 1300 m^/g, a pore volume of 0 7 to 0 85 cm ³ /g, and an average pore radius of 12 3 to 14 angstroms Based on an X-ray fluorescence analysis of o this carbon, a typical bulk composition of the BPLF3 carbon has been determined to be as follows (by weight percent): silicon, 1.5 percent; aluminum, 1 4 percent, sulfur, 0 75 percent, iron, 0 48 percent, calcium, 0 17 percent; potassium, 0 086 percent, titanium, 0 059 percent, magnesium, 0 051 percent; chlorine, 0 028 percent; phosphorus, 0 026 percent; vanadium, 0 010 percent, nickel, 0 0036 percent; copper, 0 0035 percent, chromium, 0 0028 percent; and

25 manganese, 0 0018 percent (the remainder being carbon)

The reaction conditions which are preferred may again vary, depending for example on the particular catalyst and the particular chlorinated alkene feedstock involved, as well as on whether the process is to be conducted in the gas phase or in the liquid phase In general, however, reaction pressures for the gas phase processes can range from atmospheric

30 pressure up to 1500 psig ( 10 3 Pa (gauge)), with temperatures of from 100 deg C to 350 deg C , residence times of from 0 25 seconds to 180 seconds, and hydrogen/chlorinated alkene feed ratios ranging on a molar basis from 0 1 : 1 to 100 1 More preferably, reaction pressures will range from 5 psig (0 03 Pa (gauge)) to 500 psig (3 4 Pa (gauge)), with temperatures of from 180 deg C to 300 deg C , residence times of from 0 5 seconds to 120 seconds, and

35 hydrogen/chlorinated alkene feed ratios of from 0 5 1 to 20 1 Most preferably, reaction pressures for the gas phase processes will range from 40 psig (0 28 Pa (gauge)) to 300 psig (2 1 Pa (gauge)), with temperatures of from 200 deg C to 260 deg C , residence times of from 1 second to 90 seconds, and hydrogen/chlorinated alkene molar feed ratios of from 0 75 1 to 6. 1

In the liquid phase processes (which can be conducted in a batchwise or continuous manner of operation, as desired), it is anticipated that reaction pressures can range from atmospheric pressure up to 3000 psig (20 6 Pa (gauge)), at temperatures ranging from 25 degrees Celsius to 350 degree:. C iius, residence times ranging from one to 30 minutes, and hydrogen to chlorinated alkene molar feed ratios of from 0 1 : 1 to 100: 1.

It will also be preferred in the context of the various processes contemplated herein to employ hydrogen chloride in the feed to reduce coking and catalyst deactivation rates Preferably the rate of conversion loss in this regard is no more than about 0.03 percent per hour, and more preferably is no more than about 0 01 percent per hour Example 1

A bimetallic platinum/copper on carbon catalyst was prepared which contained 0 25 percent by weight on an elemental basis of platinum and 0.50 percent by weight of copper on Calgo BPLF3 activated carbon (6 x 16 mesh, Calgon Carbon Corp , Pittsburgh, Pa ) In making this catalyst, an aqueous H ₂ PtCI ₆ stock solution was prepared by dissolving H ₂ PtCl _t) 6H2θ (J T Baker, Inc.; Baker Analyzed Grade, 37 6 percent Pt) in deionized and distilled water An amount of CuCI ₂ (Aldnch Chemical Company, Inc , 99 999 percent purity) was placed in a 250 nriL Erlenmeyer flask, and an appropriate amount of the H ₂ PtCl5 stock solution added with swirling to dissolve the CuCI ₂ . The solution was then diluted with deionized, distilled water and swirled Calgon BPLF3 activated carbon was added to the flask, and the flask agitated rapidly so that the carbon carrier was evenly coated with the aqueous Pt/Cu solution The catalyst preparation was dried in an evaporating dish in air at ambient temperatures for 18 hours, and then further dried in an oven in air at 120 degrees Celsius for 2 hours.

After drying, the catalyst charge (0.6 grams) was placed in a tubular reactor (1/2 inch ( 1.27 cm) O D , 12 inches (30.6 cm) in length) located within an aluminum block heated by a cartridge heater and controlled via a computer, over a glass wool support contained in the center of the reactor tubing The catalyst was covered with a plug of glass wool and dried over a period of 8 to 24 hours at 150 degrees Celsius (using the chromatograph's temperature controller) under a nitrogen purge. The catalyst was thereafter reduced by passing hydrogen through the reactor at a flow rate of 34 mL minute for 24 hours, and the reactor temperature was lowered to the temperature setpoint of the particular catalyst run The reactor temperature and hydrogen gas flow were allowed to equilibrate for about 1 hour before the liquid feedstock flow was started into the apparatus

Thereafter a mixed feed containing, on a molar basis, 30 percent of 2- chloropropene, 30 percent each of trans- and cis-1-chloropropene, and 10 percent of 1 ,2- dichloropropane was pumped via a high pressure syringe pump through 1/16 inch ( 1 6 mm) (O D ) Monel '" nickel alloy tubing (unless specifically noted below all of the components, tubing and fittings of the test reactor apparatus were also made of Monel '" nickel alloy

(Huntington Alloys, Inco Alloys International, Inc )) into a packed sample cylinder serving as a feed evaporator

The 1/16th inch tubing extended almost to the center of the packed cylinder, which was heated to a vaporizing temperature of 180 degrees Celsius using electrical heat tracing Vaporization of the mixed organic feed was accomplished in the feed line, so that this feed was superheated when combined with the hydrogen feed stream Thermocouples were used to monitor the skin temperature of the feed evaporator and the temperature of the gas exiting the feed evaporator

The hydrogen feed stream was metered to a preheater using a Model 8249 linear

10 mass flow controller from Matheson Gas Products, Inc. Secaucus, N.J., with the preheater consisting of a packed sample cylinder wrapped with electrical heat tracing Thermocouples were used to monitor both the skin temperature of the preheater and the temperature of the gas exiting the preheater The preheater temperature was set at 140 degrees Celsius

Vaporized feed exiting the evaporator was mixed with the hydrogen gas (in an

15 1 1 7: 1 molar ratio of hydrogen to 2-chloropropene) from the preheater in a 2 foot (0 61 meter) long section of 1/4 inch (0 64 cm) tubing maintained at a temperature of 140 degrees Celsius. The mixed gases then were passed into and reacted within the above-described tubular reactor over a residence time of 2 9 seconds The reaction temperature was set at 220 degrees Celsius After reacting the feed and hydrogen in the gas phase in the tubular reactor thus

20 prepared, the products from the reaction were passed to a gas sampling valve, which provided gaseous aliquots for online gas chromatographic analysis in a Hewlett-Packard Model 5890 Series II gas chromatograph (Hewlett-Packard Company) The gas chromatograph was equipped with a flame ionization detector, and used 30 meter by 0.53 millimeter (I D ) 100 percent methyl silicone/fused silica and 30 meter by 0 53 millimeter (I.D.) porous polymer-lined

2 fused silica columns to separate the various reaction products

Response factors were conventionally determined by injections of gravimetπcally- prepared standards of the individual reaction products These response factors were applied in conjunction with individual peak areas and the total mols of ail reaction products to determine the mol percents of individual components in the reactor effluent, and the selectivity to

30 individual reaction products (in terms of mols of a given component produced per mol of feedstock converted, multiplied by 100).

Analysis of the reaction products under the conditions indicated above showed a 98 percent conversion of the incoming 2-chloropropene, with 98, 93 and 100 percent of the cis-1-chloropropene, t-1 -chloroρropene

35 and 1 ,2-dιchloropropane being converted, respectively Selectivities to propylene and propane were each at 49 percent, with the balance being miscellaneous hydrocarbons

Example 2

The methods and apparatus of Example 1 were employed for converting tπchloroethylene to reaction products including ethane over a catalyst of 0.24 percent by weight of platinum and 1.37 percent by weight of gold on the BPLF3 carbon support The catalyst was prepared from a solution of H ₂ PtCI ₆ H ₂ 0 and HAuCI ₄ H 0 in water, and to which the BPLF3 carbon had been added The catalyst was then charged, dried and reduced as in Example 1

At a reaction temperature of 235 degrees Celsius, a pressure of 76 psig (0 52 Pa (gauge)), a 4 9 second residence time, and a molar feed ratio of hydrogen to vaporized o tπchloroethylene of 2.75, there was a 75 percent conversion of tnchloroethylene to reaction products including ethane at 80 percent selectivity, ethylene ( 16 percent selectivity), cιs- 1 ,2- dichloroethylene (2 percent) and vinyl chloride, ethyl chloride, viny dene chloride, trans-1 ,2- dichloroethylene and 1 ,2-dιchloroethane (or EDC) at less than 1 percent total Ethane yield under these conditions was thus 60 percent, or (75 x 80)/100 5 Example 3

The same catalyst, procedures and apparatus were used as in Example 2, but at a reaction temperature of 235 degrees Celsius, a pressure of 76 psig (0 52 Pa (gauge)), a residence time of 4 9 seconds and a molar feed ratio of hydrogen to trichloroethylene of 5 5 After 23 hours on line, trichloroethylene conversion was at 93 percent, with ethane being produced o therefrom at a selectivity of 96 percent, ethylene at 2 percent, cis-1 ,2-dichloroethylene at 0.5 percent, and vinyl chloride and the other minor products of Example 1 being produced at a selectivity of less than 0.5 percent The ethane yield under the conditions of this Example was (after 23 hours on-line) accordingly 89 3 percent (93 x 96)/100

While various embodiments of the processes and catalysts of the present 5 invention have been described and/or exemplified herein, those skilled in the art will readily appreciate that numerous changes can be made thereto which are nevertheless properly considered to be within the scope or spirit of the present invention as more particularly defined by the claims below

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