Simultaneous hydrodehalogenation of two streams containing halogenated organic compounds

Abstract: A first feedstock comprising unsaturated, halogenated organic compounds and a second feedstock comprising saturated, halogenated organic compounds are simultaneously hydrodehalogenated by reacting the first feedstock with hydrogen at hydrogenation conditions selected to minimize the polymerization of unsaturated organic compounds and to produce a first effluent stream; thereafter reacting at least a portion of said first effluent stream and said second feedstock with hydrogen at hydrogenation conditions selected to produce a second effluent stream comprising hydrocarbonaceous compounds and to generate at least one water-soluble inorganic halide compound; and recovering a hydrogen-rich gaseous stream, a hydrogenated stream comprising hydrocarbonaceous compounds and said water-soluble inorganic halide compound from the second effluent stream.

Description: The field of art to which this invention pertains is the simultaneous production of a hydrogenated hydrocarbonaceous product stream from an unsaturated, halogenated organic feed stream and a saturated, halogenated organic feed stream. BACKGROUND OF THE INVENTION There is a steadily increasing demand for technology which is capable of the simultaneous hydroconversion of a first feedstock comprising olefinic, halogenated organic compounds and a second feedstock comprising saturated halogenated organic compounds. Previous techniques utilized to dispose of such feedstocks which are often undesirable by-products of other processes such as epichlorohydrin production, for example, have frequently become environmentally unpopular or illegal and, in general, have always been expensive. With the increased environmental emphasis for the treatment and recycle of chlorinated organic products, there is an increased need for the conversion of these products in the event that they become unwanted or undesirable. For example, during the disposal or recycle of potentially environmentally harmful halogenated organic waste streams, an important step in the total solution to the problem is the conditioning of the halogenated organic stream which facilitates the ultimate resolution to provide product streams which may be handled in an environmentally acceptable manner. Therefore, those skilled in the art have sought to find feasible techniques to hydroconvert unsaturated and saturated halogenated organic compounds to provide hydrocarbonaceous product streams which may be safely and usefully employed or recycled. Previous techniques which have been employed include incineration which in addition to potential pollution consideration fails to recover valuable hydrocarbonaceous materials. In US-A-3133013, a process is disclosed which relates to the hydrorefining of hydrocarbons for the purpose of removing diverse contaminants therefrom and/or reacting such hydrocarbons to improve the chemical and physical characteristics thereof. In addition, the process is directed toward the selective hydrogenation of unsaturated, coke-forming hydrocarbons through the use of particular conditions whereby the information of coke, otherwise resulting from the hydrorefining of such hydrocarbon fractions and distillates, is effectively inhibited. DD-A-105194 discloses a process for converting hydrocarbon chlorides into chlorine-free hydrocarbons, by reaction in the gaseous phase, in the presence of hydrogen and a rhodium-containing catalyst, at a temperature of 50 to 500°C. The reaction described in DD-A-105194 does not essentially involve saturation of unsaturated compounds: indeed, depending on conditions, a saturated starting material may given an unsaturated product. The present invention provides an improved process for the production of a hydrogenated hydrocarbonaceous product from an unsaturated, halogenated organic feed and a saturated, halogenated organic feed by means of contacting the unsaturated organic feed in a first hydrogenation reaction zone at hydrogenation conditions selected to saturate the feedstock with hydrogen while minimizing the polymerization of the unsaturated halogenated organic compounds and to contact the effluent from the first hydrogenation zone and the saturated, halogenated organic feed in a second hydrogenation reaction zone at hydrogenation conditions to produce a hydrogenated saturated hydrocarbonaceous product and at least one water-soluble inorganic halide compound. Important elements of the process are the integrated hydrogenation reaction zones which reduce capital and utility costs, and the elimination or at least the minimization of the polymerization of unsaturated halogenated organic compounds which prevents excessive buildup of carbonaceous deposits in the processing equipment and in the catalyst, improves the recovery of inorganic halide compounds and maximizes the quantity of hydrogenated hydrocarbonaceous product. More specifically, the present invention provides a process for the simultaneous hydrodehalogenation of a first feedstock containing unsaturated, halogenated organic compounds and a second feedstock containing saturated, halogenated organic compounds which process comprises: (a) reacting said first feedstock with hydrogen in a first reaction zone operated at a pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge), a maximum catalyst temperature from 122°F (50°C) to 650°F (343°C) and a hydrogen circulation from 200 SCFB (33.7 normal m³/m³) to 100,000 SCFB (16851 normal m³/m³) said hydrogenation conditions being selected to minimize the polymerization of unsaturated organic compounds and to produce a first effluent stream of saturated hydrocarbonaceous compounds; (b) reacting said first effluent stream and said second feedstock with hydrogen in a second reaction zone operated at a pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge), a maximum catalyst temperature from 122°F (50°C) to 850°F (454°C) and a hydrogen circulation rate from 200 SCFB (33.7 normal m³/m 3) to 50,000 SCFB (8427 normal m³/m³), at hydrogenation conditions which are more severe than those in step (a) selected to dehalogenate said feedstocks and to produce a second effluent stream of saturated hydrocarbonaceous compounds, unreacted hydrogen and a water-soluble hydrogen halide compound; and: (c) recovering a hydrogen-rich gaseous stream, a hydrogenated stream comprising hydrocarbonaceous compounds and said water-soluble hydrogen halide compound from the second effluent stream. In one embodiment said second effluent steam is contacted (in step (c)) with halide-lean aqueous scrubbing solution to produce the hydrogenated stream comprising hydrocarbonaceous compounds and a halide-rich aqueous scrubbing solution containing at least a portion of said water-soluble hydrogen halide compound. Advantageously, (c) can comprise the sub-steps of: (a) contacting the second effluent stream from said hydrogenation zone with a first halide-lean absorber solution in an adsorption zone. (b) withdrawing a halide-rich absorber extract solution containing at least a portion of said water-soluble hydrogen halide compound from said adsorption zone (c) withdrawing a raffinate stream comprising hydrogenated hydrocarbonaceous compounds, residual trace quantities of halogenated organic compounds and a hydrogen-rich gas from said adsorption zone (d) introducing said raffinate stream recovered in step (c) into a third reaction zone operated at hydrogenation conditions selected to hydrogenate essentially all of said residual trace quantities of halogenated organic compounds to produce a third effluent stream comprising hydrocarbonaceous compounds and at least one water-soluble hydrogen halide compound; (e) contacting said third effluent stream with a second halide-lean aqueous scrubbing solution and (f) introducing a resultant admixture from sub-step (e) into a separation zone to provide said hydrogen-rich gaseous steam, said hydrogenated stream comprising hydrocarbonaceous compounds, and a halide rich aqueous scrubbing solution containing at least a portion of the water-soluble hydrogen halide compound produced in sub-step (d). If desired, at least a portion of said hydrogen-rich gaseous stream (18) recovered in step (c) is recycled to step (a). The drawing is a simplified process flow diagram of a preferred embodiment of the present invention. The present invention provides an improved integrated process for the simultaneous hydroconversion of a first feedstock comprising unsaturated, halogenated organic compounds and a second feedstock comprising saturated, halogenated organic compounds. A wide variety of halogenated organic compounds, both unsaturated and saturated, are candidates for feed streams in accordance with the process of the present invention. Examples of organic streams comprising halogenated organic compounds which are suitable for treatment by the process of the present invention are dielectric fluids, hydraulic fluids, heat transfer fluids, used lubricating oil, used cutting oils, used solvents, halogenated hydrocarbonaceous by-products, oils contaminated with polychlorinated biphenyls (PCB), halogenated wastes, petrochemical by-products and other halogenated hydrocarbonaceous industrial wastes. Often, in a particular place or location, two or more halogenated organic streams are present and require further treatment. It has now been discovered that unsaturated halogenated organic compounds present a greater challenge for subsequent processing such as hydrogenation as compared with the saturated halogenated organic compounds. When both types of halogenated organic streams are present, they may readily be processed in the integrated hydrodehalogenation process of the present invention. The halogenated organic feed streams which are contemplated for use in the present invention may also contain organic compounds which include sulfur, oxygen, nitrogen or metal components which may be simultaneously hydrogenated to remove or convert such components as desired. The halogenated organic compounds may also contain hydrogen and are therefore then referred to as hydrocarbonaceous compounds. Preferred first feedstocks containing unsaturated, halogenated organic compounds are: fractionation column bottoms formed in the production of allyl chloride, fractionation column bottoms formed in the production of ethylene dichloride, fractionation column bottoms formed in the production of trichloroethylene and perchloroethylene, used dielectric fluid containing polychlorinated biphenyls (PCB) and chlorinated benzene, used chlorinated solvents, and mixtures thereof. Preferred second feedstocks containing saturated, halogenated organic compounds are: fractionation bottoms from the purification column in epichlorohydrin production, carbon tetrachloride, 1,1,1 trichloroethane, chlorinated alcohols, chlorinated ethers, chlorofluorocarbons and mixtures thereof. The halogenated organic compounds which are contemplated as feedstocks in the present invention preferably contain a halogen selected from the group consisting of chlorine and fluorine. In accordance with the present invention, a feedstock comprising unsaturated, halogenated organic compounds is introduced in admixture with a hydrogen-rich gaseous stream into a catalytic hydrogenation zone containing hydrogenation catalyst and maintained at mild hydrogenation conditions. This catalytic hydrogenation zone may contain a fixed, ebullated or fluidized catalyst bed. This reaction zone is maintained at mild conditions which are chosen to selectively saturate unsaturated organic compounds such as olefins, for example, while simultaneously preventing the formation of polymers or higher molecular weight carbonaceous material. The reaction zone conditions include an imposed pressure from atmospheric (0 kPa gauge) to 2,000 psig (13790 kPa gauge) and preferably a pressure 100 psig (689.5 kPa gauge) to 1800 psig (12411 kPa gauge). The reaction is conducted with a maximum catalyst bed temperature in the range of 122°F (50°C) to 650°F (343°C) selected to perform the desired saturation of unsaturated organic compounds in order to reduce or eliminate the propensity of the unsaturated feed stream to form polymers and gum which are undesirable for further use or processing of the resulting hydrocarbonaceous stream. Although the primary function of this hydrogenation zone is used to saturate the unsaturated halogenated organic charge stream, it is also contemplated in accordance with the present invention that the desired hydrogenation conversion may also include, for example, dehalogenation, desulfurization, denitrification, oxygenate conversion and hydrocracking. Further preferred operating conditions include liquid hourly space velocities in the range from 0.05 hour⁻¹ to 20 hr⁻¹. The hydrogen circulation rate is from 200 standard cubic feet per barrel (SCFB) (33.71 normal m³/m³) to 100,000 SCFB (16851 normal m³/m³), preferably from 300 SCFB (50.6 normal m³/m³) to 50,000 SCFB (8427 normal m³/m³). The resulting effluent stream from the first hydrogenation reaction zone is admixed with the saturated, halogenated organic feed stream without intermediate separation thereof and the resulting admixture is introduced into a second catalytic hydrogenation zone containing hydrogenation catalyst and maintained at hydrogenation conditions. This second catalytic hydrogenation zone may contain a fixed, ebullated or fluidized catalyst bed. The operating conditions selected for this catalytic hydrogenation zone are selected primarily to dehalogenate the halogenated organic compounds which are introduced thereto and these operating conditions are more severe, i.e., promote greater hydrogenation than the operating conditions utilized in the first catalytic hydrogenation zone. This second catalytic hydrogenation zone is maintained under an imposed pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge) and preferably under a pressure from 100 psig (689.5 kPa gauge) to 1800 psig (12411 kPa gauge). The reaction is conducted with a maximum catalyst bed temperature in the range of 122°F (50°C) to 850°F (454°C) selected to perform the desired hydrogenation and dehalogenation conversion to reduce or eliminate the concentration of halogenated organic compounds contained in the combined feed stream. In accordance with the present invention, it is contemplated that the desired hydrogenation conversion includes, for example, dehalogenation, desulfurization, denitrification, olefin saturation, oxygenate conversion and hydrocracking. Further preferred operating conditions include liquid hours space velocities in the range from 0.05 hr.⁻¹ to 20 hr.⁻¹ The hydrogen circulation rate is from 200 SCFB (33.71 normal m³/m³) 100,000 SCFB (16851 normal m³/m³), preferably from 200 SCFB (33.71 normal m³/m³) to 50,000 SCFB (8427 normal m³/m³). In the event that the temperature of the combined halogen-containing, organic feed stream which is introduced into the second hydrogenation reaction zone is not deemed to be exactly the temperature selected to operate the second catalytic hydrogenation zone, it is contemplated that the temperature of the feed stream to be introduced into the hydrogenation zone may be adjusted either upward or downward in order to achieve the desired temperature in the catalytic hydrogenation zone. Such a temperature adjustment may be accomplished, for example, by either indirect heat exchange or by the addition of either cool or hot hydrogen. The hydrogen-rich gaseous stream which is recovered from the effluent from the second hydrogenation zone may be recycled to the first and/or the second hydrogenation zone. The first and/or the second hydrogenation zone may contain one or more catalyst beds. The preferred catalytic composites disposed within any of the reaction zones of the present invention can be characterized as containing a metallic component having hydrogenation activity, which component is combined with a suitable refractory inorganic oxide carrier material of either synthetic or natural origin. The precise composition and method of manufacturing the carrier material is not considered essential to the present invention. Preferred carrier materials are alumina, silica, carbon and mixtures thereof. Suitable metallic components having hydrogenation activity are those selected from the group comprising the metals of Groups VI-B and VIII of the Periodic Table, as set forth in the Periodic Table of the Elements , E. H. Sargent and Company, 1964. Thus, the catalytic composites may comprise one or more metallic components from the group of molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, palladium, iridium, osmium, rhodium, ruthenium, and mixtures thereof. The concentration of the catalytically active metallic component, or components, is primarily dependent upon a particular metal as well as the physical and/or chemical characteristics of the particular hydrocarbon feedstock. For example, the metallic components of Group VI-B are generally present in an amount within the range of from 1 to 20 weight percent, the iron-group metals in an amount within the range of 0.2 to 10 weight percent, whereas the noble metals of Group VIII are preferably present in an amount within the range of from 0.2 to 5 weight percent, all of which are calculated as if these components existed within the catalytic composite in the elemental state. It is further contemplated that hydrogenation catalytic composites may comprise one or more of the following components: cesium, francium, lithium, potassium, rubidium, sodium, copper, gold, silver, cadmium, mercury and zinc. The hydrocarbonaceous effluent from the second hydrogenation zone is preferably contacted in one embodiment with an aqueous scrubbing solution and the admixture is admitted to a separation zone in order to separate a halide-rich aqueous stream, a hydrogenated hydrocarbonaceous liquid phase and a hydrogen-rich gaseous phase. The contact of the hydrocarbonaceous effluent from the second hydrogenation zone with the aqueous scrubbing solution may be performed in any convenient manner and is preferably conducted by co-current, in-line mixing which may be promoted by inherent turbulence, mixing orifices or any other suitable mixing means. The aqueous scrubbing solution is preferably introduced in an amount from 1 to 100 volume percent of the total feedstock charged to the second hydrogenation zone based on the composition of the effluent from the second hydrogenation zone. The aqueous scrubbing solution is selected depending on the characteristics of the organic feed stream introduced into the second hydrogenation zone. In accordance with the present invention, at least some halogenated organic compounds are introduced as feedstock and therefore the aqueous scrubbing solution in one embodiment preferably contains a basic compound such as calcium hydroxide, potassium hydroxide or sodium hydroxide in order to neutralize the acid such as hydrogen chloride, hydrogen bromide and hydrogen fluoride, for example, which is formed during the hydrogenation of the halogen compounds. In another preferred embodiment, the halide compound is recovered by dissolution in water or a lean aqueous solution of the halide compound. This embodiment permits the subsequent recovery and use of a desirable and valuable halide compound. The final selection of the aqueous scrubbing solution is dependent upon the particular halide compounds which are present and the desired end product. The resulting hydrogenated hydrocarbonaceous liquid phase is recovered and the hydrogen-rich gaseous phase may be recycled to the hydrogenation zones if desired. The resulting hydrogenated hydrocarbonaceous liquid phase is preferably recovered in one embodiment from the hydrogen-rich gaseous phase in a separation zone which is maintained at essentially the same pressure as the second hydrogenation reaction zone and as a consequence contains dissolved hydrogen and low molecular weight normally gaseous hydrocarbons if present. In accordance with the present invention, it is preferred that the hydrogenated hydrocarbonaceous liquid phase comprising the hereinabove mentioned gases be stabilized in a convenient manner, such as, for example, by stripping or flashing to remove the normally gaseous components to provide a stable hydrogenated distillable hydrocarbonaceous product. In some cases, it is contemplated that a significant portion of the hydrogenated hydrocarbonaceous product may comprise methane, ethane, propane, butane, hexane and admixtures thereof. An adsorbent/stripper arrangement may conveniently be used to recover methane and ethane. Fractionation may conveniently be used to produce purified product streams such as liquid propane or LPG containing propane and butane. In accordance with one embodiment of the present invention, the hydrocarbonaceous effluent containing at least one water-soluble hydrogen halide from the second hydrogenation zone is contacted with an absorber solution to recover the hydrogen halide and to provide a hydrogenated hydrocarbonaceous liquid phase and a hydrogen-rich gaseous phase. The contact of the hydrocarbonaceous effluent from the second hydrogenation zone with the absorber solution may be performed in any convenient manner and in one embodiment is preferably conducted by a countercurrent contacting of the hydrocarbonaceous effluent with water or a lean absorber solution in a absorber or an absorption zone. An extract solution rich in hydrogen halide is then recovered from the absorber and may be used as recovered or may be regenerated to provide a lean absorber solution which may be recycled to the absorber to accept additional hydrogen halide. The absorber solution is preferably introduced into the absorber in an amount from 1 to 20 times the mass flow rate of the total feedstock charged to the second hydrogenation zone based on the composition of the effluent from the second hydrogenation zone. The absorber is preferably operated at conditions which include a temperature from 122°F (50°C) to 221°F (105°C) and a pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge). The absorber is preferably operated at essentially the same pressure as the second hydrogenation zone subject to fluid flow pressure drop. The absorber solution is selected depending on the characteristics of the organic feed stream introduced into the second hydrogenation zone. In accordance with the present invention, at least some halogenated organic compounds are introduced as feedstock and therefore the absorber solution preferably contains water or a lean absorber solution containing a water-soluble hydrogen halide. The resulting raffinate effluent from the absorber containing hydrogenated hydrocarbonaceous liquid phase and a hydrogen-rich gaseous phase is recovered and separated in a vapor-liquid separator. The hydrogen-rich gaseous phase which is recovered and separated may be recycled to the hydrogenation zones if desired. In a preferred embodiment of the present invention, the resulting raffinate effluent from the absorber containing hydrogenated hydrocarbonaceous liquid phase and a hydrogen-rich gaseous phase is recovered and introduced into a third catalytic hydrogenation zone containing hydrogenation catalyst and maintained at hydrogenation conditions. This third catalytic hydrogenation zone may contain a fixed, ebullated or fluidized catalyst bed. The operating conditions for this catalytic hydrogenation zone are selected to convert by hydrogenation the residual trace quantities of halogenated organic compounds. The operating conditions selected for this catalytic hydrogenation zone are selected primarily to dehalogenate the trace quantities of halogenated organic compounds which are introduced thereto and these operating conditions are selected to convert these trace quantities. This third catalytic hydrogenation zone is preferably maintained under an imposed pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge) and more preferably under a pressure from 100 psig (689.5 kPa gauge) to 1800 psig (12411 kPa gauge). Suitably, such reaction is conducted with a maximum catalyst bed temperature in the range of 122°F (50°C) to 50°F (454°C) selected to perform the desired hydrogenation and dehalogenation conversion to reduce or eliminate the trace concentration of halogenated organic compounds contained in the combined feed stream. Further preferred operating conditions include liquid hourly space velocities in the range from 0.05 hr.⁻¹ to 20 hr.⁻¹ and hydrogen circulation rates from 200 SCFB (33.71 normal m³/m³) to 500,000 SCFB (84255 normal m³/m³), preferably from 200 SCFB (33.71 normal m³/m³) to 100,000 SCFB (16853 normal m³/m³). In the event that the temperature of the combined halogen-containing, organic feed stream which is introduced into the third hydrogenation reaction zone is not deemed to be exactly the temperature selected to operate the third catalytic hydrogenation zone, it is contemplated that the temperature of the feed stream to be introduced into the third hydrogenation zone may be adjusted upward in order to achieve the desired temperature in the catalytic hydrogenation zone. The resulting effluent from the third catalytic hydrogenation zone containing hydrogenated hydrocarbonaceous compounds and hydrogen-rich gaseous phase is contacted with an aqueous scrubbing solution, is cooled and is introduced into a vapor-liquid separator. The contact of the effluent from the third catalytic hydrogenation zone with the aqueous scrubbing solution may be performed in any convenient manner and is preferably conducted by co-current, in-line mixing which may be promoted by inherent turbulence, mixing orifices or any other suitable mixing means. The aqueous scrubbing solution is preferably introduced in an amount from 1 to 100 volume percent of the total feedstock to the third hydrogenation zone. The aqueous scrubbing solution is selected depending on the characteristics of the organic feed stream introduced into the third hydrogenation zone. In accordance with the present invention, at least some halogenated organic compounds are introduced as feedstock and therefore the aqueous scrubbing solution preferably contains a basic compound such as calcium hydroxide, potassium hydroxide or sodium hydroxide in order to neutralize the hydrogen halide acid which is formed during the hydrogenation of the halogen compounds. The hydrogen-rich gaseous stream which is recovered from the effluent from the third hydrogenation zone may be recycled to the first, second and/or third hydrogenation zone. In the embodiment utilizing a third hydrogenation zone, the resulting hydrogenated hydrocarbonaceous liquid phase which preferably comprises less than about 0.1% of the halogenated organic compounds processed is preferably recovered from the hydrogen-rich gaseous phase in a separation zone which is maintained at essentially the same pressure as the third hydrogenation zone and, as a consequence, contains dissolved hydrogen and low molecular weight normally gaseous hydrocarbons if present. In accordance with the present invention, it is preferred that the hydrogenated hydrocarbonaceous liquid phase comprising the hereinabove mentioned gases be stabilized in a convenient manner, such as, for example, by stripping or flashing to remove the normally gaseous components to provide a stable hydrogenated distillable hydrocarbonaceous product as described hereinabove. In the drawing, the process of the present invention is illustrated by means of a simplified flow diagram in which well-known details have been deleted as being non-essential to an understanding of the techniques involved. With reference now to the drawing, the unsaturated halogenated organic first feed stream is introduced into the process via conduit 1 and is contacted with a hydrogen-rich gaseous recycle stream which is provided via conduit 18. The mixture of the first feed stream and the hydrogen-rich gaseous recycle stream are introduced into hydrogenation reaction zone 2. The resulting hydrogenated organic stream is removed from hydrogenation reaction zone 2 via conduit 3, is admixed with the second feed stream comprising saturated, halogenated organic compounds introduced via conduit 4, and is introduced into hydrogenation reaction zone 5 without intermediate separation thereof. The resulting hydrogenated hydrocarbonaceous stream is removed from hydrogenation reaction zone 5 via conduit 6, is cooled in heat exchanger 7 and introduced into absorber 8 via conduit 6. The hydrocarbonaceous stream is contacted in a countercurrent flow with a first halide-lean absorber solution which is introduced via conduit 9. A halide-rich absorber extract solution is removed from absorber 8 via conduit 10. A raffinate stream containing hydrogenated hydrocarbonaceous compounds is removed from absorber 8 via conduit 11, is passed via conduit 11 into heat exchanger 12 for heating and is subsequently passed via conduit 11 into hydrogenation reaction zone 13. The resulting hydrogenated hydrocarbonaceous stream is removed from hydrogenation reaction zone 13 via conduit 14 and is contacted with an alkaline scrubbing solution introduced via conduit 15. The resulting admixture of scrubbing solution and hydrogenated hydrocarbonaceous stream is cooled in heat exchanger 16 and introduced via conduit 14 into high pressure vapor/liquid separator 17. A hydrogen-rich gaseous stream is removed from high pressure vapor/liquid separator 17 via conduit 18 and recycled as described hereinabove. Since hydrogen is lost in the process by means of a portion of the hydrogen being dissolved in the exiting liquid hydrocarbon and hydrogen being consumed during the hydrogenation reaction, it is necessary to supplement the hydrogen-rich gaseous stream with make-up hydrogen from some suitable external source, for example, a catalytic reforming unit or a hydrogen plant. Make-up hydrogen may be introduced into the system at any convenient and suitable point, and is introduced in the drawing via conduit 19. A spent aqueous scrubbing solution is removed from high pressure vapor/liquid separator 17 via conduit 20. A liquid hydrogenated hydrocarbonaceous stream comprising hydrogen in solution is removed from high pressure vapor/liquid separator 17 via conduit 21 and is introduced into low pressure vapor/liquid separator 22. A gaseous stream comprising hydrogen and any normally gaseous hydrocarbons present is removed from low pressure vapor/liquid separator 22 via conduit 23 and recovered. A normally liquid distillable hydrogenated hydrocarbonaceous product is removed from low pressure vapor/liquid separator 22 via conduit 24 and recovered. In the event that the liquid distillable hydrogenated hydrocarbonaceous product removed via conduit 24 is propane, for example, and is therefore not accurately described as normally liquid, the low pressure vapor/liquid separator 22 may be necessarily operated at a pressure in the range from 300 psig (2068 kPa gauge) to 500 psig (3447 kPa gauge). In the event that the feed stream contains water, this water is recovered from absorber 8 via conduit 10 together with the halide-rich absorber solution as hereinabove described. EXAMPLE An unsaturated, halogenated organic feedstock having the characteristics presented in Table 1 was charged at a rate of 68 mass units per hour to a first hydrogenation zone containing a palladium on alumina catalyst which was conducted at hydrogenation conditions which included a temperature of 176°F (80°C), a pressure of 750 psig (5171 kPa gauge) and a hydrogen circulation rate of 50,000 SCFB (8427 normal m³/m³). Unsaturated, Halogenated Hydrocarbonaceous Feedstock Properties Specific Gravity @60°F (15°C) 1.1955 Distillation, °C IBP 94 5 97 10 98 50 102 90 113 95 130 EP 134 % Over 97 % Residue 3 Composition, Weight Percent Chlorinated Propenes 64.7 Chlorinated Propane 26.8 Chlorinated Alcohols 0 Chlorinated Ethers 0 Chlorinated Hexadiene 0.7 Chlorinated Hexane - Chlorinated Benzene 0.2 Other 7.6 The resulting effluent from the first hydrogenation zone and a saturated, halogenated organic feedstock having the characteristics presented in Table 2 in an amount of 102 mass units per hour was charged to a second hydrogenation reaction zone containing a palladium on alumina catalyst which was conducted at hydrogenation conditions which included a temperature of 600°F (315°C), a pressure of 750 psig (5171 kPa gauge) and a hydrogen circulation rate of 25,000 SCFB (4213 normal m³/m³). Saturated, Halogenated Hydrocarbonaceous Feedstock Properties Specific Gravity @60°F (15°C) 1.3824 Distillation, °C IBP 96 5 119 10 132 50 156 90 252 95 258 EP 259 % Over 96 % Residue 4 Composition, Weight Percent Chlorinated Propenes - Chlorinated Propane 49.8 Chlorinated Alcohols 12.1 Chlorinated Ethers 31.1 Chlorinated Hexadiene - Chlorinated Hexane 3.4 Chlorinated Benzene - Other 3.6 The resulting effluent from the second hydrogenation reaction zone was contacted with a halide-lean absorber solution to recover 65 mass units of hydrogen chloride and was found to contain 38 mass units of hydrocarbonaceous compounds containing trace quantities of less than 1 mass unit of chlorinated propane. The resulting scrubbed effluent from the second hydrogenation zone was charged to a third hydrogenation reaction zone containing a palladium on alumina catalyst which was conducted at hydrogenation conditions which included a temperature of 400°F (204°C), a pressure of 750 psig (5171 kpa gauge) and a hydrogen circulation rate of 68,000 SCFB (11,460 normal m³/m³). The resulting effluent from the third hydrogenation reaction zone was neutralized with an aqueous solution containing potassium hydroxide and was found to contain about 38 mass units of hydrocarbonaceous products having the characteristics presented in Table 3 and containing less than 0.1 mass unit of halogenated organic compounds. Hydrocarbonaceous Product Stream Properties Composition, Weight Percent Ethane 0.3 Propane 96.6 Butane Trace Pentane 0.0 Hexane and Nonane 3.1 100.0

Claims: A process for the simultaneous hydrodehalogenation of a first feedstock (1) containing unsaturated, halogenated organic compounds and a second feedstock (4) containing saturated, halogenated organic compounds which process comprises: (a) reacting said first feedstock (1) with hydrogen in a first reaction zone (2) operated at a pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge), a maximum catalyst temperature from 122°F (50°C) to 650°F (343°C) and a hydrogen circulation from 200 SCFB (33.7 normal m³/m³) to 100,000 SCFB (16851 normal m³/m³), said hydrogenation conditions being selected to minimize the polymerization of unsaturated organic compounds and to produce a first effluent stream (3) of saturated hydrocarbonaceous compounds; (b) reacting said first effluent stream (3) and said second feedstock (4) with hydrogen in a second reaction zone (5) operated at a pressure from atmospheric (0 kPa gauge) to 2000 psig (13790 kPa gauge), a maximum catalyst temperature from 122°F (50°C) to 850°F (454°C) and a hydrogen circulation rate from 200 SCFB (33.7 normal m³/m³) to 50,000 SCFB (8427 normal m³/m³), at hydrogenation conditions which are more severe than those in step (a) selected to dehalogenate said feedstocks (1,4) and to produce a second effluent stream (6) of saturated hydrocarbonaceous compounds, unreacted hydrogen and a water-soluble hydrogen halide compound; and (c) recovering a hydrogen-rich gaseous stream (18), a hydrogenated stream (21) comprising hydrocarbonaceous compounds and said water-soluble hydrogen halide compound (10) from the second effluent stream. The process of Claim 1 wherein in step (c) of said second effluent steam (6) is contacted with halide-lean aqueous scrubbing solution (9) to produce the hydrogenated stream comprising hydrocarbonaceous compounds and a halide-rich aqueous scrubbing solution containing at leats a portion of said water-soluble hydrogen halide compound. The process of Claim 1 wherein step (c) of said process comprises the sub-steps of: (a) contacting the second effluent stream (6) from said second hydrogenation zone (5) with a first halide-lean absorber solution (9) in an adsorption zone (8); (b) withdrawing a halide-rich absorber extract solution (10) containing at least a portion of said water-soluble hydrogen halide compound from said adsorption zone (8); (c) withdrawing a raffinate stream (11) comprising hydrogenated hydrocarbonaceous compounds, residual trace quantities of halogenated organic compounds and a hydrogen-rich gas from said adsorption zone (8); (d) introducing said raffinate stream (11) recovered in step (c) into a third reaction zone (13) operated at hydrogenation conditions selected to hydrogenate essentially all of said residual trace quantities of halogenated organic compounds to produce a third effluent stream (14) comprising hydrocarbonaceous compounds and at least one water-soluble hydrogen halide compound; (e) contacting said third effluent stream (14) with a second halide-lean aqueous scrubbing solution (15); and (f) introducing a resultant admixture from sub-step (e) into a separation zone (17) to provide said hydrogen-rich gaseous steam (18), said hydrogenated stream (21) comprising hydrocarbonaceous compounds and a halide rich aqueous scrubbing solution (20) containing at least a portion of the water-soluble hydrogen halide compound produced in sub-step (d). The process of Claim 1 wherein at least a portion of said hydrogen-rich gaseous stream (18) recovered in step (c) is recycled to step (a). The process of Claim 1 wherein said first feedstock containing unsaturated, halogenated organic compound is: fractionation column bottoms formed in the production of allyl chloride, or fractionation column bottoms formed in the production of ethylene dichloride, or fractionation column bottoms formed in the production of trichloroethylene and perchloroethylene, or used dielectric fluid containing polychlorinated biphenyls (PCB) and chlorinated benzene, used chlorinated solvents, or mixtures thereof. The process of Claim 1 wherein said second feedstock containing saturated, halogenated organic compound is: fractionation bottoms from the purification column in epichlorohydrin production, or carbon tetrachloride, or 1,1,1 trichloroethane, or chlorinated alcohols, or chlorinated ethers, or chlorofluorocarbons or mixtures thereof. The process of Claim 1 wherein said halogenated organic compounds contain a halogen selected from the group consisting of chlorine and fluorine. The process of Claim 1 wherein said water-soluble hydrogen halide compound is selected from the group consisting of hydrogen chloride and hydrogen fluoride.

Inventors: JAMES ROBERT B JR, KALNES TOM N, JAMES, ROBERT B., JR., KALNES , TOM N.
Applicants: UOP INC, UOP
Application year: 1989
Main classification: C07C1
IPC codes: A62D101, A62D3, C07B61, C07C9, C10G1, B01J23, C07C5, C07C1, C07C17