JPH08143479A - Method for hydrogenation treatment of organic feed stock containing olefinic compound and halogen component - Google Patents

Abstract

PURPOSE: To provide a method for carrying out the hydrogenation of an organic feed stock containing a thermally unstable compound and a halogen component while minimizing the thermal degradation and polymerization of the thermally unstable compound and stabilizing the activities of a hydrogenation treatment catalyst.

CONSTITUTION: This method for carrying out the hydrogenation of an organic feed stock containing a thermally unstable compound and a halogen component comprises following steps: (a) a step for bringing an organic stream including the thermally unstable compound and the halogen component, and a recycle stream of a gas containing a hydrogen halide compound into contact with a hydrogenation catalyst in a hydrogenation reaction zone; (b) a step for condensing an effluent formed from the hydrogenation reaction zone to produce a gas stream comprising the hydrogen and the hydrogen halide compound, and a liquid stream comprising a hydrocarbon- based compound; (c) a step for recycling the gas stream comprising the hydrogen and the hydrogen halide compound recovered at the step (b) to the hydrogenation reaction zone of the step (a); and (d) a step for recovering a stream comprising the hydrocarbon and having a low halogen component content.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

The field of art to which this invention pertains is the conversion of organic feeds containing thermally labile compounds and halogen components to produce hydrocarbon-based compounds having reduced concentrations of halogen moieties.

There is always a demand for conversion or treatment of wastes and by-products from the petroleum, chemical and petrochemical industries. More particularly, these by-products result from the chlorination of olefins, for example in the production of epichlorohydrin, propylene oxide and vinyl chloride monomers. In such streams, the predominant species are typically halogenated alkanes, but in addition
In some cases, there are higher reactive species that may polymerize or decompose during processing, such as olefins and other thermally labile compounds, and thereby the reactor. And associated plumbing plugging. This polymerization or decomposition process is the main mechanism leading to the formation of carbonaceous deposits and consequent deprivation activity of the conversion catalyst. Halogen component,
Prior art techniques used to treat waste streams containing olefins and other heteroatom compounds were often environmentally problematic or illegal and were generally always expensive. The environmental importance to the treatment and recycling of chlorinated organic compounds has increased, increasing the need to convert these products when they are not desired. Therefore, those skilled in the art have sought to find available techniques for converting such feedstocks to provide a hydrocarbon-based stream having a reduced concentration of halogen that may be used or recycled. Techniques previously used include combustion and dumping, which, in addition to potential pollution problems, fail to recover valuable hydrocarbonaceous materials and resulting halogenated compounds.

The present invention provides a method for hydrotreating an organic feedstock containing a thermally labile compound and a halogen component, the method comprising: treating an organic feed and a gas recycle stream containing hydrogen and a hydrogen halide; The means for contacting the hydrogenation catalyst in the hydrogenation reaction zone provides a hydrogenated hydrocarbon-based stream and a halogenated compound stream having a reduced concentration of halogen. The effluent obtained from the hydrogenation zone is separated to produce a recycle stream containing hydrogen halide compounds. A key element of the improved process is the ability to reduce the production of polymerized olefins and cracked compounds in the processing plant, reduce coke formation or carbonaceous deposits on the hydrogenation catalyst, and achieve longer run times. , And higher conversion per pass can be achieved. In addition to these operational advantages, valuable products containing hydrogenated hydrocarbon-based compounds and hydrogen halide compounds are produced while at the same time converting unwanted by-products or waste, thereby potentially Solve the traditional pollution problem. In particular, the recycling of the halogen compound hydrogen suppresses or reduces the radical polymerization reaction and acts as a heat sink to suppress the temperature increase in the reactor caused by heat generation. Both of them provide more stable catalytic performance.

One basic aspect of the present invention is to hydrotreate an organic stream containing thermally labile compounds and halogen components while minimizing thermal decomposition of thermally labile compounds, And a method of stabilizing the activity of the hydrogenation catalyst can be characterized, which method comprises the following steps: (a) increasing the hydrogen content of the organic feedstock, and at reaction conditions resulting in a hydrogen halide compound. Contacting an organic stream containing thermally labile compounds and halogen components and a gas recycle stream containing hydrogen and hydrogen halide compounds with a hydrogenation catalyst in a hydrogenation reaction zone; (b) hydrogen and hydrogen halide compounds. Less effluent from the hydrogenation reaction zone, such as to produce a gas stream containing hydrogen and a liquid stream containing hydrocarbon-based compounds. Also to condense a portion;
(c) at least a portion of the gas stream containing hydrogen and hydrogen halide compounds recovered in step (b) is processed
recycling to the hydrogenation reaction zone in (a);
And (d) recovering a stream containing a hydrocarbon-based compound and having a reduced content of halogen components.
including. A preferred further step involves recovering the hydrogen halide in the acid anhydride stream from a portion of the gas stream that is not recycled in step (c).

Other aspects of the invention include other additional details such as preferred feedstocks, hydrogenation catalysts and operating conditions, all of which are disclosed below in each of these discussions of the invention below. It

The present invention comprises thermally labile compounds and halogen moieties while minimizing the thermal decomposition and polymerization of thermally labile compounds, and thereby stabilizing the activity of hydrotreating catalysts. An improved integrated method for hydrotreating organic feedstocks is provided. There is a steady growing demand for technologies capable of converting organic stocks containing halogen components, especially for processes capable of processing such streams containing more thermally labile compounds. It has been unexpectedly discovered by the present invention that a highly improved process is achieved if the hydrogen halide compound is recycled to the hydrogenation reaction zone. Many halogenated organic compounds, including thermally labile compounds, can be feed streams in the process of the invention. Examples of organic streams containing halogenated organic compounds suitable for treatment by the method of the present invention are dielectric fluids, hydraulic fluids, heat transfer fluids, used lubricating oils, used cutting oils, used solvents, halogenated carbonisation. Hydrogen-based by-products, oils contaminated with polychlorinated biphenyls (PCBs), halogenated wastes, vinyl chloride monomers, propylene oxide, allyl chloride, epichlorohydrin and other halogenated intermediates and end products By-products, petrochemical by-products, and other halogenated hydrocarbon-based industrial wastes. Often, more than one halogenated organic stream is present at a particular location and requires further treatment. Halogenated organic compounds can also contain hydrogen and are therefore called hydrocarbon-based compounds.

The process of the present invention is most useful when the feedstock contains thermally labile compounds that have a marked tendency to polymerize when raised to elevated temperatures or to form coke or carbonaceous deposits. Used to advantage. In the past, undesired reactions with thermally labile compounds have presented great difficulty in attempting to treat such streams because they cause operational problems in operating plants. Although not intended to be limiting, it is believed that the presence of hydrogen halide compounds when the thermally unstable compounds in the feedstock are at elevated temperatures prevents previous operational problems. .

According to the invention, the halogenated organic feed preferably contains less than 500 ppm by weight of water or water precursors. An example of a water precursor is an oxygenated compound, which is converted to a hydrogenated compound and water when exposed to hydrogenation conditions. In one preferred embodiment of the present invention, the resulting hydrogen halide is conveniently recovered as an anhydrous hydrogen halide stream. As used herein, "anhydrous acid anhydride containing hydrogen halide"
The term includes a stream having less than 50 ppm water on a weight basis.

Preferred feedstocks are rectification column bottoms resulting from the production of allyl chloride, rectification column bottoms resulting from the production of ethylene dichloride, by-products resulting from the production of vinyl chloride monomers, rectification resulting from the production of trichloroethylene or perchloroethylene. Tower bottom,
Used dielectric fluids containing polychlorinated biphenyls (PCB) or used solvents for halogenated benzene, rectification bottoms from purification towers in the production of epichlorohydrin, carbon tetrachloride, 1,1,1-trichloroethane, Includes halogenated alcohols, halogenated ethers, chlorofluorocarbons or mixtures thereof.

The halogenated organic compounds considered as feedstock in the present invention may contain chlorine, bromine, fluorine or iodine. Preferred halogen compounds include chlorine or fluorine. Furthermore, the halogenated organic compound preferably contains from 1 to 20 carbon atoms per molecule.

In accordance with the present invention, a feedstock containing a halogenated organic compound is provided as a mixture with a hydrogen rich gas recycle stream containing hydrogen halide and optionally with a recycle stream containing unreacted halogenated organic compound. It is introduced into the catalytic hydrogenation zone. The catalytic hydrogenation zone contains a hydrogenation catalyst and is maintained in hydrogenation conditions. This catalytic hydrogenation zone can include a fixed bed, a boiling bed or a fluidized catalyst bed. Further, the hydrogenation reaction zone may consist of multiple catalyst beds operating at various conditions. This reaction zone is preferably maintained at conditions selected to dehalogenate the halogenated organic compound introduced therein. The catalytic hydrogenation zone is preferably under pressure from atmospheric pressure to 2000 psig (13.8 MPa gauge), more preferably from 100 psig (0.7 MPa gauge) to about 1800 psig (12.
4MPa gauge). Suitably, such a reaction reduces or eliminates the concentration of halogenated organic compounds contained in the mixed feed stream, and consequently the desired dehalogenation conversion to increase the hydrogen content of the stream. Selected to do, 50 ° F
It operates at maximum catalyst bed temperatures ranging from (10 ° C) to 850 ° F (454 ° C). According to the invention, the desired hydroconversions include, for example, dehalogenation and hydrocracking. Furthermore, the effluent resulting from the hydrogenation zone is preferably essentially free of olefinic compounds or other thermally labile compounds that can be detrimental to any other further processing step. Further preferable operating conditions are 0.05 hr ^{-1 to} 20 hr
Liquid hourly space velocity in the range of ^-1 and 200 standard feet ³ / barrel (SCFB) (33.7 Nm ³ / m ³ ) to 150,000 SCFB (25,274 Nm ³ /
m ³ ), preferably 200 SCFB (33.7 Nm ³ / m ³ ) -100,000 SCF
Includes hydrogen circulation rate of B (16,850 Nm ³ / m ³ ).

As used in the present invention, the term "hydrotreating" or "hydrogenation" refers to hydrogen contents such as olefin saturation, diolefin saturation, desulfurization, denitrogenation or dehalogenation. It is broadly meant that the organic reactant comprises a reaction that increases hydrogen content, regardless of which is accomplished by.

In addition to the above operating conditions, the present invention achieves the surprising result of minimizing polymerization of olefinic compounds or decomposition of other thermally labile compounds contained in the fresh feedstock. Therefore, it is important that the hydrogen halide be recycled along with the hydrogen rich gas recycle stream. The content of hydrogen halide recycled to the hydrogenation reaction zone is a function of the content of thermally labile compounds in the initial feedstock. Although a specific content of hydrogen halide in the hydrogenation zone is required to obtain the results of the present invention, higher contents or concentrations of hydrogen halide are contemplated and included in the specification. It should not be excluded by teaching. The concentration of hydrogen halide in the hydrogen-rich gas recycle stream is preferably 2 mol%.
~ 60 mol%. Further, it is believed that it is present in an amount of 5% to 200% by weight, based on the weight of the mixed feedstock and any recycle, to the hydrogenation reaction zone. Although the overall purpose of the present invention is to remove halogen by dehalogenation of halogenated organic compounds, when the feedstock is thermally unstable, it is initially exposed to a hydrogen halide containing recycle stream. It has been found to be advantageous.

A preferred catalytic composite disposed within the hydrogenation zone described above comprises a metal component having hydrogenation activity in combination with a suitable refractory support material of either synthetic or natural origin. It can be a feature. The exact composition and method of making the carrier material is not considered essential to the invention. Preferred carrier materials are alumina, silica, carbon or mixtures thereof. A suitable metal component having hydrogenation activity is the Periodic Table of Elemen.
ts, EHSargent and Company, 1964, and is selected from the group containing metals of Groups VIB and VIII of the Periodic Table. Thus, the catalyst composite is molybdenum, tungsten, chromium, iron, cobalt, nickel,
1 selected from the group of platinum, palladium, iridium, osmium, rhodium, ruthenium and mixtures thereof
One or more metal components can be included. The concentration of catalytically active metal components depends primarily on the physical and / or chemical properties of the particular metal and the particular hydrocarbon-based feedstock. For example, the metal components of Group VIB are typically 1-20.
Present in an amount in the range of wt%, iron group metals 0.2 to 10 wt%
Noble metals of Group VIII are preferably present in an amount of 0.1
Present in an amount of ~ 5% by weight. All of these are calculated as if these components were present in elemental state in the catalyst composite. It is further envisioned that the hydrogenation catalyst composite may include one or more of the following components: cesium, francium, lithium, potassium, rubidium, sodium,
Copper, gold, silver, cadmium, mercury and zinc. Preferred hydrogenation catalysts include alumina and palladium.

In accordance with the present invention, the hydrogenation zone resulting from:
A hydrocarbon-based effluent containing at least one hydrogen halide is cooled and introduced into a vapor / liquid separator, a hydrogen-rich gas recycle stream containing hydrogen halide and a hydrogenated hydrocarbon-based compound and A liquid stream containing hydrogen halide is produced. One technique used to regulate the amount of hydrogen halide recycled in a hydrogen-rich gas recycle stream is operating pressure and effluent cooling and, consequently, vapor / liquid separator operation. The choice is temperature.
According to the present invention, the vapor / liquid separator is -70.
400 psig at temperatures from ° F (-57 ° C) to 60 ° F (16 ° C)
(2.76MPa gauge) ~ 1800psig (12.4MPa gauge) It is possible to operate at pressure. The resulting liquid stream containing the hydrogenated hydrocarbon-based compound and the hydrogen halide is separated in a preferred further step to provide an acid anhydride stream containing the hydrogen halide with the hydrogenated hydrocarbon-based compound and unreacted To produce a liquid stream containing organic compounds of. The resulting liquid is then separated to produce an unreacted halogenated organic compound introduced into the hydrogenation reaction zone and a hydrogenated hydrocarbon-based stream having a reduced halogen content. According to one preferred embodiment of the present invention, the hydrogen halide compound is thus recovered as an acid anhydride product. This allows subsequent recovery and the use of desirable and valuable hydrogen halide compounds.

As noted above, the hydrogenated hydrocarbon-based effluent produced from the hydrogenation reaction zone is preferably at essentially the same pressure and -70 ° F (-57 ° C) as the hydrogenation reaction.
C.) to 60.degree. C. (16.degree. C.) in a separation zone maintained at a temperature in the range of 60.degree. C. to 60.degree. In addition, the liquid hydrocarbon-based stream contains dissolved hydrogen, dissolved hydrogen halide, and, if present, low molecular weight normally gaseous hydrocarbons. According to the invention, the hydrogenated liquid phase containing hydrogen chloride is separated to give an anhydrous hydrogen halide stream by separation such as stripping, flushing or rectification. After the hydrogen halide stream thus occurs and is removed from the process, the resulting hydrocarbon-based stream is a hydrocarbon-based stream mainly containing hydrogenated hydrocarbon-based compounds and a stream mainly containing halogenated organic compounds. Are separated to produce. The latter can then be recycled to the hydroconversion zone if desired. Such a separation can be, for example,
It may be done by any convenient method such as stripping, flushing or rectification.

In the figures, the method of the present invention is illustrated by means of a simple flow diagram. Details such as total number of reaction zones and dryer vessels, pumps, meters, heat exchange and heat recovery circuits, compressors and similar hardware are not essential to an understanding of the technology involved and have been omitted. The use of such various accessories is well within the purview of those skilled in the art.

Referring to the drawings, an organic feed stream containing thermally labile compounds and halogen components is shown in conduit 1.
Is introduced into the process through and is provided through conduit 7 and is contacted with a hydrogen-rich gas recycle stream containing a hydrogen halide compound described below. An organic feed stream containing thermally labile compounds, a hydrogen-rich gas recycle stream containing hydrogen halide compounds, and an unconverted organic recycle stream described below introduced through conduit 14 are in hydrogenation reaction zone 2. be introduced. The resulting hydrogenated hydrocarbon-based stream is withdrawn from the hydrogenation reaction zone 2 via conduit 3, cooled in heat exchanger 4 and introduced via conduit 5 into a vapor / liquid separator. A hydrogen-rich gas stream containing hydrogen halide is removed from the vapor liquid separator 6 via conduit 7 and recycled as described above. Hydrogen is lost in the process due to the dissolution of a portion of the hydrogen in the hydrocarbons of the outlet liquid and the consumption of hydrogen during the hydrogenation reaction, so that a suitable external source, such as a catalytic reforming unit Or it is necessary to supplement the hydrogen-rich gas stream with make-up hydrogen gas from the hydrogen plant. Makeup hydrogen gas is
It may be introduced into the system at any convenient and appropriate point not shown in the drawings. A liquid hydrogenated hydrocarbon-based stream containing hydrogen and hydrogen halide in solution is withdrawn from the vapor / liquid separator 6 and introduced into the rectification zone 9 via conduit 8.
A product stream containing hydrogen halide is withdrawn from rectification zone 9 via conduit 10 and recovered in the form of acid anhydride. A liquid distillable hydrogenated hydrocarbon-based stream is withdrawn from rectification zone 9 via conduit 11 and introduced into rectification zone 12. A product stream containing a reduced halogen content hydrocarbon-based compound is withdrawn from rectification zone 12 via conduit 13 and recovered. A liquid stream containing unconverted organic compounds is withdrawn from rectification zone 12 via conduit 14 and recycled to hydrogenation reaction zone 2 via conduit 14 as described above.

The following example further illustrates the method of the present invention,
It is shown for comparison purposes and shows the advantages gained by using it in the production of hydrogenated hydrocarbon-based streams from organic feedstocks containing thermally labile compounds and halogen components. Example 1 is a control experiment using an olefin feedstock without hydrogen halide recycle. Example 2 is another control experiment using a non-olefin feedstock with thermal instability without hydrogen halide recycle.

Example 1 This example illustrates a process for conversion of a feedstock containing 70% dichloropropane and 30% dichloropropene,
Here, the feedstock is a 0.6 weight-hour space velocity (WHS) over a dechlorination catalyst containing palladium and alumina.
V), at a pressure of 750 psig (5.2 MPa gauge), at a hydrogen circulation rate of 91,000 standard foot ³ / barrel (SCFB) (15,333 Nm ³ / m ³ ), without recycle of hydrogen halides and at about 140 ° Passed at an average catalyst bed temperature of F (60 ° C). About 42
After running for hours, the bench scale reactor plugged with carbonaceous deposits due to olefin polymerization.

Example 2 This example shows a process for the conversion of a feedstock having the properties shown in Table 1, where the feedstock is over a dechlorination catalyst containing palladium and alumina at a weight time space of 0.6. Speed (WHSV), pressure of 750 psig (5.2 MPa gauge), gas circulation rate of 55,000 SCFB (9,268 Nm ³ / m ³ ) (> 80
Mol% hydrogen, 0 mol% HCl, and the balance propane), and 248 ° F (120 ° C) to 32
Passage was at an average catalyst bed temperature in the range of 0 ° F (160 ° C).
After about 162 hours of operation, the operation was stopped and the catalyst was analyzed for coke and carbonaceous material. At the top of the catalyst bed the catalyst contained 5.63 wt% carbonaceous deposits and at the bottom of the catalyst bed the catalyst contained 2.65 wt% carbonaceous deposits.

Table 1 Feedstock Analysis Components Weight% 1,2-Dichloropropane 77.0 Epichlorohydrin 4.1 2-Methyl-2-pentenol 1.7 Trichloropropane 0.9 Dichloropropyl ether isomer (Isomers) 10.6 Unidentified chlorinated hydrocarbons 4.7 Trace component 1.0 Olefin species 0

Example 3 This example is conducted in accordance with one aspect of the present invention, wherein a hydrogen halide recycle stream reduces carbonaceous or coke deposits. 91.9% by weight dichloropropane and 7.5% by weight
The feedstock containing dichloropropene contains 0.3
45,000 at 750 psig (5.2 MPa gauge) operating pressure at WHSV
At hydrogen circulation rate of SCFB (7,583 Nm ³ / m ³ ), and about 311 °
The catalyst was contacted with a dechlorination catalyst containing palladium and alumina at an average catalyst bed temperature of F (155 ° C). Hydrogen chloride generated in the dechlorination reaction was 31 mol% in the recycled gas.
Was recycled with an average value of. Runs were considered good, but were stopped after 1350 hours at stable performance and the catalyst was analyzed for coke or carbonaceous constituents. The catalyst at the top of the catalyst bed contained 2.93 wt% carbonaceous deposits, while the catalyst at the bottom of the catalyst bed contained only 0.14 wt% carbonaceous deposits. These results show inhibition of carbonaceous deposits on the catalyst during hydrogen chloride recycling.

[Brief description of drawings]

FIG. 1 is a simple process flow diagram of the preferred embodiment of the present invention.

[Explanation of symbols]

 1 ... Organic feed stream conduit 2 ... Hydrogenation reaction zone 4 ... Heat exchanger 6 ... Vapor liquid separator 9 ... Fractionation zone

Front page continuation (72) Inventor Celio Lume Pereira Stade, Nafty Gallenbeek, Federal Republic of Germany 22 (72) Inventor Barbara Beheimer, Federal Republic of Germany, 21682, Stade, Salzstraße 18

Claims (11)

[Claims] 1. A method for hydrotreating an organic feedstock containing a thermally labile compound and a halogen component, which minimizes the thermal decomposition of said thermally labile compound and hydrotreating. The method is carried out while stabilizing the activity of the treated catalyst, and the method comprises the steps of: (a) the organic stream containing a thermally labile compound and a halogen component, and the gas recycle stream containing hydrogen and a hydrogen halide compound. Contacting with a hydrogenation catalyst in a hydrogenation reaction zone to increase the hydrogen content of the organic stream and under hydrogenation reaction conditions that result in a hydrogen halide compound, (b) the hydrogenation At least a portion of the effluent resulting from the reaction zone is condensed to form a gaseous stream containing hydrogen and hydrogen halide compounds and hydrocarbon-based compounds. Producing a liquid stream comprising: (c) recycling at least a portion of said gas stream comprising hydrogen and a hydrogen halide compound recovered in step (b) to a hydrogenation reaction zone in step (a), and ( d) recovering a stream containing a hydrocarbon-based compound and having a low halogen component content. 2. The organic feedstock comprises a compound having 1 to 20 carbon atoms per molecule.
The method described in. 3. The method of claim 1 wherein said organic feedstock comprises thermally labile components in the form of olefins or heteroatom compounds. 4. The method of claim 1, wherein the organic feed comprises chlorine, fluorine, bromine or iodine. 5. The method of claim 1, wherein the gaseous recycle stream containing hydrogen and hydrogen halide comprises 2 to 60 mol% hydrogen halide. 6. The method of claim 5, wherein the hydrogen halide is present in an amount sufficient to minimize thermal decomposition of at least the thermally labile compound. 7. The method of claim 1, wherein the hydrogenation catalyst comprises a Group VIII metal on a refractory inorganic oxide support. 8. The method of claim 1, wherein the hydrogenation catalyst comprises palladium and alumina. 9. The hydrogenation reaction zone is 10 ° C. to 454.
C temperature, 0.7 MPa gauge to 12.4 MPa gauge pressure, 33.7 Nm ³ / m ^{3 to} 25,274 Nm ³ /
The method according to claim 1, wherein the feedstock to the hydrogen circulation rate and the hydrogenation reaction zone of m ³ is operated at hydrogenation reaction conditions including a recycling rate of hydrogen halide recycle 5-200% by weight, based on. 10. A rectification column bottom of allyl chloride, ethylene dichloride, trichloroethylene, epichlorohydrin or perchloroethylene; a used dielectric fluid containing polychlorinated biphenyls, a by-product resulting from the production of vinyl chloride monomers, A process according to claim 1 comprising halogenated benzene, carbon tetrachloride, 1,1,1-trichloroethane, halogenated alcohols, halogenated ethers, chlorofluorocarbons or mixtures thereof. 11. The method of claim 1 further comprising recovering hydrogen chloride in the form of an acid anhydride from a portion of the gas stream of step (b) that is not recycled in step (c).