Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C7/00—Purification; Separation; Use of additives
  • C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
  • C07C7/152—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound by forming adducts or complexes
  • C07C7/156—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound by forming adducts or complexes with solutions of copper salts
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S585/00—Chemistry of hydrocarbon compounds
  • Y10S585/949—Miscellaneous considerations
  • Y10S585/95—Prevention or removal of corrosion or solid deposits

Definitions

• This invention relates to an improvement in the process for ligand recovery which utilizes complexing of the ligands with aromatic sorbent solutions of cuprous halide-Lewis acid combinations such as cuprous tetrachloroaluminate.
• the improvement comprises the inclusion in said sorbent solutions of soluble components of antimony, arsenic and bismuth which when dissolved in said solutions prevent the pitting corrosion of carbon steel.
• patentees discuss the corrosion caused by molten ash deposits in various furnace operations.
• the patentees teach the use of mixtures of antimony I with siliceous material and antimony halides aredisclosed to be used in combination with siliceous materials as coatings for the furnace walls to prevent corrosion by the moltenash deposits.
• a corrosion inhibitor selected from the group consisting of soluble compounds of Group V metals such as antimony, arsenic and hisprises dissolving into the sorbent solution an effective amount of corrosion inhibitors such as the halides of arsenic, antimony and bismuth.
• a corrosion inhibitor selected from the group consisting of soluble compounds of Group V metals such as antimony, arsenic and hisprises dissolving into the sorbent solution an effective amount of corrosion inhibitors such as the halides of arsenic, antimony and bismuth.
• triphenyl compounds of the metals, soluble in the sorbent solutions are also useful as corrosion inhibitors.
• the process then of the invention is one wherein various complexible ligands may be recovered in a ligand exchange process by contacting the feedstream containing the complexible ligands with an aromatic sorbent solution comprised of a cuprous aluminum halide, particularly usefulisthe cuprous tetrachloroaluminate whereby all or substantially all of the complexible ligands are complexed by the sorbent.
• the complexed ligands thereafter may be recovered by contacting the complex with an exchange ligand,.which is a ligand which forms a more stable complex with the complexing solution than the ligand to be recovered, and the exchange process is continued'until all the desired complexible ligands have been recovered.
• Another way in which the desired ligand is separated is by means of accordance with the method set forth in Ser. No.
• aromaticv solvent employed is one which may contain specific multi-ringed, high boiling, low melting aromatic solvent compositions, in a major amount together with a minor amount of a single-ringed, strongly complexing, high boiling aromatic. More particularly, the preferred solvents are described adequately in copending application Ser. No. 259,077.
• the present process wherein effective amounts of the various above-described corrosion inhibitors are included in the sorbent solvents is amenable for the separation and recovery of a wide variety of complexible ligands.
• Illustrative of the complexible ligands which may be recovered by means of the present process are olefms, acetylenes, aromatics, carbon monoxide and the like.
• unsaturated hydrocarbons can be acetylenes such as C C acetylenes, preferably C -C acetylenes, for example, acetylene, methyl acetylene, ethyl acetylene, dimethyl acetylene, vinyl acetylene, etc; monoolefins such as C -C monoolefins, preferably C C, more preferably C C, monoolefins, most particularly ethylene and propylene; conjugated diolefins such as C,,C conjugated diolefins, preferably C -C for example butadiene, isoprene and the like; polyolefins such as C C,,,, preferably C,,-C polyolefins, for example, cyclododecatriene, cyclooctadiene, cyclic olefins and alicyclic olefins, such as C -C
• the complexible ligands to be separated and recovered by the process are contained in a feedstream in admixture with other components which are not as preferentially complexed.
• feedstreams as ethane-ethylene or propane-propylene can be treated to concentrate the olefin.
• the corrosion problem arises because the copper in materials such as cuprous tetrachloroaluminate, is more noble or less active than the iron in carbon steel, and therefore tends to become metallic copper while the iron is oxidized to ferrous ion.
• the following half cell reactions can occur:
• the deposition of the copper from the complexing solution causes the pitting of the carbon steel vessel.
• soluble compounds of the metals such as the halides of Group VA metals, i.e., arsenic chloride- ,antimony chloride, bismuth chloride and the like, as well as various triphenyl compounds of these metals, the pitting corrosion caused by the above half cell reactions may be prevented.
• the metals of Group V are useful as corrosion inhibitors in the operation of the present process, however, it must be stated that these metals are not necessarily equivalent in the degree to which they inhibit the corrosion, since some of the metals are more effective in their corrosion inhibiting properties than others.
• the amount of specific inhibitor material to bemaintained within the complexing sorbent solution will vary in accordance with variations and operating conditions in the composition of the metal surface in contact therewith.
• the concentration of the inhibitor metal to be maintained in the reaction zone will generally range from about 0.05 to about 10 wt. based on the cuprous complex and preferably from about 0.1 to about 5 wt. based on the amount of cuprous complex in solution.
• the inhibitor metal is preferably employed in the form of a suitable compoundsuitable compounds of the inhibitor metals comprise the metal in chemical combination with one or more of the halides such as the chlorides, bromides and fluorides, for example, antimony chloride, antimony fluoride, antimony bromide, and like halides of arsenic and bismuth.
• the halides such as the chlorides, bromides and fluorides, for example, antimony chloride, antimony fluoride, antimony bromide, and like halides of arsenic and bismuth.
• triphenyl compounds of the metals are also suitable, triphenyl compounds such as triphenyl arsine, triphenyl stibine and triphenyl bis-muthine are suitable and may in fact be preferable because they exhibit less of a tendency to promote Friedel Crafts-type side reactions.
• Alkyl and naphthyl compounds may also be suitable; mixed alkyl and aryl compounds of the metals may likewise be used.
• the inhibitor material may be independently injected into the system and maintained at various levels depending on operating conditions.
• the inhibitor material or a compound comprising said material may be employed in the form of an admixture or in chemical combination with organic compounds such as the triphenyl phosphines.
• the inhibitor metal will be included in the complexing sorbent solutions prior to the employment of said solutions in the ligand exchange apparatus. It is important for the overall prevention of corrosion that the inhibitor material be maintained in the prescribed concentrations throughout the operation. This is because the subjection of the metal surface to contact with the inhibitor metal prior to or during intermittant stages of operation, will generally not render such surfaces immune to subsequent corrosion by the cuprous tetrachloroaluminate. Since the sorbent solution is generally passed in a continuous stream through the system, the continuous presence of the inhibitor material is thereby necessitated.
• any particular compound of a suitable inhibitor material may be governed by the temperatures, pressures and concentrations of salt used in the process and the nature of the steel used.
• ethylene and propylene are separately recovered from a feedstream as may be obtained from thelight ends section of a conventional stream cracking unit.
• a feedstream from which acetylene and'carbon monoxide may havepreviously been removed e.g., by cuprous ammonium acetate complexing and conventional carbon monoxide absorption.
• Such a stream contains methane, ethane, propane and hydrogen in addition to the desirable ethylene and propylene ligands.
• a luggin capillary tip entering the side of the cell with a small opening near the working electrode contained a copper wire reference electrode.
• the potential of the working electrode relative to the reference electrode was measured with Kiethley electrometer of IO ohms impednace.
• the impedance of the working-reference electrode circuit was of the order of 10 ohms.
• Table I The corrosion data on aromatic solutions of cuprous tetrachloroaluminate and other cuprous salts are summarized in Table I.
• the open circuit or rest potential of the iron coupon, versus the reversible copper potential is given.
• a negative potential means that the iron is spontaneously dissolving in the solution causing copper metal precipitation.
• a positive potential indicates that this exchange is thermodynamically unfavorable.
• the current at zero millivolts versus reversible copper is a rough measure of the rate of corrosion (l mil/yr.
• the results of these studies are summarized in Table l, and show that the inclusion of effective amounts of corrosion inhibitors based on Group VA. metals, will prevent copper deposition and the subsequent pitting of any ferrous surfaces such as carbon'steel, in contact with the solutions of CuAlCl material was dissolved in benzene and isopropylbiphenyl solvents.
• the test equipment for the tests in benzene comprised of 6l00 cc glass tubes connected to a common manifold having a plastic gas expansion bag. Each tube 5 contained a magnetic stirrer. The equipment was assembled and filled in the nitrogen dry box. The tubes were filled about half full with complex and the coupon was held totally immersed under the complex solution suspended from a glass hook.
• test coupons before terminating the tests, were visually inspected and were thereafter removed, washed in benzene, followed by acetone, padded dry, and sent for determination fo corrosion and the presence of copper particles.
• the results of the test may be found in Tables Ila and Ilb.
• the test in the benzene solvent was conducted at 176F. for approximately 200 hours.
• the test conducted in the isopropylbiphenyl solvent was as follows: the carbon steel coupons were hung on glass stirrups in the complex for 402 hours at C. and inert nitrogen atmosphere was passed over the complex.
• the results are summarized in Tables Ila and Ilb, and show that the addition of an additive reduces the corrosion rate in mils per year of the carbon steel coupons and also prevents the pitting and deposition of copper particles on the coupons.
• EXAMPLE 2 In this Example several static corrosion tests were conducted, wherein the cuprous tetrachloroaluminate matic sorbent solution containing cuprous halide-Lewis acid salt combinations wherein the improvement comprises incorporating into said aromatic sorbent solution an effective amount of a corrosion inhibitor, selected from the group consisting of soluble compounds of group V metals comprising arsenic chloride, antimony chloride, bismuth chloride, triphenyl compounds of these metals, alkyl and naphthyl and mixed alkyl and aryl compounds of antimony, bismuth and arsenic to thereby substantially reduce the overall corrosion effect of the cuprous salt solution.
• a corrosion inhibitor selected from the group consisting of soluble compounds of group V metals comprising arsenic chloride, antimony chloride, bismuth chloride, triphenyl compounds of these metals, alkyl and naphthyl and mixed alkyl and aryl compounds of antimony, bismuth and arsenic to thereby substantially reduce the
• An improved process for the separation and recovery of complexible ligands from feedstreams by contacting said feedstreams with an aromatic sorbent solution containing cuprous tetrachloroaluminate wherein the improvement comprises dissolving into said solution an amount of a corrosion inhibitor selected from the group consisting of halides of arsenic, antimony and bismuth and mixtures thereof, said amount ofinhibitor being effective to prevent the deposition of copper from the cuprous tetrachloroaluminate solution.
• the corrosion inhibitor is arsenic chloride, antimony chloride or bismuth chloride.
• the complexible ligands to be recovered are ones selected from the group consisting of C C acetylenes, C C monoolefins, C --C, conjugated diolefins, C C, aromatics and carbon monoxide.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Water Supply & Treatment (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Extraction Or Liquid Replacement (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Sorption Type Refrigeration Machines (AREA)

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Citations (4)

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• 1972
  • 1972-06-02 US US00259258A patent/US3758606A/en not_active Expired - Lifetime
• 1973
  • 1973-05-30 DE DE2327600A patent/DE2327600C2/de not_active Expired
  • 1973-05-31 GB GB2602373A patent/GB1419866A/en not_active Expired
  • 1973-06-01 JP JP6176073A patent/JPS5635921B2/ja not_active Expired
  • 1973-06-01 CA CA173,006A patent/CA999604A/en not_active Expired
  • 1973-06-01 FR FR7320106A patent/FR2186276B1/fr not_active Expired

Patent Citations (4)

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