EP0912444A1 - Perfectionnement d'un procede de preparation de hcn anhydre - Google Patents

Perfectionnement d'un procede de preparation de hcn anhydre

Info

Publication number
EP0912444A1
EP0912444A1 EP97926595A EP97926595A EP0912444A1 EP 0912444 A1 EP0912444 A1 EP 0912444A1 EP 97926595 A EP97926595 A EP 97926595A EP 97926595 A EP97926595 A EP 97926595A EP 0912444 A1 EP0912444 A1 EP 0912444A1
Authority
EP
European Patent Office
Prior art keywords
cyanide
hcn
acid
reactor
batch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97926595A
Other languages
German (de)
English (en)
Inventor
Philip Osborne Moss
Charles Robert Sweval, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of EP0912444A1 publication Critical patent/EP0912444A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C3/00—Cyanogen; Compounds thereof
    • C01C3/02—Preparation, separation or purification of hydrogen cyanide
    • C01C3/0262—Preparation, separation or purification of hydrogen cyanide from cyanides
    • C01C3/0266—Preparation, separation or purification of hydrogen cyanide from cyanides from simple alkali or alkaline earth metal cyanides
    • C01C3/027—Alkali metal cyanides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C3/00—Cyanogen; Compounds thereof
    • C01C3/02—Preparation, separation or purification of hydrogen cyanide
    • C01C3/0262—Preparation, separation or purification of hydrogen cyanide from cyanides
    • C01C3/0266—Preparation, separation or purification of hydrogen cyanide from cyanides from simple alkali or alkaline earth metal cyanides
    • C01C3/0275—Alkaline earth metal cyanides

Definitions

  • This invention relates to a process for producing anhydrous hydrogen cyanide and more particularly to a batch or continuous process for producing anhydrous hydrogen cyanide from sodium cyanide and sulfuric acid.
  • the batch and continuous processes of the invention have been developed to offer safe, practical methods of producing anhydrous HCN from its sodium salt and results in low polymer formation and high chemical yield on a scale of .05-5MM lb/yr.
  • the low polymer formation is key to being able to achieve practical, commercial scale fractional distillation of the resulting aqueous solution in high yield.
  • the following reaction conditions further define the invention.
  • the process of the invention can be carried out batchwise or continuously. In the batch mode, all the acid can be charged first, or it can be co-fed with the cyanide salt solution.
  • the pH should be acidic throughout the reaction from pH 0 to 4 preferably below 3 to prevent HCN polymer formation.
  • the cyanide salt solution and acid are co-fed in the mole ratio described herein to a reactor with agitation.
  • the discharge from the reactor is controlled by its level. Since the reaction is immediate in both the batch and continuous process, from a practical standpoint, there is no upper or lower residence time on this reactor.
  • the only known suitable solvents are water or an aqueous reaction product recycled from the fractionating column which is typically present at between about 50-99% by weight water.
  • the reaction temperature should be maintained between 10 and 60°C, with the preferred temperature range between 20 and 40°C to minimize HCN hydrolysis, and to maintain solubility of the HCN and salt by-products in the reaction mass.
  • the mineral acids of the invention are sulfuric and phosphoric. However, sulfuric acid is preferred for economy and environmental reasons.
  • the mineral acid Before feeding into the reactor, the mineral acid is diluted below 90% with water, or the recycled reaction product from the bottom of the distillation column.
  • the sulfuric or phosphoric acid concentration is 25-45% on a salt-free basis or 15-35% including the salts in the recycled reaction product from the bottom of the distillation column.
  • a lower concentration can be used, but aqueous waste increases and the batch reactor and the distillation column become larger as a result of higher dilution. Somewhat higher concentrations can be tolerated, up to 70%, but increased yield loss to formate results. It may be necessary to add NaOH to stabilize aqueous NaCN.
  • the dilution of the mineral acid is preferably below a concentration of 50% with the water or the stripped salt solution recycled from the bottom of the fractionating column.
  • the major consideration here is the amount of water to be introduced to the reactor. There must be sufficient water to prevent large amounts of the by-product salts from precipitating out of solution during the reaction and prior to distillation.
  • Alkali metal and alkaline-earth metal salts of cyanide can be used, however, the preferred salt is sodium cyanide for reasons of availability and economy.
  • the cyanide salt should be dissolved completely in water before introduction into the reaction process.
  • the mole ratio of cyanide salt to acid is related to the number of available acidic protons. In theory there are two available protons for (H2SO 4 ) and three available protons for (H 3 PO 4 ).
  • the mole ratio of salt (NaCN) to acid (H2SO 4 ) is less than 2 and the mole ratio of salt (NaCN) to (H 3 PO 4 ) is less than 3.
  • the preferred mole ratio should be between 1.5 and 1.85 for environmental reasons, economy and safety.
  • the preferred mole ratio for NaCN and H3PO 4 should be between 2.5 and 2.85.
  • the cyanide is added to the: acidic reactor employing typical techniques that ensure good micro-mixing al the addition point. It is important to minimize the lime that the hydrogen cyanide might "see" a pH of above 4 to minimize HCN polymer formation. Addition time is not important and is only limited by the capacity of the equipment to remove the heat generated by the reaction. The reaction occurs immediately at all temperatures outlined above.
  • the water/HCN/salt reaction product feed to the fractionating column must be low in HCN polymer for the purpose of reliability.
  • a dark (high polymer) reaction product will lead to fouling and pluggage of the column that will require clean-out more often.
  • the HCN concentration in the reactor before transfer to the fractionating column is 1-10% preferably 3-7%. Higher concentrations of HCN can lead to increased vaporization loss and polymer formation at the operating temperatures.
  • anhydrous HCN is at least 98.5% HCN.
  • the process of the invention produces less HCN polymer and results in less hydrolysis of the HCN and is therefore superior to processes known presently.
  • the 66 degree Baume (93.7%) sulfuric acid charge of 2970 lb (1348 Kg) was mixed in-line with 9735 lb (4420 Kg) of recycle brine (20-25 wt % salts) and cooled in line to 35 °C while feeding the reactor over 70 to 80 minutes.
  • 15,397 lb (6990 Kg) of prechilled (15 °C) 14.3 wt % aqueous sodium cyanide was mctered in over 80 to 90 minutes while maintaining the reactor temperature at 35 C.
  • the sodium cyanide feed was introduced subsurface near the agitator to ensure good mixing with an endpoint pH of less than 3.0.
  • HCN crude yield basis distillate (6 batch ave.): 91.9%, 1 1 15 lb, 507 kg, bp 26-27 °C.
  • EXAMPLE 3 Preparation of HCN - Continuous Process An apparatus consisting of a reaction and distillation system in series was set up.
  • the reaction system was made up of a 1 liter resin flask, with cooling, mechanical stirring, two charging reservoirs with their accompanying charging metering pumps feeding to the reactor subsurface, dry ice condenser, and a reactor discharge metering pump for transfer to the distillation system.
  • the distillation system consisted of a 20 plate Oldershaw column, round bottom flask reboiler with discharge pump, timed distillate reflux control, refrigerated glycol cooled condenser, and distillate receiver. Both the reactor and distillation systems were vented to a common aqueous scrubber.
  • the reactor and distillation column reboiler each were charged with 256.4 g of a 2.5% H2SO 4 solution.
  • reactant solutions were made up: 1) NaCN solution consisted of 281.3 g 99% NaCN, 1 114.7 g water and 1 1.3 g 50% NaOH, and 2) a 43% sulfuric acid solution consisted of 331.2 g 98% H 2 S0 4 and 423.8 g water.
  • the NaCN solution and the 43% sulfuric acid solution were partially charged separately to the two charging reservoirs which were then started simultaneously, maintaining even Hows and a reactant mole ratio of 1.7 moles cyanide per mole sulfuric acid over a period of about 4 hrs. Both additions were made subsurface near the agitator for good mixing.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)

Abstract

La présente invention concerne un procédé de préparation par lots ou en continu de HCN anhydre. Ce procédé consiste à faire réagir dans un réacteur un métal alcalin ou des sels de métaux alcalino-terreux de cyanure avec des acides minéraux, cette réaction étant suivie d'un transfert vers une colonne de fractionnement. Il en résulte une faible formation de polymères pour une production élevée de produit.
EP97926595A 1996-05-30 1997-05-19 Perfectionnement d'un procede de preparation de hcn anhydre Withdrawn EP0912444A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US1863796P 1996-05-30 1996-05-30
US18637P 1996-05-30
PCT/US1997/008465 WO1997045369A1 (fr) 1996-05-30 1997-05-19 Perfectionnement d'un procede de preparation de hcn anhydre

Publications (1)

Publication Number Publication Date
EP0912444A1 true EP0912444A1 (fr) 1999-05-06

Family

ID=21788991

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97926595A Withdrawn EP0912444A1 (fr) 1996-05-30 1997-05-19 Perfectionnement d'un procede de preparation de hcn anhydre

Country Status (4)

Country Link
EP (1) EP0912444A1 (fr)
AU (1) AU3131897A (fr)
CA (1) CA2255709A1 (fr)
WO (1) WO1997045369A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10317929A1 (de) 2003-04-17 2004-11-11 Basf Ag Verfahren zur Aufreinigung von Blausäure
WO2007143454A2 (fr) * 2006-05-31 2007-12-13 Shell Oil Company Procédé et appareil servant à préparer un concentré de savon, une composition lubrifiante et des associations de ceux-ci

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1347518A (en) * 1919-08-25 1920-07-27 Max E Mueller Method of making hydrocyanic acid and cyanids
US1352655A (en) * 1919-11-12 1920-09-14 American Cyanamid Co Method of producing hydrocyanic acid
US1680662A (en) * 1925-10-19 1928-08-14 Roessler & Hasslacher Chemical Process for producing hydrocyanic acid
GB599606A (en) * 1942-11-11 1948-03-17 American Cyanamid & Chem Corp Improvements in or relating to the continuous production of hydrogen cyanide
US5160413A (en) * 1990-08-16 1992-11-03 Conoco Inc. Micro-distillation process for cyanide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9745369A1 *

Also Published As

Publication number Publication date
CA2255709A1 (fr) 1997-12-04
AU3131897A (en) 1998-01-05
WO1997045369A1 (fr) 1997-12-04

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