Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D301/00—Preparation of oxiranes
  • C07D301/02—Synthesis of the oxirane ring
  • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
  • C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
  • C07D301/08—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase
  • C07D301/10—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase with catalysts containing silver or gold
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/48—Silver or gold
  • B01J23/50—Silver
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/18—Carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/612—Surface area less than 10 m2/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/66—Pore distribution

Definitions

• the present invention relates to silver-based catalysts on a graphite support for the vapor phase epoxidation of olefins and more particularly for the production, by this technique, of ethylene oxide from ethylene and oxygen. molecular.
• ethylene oxide is carried out in the vapor phase, in tubular reactors with a fixed bed, by reaction of oxygen and ethylene on catalytic phases based on silver deposited on refractory supports. and inert formed mainly of alumina, silica-alumina, magnesia, pumice, zirconia, clay, ceramic, asbestos, natural or artificial zeolite or silicon carbide.
• the prior art generally prefers supports based on ⁇ alumina having a specific surface of less than a few m2 / g. This specific surface is determined by the nitrogen adsorption method, known as B.E.T. described by BRUNAUER, EMMET and TELLER in "The journal of the american chemical Society" vol.
• porous artificial graphites can be obtained in very different forms such as spheres, pellets, rings, cassons or extruded shapes.
• French patent n ° 1.079.601 does not specify any textural characteristic: granulometry, porosity, specific surface of the graphite used and in addition to a good absorption capacity the only quality required is limited to a perfect deburring of the solid.
• the catalysts of this patent were tested on loads of 1,100 to 1,200 kg and under these conditions the productivities obtained are low, less than 15 g of ethylene oxide per liter of catalyst per hour for tests at atmospheric pressure and of the order of 115 g for tests under 10 bars. The selectivities announced in the latter case are poor: 60 to 68%.
• German Patent No. 1,066,559 very briefly describes a single test in a reactor 3 m long and 25 mm in diameter.
• the artificial graphite used is not defined and the authors report low productivity accompanying poor selectivity not exceeding 55%.
• the silver compounds used can be either salts: nitrate, formate, lactate, citrate, carbonate, oxalate, silicylate, acetate, sulfate, propionate, maleate, malate, malonate, phthalate, tartrate, glycolate, succinate, oxide, hydroxide, acetylide or ketenide, either complexes of silver salts with nitrogenous molecules, ammonia, acrylonitrile, pyridine, ethanolamine, ethylene diamine, or with P-diketones.
• the main solvents or suspension liquids used are water, acetone, light alcohols, ether, pyridine, ethylene glycol, diethylene glycol or chlorinated solvents.
• All the techniques which allow the passage of these compounds to the metal or to the oxide can be applied in the presence of graphite or of graphitized materials, for example precipitation, thermal decomposition in an inert, oxidizing or reducing atmosphere and chemical reduction.
• a particularly suitable treatment is thermal decomposition on the supports of silver acetate under the following conditions: thermal rise from 20 to 280 ° C at a rate of 20 ° C / hour followed by a plateau of 10 to 30 hours at 280-300 ° C, the entire operation being carried out with nitrogen sweeping with the possible addition of oxygen or hydrogen.
• the temperature of the oil bath of the evaporator is brought to 120 ° C. and the support is left to degas for one hour under a partial pressure of 100 mm of mercury. Under the same conditions of temperature and pressure, 200 ml of a pyridine solution at 5% by weight of silver acetate are then introduced dropwise over 3 hours. Under these conditions the evaporation of the solvent is instantaneous. After introduction of all of the solution, the impregnated and dried support is transferred to a tubular reactor to decompose, in a stream of nitrogen, the silver acetate according to the known reaction:
• this treatment is carried out with a temperature rise of 20 ° C / h up to a plateau of 18 hours at 270 ° C. Analysis indicates that the catalyst thus prepared contains 10% by weight of silver.
• the reactor Charged into a laboratory reactor working at atmospheric pressure 30 ml of catalyst prepared in Example No. 1.
• the reactor consists of a stainless steel tube 600 mm long and 16 mm inside diameter.
• the reagents are admitted from below and are preheated on a bed of 200 mm high porcelain rings, which also supports the catalyst charge.
• the whole is heated by an oil circulation in a double jacket.
• the gases entering and leaving the reactor are analyzed online using a double detection chromatograph: a flame ionization detector for ethylene oxide, methane, formaldehyde, propylene, propane, methanol and acetaldehyde, and a thermal conductivity detector for oxygen-nitrogen, carbon dioxide, ethylene and water.
• the two columns, 1/8 inch in diameter and 2.5 meters long, mounted in series, are filled one with chromosorb 101, the other with porapak Q.
• Example No. 3 a charge of 30 ml of catalyst prepared in Example No. 2 is introduced. After an activation treatment of 30 hours consisting in passing an air-mixture over the catalyst. ethylene 50% -50% at a temperature below 200 ° C, a gas stream of 14 liters / hour is introduced into the reactor consisting of a mixture of 14% ethylene, 4.6% oxygen, 81, 4 nitrogen and 200 ppb of 1,2-dichloroethane. After 60 hours under reagents, a conversion rate of ethylene of 7% is obtained at 230 ° C. with a selectivity to ethylene oxide of 70%.
• Example 2 30 ml of the catalyst prepared in Example 2 are loaded into a laboratory reactor operating under pressure and consisting essentially of a stainless steel tube 355 mm long and 16 mm in internal diameter, heated by a bath of molten nitrates .
• the reagents admitted from the bottom of the reactor are preheated on a 42 mm high porcelain filling.
• the analytical device is identical to that described in Example 3.
• a gas stream containing 13% ethylene, 5% oxygen and 82% nitrogen is passed over the catalyst, at a pressure of 20 bars, at a specific hourly flow rate of 9000 liters / hour normal per liter of catalyst.
• an ethylene conversion rate of 8.5% and a selectivity to ethylene oxide of 71% an ethylene oxide productivity of 139 g per hour and per liter of catalyst is obtained at 221 ° C.
• a catalyst is prepared with an artificial graphite of Le Carbone Lorraine origin, the characteristics of which are collated in Table No. 5 . Analysis indicates that the catalyst thus prepared contains 13% by weight of silver.
• a comparative example was carried out on a catalyst prepared according to the procedure described in Example 1, with an artificial graphite with a particle size of 4 to 5 mm and a total volume of low porosity formed only of pores with radii less than 6.6 microns.
• the characteristics of the graphite used are collated in Table No. 7. Analysis indicates a silver content of the catalyst of 11% by weight. 30 ml of this catalyst are loaded into the reactor described in Example No. 3. After activation treatment identical to that of Example No. 5, a gas flow rate of 14 liters / hour is formed at atmospheric pressure. of a mixture of 13% ethylene, 4.7% oxygen, 82.3% nitrogen and 600 ppb of 1,2-dichloroethane.
• a comparative example was carried out on a catalyst prepared, according to the procedure described in Example 1, with an artificial graphite with a particle size of 200 to 700 microns and a low volume of porosity.
• the characteristics of the graphite used are collated in Table No. 8. Analysis indicates a silver content of the catalyst of 11% by weight. 30 ml of this catalyst are loaded into the reactor described in Example No. 3. After an activation treatment of 50 hours with a 50% -50% air-ethylene mixture at a temperature of 175 to 215 ° C., introduced into the reactor a gas stream of 14 liters / hour formed of a mixture of 14% ethylene, 4.8% oxygen, 81.2% nitrogen and 200 ppb of 1,2-dichloroethane. The best results obtained are shown in Table 9.
• Example 8 30 ml of the catalyst prepared in Example 8 are loaded into the reactor described in Example 3.
• a selectivity to propylene oxide of 25.7% is obtained for an overall conversion of propylene of 1.1%.
• a comparative example was carried out on a catalyst with a silver content of 12.4%, prepared according to the procedure described in Example 1, with an artificial graphite in grains of diameter 400 to 500 millimicrons, with a specific surface of 10 m2 / g and total volume of porosity 0.085 cm3 / g.
• the specific surface of this catalyst is 7 m2 / g.
• a gas stream containing 5% ethylene, 5% oxygen and 90% nitrogen is passed over the catalyst at a pressure of 20 bars and at a temperature of 276 ° C. at a specific hourly flow rate of 9,000 1 / h / normal per liter of catalyst.
• the ethylene conversion rate is 4.7% and the selectivity for ethylene oxide is 36%, which shows that a specific surface area of the catalyst of less than 10 m2 / g is not a sufficient characteristic for that graphite is a good support for silver.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Epoxy Compounds (AREA)

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• 1977
  • 1977-07-08 FR FR7721118A patent/FR2396588A1/fr active Granted
• 1978
  • 1978-06-09 IT IT68356/78A patent/IT1107804B/it active
  • 1978-07-03 EP EP78400048A patent/EP0000460B1/fr not_active Expired
  • 1978-07-03 DE DE7878400048T patent/DE2861279D1/de not_active Expired
  • 1978-07-07 ES ES471577A patent/ES471577A1/es not_active Expired
  • 1978-07-07 JP JP8214978A patent/JPS5418493A/ja active Granted
  • 1978-07-07 AT AT0494478A patent/AT363098B/de not_active IP Right Cessation
  • 1978-07-07 CA CA307,018A patent/CA1110610A/fr not_active Expired
  • 1978-07-07 DK DK306078A patent/DK158774C/da not_active IP Right Cessation

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