Classifications

• • 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
  • B01J23/90—Regeneration or reactivation
  • B01J23/94—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the iron group metals or copper
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/28—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation of CHx-moieties
• • 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
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/005—Separating solid material from the gas/liquid stream
  • B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
• • 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
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
  • B01J8/1845—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised
  • B01J8/1863—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised followed by a downward movement outside the reactor and subsequently re-entering it
• • 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
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
  • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
  • B01J8/26—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with two or more fluidised beds, e.g. reactor and regeneration installations
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/584—Recycling of catalysts

Definitions

• This invention relates to an improved vapor phase process for the catalytic oxidation of propylene to acrolein using as oxidant reducible particulate solids in an oxidized state, and where the resulting reduced solids are separately regenerated using molecular oxygen.
• acrolein An important route to acrolein is the vapor phase oxidation of propylene over a multicomponent catalyst containing molybdenum and/or other metals, usually as their oxides.
• the reaction step involves oxidation of propylene with air (oxygen) to form acrolein, along with carbon oxides, water and smaller amounts of other oxidized byproducts.
• air oxygen
• the reaction is carried out in multitubular fixed-bed reactors.
• the large exothermic heat of reaction and the thermal sensitivity of the propylene oxidation requires low feed concentrations, expensive heat transfer equipment, handling of a large volume of gas, and good reactor temperature control. Low propylene concentration is also required to avoid flammability conditions.
• Modified forms of fluidized-bed reactor are known as recirculating solids reactor, transport bed reactor, transport line reactor, riser reactor, fluidization reactor, multi-chamber fluidized bed reactor, and by other names, depending on design and/or personal preference.
• transport bed reactor to mean any reactor in which solid particles are injected at one end of the reactor and carried along with gas reactants at high velocities and discharged at the other end of the reactor to a gas-solids separation vessel.
• a riser reactor in which the reactor is a vertical pipe wherein the reactive solids and gases are fed in at the bottom, transported in essentially plug flow and removed at the top, is one example of a transport bed reactor.
• a transport bed reactor includes a riser reactor or pipeline reactor which also incorporates a zone for fluidization; i. e., a zone where the gas velocities are sufficiently high to cany out a substantial portion of the solids fed, but with more back-mixing of solids than would occur in plug flow.
• a zone for fluidization i. e., a zone where the gas velocities are sufficiently high to cany out a substantial portion of the solids fed, but with more back-mixing of solids than would occur in plug flow.
• recirculating solids reactor system to mean a general reaction system with two reaction zones, in which two separate reactions take place, and which uses a particulate solid which circulates between the two reaction zones and takes part in both reactions.
• either or both reaction zones may take place in a transport bed reactor or a fluidized bed.
• Such reaction systems have found use in catalytic cracking in petroleum refining and in other reactions.
• U.S. Pat. No. 4, 102,914 discloses a process for the preparation of acrylonitrile by passing a mixture comprising gaseous oxygen, propylene and ammonia, together with an ammoxidation catalyst, in a transport bed reactor while controlling the superficial linear gas velocity and solids feed rate at specific rates.
• European Patent Office Publication No. 0 034 442 discloses a process for preparing unsaturated aldehydes by passing an unsaturated olef ⁇ n and an excess of gaseous oxygen into a transport bed reactor with a solid oxidation catalyst at a linear gas velocity of 1.5 to 7.5 meters/second to achieve substantially plug flow within the reactor. Reaction products are stripped from the catalyst with steam in the stripper chamber.
• U.S. Pat. No. 4,668,802 discloses a process for preparing maleic anhydride by oxidizing butane using an oxidized vanadium-phosphorous oxide catalyst as oxidant rather than oxygen wherein the resulting reduced catalyst is separately regenerated, and the use of a recirculating solids reactor system for this reaction.
• Japanese Kokai 3-170,445 discloses a similar process for preparing acrolein and acrylic acid by oxidizing propane using an oxidized bismuth-molybdenum catalyst as oxidant.
• U.S. Pat. No. 4, 152,393 and 4,341,717 disclose a specific design of reactor which it is said could be used, among a variety of applications, for the oxidation of propylene to acrolein using an oxidized solids as oxidant and regenerating the resulting reduced solids in its regeneration zone.
• a process example shows the ammoxidation of propylene using ammonia and an oxidized molybdenum-based catalyst as oxidant.
• the reactor consists of a single shell containing a reaction zone and a regeneration zone, using a specific design containing a first up-leg, a first down-leg, a second up-leg, a second down-leg and a return leg such that fluidized solids may be transferred from one zone to the other by one route and back by a second route, and so that the gases from one zone are not transferred to the other zone.
• This reactor has a complicated design which offers numerous places for potential plugging and which limits the ability to independently monitor and contiol oxidation zone and reduction zone conditions. This patent does not disclose the improved reaction conditions of the present invention.
• 4,604,370 discloses a process for regenerating a spent molybdenum-bismuth based multi-oxide catalyst resulting from its use for the oxidation of propylene to acrolein by heating it in air to 380 to 500°C for at least 12 hours or to 500 to 540°C for at least 2 hours.
• the present invention relates to an improved process for the selective vapor oxidation of propylene to acrolein in a recirculating solids reactor system using a bismuth molybdate multimetal oxide solids in oxidized form, the improvement comprising: (a) contacting a feed gas containing from 1 mol % to 100 mol % (preferably from 5 mol % to 30 mol %) propylene, 0 to 20 mol % oxygen, 0 to 70 mol % water, and the remainder inert gas with an effective amount of a bismuth molybdate multimetal oxide in oxidized form comprised of particles from 10 to 300 micrometers in size, in a tiansport bed reactor at a temperature of 250 to 450°C, a gas residence time in the reaction zone from 1 second to 15 seconds, and a solids residence time in the reaction zone from 2 seconds to 60 seconds; (b) removing the effluent produced in the tiansport bed reactor of step (a) and separating the result
• Figure 1 shows a schematic drawing of a recirculating solids reactor configuration in which the reaction zone is comprised of two parts, a fluid bed section and a riser section and the regeneration zone is comprised of a fluid bed section.
• Figure 2 shows a schematic drawing of a recirculating solids reactor configuration in which the reaction zone is comprised of a riser section and the regeneration zone is comprised of two parts, a riser section and a fluid bed section.
• the present invention relates to an improved process for the selective vapor oxidation of propylene to acrolein in a recirculating solids reactor system which includes a ti'ansport bed reactor and a solids regenerator.
• the transport bed reactor is preferably a riser reactor in which solid particles are injected at the bottom of a vertical pipe, carried upwards with gas reactants at high velocities and discharged to a gas-solids separation vessel, or a combination of a riser reactor with a fluidization zone.
• the reaction between gas and solids occurs in the riser pipe in a matter of seconds, as distinguished from a conventional fluidized bed reactor where the reaction time is a matter of minutes.
• Gas velocities in a riser reactor are about 2 to 15 times higher than in fluidized bed reactors; solids concentrations range from 2 up to about 40 times lower.
• the products of the above reaction are then sent to a conventional processing unit where the desired acrolein is separated and recovered with any unreacted gasses being recycled for further processing.
• the reduced solids are then re-oxidized in a separate oxidation step to enable their reuse for the oxidation of propylene.
• the reduced solids from the riser zone are first separated from the product gas, stripped of any carbonaceous species in a separate stripper zone and returned to the regenerator. This process permits independent control of the reactant gas concentrations, the gas residence time, and the solids residence time in each zone for optimum operation.
• the feed gas to the propylene oxidation step contains about 1 mol % to 100 mol % propylene, preferably about 5 mol % to about 30 mol % propylene. Some of the propylene used in the feed may be provided by the unconverted propylene which is present in the recycled reaction gas.
• propylene may be available as the predominant component in a mixture of gases including other hydrocarbons; for example, technical propylene used in industry may contain 95 mol % propylene and 0 to 5 mol % propane. As long as none of the other gases present significantly adversely affects the process, it may be more convenient to use this propylene-rich mixture in the feed gas as the source of propylene.
• the oxygen concentration in the feed gas can be from 0 to 20 mol %. Air can be used as the source of oxygen.
• the remainder of the feed can be any inert gas, such as nitrogen or recycled reaction gas containing mostly water, carbon monoxide and carbon dioxide, and possibly unconverted propylene.
• the present invention uses an effective amount of a bismuth molybdate multimetal oxide in oxidized form.
• a bismuth molybdate multimetal oxide in oxidized form.
• this is a specially hardened solid particle which resists attrition, such as disclosed in previously referenced U.S. Pat. No. 4,677,084 and 4,769,477.
• Numerous other bismuth molybdate metal oxide compositions are disclosed in the art for the vapor phase oxidation of propylene to acrolein, and are also suitable for the operation of this invention.
• other transition metal oxidant systems known in the art to promote the oxidation of propylene to acrolein such as for example but not by way of limitation the iron/antimony metal oxide solids, should be considered equivalent for purposes of the process of the present invention.
• the solid particles are preferably about 20 to about 300 micrometers in size.
• the oxidation step is carried out in the reaction zone at a temperature of about 250 to about 450°C.
• the reactor gas exit pressure is typically 0-50 psig.
• the gas residence time in the reaction zone is about 1 second to about 15 seconds, and the solids residence time in the reaction zone is about 2 seconds to 60 seconds.
• the upper limit of solids residence time will, of course, depend on the activity of the solids. If still active, the solids can be retained in the reaction zone for longer than 60 seconds.
• the solids are removed from the oxidation step when the oxidative surface layer of the solids have been essentially reduced to a non-oxidized form.
• the solids in the reactor effluent are separated from the effluent gases, and the acrolein product is recovered from the effluent gases, both separations employing conventional techniques and equipment.
• the separated solids are referred to herein as the reduced solids because they are in a lower oxidation state than that of the fresh solids which enter the reaction zone.
• the reduced solids are preferably stripped of any reactor gases and then transported to the regeneration zone of the recirculating solids reactor system.
• the stripped reactor gases are mixed with the reactor effluent gases.
• Acrolein is recovered from the effluent gases of the reaction zone, and remaining gases may be vented or recycled to the reaction zone. Any off-gases from the regeneration zone can be vented after heat recovery. Since this reaction is highly exothermic, the heat removal from the recirculating reactor system can be done by use of cooling coils , preferably at the solids regenerator but if necày also at the fluidization of feed and/or eventually at the riser.
• the reduced solids are re-oxidized in the regeneration zone using an oxygen-containing gas such as air.
• the regeneration zone temperature is maintained at about 250 to about 500°C.
• the solids residence time in the regenerator zone is about 0.5 minute to, typically, about 10 minutes.
• the oxygen- containing gas residence time is about 3 seconds to about 30 seconds. Total gas flow rate and oxygen concentr ation must be sufficient to provide the needed oxygen for solids re-oxidation to occur within the selected gas and solids residence time.
• the oxidized solids are then recycled to the reaction zone.
• the required amount of solids and the required solids circulation rate depend on the extent to which the solids oxidation reaction is carried out in the regeneration zone (as opposed to the reaction zone), the amount of propylene to be reacted, the amount of mobile (or reactive) oxygen contained by the solids, and the reaction zone process conditions that determine the amount of solids oxygen used per pass.
• oxygen concentration in the reaction zone is low, or zero, and substantially all of the solids re-oxidation reaction is carried out in the regeneration zone, a high solids circulation rate is required. This rate may be reduced, to the extent that the solids re-oxidation reaction is carried out in the reaction zone.
• a recirculating solids reactor system can be operated continuously to oxidize propylene without any gas-phase oxygen in the reaction zone. Such operation results in a higher selectivity to make acrolein than can be attained with conventional reactors, providing an adequate solids circulation rate is maintained to supply the needed oxidized solids.
• gas phase oxygen is shipped from the oxidized solids before recycling them to the reaction zone.
• the high selectivity to acrolein attained in the transport bed reactor is maintained even if the feed to the reaction zone has a very high propylene concentration.
• the gas feed can be 100% propylene.
• Recirculating solids reactor systems can in general have many different reactor/regenerator configurations.
• the reaction zone of the system can be comprised of a tiansport bed reactor, a fluidized bed reactor or other gas-solid reactors, as can the regeneration zone.
• the recirculating solids reactor system employed in this invention utilizes a tiansport bed reactor for the reaction zone.
• the transport bed reactor may comprise a riser reactor, a pipeline reactor, or a riser or pipeline reactor combined with a fluidization zone.
• the regeneration zone of the regenerator can be comprised of a riser reactor, a pipeline reactor, a fluidized bed reactor of any type, or a combination of the above reactors. It is to be understood that the invention is not limited to the specific combination of reactors listed above.
• a transport bed reactor is characterized by high gas velocities of from about 5 ft/sec (about 1.5 m/sec) to greater than 40 ft/sec (12 m/sec). At the lower end of the velocity range there can be a significant amount of local back- mixing of solids.
• the reactor line is vertically mounted with gas and solids flowing upward in essentially plug flow; i.e., a riser reactor.
• the superficial gas velocity in the riser is maintained at 1 to 10 meters/sec.
• the flow can also be downward and the reactor line can be mounted other than vertically, i.e., a pipeline reactor.
• the solids concentration in the reaction zone of the reactor can range from, typically, about 1 lb/ft 3 (16 kg/m 3 ) to, typically, about 10 lb/ft 3 (160 kg/m 3 ), depending on the gas velocity, particle size and density, and the solids circulation rate.
• the solids flux mass flow rate per unit area is at 50 to 1000 kg/m 2 sec.
• FIG. 1 is a schematic drawing of one of the recirculating solids reactor systems used in the examples.
• the reaction zone is comprised of a fluidization section 1 and a riser section 2.
• the feed gas enters 1 and the oxidation of propylene takes place in sections 1 and 2.
• the separator-stripper unit 3 separates and strips off the reaction zone effluent gases from the reduced solids.
• the acrolein product is recovered from the reactor effluent gases leaving 3.
• the reduced solids are transported to the regeneration zone which is comprised of the fluidized bed section 4.
• the reduced solids are re-oxidized in section 4 and the oxidized (regenerated) solids are then recycled to the fluidization section 1.
• the alternate/additional feed line 5 can be used to feed additional oxygen to riser section 2.
• FIG. 2 is a schematic drawing of another recirculating solids reactor system used in the examples.
• the reaction zone is comprised of a riser section 11.
• the feed gas enters 11 and the oxidation of propylene takes place in 11.
• the separator-stripper unit 12 separates and ships off the reaction zone effluent gases from the reduced solids.
• the acrolein product is recovered from the reactor effluent gases leaving 12.
• the reduced solids are tiansported to the regeneration zone which is comprised of a riser section 13 and a fluidized bed section 14. The reduced solids are oxidized in this regeneration zone and the oxidized (regenerated) solids are then recycled to the riser section 11.
• reaction and regeneration zones can be within a single reactor, although better process contiol usually is achieved if the two are in separate units.
• the conversion of propylene in percent is defined as 100 times the number of mols of propylene converted, divided by the number of mols of propylene in the feed.
• the selectivity to acrolein in percent is defined as 100 times the number of mols of propylene converted to acrolein divided by the total number of mols of propylene converted.
• the yield of acrolein in percent is defined as 100 times the number of mols of acrolein formed divided by the number of mols of propylene in the feed.
• Example 1 The attrition resistant solids used in the examples of this invention were prepared by substantially following the procedure in U.S. Pat. No. 4,677,084 and in particular the procedure found in Example 10.
• the stalling solids used to make the attrition resistant solids were obtained following the procedure described in French patent application 97 0243 filed February 27, 1997 in the name of ELF ATOCHEM S.A. and in particular by using multicomponent molybdate obtained according to example 5 of the French patent application.
• the stalling solids prepared according to this French application corresponds to the formula: Mo Cos. 5 Bii Fe 0.8 W 0.5 Si 1.4 K 0.0 5O ,.
• the aqueous solution containing the cobalt was introduced dropwise over 20 minutes into the aqueous solution of the ammonium salts.
• the fenic solution was next introduced over 10 minutes and then the solution containing the bismuth over 15 minutes.
• a solution obtained by dissolving 0.2 grams of KOH and 12,8 grains of colloidal silica (at a concentration of 40 weight %) in 15 mL of water was added over 10 minutes to the resulting gel.
• the gel thus obtained was blended for 1 hour at ambient temperature and then 1 hour at 70°C.
• the gel was next dried for 18 hours at 130°C to obtain a solid precursor.
• the solid obtained was precalcined at about 225°C in air.
• a recirculating solids reactor system of the type shown in FIG. 1 was used to oxidize propylene to acrolein.
• the tiansport bed reactor consisted of a small fluidization section surmounted by a 5/8" diameter by 10' tall riser tube.
• the recirculating solids were transported up the riser tube with the reactant and product gases which are in plug flow.
• Reactant gas contact times were on the order of 1-5 seconds.
• Isothermal conditions were maintained by an electric furnace.
• Temperatures were maintained in the range of 250-450°C.
• Reactor pressure was maintained at atmospheric to 2 psig.
• Riser superficial gas velocity was in the range of 6.6-10.5 ft/sec.
• Riser gas contact time was in the range of 1.3 to 1.5 seconds.
• Propylene feed concentration was varied as shown in the tables which follow. Steam feed concentrations were in the range of 9-33 mol%. All feed flows were controlled by thermal mass flow controllers. Propylene and nitrogen were fed either to the fluidization zone or directly to the riser tube (by-passing the fluidization zone).
• the solids and the product gas stream were separated in a stripper and a series of cyclones.
• the stripper was a 4' diameter fluidized bed. After disengagement and shipping from the solids, the product off-gas was fed to the product quench/absorption system. Solids contact time in the stripper was in the range of 15 seconds to 10 minutes. From the shipper, the solids were then transported to the regenerator.
• the regenerator was a 4.5" diameter fluidized bed. Solids bed height (solids contact time) in the regenerator was controlled by differential pressure control between the shipper and regenerator. Air was fed to the regenerator to re- oxidize the solids. The solids contact time was in the range of 1-21 minutes. The off-gas from the regenerator off-gas was fed to the regenerator quench system after disengagement from the solids in a series of cyclones. From the regenerator, the oxidized solids were then fed back to the fluidization section of the transport bed reactor. The solids circulation rate was in the range of 15-250 kg/hr.
• the two off-gas quench systems for the product and regenerator off- gases were of identical design.
• a recirculating liquid served as a direct contact condenser/absorber for the products.
• Caustic was used on the product off-gas to absorb organic products and to dimerize the acrolein produced.
• Water was used on the regenerator off-gas.
• a hot gas sample stream from the product off-gas was taken to two static water absorbers. The first was used to absorb C 2 /C 3 aldehydes and acids for quantitative analysis by an off-line gas chromatograph. The second was used as a pre-treatment absorber to remove aldehydes and acids which interfere with the analysis, prior to on-line gas chromatographic analysis of N2, O2, propylene, CO and C0 2 .
• the regenerator off-gas was sampled down-stream of the water quench and analyzed for N 2 , 0 2 , propylene, CO and C0 2 . Reactor performance was determined by on-line gas chromatograph analysis for non-absorbed components in each of the two off-gas streams.
• Water absorbed products were measured by off-line gas chromatograph analysis of the liquid sample absorber.
• the composition of the feed gases are presented in the tables as mol % of propylene, steam and nitrogen. If air was employed the amount is identified in a footnote. In some of the tests the contact time may have been increased by directing the gasses to the bottom of the fluidized bed rather than the base of the riser (see FIG.1 feed line 5).
• the primary process variables in the tables below are abbreviated as follows: Fluid. Bed Temp °C (fluidized bed temperature in °C), C3H6 Feed Cone, mol % (propylene feed concentration in mol percent), Gas Cont. Time sec (gas contact time in seconds),and Sol.
• Rate kg/hr solids circulation rate in kilograms per hour.
• the primary responses were measured as key process variables were changed, and are abbreviated in the tables below as follows: Propylene Conver. % (percent propylene conversion), and C 3 /C 2 Select. % (percent selectivity to C 3 and C 2 reaction products).
• the tests were grouped into three sets (Tables 1, 2 and 3 below).
• the first set (Table 1) included tests where all riser side feeds were to the fluidization bed.
• the third set of tests included tests where all propylene feed was to the riser (no propylene in the fluidization bed).
• Test Fluid C 3 H 6 /steam /N 2 Gas Sol. Propylene C 3 /C 2
• Test Fluid C 3 H 6 /sle m /N-> Gas Sol.
• Example 2 In a manner analogous to the procedure of Example 1, a series of four additional runs were performed in the recirculating solids reactor of the type shown in FIG. 1. In these runs propylene was converted to acrolein using essentially the same bismuth molybdate multimetal oxide composition as was used in Example 1. The only difference was that the salt precursor after drying was not precalcined at 225°C in air but instead was directly milled to the desired particle size range and mixed with polysilicic acid solution. This slurry was then spray dried and the resulting solids were precalcined at 225°C in air and then calcined at 450°C for 9 hours in air to produce the attrition resistant solids. The process variables and test result data for these additional runs are presented in Table 5.
• Test Fluid C 3 H 6 /steam /N-. Gas Sol. Propylene Acrolein and

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• 1998
  • 1998-07-14 AU AU84007/98A patent/AU8400798A/en not_active Abandoned
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