CA1076775A - Process for the manufacture of sulfur trioxide from sulfur dioxide and oxygen - Google Patents

Process for the manufacture of sulfur trioxide from sulfur dioxide and oxygen

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Publication number
CA1076775A
CA1076775A CA224,398A CA224398A CA1076775A CA 1076775 A CA1076775 A CA 1076775A CA 224398 A CA224398 A CA 224398A CA 1076775 A CA1076775 A CA 1076775A
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CA
Canada
Prior art keywords
oxygen
liquid
catalyst
reaction
sulfur
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.)
Expired
Application number
CA224,398A
Other languages
French (fr)
Inventor
Karl Walderbach
Hansjorg Mathieu
Heinz Steinrotter
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Hoechst AG
Original Assignee
Hoechst AG
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 Hoechst AG filed Critical Hoechst AG
Application granted granted Critical
Publication of CA1076775A publication Critical patent/CA1076775A/en
Expired legal-status Critical Current

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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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B01J23/22—Vanadium
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • 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
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • 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
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/06—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds in tube reactors; the solid particles being arranged in tubes
    • B01J8/067—Heating or cooling the reactor
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C01B17/78—Preparation by contact processes characterised by the catalyst used
    • C01B17/79—Preparation by contact processes characterised by the catalyst used containing vanadium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C01B17/80—Apparatus
    • C01B17/803—Converters

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

Abstract

PROCESS FOR THE MANUFACTURE OF SULFUR TRIOXIDE FROM
SULFUR DIOXIDE AND OXYGEN
Abstract of the disclosure Sulfur trioxide is prepared from SO2 and technical O2 in a reactor filled with catalyst and constructed as tubular heat exchanger. The reactor is cooled on the outside by a liquid coolant.

Description

HOE 74/~ 112 10'767'75 The invention relates to a proce~s for the manufacture of sulfur irioxide from sulfur dioxide and technical oxygen by carrying out the reaction in tubular heat exchangers in the presence of catalysts.
The pr~paration Or sulfur trioxide on a large scale which i8 the basis of the sulfurio acid manufacture generally is per-- formed according to the so-called contact process. Thereby gases resulting from the sulfur combustion or the metal sulfide roasting and having a content of about 10 to 18% by volume of 10 S02 are oxidized in the presence of air on vanadium pentoxide contacts to yield gases containing sulfur trioxide. A solution of sulfur trioxide in sulfuric acid (oleum) and sulfuric acid is obtained by absorption. The contact gases mixed with the air generally contain maximally 10.5% of S02. Most frequently 15 so-called grid type catalysts are used, where the contact msterial is extended on slit grids. Usually 4 or 5 grids are superposed each time. The operating temperatures depending !,, on the catalyst uaed are in the range of from 400 to 620 C
when using a catalyst containing vanadium pentoxide. At a tem- -~
20 perature below this operating temperature a reaction does not take place on the contact. Therefore the gas must be heated to the operating temperature. An exothermal oxidation is then effected on the contact giving S03, whereby the tempera-ture of the gas further increases.
In the case of gases containing about 10 to 11~ of S02 the temperature increases to approximately 620C. In the case of gases ha~ing a substantially higher content of S02, for example of more than ~0~, the temperature may even further 29 increase, if there are not made any particular arrangements.
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10767~75 The catalyst would be damnged, however, by the high tempe-ratures obtained.
In the described process the reaction ~s efrected adia-batically and the reaction heat l~ emitted st~pwise in the interconnected cooling segments. Several process are known for avolding a damaging of the catalyst becau~e of overheating when using ga~es of a high content Or S02.
It is for example known for the oxidation of pure S02 with oxygen to add circulating already converted sulfur tri-o~ide to the starting gasQsfor reducing the ~emperature thus still enabling controlling the reaction temperature obtained (cf. German Offenlegungsschrirten Nos. 2,159,789 and 2,223,131).
~` These processes are based on the contact materials tradi-.
tionally used in industry and are working adiabatically. The heat released in the reaction, consequently, may only be : :. . .
transrerred, to the gase within the grid. The portion of inert gas, consequently, cannot be substantially reduced.
The apparatus dimensions required are therefore relatively ` large and limit the ~uantity of S03 produced per unit of vo-~; 20 lume.
A process is also known wherein a mixture of air and roaster gases is introduced into the tubes filled with contact ~.
material and the reaction heat produced in said tubes is absor-bed by the cold mixture of sulfur dioxide and air passing outside. This process may not be transferred, however, .
on gas mixtures practically free from inert gases when using i the usual catalyst materials.
Desiring toconstruct plants as economic as possible, the 29 dimensions of the grids were increased to obtain a daily out-`
:: -- 3 --'~-; -- ~ : .
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~ 1076'775 put of up to about 1200 t of SO3. In the case of a still greater lay out the investment costs increase overproportionately.
The invention consequently was concerned with the problem to develop a contact process for preparing SO3 from SO2, wherein the reactor may be reduced while having the same output.
According to the present invention, there is provided process for preparing sulfur trioxide on an industrial scale from sulfur dioxide and oxygen, which comprises using technically pure S02 and technical oxygen and carrying out the reaction in tubular heat exchangers, an outer surface of which is liquid cooled, in the presence of a V205 catalyst containing less than 5% by weight of V2O5 disposed inside tubes of the tubular heat exchangers, the proportion of 02/SO2 being in the range of from 0.525 to 0.55, said , liquid cooling being performed to an extent sufficient to maintain favourable operating conditions for the particular oxidation catalyst employed.
In this way nearly pure SO3 (without admixtures of air) may be obtained. Because of the high concentration of SO3 the product obtained may also be condensed by cooling and split off in a liquid form.
The degree of purity of the technical oxygen used preferably is superior to 90% by volume. Small quantitites of SO3 (of up to 5% by volume calculated on SO2) formed during the preparation of SO2 may be admixed. It is true that SO3 may be admixed to SO2 for reasons of a better heat emission, but is is not required in the process according to the invention. The degree of conversion of S02 depends, besides its retention time in the catalyst bed, ~; on the temperature of the reactor (which may be controlled by the temperature of the exterior cooling medium) and on the quantity of the oxygen used. Owing to the fact that the reaction is effected according to the equation 2 S02 + 2---~ 2 S03, the proportion 02/S02 is at least 0.5, preferably in the range of from 0.525 to 0.55. An excess of oxygen in the case of the same temperature may shift the equilibrium towards S03. If a great excess of oxy-.~, .- ~.

.: . ; , : ', ,: ,, .
~ ' , ' ` ' ~ HOE 74/F 112 gen shall be maintained in the reactor, the added quantities f S2 and 2 being however stoichiometric~ it may be advantage-OU8 to recycle the re~idual gas to the reactor after conden-~ation of S03. The same applies if the conversion Or S02 has - 5 not been complete.
It is surprising that highly concen~rated mixtures of S02/
2 may be reacted according to the process of the invention, ~ince it was not expected that gases containing more than 9% of S2 could be reacted on catalyst materials without damaging the 10 catalyst (German Offenlegungsschrift No. 2,159,789).
The process according to the invention solved the problem to reduce the dimensions of the reactor containing the contact . ~
by dispensing with the use of inert gases as well as by desig-ning the reaction tubes as heat exchangers. The complicated re-circulating pump installations may be substantially reduced in ~, thi~ process. The heat exchanger is improved in the process by a higher speed of the gas in the reaction tube and by im-, mediatiely emitting the liberated heat from the contact bed.
The problem to prepare pure S03 without necessarily ob-taining su~furic acid is also solved by the process, owing tothe fact that the oxidation is effocted with oxygen and no longer with air. The process consequently is no longer concer-ned with problems connected with the use of air and the ab-sorption of the water vapon contained therein by means of concentrated sulfuric acid.
It has now been-found that catalyst based on vanadium pentoxide, but only having a content of less than 5%, especi-;
ally of from 0.2 to 2~, preferably of from 0.5 to 1~ of V205, 29 in contrast to catalyst used in the oxidation of roaster gases .~, .

: ~ .
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, :
.

:-: :
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are especially suitable for oxid~ing concentrated gaA mi~tures according to the proce~ of the invention. Higher contents of V~05 are possible, but the diameter of the heat exchanger tube must then be further rsduced. Iron oxide catalycts may also be used. These catalysts are substantially less suscepti-ble to damaging by high temperatures. The equilibrium is how-ever less favorable in this case because of the required high-er operating temperatures. It is operated at a temperature of from 420 to 630 C in the presence of V205 catalysts, at a temperature of from 500 to 780 C in the presence of Fez03 catalysts and at a temperature of from 400 to 750 C in the presence of platinum catalysts.
~- It is also possible to work with platinum as catalyst.
The heat exchanger surfaces for example may be coated on the reaction side with platinum or a platinum network may be hung into the reaction zone, for example in a parallel manner with regard to the axis of the heæt exchanger tubes or the reactio zone may be charged with spirally rolled nets.
Oxidation and heat development are effected inside the heat exchanger tubes being preferably filled with a lumpy contact. The reaction heat is conducted off directly via the-tube walls. The process consequently is isothermal. A heat profile is formed inside the individual tubes, the tempera-- tures decreasing from the inside to the outside. The peak of the temperature produced may be placed in the desired zone by selecting the tube diameter or the diameter of the contact and by the impregnation of the contact with the cata-lyst as well as by the gas speed. The length of the tubes 29 depends on the resting time and consequently on the gas speed.
' ' ' .

~ . ~

The resting time required for attaining the equilibrium decrea-~es ~ith an increasing content of the catalyst of V205 (cf.
Helv. Chim. Acta, volume 24, page 71, E 1941).
~or reasons of a better heat transmiss~on it i9 advisable in any case to U~Q tubes as long as possible, ir the volume is given, in order to obtain a greater proportion of ~urface/vo-lume. For economic reasons (costs, pressure loss Or the gas) the tubes used should not be too long, however, so that the real tube length is a compromise. -tO The heat flow from the outer surface of the tubular heat - exchanger i~effected by liquid coollng. The heat may especi-ally be emitted to liquids under pres~ure, for example to water. Salts melts, mercury or heat resistant oils may also . ,:
be used for cooling.
Heat transfer oils which do not decompose below 320C
may also be used. Even when the inner temperature of the reac-tion tube i8 500 C, it is possible to maintain the temperature Or the heat transfer medium at 200C by recirculating rapidly enough.
It is advantageous for reasons of rentability that the tu-~ bes of the heat exchanger filled with a catalyst have a circular :. .
cross section.
A higher limiting temperature in the reaction and a redu-ced` convérsion of sulfur trioxide (a yield of about 70% at about 700 C) were obtained in tests with iron oxide as catalyst.
Such an arrangement is important for cases where a complete conversion is not desired, for example when a part of the sul-... .
~ ~ fur dioxide is required elsewhere, for example, in plants for , 29 preparing sulfites.

It is likewise possible to perform the main reactionat a ~gher ., - ~ .
-: . . :
. ' . :
:- -- , .
- : : .

,........................................... .
. . .
. . . .

- -"` 107~775 o tcmperature (of up to 780 C) on iron o~ide and the secondary reaction after cooling the gases at a lower temperature on vanadium o~ide catalysts. Thereby profit is taken from the more favorable equilibrium at lower temperatures.
The mixture leaving the reactor consisting of S03, oxygen, non reacted S02 and various inert gases (argon and nitrogen) i8 cooled in known manner to enable a condensation of the sul-fur trioxide as complete as possible. Thereby the entering gas mixture (S02/02) may be previously heated to the opsrating temperature or a part Or the heat energy may be used for pro-ducing steam. The residual gas quantity having about 40 C
when leaving the reactor has the sulfur trioxide tension ; corresponding to this temperature.
A great part of the non reacted gases may be recycled to the reactor according to the conversion obtained. For re-moving the inert gas portions a small part of the non reacted gases, depending on the impurities of the starting gas, is withdrawn from the cycle, purified (for example by adsorption ~- of S03 and S02) and released at the open air.
The invention will be illustrated diagrammatically by way of example in the accompanying drawing which is a flow :
scheme of the process of the invention.
. .
S2 and 2 are introduced via conduit 1 into the contact furnace 2 where they react in the tubes filled with the contact.
,; .
25 The reaction heat i8 conducted off by a heat emitting agent ` entering at ~ and leaving when heated via 4. The reaction gases are further cooled in the heat exchanger ~ and liquified in the condenser 6 by means of the cooling water introduced 29 at 7 and leaving at 7a. The liquid S03 is removed at 8. A
, .
... . .
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~ HOE 74/F 112 .1076775 k part of the residual gas flow optionally i8 recycled to the ~ contact furnace 2 by passing over the blast 2 and conduit 10.
- The residual gas to be removed i9 introduced into the wa~her 11 by passing over conduit 15, liberated from S02 and S03 and led in the open air by the chimney 12.
By pump 13 a washing liquid is conveyed in a circuit which liquid is discharged at 14 after being exhausted.
The following example illustrates the invention.
. E X A M P L E:
' A mixture of sulfur trioxide and oxygen (66% by volume of S02, 34% by volume of 2) was heated to 550 C and intro-duced into a tubular reactor. The reaction tubes were filled with a catalyst, containing at the ~eginning of the reaction ~ zone 0.5% and at the end 1~ of V205. The catalyst was prepa-l 15 red from a commercial catalyst with 10~ V205 by diluting with inert Al203 filler to the desired V205 content. The lowest operating temperature for,the catalyst was 550 C, the inacti-... .
vating temperature from 620 to 650C, the length of the tubes (filled with the catalyst) 5 m, the inner diameter 40 mm, the thickness of the tube wall 2.5 mm, the retention ~`~ time of the gas 17.8 sec. . The tubes were cooled by evapora-, , .
' ting compressed water of 250C (of about 64 atmospheres gauge)-The conversion of S02 was 99% of the theory.

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for preparing sulfur trioxide on an industrial scale from sulfur dioxide and oxygen, which comprises using technically pure SO2 and technical oxygen and carrying out the reaction in tubular heat exchangers, an outer surface of which is liquid cooled, in the presence of a V2O5 catalyst containing less than 5% by weight of V2O5 disposed inside tubes of the tubular heat exchangers, the proportion of O2/SO2 being in the range of from 0.525 to 0.55, said liquid cooling being performed to an extent sufficient to maintain favourable operating condi-tions for the particular oxidation catalyst employed.
2. Process as claimed in claim 1, wherein the oxygen content of the technical oxygen is greater than 90% by volume.
3. Process as claimed in claim 1, wherein up to 5% by volume, calculated on SO2, of gaseous SO3 are admixed to SO2.
4. Process as claimed in claim 1, wherein the heat exchanger is cooled with an evaporating liquid.
5. Process as claimed in claim 1, wherein the cooling liquid is evaporating water.
6. Process as claimed in claim 1, which comprises forced circulation of the cooling liquid.
7. Process as claimed in claim 1, wherein the cooling liquid is mercury, a salt melt or a heat resistant oil.
CA224,398A 1974-04-13 1975-04-11 Process for the manufacture of sulfur trioxide from sulfur dioxide and oxygen Expired CA1076775A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2418216A DE2418216C2 (en) 1974-04-13 1974-04-13 Process for the production of sulfur trioxide from sulfur dioxide and oxygen

Publications (1)

Publication Number Publication Date
CA1076775A true CA1076775A (en) 1980-05-06

Family

ID=5912998

Family Applications (1)

Application Number Title Priority Date Filing Date
CA224,398A Expired CA1076775A (en) 1974-04-13 1975-04-11 Process for the manufacture of sulfur trioxide from sulfur dioxide and oxygen

Country Status (7)

Country Link
JP (1) JPS50137889A (en)
BE (1) BE827914A (en)
CA (1) CA1076775A (en)
DE (1) DE2418216C2 (en)
FR (1) FR2267283B1 (en)
GB (1) GB1504725A (en)
NL (1) NL7504164A (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2648011C2 (en) * 1976-10-23 1983-02-17 Adolf Dipl.-Chem. 5024 Pulheim Stauffer Method and device for the catalytic oxidation of sulfur dioxide to sulfur trioxide
DE2711897C3 (en) * 1977-03-18 1980-01-10 Davy International Ag, 6000 Frankfurt Process and device for the catalytic oxidation of gaseous sulfur compounds to sulfur trioxide
DE3006900C2 (en) * 1980-02-23 1982-07-01 Davy McKee AG, 6000 Frankfurt Device for carrying out the catalytic oxidation of gaseous sulfur compounds to sulfur trioxide
SE422317B (en) * 1980-06-19 1982-03-01 Boliden Ab PROCEDURE FOR THE PRODUCTION OF Sulfuric Acid from Sulfur Dioxide CONTAINING GAS
DE102006051899A1 (en) * 2006-10-31 2008-05-15 Bayer Technology Services Gmbh Process and apparatus for the catalytic oxidation of SO2-containing gases with oxygen
WO2015191212A1 (en) 2014-06-09 2015-12-17 Chemetics Inc. Single contact, single absorption system for producing sulfuric acid with high conversion efficiency
WO2021118599A1 (en) 2019-12-13 2021-06-17 Chemetics Inc. Integrated ammonia and sulfuric acid production plant and process

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE428279A (en) * 1937-06-28
DE692836C (en) * 1938-04-24 1940-06-27 Fried Krupp Germaniawerft Akt r catalytic gas reactions
DE1542494C3 (en) * 1966-07-21 1975-06-05 Veba-Chemie Ag, 4660 Gelsenkirchenbuer Device for carrying out catalytic reactions

Also Published As

Publication number Publication date
BE827914A (en) 1975-10-14
FR2267283B1 (en) 1978-09-01
DE2418216A1 (en) 1975-10-30
FR2267283A1 (en) 1975-11-07
JPS50137889A (en) 1975-11-01
GB1504725A (en) 1978-03-22
DE2418216C2 (en) 1983-02-17
NL7504164A (en) 1975-10-15

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