DE2118946A1 - Process for the production of a strongly reducing gas - Google Patents

Description

DR. ILSE RUCH

PATENT ADVOCATE

MUNICH 5 011OQ / C

REICHENBACHSTR. 51 Z || O 9 4

TEL. 203251

Pullman Incorporated, Chicago, Illinois, USA Process for the creation of a strongly> reducing oasis

The invention relates to a method for producing a reducing gas and in particular a hot oasis of high reducing power thanks to a two-stage catalytic Steam reforming of hydrocarbons.

There is a considerable need in metallurgy for a process for the production of a hot, strongly reducing oase, the H ₂ + CO content of which is not less than 88 mol / o and preferably at least 93 mol or more and that at a temperature of at least 955 ⁰ C and preferably between about 98I and about 1150%, so that it can be used directly for the reduction of various ores, for example Elsenerze »and as a replacement for part of the coke in blast furnaces to reduce the coke consumption and increase the blast furnace capacity.

E? J is known to contain gases containing hydrogen and carbon monoxide through catalytic steam reforming of hydrocarbons,

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like methane (natural gas) ”and higher hydrocarbons, 'JUh. by toset ze η of hydrocarbons with Danpf using a catalyst, for example a nickel-containing catalyst. The reaction is carried out with the use of methane as the hydrocarbon by the following equation}

CH ₄ + H ₂ O ■ » G® * 3H ₂ (1)

OemäS of this equation is 1 haul of steam per carbon atom in the hydrocarbon required or in other words, the steam / carbon ratio is 1.0. However, other conversions can also take place in the reforming zone. For example, there may be disproportionation of carbon monoxide according to the following equation:

2 CO> CO ₂ + C (2)

or to a crack according to the following equation:

C + 2H ₂ (5)

come.

In the above reactions (2) and (3), carbon is deposited on the catalyst, which is thereby deactivated and, in the worst case, a blockage of the catalyst bed. To prevent this carbon deposition, the steam is generally in considerable Overshoe used, i.e. in practice the ratio lies Steam / carbon usually in the range of about 3: 1 to about 10: 1.

Using such an excess of steam does it but impossible, by direct steam reforging a hot,

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produce strongly reducing gas. Rather, the drain must the steam reforming zone in at least two further process stages are freed of water, usually first being cooled in order to condense out the steam, and the The temperature of the best gas is then increased again. Auflerdee required but the use of steam in such excess requires a reforming plant of correspondingly large dimensions and the generation of the required quantities of steam of sufficient temperature.

It is also already known, directly through hydrocarbon formation with a conventional reforming catalyst Produce strongly reducing gas by removing the hydrocarbon feed a considerable one for the reforming zone «Close to hydrogen to prevent the deposition of carbon on the catalyst. From the USA patent 5 119 667 it is also known that the required steam / carbon ratio can be reduced considerably by that the steam reforming is carried out in the presence of a nickel catalyst, to which an active alkali compound is added. The alkali-containing catalyst is, however, because of the Volatility of the alkali component is unstable, i.e. it has only a short service life and corrosion easily occurs the plant.

The invention relates to a process for the production of a gas of high reduction capacity by reacting a hydrocarbon charge with steam in a reforming zone in the presence of a refining catalyst which contains at least 0.5% by weight of an added active alkali compound at an elevated temperature and one Pressure in the range from atmospheric pressure to about 17.5 atmospheres, which is characterized in that at. Compliance with a steam / carbon off ratio of not more than 1.5: 1 a Te 11 reforming is carried out and the te: *.! reformed gas then under steam reforming conditions

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in the presence of a steam reforming catalyst which practically is free from an added active alkali compound, is further reacted.

The method according to the invention has the advantage that through the use of an alkaline reforming catalyst only in the first stage the formation of carbon and its deposition on the catalytic converter, which otherwise occurs at the high refining temperatures. and the low steam / carbon ratio would be avoided. The formation of Carbon is mainly due to the disproportionation of carbon monoxide to carbon dioxide and carbon. In addition, in the first stage of the process according to the invention there is a considerable conversion of methane to steam to hydrogen and carbon monoxide, so that the methane concentration or the methane partial pressure in the second stage is relative low 1st. But that is for the separation of carbon by cracking methane, which is otherwise in the case of the second Stage applied high temperatures would take place, both for thermodynamic and kinetic reasons unfavorable.

A reducing gas of high reducing power ("high "strength reducing gas" is defined as a gas containing at least 88 moles of hydrogen plus carbon monoxide, wet basis.

The reforming zone can be of any suitable construction. For example, a separate chamber can be provided within the reforming zone for each stage of the process. Each reforming zone expediently consists of a vertical tubular reactor Inside a furnace that is hot-burned "- Products is heated, usually many such tubular reactors are arranged in parallel within a furnace. Everyone The reactor is then charged with both catalysts in such a way that one catalyst bed is directly above the other.

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The feed to the refilling zone can consist of hydrocarbons, liquid or gaseous under Noitaal conditions, or mixtures thereof. Also, the process can be applied to a feed containing aliphatic and aromatic hydrocarbons, including acyclic and alicyclic paraffinic and olefinic organic components. The feed may also contain unsaturated hydrocarbons such as acetylenes, dienes, etc. an average molecular weight of about 60 or less, or having an average of about 4 or less carbon atoms per Hol Beechickungsgaa used. Such a preferred boiling gas can consist of a virtually unlimited number of combinations of individual hydrocarbons, ie the feed can consist of a mixture of individual hydrocarbons having 4 or more carbon atoms and 4 or fewer carbon atoms per molecule. The feed preferably contains a substantial proportion of methane, ie is a natural gas or a cracked product high in methane.

If the hydrocarbon feed contains significant amounts of sulfur it is usually advisable to remove it sulfur before it is introduced into the reforming zone. Conveniently, the sulfur content of the feed to one To prevent reduction in the activity and selectivity of the catalyst, at a maximum of about 10 ppm and especially at below about 5 and better below 1 ppm.

The amount of steam supplied to the re-oxygenation zone depends on the Hydrocarbon feed rate from. The steam / carbon ratio, i.e. the number of moles of steam per gram atom of carbon should not be kept above 1.5 * 1 and preferably below 1.4: 3 will. The lower limit of this ratio at which the method can still be carried out if with only one throughput

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is usually little above ItI. This limit however, it can be reduced considerably * if a hydrogen-free gas such as a spent gas is a subsequent reduction zone, is returned to the reforming zone. In this case, the consumed gas usually undergoes a single or multi-stage treatment for at least one subject to partial separation of water and carbon dioxide, before it is returned to the reforming zone.

Steam and hydrocarbon feed are first brought into contact with one another in the presence of a steam refining catalyst which contains an added active alkali compound. "Alkali compound ¹¹ " is to be understood as meaning a compound of an alkali metal or alkaline earth metal. Among these, the alkali metal compounds, for example compounds of sodium, lithium and potassium, are preferred. The active catalytic component for the steam reforming in the first stage is usually a metal Bis group of the periodic table, such as nickel, cobalt, etc., and is present in the catalyst in amounts above about 4 wt .- ^, generally between about 10 and about 50 wt .- ^ or in an even higher concentration, calculated as oxide The amount of active alkali compound added, calculated as metal, should be at least 0.5% by weight and is preferably between about 2 and about 20% by weight of the catalyst.The catalyst also contains a carrier and may also contain a binder Such supports and binders are known and buses will not be described in detail. Examples of catalysts which are particularly suitable for the In US Pat. No. 3,119,667, suitable implementation of the first stage of the process according to the invention are described. Xa Bändel receives loaned is the catalyst 46-1 Imperial Chemical Industries, of about 7 wt -.% Potassium, calculated as containing oxide.

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The term "added active alkali metal compound" ("added active alkaline metal oonpound") is used in the same way as in the US Pat. No. 3,119,667 mentioned above the various processes for the production of such a catalyst as well as the composition of the catalyst support « and the binder are described. Since the carrier and binding agent contain considerable amounts of various alkali metal compounds together with other components which are able to neutralize the alkali metal compounds can, the alkali metal component must be in sufficient amount to compensate for such a loss of neutralization and, in addition, the amount of active unbound alkali compound needed to lower the amount of steam required is necessary to deliver, used.

The AbfIuS the first stage of the process acc to the invention is then contacted with a "conventional active steam reforming catalyst approximately le good heat resistance at Refornierungetemperaturen raised, ie at temperatures of about 953 ⁰ C and above, into contact. This catalyst, too, usually contains a metal from the iron group of the periodic table, for example nickel or cobalt, as the active component. The active component content of this catalyst is preferably greater than that of the catalyst used in the first stage. In the fresh state, the catalyst used in the second stage should at most contain only small amounts of added active alkali metal compound and should advantageously be practically free thereof. Examples of such commercially available catalysts are catalysts 54-2 and 57-1 from Imperial Chemical Industries and G 56-B (Girdler). In the case of the catalyst of the first stage, the carrier and binder of the catalyst of the second stage, if present, can contain considerable amounts of various alkali compounds in the bound or neutralized state.

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The quantitative ratio of the catalyst of the first to the catalyst of the si $ eifc @ ra Stiaf® kasm in Elßan w «itesa Bereist! vary. X & Generally, tos Volumverhältsiis ~ of catalyst of the first stuf © sn tessiufckatelysatorsinsafcs to desi range of about O ₉ SSi Ibis © fewa O ₀ SaI ₈ The ratio tatsäehlieb used depends t TWSS, ®-won the EialaStemperatiir the first stage, ö®r Auslaßtemperatei ⁵ 4 © f salten level and Ö <em temperature profii in the entire B. @ t <®m & em®gßZQne . The catalyst of the first ice cream. Level is "<§ @ imliiig we send in soloter amount uer Reforroleruiigssone = on, dai d © ^ share d © r Rtforaiemmggwsefczung which at Temp®" = temperatures föter € 64% TOFSug © s? @Ise la the area on ¥ 6645Ϊ until done, Ib togsisstarfe di @ s © s catalyst durehg® leads Innerfealb des @ fe © s @ nfMfeat @ ß Seropefatiaffeereiohes lies narrower terapes ^ fearte2 ³ SIeMj, in which carbon are deposited ^ iXfUe ₀ always the VerfaSirea rait ö © ra encountered low Ratio of steam ^ © fel © iaafc @ ff in fcgenwas * © ines alkalifr © i @ B Re

Because of Äer FlfieSiSfelgkeife ä © ^ Iltelikeepesoat © feel s © hr peratufen g @ li ii @ fesiperafeas ⁵ ö @ s Eat © ly © at ©? Bettee level 8? OT imü ^ © i? Seggij © ise © tgsia 815 ¹ ^ ®l © Sifa transfer

The EiisstellMsig tmä uaiiaaife ^ Mg gesifagfeei ⁹ Teepe ^ afein ^ a In HefoiBi © Susis

If di © B @@ © läi @ lcMss feel sia a £ © Ö £? Lg © a foEjpeamtB ^ fn with d © si catalyzer Sb loafeatefe te ^ sfe _s wäM a «! I & © £ a £; onst ten relationship Steam / tohlensfeöff the l © W.enstDffbildung EinlaSend © od © r iß äei ° läte © of the inlet @ Rä @@ bed rivets v @ ffein <ä © f'fe _a Ba ile katalytiseke endotherro isfe and äew MSgliehkelt uer Häzsnesul'ihr 6r . @ n2eE set Sinai, WiS ⁵ Cl di © BesQhickung preferably on a si © g «lent hell® Taaper & tus?» for a pyrolysis or other food

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Scoring the load is still avoided, preheated. the Preheating can be done by indirect heat exchange either before the feed is introduced into the reforming zone or » if possible, before introducing the feed into a Desulfurization zone.

The load temperature of the second stage should be global Temperature at which the product is to be fed to a subsequent process, for example a reduction zone, correspond. Suitably the outlet temperature will be at least 953 ° C and preferably in the range of about 981 "C and held about 1150%.

The pressures used in the method according to the invention can be between about atmospheric pressure and about 17.5 atmospheres. The pressure actually applied is mainly determined by the pressure in the subsequent reduction zone, measured at the outlet » end for the consumed reducing gas and taking into account the pressure drop within this reduction zone and other necessary system parts, such as valves, lines, etc. Preferably, pressures between about 0.7 and about 10.5 atmospheres are used in the steam reforming zone.

The throughput rate should be at least 276 liters of methane equivalent in the hydrocarbon feed per hour per ttr of seed catalyst in the first and second stages and is preferably in the range between about 470 and about 1880 Nm. H . m ^ held.

The following examples illustrate the invention. example 1

The lower part of a pilot plant tube reforming reactor with an internal diameter of 7.1 cm was loaded with 17 # 097 kg

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ίο -

Catalyst »54-2 from Imperial Chemical Industries in the form of Rasehig rings of 1.59 x 1 * 59 cm, which occupied 4.39 si the entire length of the reactor. 12.675 kg of catalyst 46-1 from Imperial Chemical Industries, which took up 3.05 m of the reactor, were introduced directly over this catalyst bed.
This second catalyst also had the Fora von Raschig rings of 1.59 x is59 cm. The total volume of the catalyst was 30.4 liters and the volume ratio of the alkali-containing catalyst of the first stage to the total catalyst was 0.38. The reactor was
inside an electric resistance furnace with an inner diameter τ? οη 58.5 Gto » whose wall was electrically heated, arranged"

The hydrocarbon oil leak was a desulphurized natural gas of the following composition?

component

CO ₂

CH ₄

^C 4 ^H i0
^C 5 ^H 12

Steam and hydrocarbon were measured separately and anschiieSsnd _s mixed in a gas heated furnace
Prewaxed to 49 ° C and into the upper end of the tubular reactor, the
kept under pressure ¥ ob4,, 06 etHCes ReaktoraixsiaS) was initiated *. Steam was iron in an amount of 1538 mol / Ii and

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Initiated hydrocarbon in an amount of 1192 Hol / h, so that the ratio of steam / carbon 1.23 and Methanäquivalentdurohsatzgeschwlndigkeit 910 only, h ^'1. E ~ ^ was. The temperature was at Einlafl the Refontiepungszone at 522NJ, at the catalyst interface at 7 & fK and held at 987 * C on the discharge «

Under the above conditions, the qesameethane equivalent conversion was 97.8 mol%. The drain of the first and the drain of the second stage had the following composition (nitrogen-free basis) ι

component First stage
MoI- * Second step
KoI- * »2 51.0 70.5 CH ₄ 14.6 0.5 CO 11.3 22.4 co ₂ 5.0 1 * 2 C ₂ H ₆ 0.2 - H ₂ O 100.0 100.0

The approach lasted ten hours, during which tent none Signs of carbon deposition were observed.

Example 2

This approach was carried out in the same plant as that of Be 1 = game 1 performed. The top of the reactor contained 3 »O5 m catalyst of the first stage (46-1 from Imperial Chemical Industries) with a weight of 11> 958 kg. The lower catalyst bed consisted of 4.35 α Girdler 0-56 B catalyst in the form of 17.549 kg of Raschig rings of 1.59 * 0.95 cn. The volume of the

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total catalyst was 28.4 1 »dec» pressure was at the outlet of the catalyst kept at 1.47 atmospheres. The one in this example Used® feed was a natural gas that cost about $ 25 one cracked öasSls with a considerable content of unsaturated hydrocarbons were added. Diesos BesaniekusagsgemiSGh had the following composition?

component

CO ₂

77.7

CgH ₂ 0.2

5 * 3

0.1

0.9

C ₄ H ₈ 0.1

C ₄ H ₁₀ 0.1

ο, ι -C ₅ H ₁₂ ο, ι

0.2

After desulfurization, the feed was mixed with steam, preheated to 454 ^ 0 and inserted into the top of the reactor in

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a Manse of 5Ö2 UOI / la Kohlenwasserstoff'miä 76? "mol / h Iteinpf sugaführto These amounts correspond to a ratio of steam / carbon VOA 1.2 and a fiethanäquivalentdurehs & tsgesehwinäigkelt of 512 NNR, h. πΓ- ⁵ catalyst. The temperature in the reactor was on inlet 52J talysatorgrenzfläche% ₃ 787 ⁰ C at the K and at the outlet 991 ⁰ C. from the Katalysatorgreri2flä.che and from the bottom of the reactor be extracted flußprobsn had the following composition?

component First stage
Mol -fi Second step H ₂ 52.2 70.7 13.7 0.3 CO 11.5 24.1 co ₂ 6.4 1.6 G ₂ H ₆ 0.7 C ₃ H ₈ 0.3

100.0 100.0

The gosarate methane equivalent conversion was 98.7 #. While of the approach there was no evidence of carbon deposition perceived on the catalytic converter.

Example 3

This run was carried out with the same hydrocarbon feed and catalyst as that of Example 2. The pressure at the reactor outlet was increased to 4.13 atm. The supplied amounts of steam and hydrocarbon were 1.290 and 1-053 mol / h », which corresponds to a steam / carbon ratio of 1.04 and a methane equivalent flow rate of 96Ο Hnr. h . m ~ * corresponds to. The reaction

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participant msi ^ sn aiif 475 ⁸ S ¥ © rgswäsajfc and the reactor trains “ leads the on Siislaü at a temperature of 474ΐ, on the KetaXysat @ rgr @ nzflache at? SS% and ata AviBlaü at 991T mm3e. The Qesairifcmeilran & qraivalent & msetsuiig betrtag 95 "7 MoX" ^, and the samples taken from the first and second stages had the following Susajssnensittung (stick "Btofff reis Basis);

Component First stage Second stage

Get- *

H ₂ 45.9 70.8

18.5 1 * 2

SO 11.1 25.3

6.1 0.6

1.2 0.1

® 2 ° 17.1

100.0

No carbon deposition was perceived during the six hour run.

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Claims (11)

Claims 1. A method for producing a gas of high reducing power by reacting a hydrocarbon solute with Steam in a reforming zone in the presence of a reforming catalyst which is at least 0.5% by weight of an added active alkali compound contains «at elevated temperature and a pressure in the range of atmospheric pressure and about 17 »5 atmospheric pressure, characterized in that if a steam / carbon ratio is maintained of not a partial reforming is carried out over 1.5il and that partially reformed gas then under Damprefoxmierungsbedlngungen in the presence of a steam reforming catalyst, the practically free from an added active alkali compound is what is implemented. 2. The method according to claim 1, characterized in that the steam reforming conditions of the first stage in the first steam reforming catalyst bed include an outlet temperature of at least above 664 ¹ C and the steam reforming conditions in the second reforming catalyst at orbet t include an outlet temperature of at least 953 ¹ C. 3. The method according to claim 2, characterized in that the temperature at the outlet of the first Bed in the range of about 664 to about 815 ° C will. 4. The method according to claim 2 or 3, characterized in that the volume ratio of catalyst of the first stage to total catalyst is between about 0.2: 1 and about 0.8: 1. 209814/1389 5. The method according to one of Amspwushe S to 4, characterized in that _s DA® first and second Catalysis "torhett within a Hobrr * aktore be arranged directly above each other. 6. The method according to any one of the preceding claims, characterized in that the catalyst of the first stage contains between about 2 and about 20 Qew. ~ £ of the added active alkali compound. 7 · Method according to one of the preceding claims «thereby characterized in that the steam reform ie tion at a pressure between about 0.7 and about 10.5 atmospheres is carried out. 8. The method according to any one of the preceding claims, characterized in that the hydrocarbon throughput rate is maintained at at least 470 ¥ hr hydrocarbon per hour per total catalyst. 9 «Method according to one of the preceding claims, characterized in that the ratio Steam / carbon is maintained below about 1.4: 1. 10. The method according to one of the preceding claims «, since« characterized in that it has a hydrocarbon feed having an average molecular weight not exceeding about 60 is used, with preferably a a significant proportion of this feed consists of methane, 11. The method according to any one of claims 1 to 9, characterized in that the hydrocarbon be «feed consists of hydrocarbons which are liquid under normal conditions. 209814/1389 12 * Method according to one of claims 1 to 9 »thereby characterized in that the hydrocarbon feed consists of hydrocarbons which are gaseous under normal conditions. 2 η «) 8 U / 1.