CA1152535A

CA1152535A - Process for the preparation of hydrocarbons

Info

Publication number: CA1152535A
Application number: CA000373306A
Authority: CA
Inventors: Henricus M. J. Bijwaard; Michael A.M. Boersma; Lambert Schaper
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1980-06-03
Filing date: 1981-03-18
Publication date: 1983-08-23
Also published as: SE8103437L; AT371793B; ZA813658B; GB2077754B; ES8303269A1; NZ197260A; IT1136783B; ES502652A0; IT8122074A0; GB2077754A; FR2483400A1; NL8003215A; ATA243881A; DE3121752C2; DE3121752A1; IN154191B; AU539212B2; JPS5724314A; BE888922A; FR2483400B1

Abstract

A B S T R A C T

A PROCESS FOR THE PREPARATION OF HYDROCARBONS

H2-poor syngas is contacted in a first stage with a Fe-comprising catalyst having Fischer-Tropsch as well as CO-shift activity; a H2/CO mixture separated from the first stage product and having as such or after adjusting a H2/CO molar ratio of at least 1.5 is contacted in a second stage with a Co- or Ru-comprising Fischer-Tropsch catalyst. In this way the stability of the process is improved.

Description

~5;253S ``

A PROCESS FOR THE PREPARATION OF HYDROCAR~ONS

The invention relates to a process for the preparation of a hydrocarbon mixture from a mixture monoxide and hydro-gen having an H2/CO molar ratio of les~ than 1.0, with the use of an Fe-containing bifunctional cataly~t or catalyat combination pos~es3ing, in addition to activity for the conversion of an H2/CO mixture into substantially hydro-carbon~, activity for the conver~ion of an H20~CO mixture into an H2/C02 mixture.
In an investigation into said process by the Applicant it has been ~ound that if the process is carried out at a certain high space velocity R, a certain high conversion C can be obtained, but that the stability oP the bifuncti-nal catalyst or catalyst combination i9 not entirely satis-factory. On ~urther investigation into said process by the Applicant it has been found that this drawback can be eli-minated by contacting carbon monoxide and hydrogen present in the reaction product, if desired together with other components o~ the reaction product, in a second stage with a cobalt- or ruthenium-containing monofunctional catalyst having activity for the conversion of an H2/CO mixture into substantially hydrocarbons, with the proviso that if the feed ~or the 3econd stage has an H2/CO molar ratio of less than 1.5, water is added to said feed and that in the seoond stage use is made of a cobalt- or ruthenium containing bifunctional catalyst or catalyst combination having, in addition to activity for the conversion of an H2/CO mixture into substantiall7 hydrocarbons, activity for the conversion of an H20/CO mixture into an H2iCo2 mixture. Thi~ process not only ensure~ that by the use of the above-mentioned high space velocity ~ (now based ';

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~SZ~35 on the total cataly~t ~y~tem in th~ ~ir3t and ~econd qtage) a high converqion can be obtained without ~tabi-lity problems becoming manifest, but that the con~ersion obtained moreover has a higher value than the above-men-tioned conversion C..
The preqent patent application therefore relates to a proceqs for the preparation of a hydrocarbon mix-ture, in which a mixture of carbon monoxide and hydrogen having an H2JC0 molar ratio of lesq than 1.0 i9 contac-ted in a first qtage with an Fe-containing bifunctional catalyst or catalyst combination as defined above and in which carbon monoxide and hydrogen preqent in the reaction product of the first qtage, if desired together with other components of said reaction product, are con-15 tacted in a second stage with a cobalt- or ruthenium-con- :
taining monofunctional catalyst a~ defined above, with the provi~o that if the feed for the second stage has an H2~C0 molar ratio of less than 1.5, water i~ added to 3aid feed and that in the seaond ~tage uqe iq made of a cobalt- or ruthenium-containing bifunctional cata-lyst or catalyst combination as defined above.
In the process according to the invention the star-ting material is an H2/C0 mixture having an H2/C0 molar ratio of le~q than 1Ø Such H2/C0 mixtures can very suitably be prepared by steam gasification of a carbon-containing material. Examples of quch materials are lignite, anthracite, coke, crude mineral oil and frac-tion3 thereof as well as oi's produced from tarsand and bituminous qhale. Steam gasification is preferably carried 30 out at a temperature of 900-1500C and a pressure of 10-100 bar. In the proce~s according to the invention the qtarting H2/C0 mixture preferably has an H2/C0 molar ratio of more than 0.25.
The Fe-containing bifunctional catalysts or cataly~t .. ' combinations that are suitable for u~e in the firYt stage of the proceYs according to the invention, should posse~3, in addition to activity for the converqion o~ an H2~C0 mixture into qubstantially hydrooarbon~, activity for the conversion of an H20/C0 mixture into an H2~C02 mixture. In the fir~t qtage of the proces~ use is pre-ferably made of a bifunctional cataly~t prepared by im-pregnation and containing iron on a carrier. Examples of such catalyqtq are:
a) catalyqts containing 30-75 part~ by weight of iron and 5-40 parts by weight of magneqium per 100 parts by weight of alumina and prepared by impregnating an alumina carrier with one or more aqueous ~olutions of qaltq of iron and magnesium and ~ubsequently dry-ing the composition, calcining it at a temperature of 700-1200C and reducing it. Special preference is given to such catalyqts containing, in addition to 40-60 part~ by weight of iron and 7.5-30 parts by weight of magnesium, 0.5-5 parts by weight o~ copper as reduction promoter and 1-5 part-q by weight o~
potassium as qelectivity promoter per tO0 parts by weight of alumina and calcined at 750-850C and reduced at 250-350C.
b) cataly3ts containing 10-40 part~ by weight o~ iron and 0.25-10 parts by weight of chromium per 100 parts by weight of ~ilica and prepared by impregnating a ~ilica carrier with one or more aqueous solutions of s~ltq of iron and of chromium ~ollowed by drying the compo~ition, calcining it and reducing it at a tempe-rature o~ 350-750C. Special preference is given to quch catalysts containing, in addition to 20-35 parts by weight of iron and 0.5-5 part~ by weight of chro-mium, 1-5 parts by weight of potaqsium as selectivi-ty promoter per 100 part~ by weight of qilica and calcined at 350-700 C and reduced at 350-500C.

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, ~ ~

53Si The first stage of the proces~ according to the in-vention can very suitably be carried out by passing the feed in upward or downward direction through a vertically arranged reactor containing a fixed or moving bed of the Fe-containing bifunctional cataly:3t or catalyst combina-tion. The first stage can, for example, be carried out in fixed-bed operation, bunker-flow operation, ebullated-bed operation or fluidized-bed operation. The ~ir~t stage of the operation i9 preferably carried out under the ~ollow-ing conditions: a temperature of 200-350C and in par-ticular of 250-350C, a pressure of 10-70 bar and in par-ticular of 20-50 bar and a space velocity of 500-5000 and in particular of 500-2500 Nl of gas/l of catalyst~h.
In the process according to the invention carbon monoxide and hydrogen pre~ent in the reaction product of the ~irst stage are used as feed ~or the second stage.
In addition to carbon monoxide and hydrogen, the feed for the qecond stage~ay contain other components oP the reaction product of the ~irst stage. For example, it is possible to use as feed for the second stage the C2 fraction or C4 fraction of the reaction product of the first stage and even the entire reaction product of the first stage. In the second stage of the procesq accor-dins to the lnvention the aim is that the largest possi-ble quantity Or the carbon monoxide present in the feedfor the second stage iq converted into substantially hydrocarbons over a monofunctional cobalt- or ruthenium-containing catalyst having activity for this reaction.
~o t~is end the H2/C0 molar ratio in the feed for the second stage must be at least 1.5 and preferably 1.75-2.25. If an H2/C0 mixture with a high H2/C0 molar ratio is used a~ reed for the first stage, it is possi-ble in the proces~ according to the inYention to obtain a reaction product from the first stage having an H2/C0 ' ' :, ' . '.,~

~52S3S

molar ratio of at least 1.5~ which is suitable as such to be converted in the second stage over said catalyst.
If in the process according to the invention a reaction product having an H2/C0 molar ratio of less than 1.5 is obtained from the first stage, water should be added to the feed for the second stage and a cobalt- or ruthenium-containing bifunctional catalyst or catalyst combination should be used in the second stage that has, in addition to activity for the conversion of an H2/C0 mixture into substantially hydrocarbons, activity for the conversion of an H20/C0 mixture into an H2/C02 mixture.
If in the process according to the invention the feed for the second stage has an H2/C0 molar ratio of less than 105, a bifunctional catalyst combination consisting of two separate catalysts is preferably used in the second stage, which catalysts will for convenience be indicated as catalysts A and B. Catalyst A is the cobalt- or ruthenium-containing catalyst having activity for the conversion of an H2/C0 mixture into substantially hydrocarbons and catalyst B is the catalyst with activity for the conversion of an H20/C0 mixture into an H2/C02 mixtureO Both in the use of a monofunctional catalyst and in the use of a bifunctional catalyst combination in the second stage of the process according to the invention, as catalyst A preference is given to a cobalt catalyst and in particular to a catalyst prepared by impregnation and containing cobalt on a carrier. Very suitable for the present object are catalysts containing 10-40 parts by weight of cobalt and 0.25-5 parts by weight of zirconium, titanium or chromium per 100 parts by weight of silica and prepared by impregnating a si~ica carrier with one or more aqueous solutions of salts of cobalt and zirconium, titanium or chromium, followed by drying the composition, calcining it at 350-700C and reducing it at 200-350C.

~-::

. : , Catalyqts containing copper and ZillC and in which the Cu/Zn ato~ic ratio lies between 0.25 and 4.0 are espe-cially eligible as catalyst~ 3. In the cobalt- or ruthe-nlum-containing bifunctional catalyst combination~ the catalysts A and B can be present as a physical mixture.
When the second stage of the proce~s i9 carried out with the use of a fixed cataly~t bed, the bed is preferably built up of two or more alternating layers of particle of cataly~t B and catalyst A, re~pectively. In the pro-ce~s according to the invention water can be added tothe feed for the second qtage and a bifunctional cata-lyst combination can be used in the qecond stage both in ca~es where the reaction product of the ~irst ~tage haq an H2/C0 molar ratio of less than 1.5, and in cases where the reaction product of the first qtage already has an H2/C0 molar ratio of at leaqt 1.5, it being desi-rable, however, that the ~eed which iq contacted with catalyst A in the qecond qtage has a higher H2/C0 molar ratio. I~ ln the process according to the invention an embodiment i9 chosen in which water iq added to the feed for the second qtage and a bifunctional catalyqt combi-nation i~ uqed in the second qtage, the quantity of ~a-ter required i3 mainly determined by the H2~C0 molar ratio of the feed for the second stage, the activity of the catalyst combination for the conversion of an H20/C0 mixture into an H2~C02 mixture and the desirable H2/C0 molar ratio of the product that i9 contacted with catalyst A.
The second qtage of the process according to the invention can very suitably be carried out by passing the feed in upward or downward direction through a ver~
tically arranged reactor containing a fixed bed of the monofunctional cataly~t or of the bifunctional catalyst or catalyst combination. The second stage of the process -.

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~ 2535 can also be carried out using a qu:3pension of the cata-lyst or catalyst combination in a hydrocarbon oil.
The ~econd stage of the Drocess ia preferably car-ried out under the followiing cond:Ltions: a temperature of 125-350C, in particular of 175--275C and a pre3sure of 1-150 bar, in particular of 5-100 bar.
The invention will now be illustrated with reference to the following example.
EXAMPLE
The following catalysts were used during the inves-tigation:
Catalyst 1 Co/Zr/SiO2 catalyst containing 25 parts by weight of cobalt and 1.8 parts by weight of zirconium per 100 parts 15 by weight of silica and prepared by impregnating a silica carrier with an aqueous solution cantaining a cobalt and a zirconium salt, followed by drying the compositiqn, calcining it at 500C and reducing it at 280C.
Catalyst 2 Fe/Mg~Cu/K/Al203 catalyst containing 50 parts by weight of iron, 20 parts by weight Or magnesium, 2.5 parts by weight of copper and 4 parts by weight of potassium per 100 parts by weight of alumina and prepared by impreg-nating an alumina carrier with an aqueous solution con-taining an iron, magnesium, copper and a potassium 3alt, followed by drying the composition, calcining it at 800C
and reducing it at 325C.
Catalyst 3 Cu/Zn/Al203 catalyst with a Cu/Zn atomic ratio of 0.55.
Catalyst mixture I
Catalyst mixture I consisted of a layer of catalyst 3 and a layer of catalyst 1 in a volume ratio o~ 1 : 2.
The catalysts 1 and 2 and the catalyst mixture I were tested for the preparation in one or two stages of a : ~., ; . :

hydrocarbon mixture from an H2/C0 mixture. The test was carried out in one or two reactors o~ 50 ml each containing a fixed catalyst bed. Fi~e experiments ~ere carried out.
Experiments 1 and 3 were carried out in one stage; the other experiments in two stages. In all experiments a temperature of 280C was used in the first stage. In all experiments that were carried out in two stages the temperature was 230C in the second stage. In all experiments the pressure was 30 bar and the space velocity based on the total catalyst system was 1000 ~l.l .h 1, In the experiments

2 and 5 the total reaction product from the first stage was used as feed for the second stage. In experiment 4 the C4 fraction of the product from the first stage was used as feed for the second stage. The results of the experiments are stated in the Table.

: ` :

cO N
N ~ O N ~ ~ ~ I I

Co ~ .
~t C`~ LS~ o H IA ~ 0 N

U~
CO ~
N O O ~ I I I I Is\ O
~ CO C-- :

N Nl u~ O O O H 11~ ~ ~ ~ ~1 N N
~O C~l Il~ O ( N O O O O O U~
~1 ~ ~ ~ ~ 0 tR h h ^ u -l ~ ~ o ~æ
h ~1 ~
Y ~ O ~ ~ ~ :
h ~q R a.) 01:
h ~ C~ ~ O ~1 u~
~ ~ $ ,~
O ~ ~ Q~
h C~
rl ~ D~co h ~ .5:: u~ u h ~q O O ~h h O ~ ~ ~ ~ ~ ~ ~h h~
O O ~ :~ ~ O O O O
~1 ~1 0 0 ~ ~ ~a r-l ~ +~ ~ ~ a) ~ ~
R ~ ~ ~$ : ~ R R ~ ~ R :=
~ dtd ~ ~ ~ ~ ~
O c~ h h h h+~ ~ h h ~ h h O q~ h h O O ~ ~il O OO O
~ æ o ~ ~d u~ O ~ o o c~ u~ o ~ ~ o ~1~1 N 06-1 U~ N O O N O
h R rl~1 0 h h ~ ~O O h h~ O ~ ~ ~ h h a) h h ) a~ a),9 0 R R _~ V ~ ~ a) 'V
NI I ~ 0~ ~ ~ ~1 ~ ~ O ~ ~
~ æ a,~~ ~ ~ ~d ~

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~5~535 . 10--Of the experiment3 3tated in the table only the two-qtage experiments 2, 4 and 5 are in accordanoe with the invention. The one-qtage experiments 1 and 3 fall outside the 3cope of the invention. For comparison they have been included in the patent application.
The advantages of the two-stage process according to the invention in re3pect of conversion of the H2/CO
mixture and 3t~bility of the Fe-containing bifunctional catalyst are evident on comparing the result~ of:
experiment 2 with that of experiment 1, and experimentS4 and 5 with that of experiment 3.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
l. A process for the preparation of a hydrocarbon mixture, characterized in that a mixture of carbon monoxide and hydrogen having an H2/CO molar ratio of less than 1.0 is contacted in a first stage with an Fe-containing bifunctional catalyst or catalyst combination having, in addition to activity for the conversion of an H2/Co mixture into substantially hydrocarbons, activity for the conversion of an H2O/CO mixture into an H2/CO2 mixture and that carbon monoxide and hydrogen present in the reaction product of the first stage, if desired together with other components of said reaction product, are contacted in a second stage with a cobalt- or ruthenium-containing mono-functional catalyst having activity for the conversion of an H2/CO mixture into substantial-ly hydrocarbons, with the proviso that if the feed for the second stage has an H2/CO molar ratio of less than 1.5, water is added to said feed and that in the second stage use is made of a cobalt- or ruthenium-containing bifunctional catalyst or catalyst combination having, in addition to activity for the conversion of an H2/CO mixture into substantially hydrocarbons, activity for the conversion of an H2O/CO mixture in an H2/CO2 mixture.
2. A process as claimed in claim 1, characterized in that the H2/CO
mixture used as feed for the first stage has an H2/CO molar ratio of more than 0.25.
3. A process as claimed in claim 1, characterized in that a catalyst is used containing 30-75 parts by weight of iron and 5-40 parts by weight of magnesium per 100 parts by weight of alumina and prepared by impregnating an alumina carrier with one or more aqueous solutions of salts of iron and magnesium followed by drying the composition, calcining it at a temperature of 700-1200°C and reducing it.
4. A process as claimed in claim 3, characterized in that a catalyst is used containing, in addition to 40-60 parts by weight of iron and 7.5-30 parts by weight of magnesium, 0.5-5 parts by weight of copper as reduction promotor and 1-5 parts by weight of potassium as selectivity promoter per 100 parts by weight of alumina and calcined at 750-850°C and reduced at 250-350°C.
5. A process as claimed in claim 1, characterized in that a catalyst is used containing 10-40 parts by weight of iron and 0.25-10 parts by weight of chromium per 100 parts by weight of silica and prepared by impregnating a silica carrier with one or more aqueous solutions of salts of iron and chromium followed by drying the composition, calcining it and reducing it at a temperature of 350-750°C.
6. A process as claimed in claim 5, characterized in that a catalyst is used containing in addition to 20-35 parts by weight of iron and 0.5-5 parts by weight of chromium, 1-5 parts by weight of potassium as selectivity promotor per 100 parts by weight of silica and calcined at 350-700°C and reduced at 350-500°C.
7. A process as claimed in claim 1, characterized in that as catalyst with activity for the conversion of an H2/CO mixture into substantially hydrocarbons that is used in the second stage of the process, use is made of a catalyst prepared by impregnation and containing cobalt on a carrier.
8. A process as claimed in claim 7, characterized in that a catalyst is used containing 10-40 parts by weight of cobalt and 0.25-5 parts by weight of zirconium, titanium or chromium per 100 parts by weight of silica and prepared by impregnating a silica carrier with one or more aqueous solutions of salts of cobalt and/or zirconium, titanium or chromium, followed by drying the composition, calcining it at 350-700°C and reducing it at 200-350°C.
9. A process as claimed in claim 1, characterized in that water is added to the feed for the second stage and that in the second stage a bifunctional catalyst combination is used consisting of two separate catalysts A and B, catalyst A having activity for the conversion of an H2/CO mixture into substantially hydrocarbons and catalyst B having activity for the conversion of an H2O/CO mixture into an H2/CO2 mixture.
10. A process as claimed in claim 9, characterized in that the second stage is carried out with the use of a fixed catalyst bed consisting of two or more alternating layers of particles of catalyst B and catalyst A respectively.