SIMELL PEKKA (FI)
REINIKAINEN MATTI (FI)
PUTKONEN MATTI (FI)
KESKIVÄLI LAURA (FI)
KAISALO NOORA (FI)
REPO TIMO (FI)
KESKIVÄLI JUHA (FI)
| WO2016039385A1 | 2016-03-17 |
| US4219447A | 1980-08-26 | |||
| US20120029250A1 | 2012-02-02 | |||
| US5387726A | 1995-02-07 |
| CLAIMS 1. A catalyst for dehydrogenation, cha r a c t e r i z e d in that - the catalyst is a Pt catalyst, in which Pt cata- lyst agent is formed by using a Pt-precursor and is arranged on a support, and - the support is selected from Ti02 or g-A1203. 2. The catalyst according to claim 1, cha r a c t e r i z e d in that the Ti02 support con- sists of anatase-rutile system. 3. The catalyst according to claim 1 or 2, cha r a c t e r i z e d in that the Ti02 support con sists of a powder with nanoparticles which have parti cle size 0.015 - 0.100 ym. 4. The catalyst according to any one of claims 1 to 3, cha r a c t e r i z e d in that the y- A1203 support has particle size of 0.02 - 32000 ym. 5. The catalyst according to any one of claims 1 to 4, cha r a c t e r i z e d in that the Pt- precursor is selected from H2PtCl6 or Pt(N03)2. 6. The catalyst according to any one of claims 1 to 5, cha r a c t e r i z e d in that the cat alyst agent is arranged by an impregnation onto the support . 7. The catalyst according to any one of claims 1 to 6, cha r a c t e r i z e d in that the cat alyst is prepared by an ALD-coating. 8. The catalyst according to any one of claims 1 to 7, cha r a c t e r i z e d in that the de- hydrogenation is a dehydrogenation of H18-DBT or of other compounds which are monocyclic or polycyclic al kanes . 9. A method for preparing a catalyst for de hydrogenation, cha r a c t e r i z e d in that the method comprises steps - forming Pt catalyst agent from a Pt-precursor, - arranging the catalyst agent onto a support which is selected from Ti02 or g-A1203 in order to form the catalyst, and - calcinating the catalyst. 10. The method according to claim 9, cha r a c t e r i z e d in that the Pt-precursor is selected from H2PtCl6 or Pt(N03)2. 11. The method according to claim 9 or 10, cha r a c t e r i z e d in that the catalyst is calci nated at 450 - 540 °C. 12. The method according to any one of claims 9 to 11, cha r a c t e r i z e d in that the catalyst agent is arranged by an impregnation onto the support. 13. The method according to any one of claims 9 to 12, cha r a c t e r i z e d in that the catalyst is prepared by an incipient wetness impregnation. 14. The method according to any one of claims 9 to 13, cha r a c t e r i z e d in that the catalyst is prepared by an ALD-coating. 15. A use of the catalyst according to any one of claims 1 to 8, cha r a c t e r i z e d in that the catalyst is used in a dehydrogenation in which hy drogen is released, in a dehydrogenation of H18-DBT, in a dehydrogenation of the compounds which are mono- cyclic or polycyclic alkanes, in use of hydrogen for different purposes, for energy or for manufacturing organic gas or liquid, in a production of hydrocarbons or fuel, or in their combinations. |
FIELD
The application relates to a catalyst for de hydrogenation as defined in claim 1 and a method for preparing the catalyst as defined in claim 9. Further, the application relates to a use of the catalyst as defined in claim 15.
BACKGROUND
Known from the prior art is that hydrogen is a flexible energy carrier, however, its production and storage is challenging in compressed and liquid form, or as adsorbed physically or binded chemically in sol id materials. Liquid organic hydrogen carriers (LOHCs) are suggested as reversible, effective, safe, user- friendly and economical hydrogen storages compatible with the existing fuel infrastructure. Many LOHC com pounds are stabile at normal temperature and pressure. The LOHC system is promising particularly for applica tions, where safety, robustness and fast kinetics of the system are priorities. Catalytic dehydrogenation of some perhydrogenated LOHC candidates are mature in dustrial processes. DBT (dibenzyl toluenes) is a com mercial LOHC hydrogen storage system.
Reforming of cycloalkanes is based on noble metals, particulartly Pt, or on lower-cost Ni and Mo and their combinations with alkali reagents. Alumina is a common support in these reactions. In the prior art, Pt on carbon has been observed to be the most ac tive amongst the tested catalysts for hydrogen release from perhydrogenated dibenzyl toluenes (H18-DBT) . OBJECTIVE
The objective is to disclose a new type cata lyst for dehydrogenation. Further, the objective is to disclose a new type method for preparing the catalyst. Further, the objective is to improve a dehydrogenation process. Further, the objective is to provide effi cient process and catalyst for releasing hydrogen in the dehydrogenation. SUMMARY
The catalyst and method and use are charac terized by what are presented in the claims.
A catalyst for dehydrogenation is a Pt cata lyst. The catalyst is prepared from a support and a Pt catalyst agent which arranged onto the support.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further understanding of the invention and constitutes a part of this specification, illus trate some embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:
Fig. 1 shows results from the tests according to three embodiments at Pt contents of 1 - 1.5 wt%.
DETAILED DESCRIPTION
A catalyst for dehydrogenation is a Pt cata lyst, in which Pt catalyst agent is formed by using a Pt-precursor and is arranged on a support, and the support is selected from Ti0 2 or g-A1 2 0 3 .
In a method for preparing a catalyst for de hydrogenation, Pt catalyst agent is formed from a Pt- precursor, the catalyst agent is arranged onto a sup port which is selected from Ti0 2 or y-Al 2 0 3 in order to form the catalyst, and the catalyst is calcinated. In this context, the support means any sup port or carrier material, onto which any Pt catalyst agent is arranged. In an embodiment, the support is in the form of powder.
In an embodiment, the support is selected from Ti0 2 . In an embodiment, the Ti0 2 support consists of anatase-rutile system. In a further embodiment, the Ti0 2 support is formed from a mixture of anatase and rutile forms.
In an embodiment, the Ti0 2 support consists of powder. In an embodiment, particles of the powder have particle size which may vary and which may be in large size range. In an embodiment, particles of the powder are nanoparticles, microparticles and/or other particles. In an embodiment, particles of the powder are nanoparticles and/or microparticles. In an embodi ment, the Ti0 2 support consists of the powder with particles which have particle size over 0.015 ym, over 0.035 ym or larger. In an embodiment, the Ti0 2 support consists of the powder with nanoparticles. In an em bodiment, the Ti0 2 support consists of the powder with nanoparticles which have particle size 0.015 - 0.100 ym, or in an embodiment the powder with larger parti cle sizes. In a further embodiment, the Ti0 2 support consists of the powder with nanoparticles which have particle size 0.015 - 0.035 ym. In a further embodi ment, the Ti0 2 support consists of the powder with na noparticles which have particle size selected from 0.015 - 0.035 ym or over 0.035 ym. In a further embod iment, the Ti0 2 support consists of the nanopowder.
In an embodiment, the support is selected from y-Al 2 0 3 . In an embodiment, the y-Al 2 0 3 support con sists of the powder. In an embodiment, the g-A1 2 0 3 sup port has particle size of 0.02 - 32000 ym.
In an embodiment, Pt-content is below 2 % by weight in the catalyst. In an embodiment, the Pt-precursor is select ed from H 2 PtCl 6 (chloroplatinic acid) or Pt(N0 3 ) 2 (platinium nitrate) . In an embodiment, the Pt- precursor is H 2 PtCl 6 . In an embodiment, the Pt- precursor is Pt(N0 3 ) 2 . When H 2 PtCl 6 or Pt(N0 3 ) 2 is used as the precursor, an efficient catalyst can be formed for the dehydrogenation, especially for the dehydro genation of H18-DBT.
In an embodiment, the catalyst agent is ar ranged by an impregnation onto the support. In a fur ther embodiment, the catalyst agent, preferably in the form of powder or alternatively in the form which is manufactured from the powder, is arranged by an im pregnation onto the support. In an embodiment, the catalyst is prepared by an incipient wetness impregna tion.
In an embodiment, the catalyst is prepared by an ALD-coating (atomic layer deposition coating) . In a further embodiment, the catalyst agent is arranged by the ALD-coating method onto the support, e.g. onto the support powder. In a further embodiment, the ALD- coating is carried out so that at least the support is in the powder form. In a further embodiment, the formed catalyst, preferably in the form of powder, is arranged by means of the ALD-coating method on the substrate in order to form a catalyst system. In this application, any suitable ALD-coating method can be used, which is preferably suitable for the ALD-coating of the powder material. By means of the ALD-coating method an amount of noble metal needed can be reduced in the catalyst.
In an embodiment, the catalyst is calcinated at 450 - 540 °C. In a further embodiment, the catalyst is calcinated at 480 - 520 °C.
An important property of the dehydrogenation catalyst is its capability to desorb hydrogen to avoid reverse reaction. In an embodiment, the dehydrogena tion is a dehydrogenation of H18-DBT (perhydrogenated dibenzyl toluenes) . Alternatively, the dehydrogenation is another dehydrogenation in which hydrogen is re leased from other compounds, which are, for example, monocyclic or polycyclic alkanes.
In the dehydrogenation, a product composition is produced. The product composition means any product from the dehydrogenation. The product composition can comprise one or more product components, e.g. hydro gen, hydrocarbons, organic liquids and/or other organ ic compounds. The product composition may contain also other components. In an embodiment, the product compo sition mainly consists of hydrocarbons and hydrogen. Preferably, the hydrogen can be released from the product composition. In one embodiment, the product composition can be post-treated after the dehydrogena tion, e.g. after releasing hydrogen. In one embodi ment, the product composition can be supplied to a de sired treatment process, e.g. for energy or for refin ing the hydrocarbons or other compounds .
In an embodiment, the catalyst is used or uti lized in a dehydrogenation in which hydrogen is re leased, in a dehydrogenation of H18-DBT, in a dehydro genation of the compounds which are monocyclic or pol ycyclic alkanes, in use of hydrogen for different pur poses, such as for energy or for manufacturing organic gas or liquid, in a production of hydrocarbons or fuel, or in their combinations.
Thanks to the invention, very efficient cata lysts can be produced for dehydrogenation of H18-DBT. Further, the present catalysts are effective also for dehydrogenation of other substrates. The present cata lysts are capable to fast release of hydrogen. Thus, the present catalysts improve efficiency of the LOHC hydrogen release system. The present catalyst offers a possibility to release hydrogen easily and effectively. The present invention provides an industrially applicable, simple and affordable way to release hydrogen in the dehydro genation .
EXAMPLES
Example 1
This example presents a Pt catalyst with a Ti0 2 support for dehydrogenation. Further, in this ex ample, the catalyst for the dehydrogenation was pro duced from the Ti0 2 support and a Pt catalyst agent.
The Pt catalyst agent is formed from a Pt- precursor which is H 2 PtCl 6 , or alternatively Pt(N0 3 ) 2 . The Pt-precursor is arranged onto the support which is Ti0 2 . The Ti0 2 support consists of anatase-rutile sys tem which comprises a mixture of anatase and rutile forms. The Ti0 2 support is nanopowder which has parti cle size about 0.020 - 0.030 ym. The catalyst agent is arranged by an incipient wetness impregnation onto the support. In addition to the impregnated catalyst, ALD technology can be used for forming platinum layer on the titania support powder.
The Pt catalyst is calcinated at about 500 °C, preferably for about two hours.
Example 2
This example presents a Pt catalyst with a y- A1 2 0 3 support for dehydrogenation. Further, in this ex ample, the catalyst for the dehydrogenation was pro duced from the g-A1 2 0 3 support and a Pt catalyst agent.
The Pt catalyst agent is formed from a Pt- precursor which is H 2 PtCl 6 , or alternatively Pt(N0 3 ) 2 . The Pt-precursor is arranged onto the support which is g-A1 2 0 3 . The g-A1 2 0 3 support has particle size of 25 - 40 ym. The catalyst agent is arranged by an incipient wetness impregnation onto the support. In addition to the impregnated catalyst, ALD technology can be used for forming platinum layer on the alumina support pow der .
The Pt catalyst is calcinated at about 500 °C, preferably for about two hours.
Example 3
In this example different catalysts were studied. Further, the effect of different Pt precur sors in combination with alumina and titania supports on activity of the prepared catalysts for hydrogen re lease from H18-DBT in comparison with commercial Pt on carbon catalyst.
Carbon supported Pt catalyst showed the high est efficiency for the dehydrogenation of H18-DBT amongst the catalysts studied. It is known that carbon has a high surface area (200-300 m 2 /g) and typically dispersion of Pt on carbon is good, which are favora ble features for the dehydrogenation catalysts. Carbon support is also low cost and abundant, but its dura bility is weak at high temperatures in the presence of oxygen. Different hydrogen release rates were observed between two different H18-DBT batches, one at 100% and the other at 95% hydrogenation degree. For 100% hydro genated H18-DBT batch, Pt/C 1 wt% catalyst released 91 % of the theoretical maximum of hydrogen in 45 minutes. When using the batch of H18-DBT having 95% hydrogenation degree, commercial Pt/C (lwt%) catalyst was capable to release only 74% of hydrogen stored in substrate at 290 °C in 45 minutes. Activity of the in- house catalysts prepared were compared to the activity of commercial Pt/C lwt% for hydrogen release from H18- DBT (95%), thus the reference dehydrogenation degree in our study is 74% at 290 °C in 45 minutes (share of hydrogen released from the theoretical maximum) . How ever, we note that complete hydrogenation release was possible in reasonable time from fully hydrogenated H18-DBT (100%), whereas this level of dehydrogenation was not achieved with H18-DBT (95%) . Using fully hy drogenated substrate could increase efficiency of to tal process in practical applications.
Metal oxides are more durable supports than carbon, and thus interesting for the dehydrogenation of H18-DBT. Alumina support is used in the commercial LOHC solution. First, it is noted that the commercial Pt on alumina (5wt%) catalyst was not active for dehy drogenation of H18-DBT showing only 9% hydrogen re lease degree at 290 °C in 45 minutes. Instead, many in-house Pt on alumina catalysts were active towards hydrogen release from H18-DBT. However, only catalysts prepared on g-A1 2 0 3 supports were active, while that prepared on ,g-A1 2 0 3 support was not particularly ac tive. In the tests, for different g-A1 2 0 3 supports, no consistent dependences between catalyst activity and different particle sizes or surface areas of alumina were found. In the tests, the most active catalysts were those prepared on g-A1 2 0 3 having 40 ym particle size and surface area of 100 m 2 /g, or 25 ym particle size and surface area of 200 m 2 /g. Also other Pt/y- A1 2 0 3 catalysts were active regardless of large varia tion of their particle sizes (from 0.02 to 32000 ym) and surface areas (from 100 and 200 m 2 /g) . Particle sizes and surface areas indicated here are for the fresh supports. Surface area of alumina may decrease in calcination.
The best activity amongst the metal supported Pt catalyst was found for that prepared on titania na nopowder support having rutile and anatase forms. This catalyst was active regardless of the Pt precursor used, although particularly high activity was observed when using H 2 PtCl 6 precursor of Pt .
Using H 2 PtCl 6 as a precursor led to higher ac tivity of the dehydrogenation catalyst than using Pt(N0 3 ) 2 . However, in the best case the nitrate precur sor led to almost as high activity of catalyst as when using the acid precursor.
The titania nanopowder support is a mixture of anatase and rutile forms. Thus, we studied also ac tivity of Pt catalyst prepared on titania nanopowder having anatase only form. However, activity of Pt on anatase titania was modest. Ti0 2 is characterised by strong metal support interaction, chemical stability, and acid-base property. However, surface area of titania is relatively low, only up to about 80 m 2 /g.
In the tests, activity of catalyst was good only for Ti0 2 containing both anatase and rutile forms, while anatase only was not active.
Example 4
In this example, catalysts were prepared us ing incipient wetness impregnation method.
Catalysts were calcinated at 500 °C tempera ture. For y-Al 2 0 3 , higher calcination temperatures starting from 600 °C would lead to phase transition to low-surface area -A1 2 0 3 (completed at 1200 °C) . For titania, phase transition from anatase to low-surface area rutile starts already at about 550 °C. The calci nation temperature of 500 °C is optimum for Ti0 2 na nopowder used to increase its photocatalytic activity. Simultaneously, a small part of anatase transformed to rutile, and surface area of Ti0 2 decreased.
Two Pt precursors used for the catalysts were choroplatinic acid (H 2 PtCl 6 , 38% (m/m) Pt content) and platinum nitrate (Pt(N0 3 ) 2 ). Pt on g-A1 2 0 3 and Ti0 2 supports were studied in comparison with commercial Pt on carbon catalyst. Be sides these catalysts, also commercial Pt/C and Pt/Al 2 0 3 were tested.
Example 5
In this example, activities of catalysts, prepared according to example 3, were tested by heat ing a mixture of H18-DBT and selected catalyst in a molar ratio of 400:1 in a round bottom flask while stirring with a magnetic stirrer at 500 min -1 . For some nanocatalysts stirring was reduced due to inertia caused by catalyst sludge. Limited tests indicated that stirring rate did not affect the results on cata lyst activity.
Two different H18-DBT substrates were used. In the first phase, Marlotherm SH, Sasol was hydrogen ated in laboratory to 100% H18-DBT (hydrogenation pro cedure, SI) . Later on, H18-DBT with a hydrogenation degree of 95% was purchased from Hydrogenious GmbH. All the results were obtained with the latter sub strate, H18-DBT 95%.
Formed hydrogen was collected in the measur ing glass and readings were recorded periodically. Volumetric measurement of hydrogen release rate is semi-quantitative due to the substantial effect of temperature on hydrogen density, and consequently, to hydrogen volume. Quantitative dehydrogenation degree was analysed using NMR (Varian 300 Hz, dichloro- methane-d2 solvent, filtered samples) . All hydrogen release rates were interpolated to 45 minutes for equal comparison of different catalysts.
Fig. 1 shows some hydrogen release results from some tests with three catalysts in which Pt contents were 1 - 1.5 wt-%. The Pt/Ti0 2 and Pt/Al 2 0 3 according to the invention and commercial Pt/C were tested .
It was observed from the tests that the effi cient catalysts can be produced for dehydrogenation of H18-DBT, and also for dehydrogenation of other sub strates. Further, it was observed that the formed Pt/Ti0 2 catalyst is capable to faster release of hy drogen than the previously known alumina catalysts. Further, from Fig. 1 can be observed that the Pt- catalyst with Ti0 2 -support, which contains anatase- rutile system, has very high efficiency. Pt/Al 2 0 3 catalyst has also high efficiency, but clearly lower efficiency than the Pt-catalyst with Ti0 2 -support . The catalyst is suitable in different embodi ments for different kinds of dehydrogenations. The method for producing a catalyst for dehydrogenation is suitable in different embodiments for forming differ ent kinds of catalysts.
The invention is not limited merely to the examples referred to above; instead many variations are possible within the scope of the inventive idea defined by the claims.