Catalyst, method and arrangement for a chemical reaction, and use

Abstract

The application relates to a catalyst, a method and an arrangement for a chemical reaction forming one or more reaction products in solid form. The catalyst is formed of catalyst material, and the catalyst comprises at least one surface for the chemical reaction, and the catalyst is pre-treated to modify the surface of the catalyst and / or to improve the activity of the catalyst. Further, the application relates to the use of the catalyst.

Description

[0001] CATALYST, METHOD AND ARRANGEMENT FOR A CHEMICAL REACTION, AND USE

[0002] FIELD

[0003] The application relates to a catalyst defined in claim 1, a method defined in claim 9 and an arrangement defined in claim 17 for a chemical reaction forming one or more reaction products in solid form. Further, the application relates to a use of the catalyst defined in claim 20.

[0004] BACKGROUND

[0005] It is known different catalysts for producing different products. For example, different catalyst particles are used in processes, e.g. fluidized bed processes, where hydrogen is formed. Metal alloy catalysts may be used in a pyrolysis, and the metal alloys typically are used at high temperatures. The thermal management of currently used catalysts is challenging.

[0006] OBJECTIVE

[0007] An objective is to alleviate the disadvantages mentioned above. In particular, the objective is to disclose a novel type of catalyst. Further, the objective is to disclose a novel type of 3D printed catalyst. Further, the objective is to achieve an effective process for forming solid products and / or hydrogen. Further, the objective is to provide an active catalyst to low temperature processes.

[0008] SUMMARY

[0009] The catalyst, method, arrangement and use are characterized by what are presented in the claims.

[0010] A catalyst for a chemical reaction forming reaction products is formed of catalyst material, and the catalyst comprises at least one surface for the chemical reaction, and the catalyst is pre-treated to modify the surface of the catalyst and / or to improve the activity of the catalyst .

[0011] The method and arrangement for producing the reaction products comprise the defined catalyst .

[0012] DETAILED DESCRIPTION

[0013] A catalyst , for a chemical reaction forming one or more reaction products in sol id form, has a shape , e . g . a fixed structure or particle , which is formed of catalyst material , and the catalyst comprises at least one surface , such as catalyst surface , for the chemical reaction, and the catalyst is pre-treated at least by an acid treatment to modify the surface of the catalyst and / or to improve the activity of the catalyst . Preferably, the catalyst is free of a catalyst support .

[0014] In this context , the catalyst means any catalyst , which is formed of catalyst material . The catalyst may have any s i ze and shape . For example , the catalyst may be in the form of particles or fixed solid structure . In one embodiment , the catalyst consists of the catalyst material . In one embodiment , the catalyst has a fixed structure which is formed of the catalyst material comprising at least one catalytic agent . In one embodiment , the catalyst consists of particles which are formed of the catalyst material comprising at least one catalytic agent . In one embodiment , the catalyst comprises a structure inside which the particles are arranged, and the particles are formed of the catalyst material comprising at least one catalytic agent . Preferably, the catalyst material comprises at least one catalytic agent . The catalyst material may be formed of one or more components . The catalyst material may contain catalytically active metals , carbon, other catalytically active agent or any combination thereof , as the catalytic agent . In one embodiment , the catalyst material is formed of one or more catalytic agents. The catalyst comprises at least one surface, such as catalyst surface, for the chemical reaction. In one embodiment, at least one surface for the chemical reaction comprises one or more catalytic agent. In one embodiment, at least one surface for the chemical reaction is formed of a composite, preferably comprising at least two catalytic agents. In one embodiment, at least one surface for the chemical reaction is made of one or more catalytically active metals, carbon, or is a composite. In one embodiment, the catalyst or at least its surface comprises one or more catalytically active metals and carbon. In one embodiment, the at least one surface of the catalyst is formed of a composition of the catalyst material which differs from the other catalyst material, and the said surface is arranged onto the other catalyst material. In one embodiment, the surface of the catalyst comprises at least one different catalytic agent than the other catalyst material in the catalyst. In one embodiment, the catalyst comprises a surface layer, e.g. an outer active layer, on the catalyst, e.g. on the surfaces of the fixed structure or surfaces of the particles, preferably as coating on other catalyst material. In one embodiment, the whole catalyst is formed of the same catalyst material. In one embodiment, the catalyst is porous, or the surface, e.g. the surface layer, is porous. In one embodiment, the catalyst is transporous . In one embodiment, the catalyst is non- porous . In one embodiment, the catalyst has a surface area of at least 2 - 30 m2 / g, in one embodiment 5 - 25 m2 / g .

[0015] In one embodiment, the catalyst with the fixed structure, i.e. a fixed-structure catalyst, has a three- dimensional structure with predetermined dimensions, e.g. length, width, depth and / or diameter, and with predetermined shape. In one embodiment, the appearance structure of the catalyst is tubular. Further, the catalyst has a predetermined cross-section. In one embodiment, the catalyst has a predetermined pattern of the cross-section, e.g. honeycomb pattern or lattice pattern. In one embodiment, the catalyst has a honeycomb structure, lattice structure, spiral structure, screw structure, tube structure, rod structure, other structure through which gas can flow, or other suitable structure. In one embodiment, the catalyst is a monolith.

[0016] In one embodiment, the catalyst with the particles consists of the particles. Size of the particles can be varied based on the purpose of use and / or the process .

[0017] In one embodiment, the catalyst for the chemical reaction comprises one or more catalytically active metals selected from the group consisting of nickel, copper, iron, aluminium, titanium, cobalt, manganese, chromium, silicon, carbon, or an oxide thereof, or any combination thereof. The catalyst is formed of the catalyst material. In one embodiment, the catalyst material and / or the at least one surface for the chemical reaction is made of one or more catalytically active metals selected from the group consisting of nickel, copper, iron, aluminium, titanium, cobalt, manganese, chromium, silicon, carbon, or an oxide thereof, or any combination thereof. In one embodiment, the catalyst material and / or the at least one surface for the chemical reaction is made of one or more catalytically active metals selected from the group consisting of nickel, copper, iron, aluminium, titanium, cobalt, manganese, chromium, silicon, carbon, and any combination thereof. In one embodiment, the at least one surface for the chemical reaction is made of two catalytically active metals, wherein the two catalytically active metals are selected from the group consisting of nickel, copper, iron, aluminium, titanium, cobalt, manganese, chromium, silicon, carbon, and any combination thereof. In one embodiment, the catalyst material and / or the at least one surface is made of nickel, copper, iron, and / or cobalt. In one embodiment, the catalyst material and / or the at least one surface for the chemical reaction is made of a metal alloy. In one embodiment, the metal alloy is Ni-Cu metal alloy .

[0018] In one embodiment, the surface of the catalyst comprises one or more surface irregularities. In one embodiment, the surface comprises pores and / or protrusions to form surface irregularities. In one embodiment the catalyst, preferably the surface, comprises microstructures, such as spikes, protruding from the surface of the catalyst. The spikes may enable carbon nanotube and / or carbon nanofiber formation. In one embodiment, the spikes are used for carbon nanotube and / or carbon nanofiber formation. In one embodiment, microstructures, such as spikes, can contain different metals than the rest of the catalyst material.

[0019] In one embodiment, the catalyst has a specific pressure profile which is determined based on a flow in the catalyst. In one embodiment, the catalyst is a monolith comprising one or more surface irregularities for providing an uneven surface pressure profile.

[0020] In one embodiment, the catalyst is formed from the catalyst material, such as from powder of the catalyst material. In one embodiment, the catalyst is formed from powder of the catalyst material to form a three-dimensional catalyst. In one embodiment, the catalyst is formed from powder of the catalyst material to form particles, such as catalyst particles. In one embodiment, the catalyst is formed from a metal alloy, preferably powder of the metal alloy. In one embodiment, the catalyst is formed by printing, 3D-printing, direct metal laser sintering (DMLS) , selective laser sintering (SLS) , laser-based powder bed fusion technology (L-PFB) , stereolithography, and / or extrusion printing, or any combination thereof. In one embodiment, the catalyst is formed by printing. In one embodiment, the catalyst is formed from the catalyst material using the 3D-printing. In one embodiment, the 3D-printing is selected from the group consisting of binder jetting, directed energy deposition, material extrusion, powder bed fusion, sheet lamination, vat polymerisation, laser-based powder bed fusion technology (L-PFB) , and wire arc additive manufacturing, or any combination thereof. The desired structure and / or shape of the catalyst is provided during the manufacture of the catalyst, e.g. during the printing. In one embodiment, the geometry of the catalyst, e.g. three-dimensional catalyst, can be optimized for catalytic activity such that solid products will not block the catalyst and will not be trapped in the catalyst, e.g. in the catalyst structure.

[0021] The catalyst is pre-treated to modify the surface of the catalyst and / or to improve the activity of the catalyst. In one embodiment, the catalyst is pretreated before the use or in the beginning of the chemical reaction. In one embodiment, the catalyst is pretreated before an attachment of the catalyst to an arrangement or before putting the catalyst to an arrangement. In one embodiment, the catalyst is treated outside the arrangement. In one embodiment, the catalyst is pretreated in the beginning of the chemical reaction. In one embodiment, the catalyst is treated inside the arrangement, e.g. in the reactor. The catalyst can be pretreated in a desired way. In one embodiment, the catalyst is pre-treated by an acid, heat or their combination. The catalyst is pre-treated at least by an acid treatment. In one embodiment, the catalyst is pretreated by an acid and heat. In one embodiment, the catalyst is treated by heat, e.g. in an oven. In one embodiment, the catalyst is heat-treated, e.g. in a muffle oven. In one embodiment, the catalyst is treated by heat at temperature of 750 - 900 °C. In one embodiment, the catalyst is activated at temperatures of 800 - 850 °C. In one embodiment, the catalyst is activated by heat for 1 - 10 hours. In one embodiment, the catalyst is activated at temperatures of 800 - 850 °C in the beginning of the chemical reaction, and after that temperature is decreased, e.g. to temperature of 600 - 650 °C in which the reaction is continued. In one embodiment, the chemical reaction at higher temperature is only fractional part of total operational time of the catalyst. In one embodiment, the catalyst is acid-treated by using an acid. In one embodiment, HNO3, HCOOH, HC1, H2SO4, H3PO4, (COOH2) or other suitable acid is used as the acid. In one embodiment, HNO3 is used as the acid. In one embodiment, the acid treatment is performed by dissolution and precipitation methods. In one embodiment, the acid treatment is performed by the dissolution. In one embodiment, the catalyst material is dissolved in the acid. In one embodiment, the catalyst material is digested and etched during the acid pretreatment. In one embodiment, temperature which is between a room temperature and 120 °C, e.g. between 50 - 100 °C, is used for the acid digestion. In one embodiment, 0.1 M to 5 M HNO3 diluted solution is used in the acid-treatment . In one embodiment, the acid digestion is performed using HNO3 diluted with 1 molar solution at temperature of about 90 °C. Further, in one embodiment rate of flow of reactant, e.g. gas, through the catalyst per time unit affects an activation of the catalyst. In one embodiment, the acid treatment is performed at a temperature of 50 - 600 °C, in one embodiment 60 - 200 °C, and in one embodiment 90 - 120 °C. In one embodiment, the acid treatment is performed at a temperature of 400 - 600 °C. In one embodiment, the catalyst material is oxidized and / or calcined. In one embodiment, the catalyst material is oxidized, e.g. at a temperature of 400 - 600 °C, in one embodiment at a temperature of 450 - 550 °C. The metal alloy surface may be, at least partially, oxidized. In one embodiment, further the catalyst material may be calcined and reduced. In one embodiment, the catalyst material is calcined at a temperature of 400 - 900 °C, in one embodiment at a temperature of 500 - 900 °C, and alternatively in one embodiment at a temperature of 400 - 700 °C. In one embodiment, the catalyst material is reduced at a temperature of 500 - 600 °C. In one embodiment, the alloy surface is activated at low temperature via oxidation and reduction of the alloy catalyst. In one embodiment, metals of the catalyst are oxidized during the acid treatment. In one embodiment, a decomposition of nitrates and a formation of oxides to metals of the catalyst are performed using heat. During the pre-treatment the surface of the catalyst may be broken, and a porous catalyst surface can be achieved. In one embodiment, the surface of the catalyst is modified such that surface irregularities, e.g. microstructures, spikes, protruding from the surface, pores or the like, are arranged onto the catalyst, preferably to the surface. By means of the pre-treatment, a surface area of the catalyst, and simultaneously a catalytic activity, can be increased, and thus yield of the products can be improved. When the catalyst is pre-treated, the performance of the catalyst can be improved at low temperatures in the process. In one embodiment, higher temperature in the beginning of the chemical reaction provides a decomposition of metal particles by means of generated reaction product on the catalyst surface for releasing primary particles from the metal particles, and thus this offers possibility to use lower reaction temperatures later. In one embodiment, carbon releases metal particles from the surface of the catalyst, when the catalyst or its surface comprises catalytically active metal and carbon. Simultaneously, the metal particles may decompose into smaller particles. Then, the catalyst can be activated, and the released metal particles catalyses the chemical reaction. Further, surface area increases on the surface of the catalyst.

[0022] The catalyst can be arranged to an arrangement, e.g. reactor, and preferably inside the arrangement. In this context, the arrangement may be any arrangement, device, apparatus, reactor or the like or any combination thereof, which preferably comprises the catalyst. In one embodiment, the arrangement comprises at least the reactor. In one embodiment, the arrangement comprises a pyrolysis reactor, fluidized bed reactor, fixed-bed reactor, rotary kiln reactor or any combination thereof.

[0023] In the arrangement for a chemical reaction forming one or more reaction products in solid form, the arrangement comprises the catalyst as defined in this description .

[0024] In one embodiment, the catalyst comprises an attachment means for attaching the catalyst, e.g. to the arrangement. The catalyst can be attached by means of the attachment means to the arrangement, e.g. reactor. Any attachment means can be used to attach the catalyst to the arrangement. In one embodiment, the catalyst comprises the attachment means for attaching the catalyst to the arrangement, and the attachments means is an integrated part of the catalyst. In one embodiment, the catalyst is attached to the arrangement walls by the attachment means. In one embodiment, the attachment is selected from the group consisting of hooks, connectors, other connecting element, or any combination thereof. Preferably, the catalyst can be easily replaced in the arrangement or removed from the arrangement, e.g. for regeneration purposes.

[0025] In one embodiment, the arrangement further comprises a reaction chamber for receiving the catalyst. In one embodiment, the reaction chamber comprises the attachment means for attaching the catalyst to the reaction chamber.

[0026] In one embodiment, the catalyst is a detachable catalyst, i.e. the catalyst can be easily detached from the arrangement, e.g. from the reactor. In one embodiment, the catalyst or the structure comprising the particles or the fixed structure of the catalyst is detached from the arrangement.

[0027] The predetermined chemical reaction is performed by the catalyst. The chemical reaction can be performed in the arrangement, e.g. in the reactor. In one embodiment, the chemical reaction is performed at a pressure between 0 - 5 bars and / or at a temperature between 600 - 900 °C. In one embodiment, the chemical reaction forming one or more reaction products in solid form is a chemical reaction selected from the group consisting of catalysed pyrolysis, catalysed hydrocarbon pyrolysis, catalysed methane pyrolysis, catalytic methane decomposition, catalysed methane splitting, chemical vapor deposition, other reaction, or any combination thereof. In one embodiment, hydrocarbon pyrolysis is the reaction, in which the hydrocarbon is selected from the group of Ci-io-alkanes , such as methane and ethane, C2-io_alkenes and C2-io_alkynes .

[0028] In the method for producing one or more reaction products in solid form by a chemical reaction, a catalyst, which has a shape, is formed from catalyst material, wherein the catalyst comprises at least one surface for the chemical reaction, and the catalyst is pre-treated at least by an acid treatment to modify the surface of the catalyst and / or to improve the activity of the catalyst, and the catalyst is arranged to an arrangement, a reactant is fed to the arrangement and the chemical reaction is performed in the arrangement, and at least one solid reaction product is recovered. In one embodiment, at least carbon is recovered as the solid reaction product. Preferably, the reactant is arranged to contact with the catalyst in the arrangement, e.g. in the reactor. In one embodiment, the steps comprising the feeding of the reactant, the performance of the chemical reaction and the recovery of the products can be repeated one or more times.

[0029] In this context, the reactant means any suitable reactant, which can be treated in the method with the defined catalyst. In one embodiment, the reactant is a hydrocarbon selected from the group of Ci-io-al- kanes, such as methane and ethane, C2-io_alkenes , and C2- 10-alkynes .

[0030] In one embodiment, the chemical reaction is performed at a reaction temperature of between 600 - 900 °C. In one embodiment, the chemical reaction is performed under the pressure of between 0 - 5 bars. In one embodiment, the contact time of the reactant with the catalyst is selected based on the reactant and the catalyst.

[0031] In one embodiment, the reactant is arranged to flow from top to bottom in the arrangement, e.g. in the reactor. The reactant flow direction from top to bottom enables easier carbon removal from the bottom.

[0032] In one embodiment, the method comprises: i) providing a catalyst as defined; ii) letting the catalyst to contact a reactant at a predefined reaction temperature, wherein the predefined reaction temperature is selected based on the catalyst and the reactant, thereby forming one or more reaction products in solid form; and iii) collecting the formed one or more reaction products in solid form. In one embodiment, hydrogen is formed in ii) , and the formed hydrogen is collected. In one embodiment, in ii) , the predefined reaction temperature is between 600 - 900 °C. In one embodiment, in ii) , the pressure is between 0 - 5 bars. In one embodiment, the steps ii) and iii) are repeated one or more times .

[0033] In one embodiment, the reaction product in the solid form comprises carbon. In one embodiment, the reaction product in solid form and hydrogen are produced. In one embodiment, the one or more reaction products in solid form comprises, or consists essentially of, carbon. In one embodiment, the reaction product in solid form comprises an allotrope of carbon, e.g. carbon nanotube, carbon nanofiber, graphite, graphene, and / or carbon black. In one embodiment, the one or more reaction products in solid form consists of an allotrope of carbon, preferably consists essentially of carbon nanotube and carbon nanofiber. In one embodiment, hydrogen and the one or more reaction products in solid form, wherein the one or more reaction products in solid form comprises, or consists essentially of, carbon, are formed in the chemical reaction, and preferably are recovered.

[0034] In one embodiment, the catalyst can be treated, e.g. by heating, regenerating and / or cleaning, e.g. leaching. In one embodiment, the catalyst is detached from the arrangement, e.g. from the reactor, before treating. In one embodiment, the catalyst is treated in the arrangement.

[0035] In one method for the preparation of the catalyst, the method comprises: providing one or more catalyst components, e.g. catalyst agents, to form the catalyst material; depositing the catalyst material and forming the catalyst from the catalyst material. The depositing may be repeated one or more times. In one embodiment, the catalyst is pre-treated before the chemical reaction, e.g. as presented above. In one embodiment , the depositing is additive manufacturing such as 3D-printing, direct metal laser sintering ( DMLS ) , selective laser sintering ( SLS ) , laser-based powder bed fusion technology (L-PFB) , stereolithography, and / or extrusion printing, or any combination thereof . In one embodiment , the 3D-printing is selected from the group consisting of binder j etting, directed energy deposition, material extrusion, powder bed fusion, sheet lamination, vat polymerisation, and wire arc additive manufacturing, or any combination thereof .

[0036] In one embodiment , the catalyst can be obtained by the method as above defined .

[0037] The catalyst can be used in a desired arrangement and / or in a desired method or process . In one embodiment, the catalyst is used in a catalysed pyrolysis , catalysed hydrocarbon pyrolysis , catalysed methane pyrolysis , catalytic methane decomposition, catalysed methane splitting, chemical vapor deposition, other reaction, or any combination thereof . In one embodiment , the catalyst is used in a reactor, fixed-bed reactor, pyrolysis reactor, fluidi zed bed reactor, rotary kiln reactor or any combination thereof .

[0038] Thanks to the invention high quality catalyst can be provided . Further, 3D printing catalyst can be prepared easily . The catalyst is an effective catalyst to produce solid products and hydrogen . The solid product with high purity can be achieved . Further, better gas flow management , easier thermal transfer and pressure optimi zation can be achieved, and various pressure zones across the catalyst are possible . Further, thanks to the invention, the f ixed catalyst with more surface area or the catalyst particles with increased surface area can be provided easily . Further, using the fixed catalysts , the better working conditions , e . g . occupational hygiene , can be achieved, because the catalyst is not dusty .

[0039] The invention offers a possibility to achieve a catalyst with good properties easily . The catalyst can be prepared with low material costs , with lower need of critical or scarce catalyst material , with better mechanical strength and with long lifetime . The catalyst is easy to use in the processes . By means of the catalyst simpler balance of the process can be achieved . Further, the catalyst has a lower carbon footprint over lifetime .

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate some embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

[0042] Fig . 1 shows catalyst ( la) and its cross-sectional structure ( lb) according to one embodiment ,

[0043] Fig . 2 shows SEM images of metal alloy before and after an acid treatment according to one embodiment , and

[0044] Fig . 3 shows SEM images of a catalyst surface during a reaction according to one embodiment .

[0045] EXAMPLES

[0046] The catalyst for a chemical reaction is formed of catalyst material , and the catalyst comprises at least one surface for the chemical reaction . The catalyst is pre-treated by means of an acid and / or heat to modify the surface of the catalyst and / or to improve the activity of the catalyst . The catalyst may compri se an attachment means for attaching the catalyst to an arrangement . The catalyst consists of the catalyst material , such as metal alloy, and the catalyst is free of a catalyst support . The catalyst may be prepared by 3D- printing from the metal alloy powder to form a fixed catalyst having desired structure and dimensions or catalyst particles having desired diameter .

[0047] In the chemical reaction, solid reaction products , such as at least carbon, and also hydrogen are formed by using the catalyst in the arrangement . The arrangement is a fixed-bed reactor with the fixed catalyst or a fluidi zed bed reactor with the catalyst particles .

[0048] Example 1

[0049] In this example , a fixed catalyst was manufactured . The catalyst was formed by 3D-printing from the metal alloy powder . The catalyst has honeycomb structure . The catalyst was acid-treated .

[0050] Fig . 1 shows one embodiment of the fixed catalyst ( la) and its cross-sectional structure ( lb) .

[0051] The catalyst was tested, and it was observed that the catalyst can be used in the chemical reaction to form solid carbon product and hydrogen .

[0052] Example 2

[0053] In this example , the catalyst comprising catalyst particles was manufactured . The catalyst was formed by 3D-printing from the Ni-Cu metal alloy powder . The catalyst was acid-treated .

[0054] It was observed that the activity of the catalyst increased, when the pre-treatment with the acid was used, and the catalyst can be used in the chemical reaction to form solid carbon product and hydrogen . Example 3

[0055] In this example , reaction products in solid form are produced by a chemical reaction by using the catalyst according to example 1 in a fixed-bed reactor or catalyst according to example 2 in a fluidi zed bed reactor . A reactant comprising hydrocarbons is fed to the arrangement and the chemical reaction is performed in the arrangement . The reactant is arranged to contact with the catalyst in the arrangement . At least carbon is recovered as the solid reaction product . Further hydrogen is formed and recovered .

[0056] Example 4

[0057] In this example , acid digested and etched metal alloy (Ni-Cu) catalysts were tested in lab and mid-scale reactors and compared to catalysts ( comparative catalysts ) without acid-treatment .

[0058] The metal alloy catalysts and especially their surface was modified by diluted 1 M HNO3 acid by etching and digestion . There was a significant difference in the catalyst activity before and after the acid treatment . After acid etching and digestion at 90 ° C the surface has been etched and the smooth alloy surface oxidised partially to be more active defect sites which are active at low temperature . The acid digested metal al loy catalysts undergo physical and chemical surface variations , i . e . partially oxidising the metal alloy surface to NiO / CuO phases and then followed by calcination and reduction processes to more active Ni-Cu sites plus creation of def ect / vacant sites . The microstructure tuned to be more porous , and the surface area is significantly increased after the acid treatment . The methane i s activated at relatively lower temperature over the acid treated catalysts than the pure metal alloy catalysts . The chemical and physical properties modified in the case of the acid treated catalysts by improving the surface restructuring and introducing new sites for the methane adsorption and surface reaction . Methane pyrolysis was activated at low temperature over acid treated catalysts at 630 ° C instead of 800 - 850 ° C . The alloy surface was activated at low temperature via oxidation and reduction of Ni-Cu alloy catalyst . The defected metal al loy grains initiate and catalyse in the carbon nanof ibers / nanostructures (CNFs ) growth, and the metal particles are disintegrated into small particles during tip and base growth . The metal alloy grains shrink and etched into smaller particles which are active at low temperature .

[0059] Fig . 2 shows SEM images of pure form of metal alloy microstructures with 200 nm si ze particles before and after the acid treatment .

[0060] It was observed from the tests that high carbon yield per gram of the catalyst was achieved compared to untreated metal alloy catalysts . The method is proven in real-time methane splitting process at relatively low temperature of 630 ° C . It was observed that the acid- treated metal alloy catalysts can be efficiently activated at low temperature with high carbon nanofibers yield and growth .

[0061] Example 5

[0062] In this example , the solid metal alloy catalysts , compri sing Ni and Cu, were modified by the acid treatment for preparing active solid metal catalysts , i . e . Ni-Cu alloy catalysts . The acid digestion was performed at a temperature of 90 - 120 ° C, and 1 M HNO3 acid . Metal-alloy oxidic phase was formed during the acid treatment , in which metals are partially oxidized and metal nitrates are leached . After the acid treatment the metal catalysts may be treated by calcination and reduction . Example 6

[0063] In this example , the Ni-Cu metal alloy catalyst was activated by the acid treatment . The acid treatment was performed with HNO3 acid . A partial oxidation and digestion at 90 ° C were performed, wherein Ni and Cu nitrates partially leached out . After that a calcination was performed at 300 - 800 ° C, and reduction was performed at 300 - 800 ° C . Activated NiCu-alloy was achieved .

[0064] Example 7

[0065] In this example , the catalyst structure was formed of catalyst material comprising catalytically active metals , such as Ni-Cu metal alloy . The catalyst was free from a catalyst carrier material . The catalyst structure was a monolith with a three-dimensional shape . The catalyst was treated by an acid digestion for breaking the surface of the catalyst .

[0066] The catalyst was arranged to a methane pyrolysis process , in which the solid carbon product and hydrogen were formed via a chemical reaction with the catalyst . It was observed that the activity of the catalyst remained during the pyrolysis process . For example , after six hours , the catalyst was still active when the catalyst was completely formed of the catalyst material . Although the surface of the catalyst wears during the process , fresh catalyst material ri ses to contact with the reactant . Thus , longer reaction runs can be carried out with the same catalyst in the process . Fig . 3 shows SEM images of the catalyst surface after the six-hour reaction .

[0067] The catalyst is suitable in different embodiments for different uses . Further, the invention is suitable in different embodiments for producing different products . The invention is not limited merely to the ex- amples referred to above ; instead, many variations are possible within the scope of the inventive idea defined by the claims .

Claims

CLAIMS1. A catalyst for a chemical reaction forming one or more reaction products in solid form, c h a r a c t e r i z e d in that the catalyst has a shape, which is formed of catalyst material, and the catalyst comprises at least one surface for the chemical reaction, and the catalyst is pre-treated at least by an acid treatment to modify the surface of the catalyst and / or to improve the activity of the catalyst.

2. The catalyst according to claim 1, c h a r a c t e r i z e d in that the at least one surface for the chemical reaction is made of one or more catalytically active metals, carbon, or is a composite.

3. The catalyst according to claim 1 or 2, c h a r a c t e r i z e d in that the catalyst for the chemical reaction comprises one or more catalytically active metals selected from the group consisting of nickel, copper, iron, aluminium, titanium, cobalt, manganese, chromium, silicon, carbon, or an oxide thereof, or any combination thereof.

4. The catalyst according to any one of claims 1 to 3, c h a r a c t e r i z e d in that the catalyst is pre-treated by an acid and heat.

5. The catalyst according to any one of claims 1 to 4, c h a r a c t e r i z e d in that the reaction product in solid form comprises an allotrope of carbon.

6. The catalyst according to any one of claims 1 to 5, c h a r a c t e r i z e d in that the catalyst is formed from powder of the catalyst material to form a three-dimensional catalyst.

7. The catalyst according to any one of claims 1 to 6, c h a r a c t e r i z e d in that the catalyst is formed by printing, 3D-printing, direct metal laser sintering (DMLS) , selective laser sintering (SLS) , laserbased powder bed fusion technology (L-PFB) ,stereolithography, and / or extrusion printing, or any combination thereof.

8. The catalyst according to any one of claims 1 to 7, c h a r a c t e r i z e d in that the catalyst comprises an attachment means for attaching the catalyst to an arrangement, and the attachment means is an integrated part of the catalyst.

9. A method for producing one or more reaction products in solid form by a chemical reaction, c h a r a c t e r i z e d in that the method comprises- forming a catalyst, which has a shape, from catalyst material, wherein the catalyst comprises at least one surface for the chemical reaction, and pre-treating the catalyst at least by an acid treatment for modifying the surface of the catalyst and / or for improving the activity of the catalyst;- arranging the catalyst to an arrangement;- feeding a reactant to the arrangement and performing the chemical reaction in the arrangement; and- recovering at least one solid reaction product.

10. The method according to claim 9, c h a r a c t e r i z e d in that at least carbon is recovered as the solid reaction product.

11. The method according to claim 9 or 10, c h a r a c t e r i z e d in that hydrogen and the one or more reaction products in solid form, which comprises carbon, are formed in the chemical reaction and recovered .

12. The method according to any one of claims 9 to 11, c h a r a c t e r i z e d in that the reactant is a hydrocarbon selected from the group of Ci-io-al- kanes, C2-io_alkenes , and C2-io_alkynes .

13. The method according to any one of claims 9 to 12, c h a r a c t e r i z e d in that the chemical reaction is performed at a reaction temperature of between 600 - 900 °C.

14. The method according to any one of claims 9 to 13, c h a r a c t e r i z e d in that the chemical reaction is performed under the pressure of between 0 - 5 bars .

15. The method according to any one of claims 9 to 14, c h a r a c t e r i z e d in that the catalyst is pre-treated by an acid and heat.

16. The method according to any one of claims 9 to 15, c h a r a c t e r i z e d in that the method comprises: digesting and etching the catalyst material during the acid treatment.

17. An arrangement for a chemical reaction forming one or more reaction products in solid form, c h a r a c t e r i z e d in that the arrangement comprises at least a catalyst which has a shape formed of catalyst material and which comprises at least one surface for the chemical reaction and which is pre-treated at least by an acid treatment to modify the surface of the catalyst and / or to improve the activity of the catalyst.

18. The arrangement according to claim 17, c h a r a c t e r i z e d in that the arrangement further comprises a reaction chamber for receiving the catalyst.

19. The arrangement according to claim 17 or 18, c h a r a c t e r i z e d in that the arrangement comprises a pyrolysis reactor, fluidized bed reactor, fixed- bed reactor, rotary kiln reactor or any combination thereof .

20. A use of the catalyst according to any one of claims l to 8, c h a r a c t e r i z e d in that the catalyst is used in a catalysed pyrolysis, catalysed hydrocarbon pyrolysis, catalysed methane pyrolysis, catalytic methane decomposition, catalysed methane splitting, chemical vapor deposition, other reaction, or any combination thereof.

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