Methanol decomposition with co-feeding of carbon monoxide

Abstract

The present application discloses methods of decomposing methanol into carbon monoxide and hydrogen The method involves providing a first feed stream comprising methanol, H2 and CO, wherein the molar ratio of H2 to CO in the first feed stream is between 1:5 and 5:1; contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2 and CO. Also disclosed are a process for performing an integrated Fisher-Tropsch synthesis using the products of the methanol decomposition as a feed stream.

Description

[0001] METHANOL DECOMPOSITION WITH CO-FEEDING OF CARBON MONOXIDE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to methods for decomposing methanol into hydrogen and carbon monoxide, and to catalysts suitable for use in such methods.

[0004] BACKGROUND

[0005] Methanol has great promise as a renewable feedstock for a range of industrial processes. It is a common and inexpensive commodity chemical which may be produced from numerous sources, including fermentation, biomass pyrolysis, catalytic reaction of syngas, and CO2 hydrogenation. Advantageously, it is a liquid at ambient temperatures and pressures, allowing it to be transported through low-pressure pipelines, ships, or trucks, and thus generally allows for increased transportation efficiency as a liquid.

[0006] Methanol holds especially great promise as a hydrogen carrier since it holds the highest hydrogen to carbon ratio of any liquid fuel and is much easier to store and transport than hydrogen itself.

[0007] One option for unlocking hydrogen from methanol is steam reforming, which produces hydrogen and carbon dioxide. Whilst carbon dioxide in itself can serve as a feedstock for other processes, a potentially more attractive route is to decompose methanol into hydrogen and carbon monoxide (i.e. syngas) through use of a suitable catalyst. The hydrogen or syngas produced from methanol decomposition has the potential to be used for a wide range of purposes, including interfacing with other industrial processes such as the Fischer-Tropsch production of hydrocarbons. Such was explored in the applicant’s earlier application WO 2024 / 033867, which discloses processes that include the production of methanol and its subsequent decomposition, forming CO which is at least partially used in a Fischer-Tropsch synthesis process. The focus of WO 2024 / 033867 is the integration of methanol decomposition within a larger scheme, rather than developments associated the methanol decomposition process itself.

[0008] Catalysed methanol decomposition has been disclosed in the art, such as in US 4,716,859, US 6,541 ,142 and US 9,833,773, Usami, et al., “Catalytic methanol decomposition at low temperatures over palladium supported on metal oxides.” Appl. Cat. A 171 (1): 123-130 (1998), and in Hargreaves, J.S.J. and Ormsby, G. Catalysis 2007, 20. 107-121. However, information on how to optimise such decomposition reactions to achieve high productivity and / or selectivity, and to allow the reaction to interface with other processes and applications, is relatively limited. Given the potential of methanol to serve as a key driver for the adoption and scaling of green technologies, there is a need to develop methods and materials which tailor methanol decomposition to suit specific industrial uses.

[0009] The present invention has been devised in light of the above considerations.

[0010] SUMMARY OF THE INVENTION

[0011] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0012] Various side-products can be generated alongside H2 and CO during methanol decomposition, including methane, CO2, dimethyl ether (CH3OCH3, typically abbreviated “DME”) and methyl formate. It is desirable to minimise the production of these side-products, since they constitute wasted carbon and hydrogen which could be used to make CO and H2. Formation of CO2 and DME can be at least partially dealt with by recycling and reprocessing these components to make further methanol which can be fed back into the decomposition process. However, recycling methane is less straightforward, and hence it is generally simpler to remove methane after its production, wasting carbon and hydrogen locked up in the starting methanol, and leading to issues around how to deal with the waste methane - a significantly more potent greenhouse gas than carbon dioxide. Thus, it is particularly beneficial to identify processes which produce carbon monoxide whilst suppressing formation of side-products such as carbon dioxide and, in particular, methane.

[0013] Surprisingly, the present inventors have discovered that when methanol is provided to a methanol decomposition catalyst alongside carbon monoxide and hydrogen, the formation of side-products such as methane and carbon dioxide can be suppressed. Thus, in a first aspect, the present invention provides a method for decomposing methanol, the method comprising: providing a first feed stream comprising methanol, H2and CO, wherein the molar ratio of H2to CO in the first feed stream is between 1 :5 and 5:1 (preferably between 1 :3 and 3:1); contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2 and CO.

[0014] The finding that co-feeding hydrogen and carbon monoxide alongside methanol leads to suppression of formation of methane and carbon dioxide was surprising. In particular, it is understood that methane side-product forms during the reaction due to the hydrogenation of carbon monoxide according to the formula: and that carbon dioxide is formed either through the water-gas shift reaction between CO and H2O: or by disproportionation of CO:

[0015] Thus, the inventors anticipated that including carbon monoxide and hydrogen to the feed stream would lead to a significant growth in the production of methane and carbon dioxide. Instead, as shown in the experimental examples, the inventors found that supplementation of the methanol feed stream with hydrogen and carbon dioxide in a ratio between 1 :5 and 5:1 actually led to consistent suppression of both methane and carbon dioxide.

[0016] The first feed stream may comprise, for example, at least 5 mol% methanol.

[0017] Optionally, the feed stream comprises up to 0.05 mol% water.

[0018] Preferably, the contacting is carried out at a temperature of at least 150°C, or at least 200°C, or at least 300°C. The pressure during contacting may be, for example, at least 5 barg (barg referring to pressure in bars above ambient or atmospheric pressure).

[0019] Optionally, the methanol decomposition catalyst comprises at least one of platinum and copper supported on a support, the support comprising titania or ceria or a mixed oxide comprising a mixture of titania and ceria. In such instances, the at least one of platinum and copper may be present, for example, in an amount of in the range of 0.5 to 10% by weight of the methanol decomposition catalyst, based on the total weight of the methanol decomposition catalyst.

[0020] Preferably, the method shows a methane selectivity of less than 10 wt.%, based on the total weight of the products.

[0021] Preferably, the method shows a CO2 selectivity of less than 10 wt.%, based on the total weight of the products.

[0022] Preferably, the method shows a dimethyl ether (DME) productivity of less than 60 g / kg(cat) / h.

[0023] The method of the first aspect of the invention may also be integrated with further follow-on processes, such as Fischer-Tropsch synthesis. Therefore, in a further aspect, the present invention provides a process for performing an integrated Fisher-Tropsch synthesis, the process comprising: providing a first feed stream comprising methanol, H2and CO, wherein the molar ratio of H2to CO in the first feed stream is between 1 :5 and 5:1; contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2and CO in a method according to the first aspect of the invention; optionally providing a second feed stream comprising H2and at least a portion of the CO of the first product stream; and contacting the first product stream or, optionally, the second feed stream, with a Fischer- Tropsch catalyst to perform a Fischer-Tropsch synthesis to provide a second product stream comprising C5+ hydrocarbons. In a further aspect, the present invention provides use of CO to reduce, minimise or eliminate the formation of at least one side-product during a methanol decomposition process. In such uses, the methanol decomposition process comprising providing a first feed stream comprising methanol and H2, and contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2 and CO. The ratio of H2 to CO in the first feed stream may be between 1:5 and 5:1, more preferably between 1 :3 and 3:1. The at least one-side product may be, for example, methane, carbon dioxide and / or dimethyl ether, more preferably methane and / or carbon dioxide, most preferably methane.

[0024] As used herein, a “feed stream” is used to mean the total material input to a process step, e.g., methanol decomposition reaction, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single inlet or multiple inlets. Similarly, a “product stream” is used to mean the total material output from a process step, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single reactor outlet or multiple reactor outlets.

[0025] BRIEF DESCRIPTION OF THE FIGURES

[0026] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0027] FIGURE 1 shows a schematic of a methanol decomposition process according to an example embodiment of the invention.

[0028] FIGURE 2 shows a schematic of an integrated methanol decomposition and Fischer-Tropsch reaction carried out in the same reactor, according to an example embodiment of the invention.

[0029] FIGURE 3 is a plot showing the effect of feeding methanol alongside a 2:1 mix of hydrogen and carbon monoxide on production of methane, carbon dioxide and DME side-products when catalysed by a copper catalyst on ceria.

[0030] FIGURE 4 is a plot showing the effect of feeding methanol alongside a 2:1 mix of hydrogen and carbon monoxide on production of methane, carbon dioxide and DME side-products when catalysed by a platinum catalyst on titania.

[0031] FIGURE 5 is a plot showing the effect of feeding methanol alongside a 2:1 mix of hydrogen and carbon monoxide on production of methane, carbon dioxide and DME side-products when catalysed by a commercially-available catalyst T-2130.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference. format

[0034] Catalytic material

[0035] The methanol decomposition catalyst may include one or more transition metals selected from Groups 6-12 of the periodic table. In particular embodiments, the methanol decomposition catalyst may comprise one or more of Cr, Fe, Co, Ni , Cu, Zn, Ru, Rh, Pd, Ir, or Pt, or mixtures thereof. Preferably, the one or more transition metals comprise or consist of one or more of Pt, Cu, Pd and Ni, further preferably one or more of Pt, Cu, and Pd, and more preferably one or more of Pt and Cu. Optionally, the one or more transition metals are selected from Groups 7-11, preferably Groups 7, 10 or 11 ; more preferably from Groups 10 or 11 , most preferably from Group 10. Optionally, the one or more transition metals comprises or consists of platinum.

[0036] Optionally, the methanol decomposition catalyst comprises a further element, such as one or more of Sc, Y, Ti, Zr, Ce, B, Al, Ga, In, Si, Ge, Sn, or Sb.

[0037] Optionally, the methanol decomposition catalyst is an alloy, such as an intermetallic alloy.

[0038] Support

[0039] The methanol decomposition catalyst is a supported catalyst. The support may be a refractory oxide, such as oxidized diamond, silica, zirconia, ceria, titania, alumina, lanthanum oxide, or magnesia.

[0040] The support material may be in the form of a powder, granulate, shaped particle, such as a preformed sphere or microsphere, or extrudate.

[0041] In instances where the methanol decomposition catalyst is a support catalyst, the one or more transition metals may constitute at least 1 wt.%, at least 2 wt.%, at least 2.5 wt.%, at least 3 wt.%, at least 3.5 wt.%, at least 4 wt.%, at least 4.5 wt.% or at least 5 wt.% of the weight of the methanol decomposition catalyst. The upper limit for the amount of the one or more transition metals may be, for example, up to 30 wt.%, up to 20 wt.%, up to 15 wt.% of the weight, or up to 10 wt.% of the methanol decomposition catalyst.

[0042] For the avoidance of doubt, any metal component of the support is not the “one ormore transition metals” of the catalyst.

[0043] Catalyst formation

[0044] The methanol decomposition catalyst may be formed by standard methods known in the art, such as impregnation or co-precipitation.

[0045] For example, the methanol decomposition catalyst may be formed by: (i) contacting a support material with an impregnating solution containing one or more catalyst-precursor compounds to form an impregnated support material; and (ii) drying and calcining the impregnated support material to form the methanol decomposition catalyst. Reference herein to "impregnation" or "impregnating" is intended to refer to contact of the support material with a solution, or solutions, of catalyst-precursor compound(s), before drying in order to achieve precipitation of the catalyst-precursor compound(s). Impregnation with a fully dissolved solution, or solutions, of the catalyst-precursor compound(s) ensures good dispersion of the catalyst-precursor compound(s) on the support material and is thus preferred. This is in contrast, for instance, to the use of partially dissolved catalyst-precursor compound(s) in 'solid solutions' or suspensions, where the level of dispersion of the catalyst-precursor compound(s) across the surface, and in the pores, of the support material can fluctuate depending on the nature of the precipitation on the support material. Furthermore, use of a fully dissolved solution, or solutions, of catalyst-precursor compound(s) also has less of an impact upon the resulting morphology and bulk crush strength of an extrudate formed thereafter compared with solid solutions. Nevertheless, benefits of the present invention can also be realised in the case where a solid solution, or solutions, of a partially undissolved catalystprecursor compound is used.

[0046] Impregnation of the support material may be achieved by any suitable method of which the skilled person is aware, for instance by vacuum impregnation, incipient wetness, or immersion in excess liquid. The incipient wetness technique is so-called because it requires that the volume of impregnating solution be predetermined so as to provide the minimum volume of solution necessary to just wet the entire surface of the support, with no excess liquid. The excess solution technique as the name implies, requires an excess of the impregnating solution, the solvent being thereafter removed, usually by evaporation. Where a powder or granulate of support material is impregnated, the powder or granulate may be admixed with the impregnating solution by any suitable means of which the skilled person is aware, such as by adding the powder or granulate to a container of the impregnating solution and stirring.

[0047] The support material may be in the form of a powder, granulate, shaped particle, such as a preformed sphere or microsphere, or extrudate. Reference herein to a powder or granulate of a support material is understood to refer to free flowing particles of a support material or particles of support material that have undergone granulation and / or sieving to be a particular shape (e.g. spherical) and size range. Reference herein to an "extrudate" is intended to mean a support material that has undergone an extrusion step and therefore may be shaped. In the context of the present invention, the powder or granulate is in a form which is suitable for impregnation with a solution of the catalyst-precursor compound(s), and subsequent extrusion or forming into other shaped particles.

[0048] Suitable catalyst-precursor compounds are those which contain the metal of interest and are thermally decomposable to an oxide of the metal following calcination and which are preferably completely soluble in the impregnating solution. The catalyst-precursor compounds may be, for example, a nitrate, acetate, acetylacetonate, chloride or sulphate of the metal of interest. The solvent of the impregnating solution(s) may be either an aqueous solvent or a nonaqueous, organic solvent. Suitable non-aqueous organic solvents include, for example, alcohols (e.g. methanol, ethanol and / or propanol), ketones (e.g. acetone), liquid paraffinic hydrocarbons and ethers. Alternatively, aqueous organic solvents, for example an aqueous alcoholic solvent, may be employed. Preferably, the solvent of the impregnating solution(s) is an aqueous solvent.

[0049] When more than one catalyst-precursor compound is used, the impregnation of the support material with the catalyst-precursor compounds may occur in a single step, without any intermediate drying or calcination steps to separate the loading of the different components. As the skilled person will appreciate, the different catalyst- precursor compounds may be applied to the support material successively or simultaneously in separate impregnation solutions or suspensions, or preferably an impregnation solution or suspension comprising all of the catalyst-precursor compounds is used.

[0050] The concentration of the one or more catalyst-precursor compounds in the impregnating solution(s) is not particularly limited, although preferably the catalyst-precursor compound(s) is / are fully dissolved. When a powder or granulate of support material is impregnated and immediately followed by an extrusion step, the amount of the impregnating solution(s) is preferably suitable for forming an extrudable paste.

[0051] Impregnation of the support material is usually followed by drying of the impregnating solution in order to effect precipitation of the catalyst-precursor compound(s) on to the support material and preferably also to remove bound solvent of the impregnating solution (e.g. water). Drying therefore does not, for instance, lead to full decomposition of the catalyst-precursor compound(s) or otherwise lead to a change in oxidation state of such compounds. As will be appreciated, in embodiments where an extrusion is performed, complete drying and removal of solvent (e.g. bound solvent) of the impregnating solution may occur after forming of a shaped particle, for example by extrusion. Drying is suitably conducted at temperatures from 50 °C to 150 °C, preferably 75 °C to 125 °C. Suitable drying times are, for example, from 5 minutes to 72 hours. Drying may suitably be conducted in a drying oven or in a box furnace, for example, under the flow of an inert gas at elevated temperature.

[0052] Next, the impregnated support material is subjected to a calcination step. As will be understood, calcination is required for converting the catalyst-precursor compound which has been impregnated on the support material into an oxide. Thus, calcination leads to thermal decomposition of the catalyst-precursor compound(s), and not merely removal of bound solvent of an impregnating solution, as for instance in the case of drying. Calcination may be performed by any method known to those of skill in the art, for instance in a fluidized bed, rotary kiln, box furnace or ashing kiln at a temperature of at least 250 °C, preferably from 275 °C to 500 °C.

[0053] Finally, the methanol decomposition catalyst may be activated prior to / during use, for example, by reduction (reductive activation). The person of skill in the art can identify suitable conditions for activating the catalyst. The methanol decomposition catalyst may be activated using hydrogen gas as reducing agent. The hydrogen gas may be mixed with other gases, such as an inert carrier gas. Examples of such inert carrier gases include nitrogen, carbon dioxide, argon, or helium.

[0054] Processing conditions

[0055] The contacting of the feed stream comprising methanol with the metal decomposition catalyst occurs at a temperature and pressure suitable to effect efficient methanol decomposition.

[0056] The temperature may be, for example, 200-500°C, for example, 200-450°C, or 200-400°C, or 200-350°C, or 200-300°C, or 250-500°C, or 250-450°C, or 250-400°C, or 250-300°C, or 300- 500°C, or 300-450°C, or 300-400°C.

[0057] The pressure is above 10 barg (barg referring to pressure in bars above ambient or atmospheric pressure). The pressure may be, for example, 10-50 barg, preferably 10-40 barg, preferably 10-30 barg, or 20-40 barg, more preferably 30-40 barg.

[0058] The gas hourly space velocity (GHSV) for continuous operation may be in the range 50 to 200,000 h’1, such as 10,000 to 200,000 h’1, 50,000 to 200,000 h’1, or 100,000 to 200,000 h’1.

[0059] Feed stream

[0060] The methanol is provided as part of a feed stream. In instances where the products of methanol decomposition are themselves used as the feed stream for a further process, the feed stream provided to the methanol decomposition catalyst may be referred to as the “first feed stream”.

[0061] Preferably the feed stream comprises at least 5 mol% methanol (the mol% being calculated as a percentage of the whole feed stream). For example, in particular embodiments, the feed stream comprises at least 7.5 mol% methanol, e.g., at least 10 mol% methanol, or at least 15 mol% methanol, or at least 20 mol% methanol, or at least 25 mol% methanol.

[0062] The feed stream also includes hydrogen and carbon monoxide in a ratio between 1:5 and 5:1, preferably 1 :3 and 3:1. That is, the ratio may be at least 1 :5 and up to 5:1 , preferably at least 1:3 and up to 3:1. In some examples, the feed stream includes hydrogen and carbon monoxide in a ratio of at least 1:5, at least 1 :4, at least 1:4.5, or at least 1:3. In some examples, the ratio may be at least 1 :1, at least 1.5:1 , or at least 2:1. In some examples, the feed stream includes hydrogen and carbon monoxide in a ratio of up to 5: 1 , up to 4: 1 , up to 4.5:1, or up to 3: 1. Any of the foregoing may be combined to form a suitable range, such as at least 1 :5 and up to 4.5:1 , at least 1 :4.5 and up to 3:1 , at least 1.4:5 and up to 4.5:1 , or at least 1:5 and up to 3:1.

[0063] In some examples, there is an excess of hydrogen compared to carbon monoxide, for example, the hydrogen to carbon monoxide ratio may be greater than or at least 1 :1 and up to 5:1 , preferably at least 1.5:1 and up to 5:1 , more preferably at least 1.5:1 and up to 4:1, or at least 2:1 and up to 5:1 , most preferably at least 1.5:1 and up to 3:1. Most preferably, the hydrogen to carbon monoxide ratio is around 2:1. In some examples, it may be preferred to have a lower amount of hydrogen from a cost perspective. In some examples, having somewhat higher amounts of CO in the feed stream may cause a shift in the equilibrium of methanol decomposition that may be desirable in some instances. Accordingly, in some examples, the hydrogen to carbon monoxide ratio may be 3:1 or below, such as at least 1 :5 and up to 3:1 , at least 1 :4 and up to 3:1 , at least 1 :3 and up to 3:1, at least 1 :1 and up to 3:1 , at least 1.5:3 and up to 3: 1 , or at least 2: 1 and up to 3: 1.

[0064] The overall combined amount of hydrogen and carbon monoxide in the feed stream may be, for example, at least 10 mol%, at least 20 mol%, at least 30 mol%, at least 40 mol%, at least 50 mol%, at least 60 mol% or at least 70 mol%. The upper limit on the combined amount of hydrogen and carbon monoxide in the feed stream may be, for example, 95 mol%, 90 mol%, 85 mol% or 80 mol%. The range for the combined amount of hydrogen and carbon monoxide in the feed stream may be, for example, 30-95 mol%, such as 40-90 mol% or 50-90 mol%.

[0065] Optionally, the feed stream may also comprise one or more additional gases, which may be inert or reactive. In such embodiments, the feed stream may further comprise, for example, an inert carrier gas, such as N2. Such a gas may serve as a diluent.

[0066] The components of the feed stream may be delivered as one or more combined feed stream(s), separate feed streams, or any combination thereof. By the term "combined feed stream" it is meant a feed stream which contains at least part of two or more of the components. By the term "separate feed stream" it is meant a feed stream which contains only one of the components.

[0067] Optionally, the feed stream may incorporate water. The water may be present in the methanol delivered to the feed stream; for example, the water content of the liquid methanol may be adjusted by addition of water or by dehydration. The molar ratio of water to methanol (water: methanol) in the feed stream may be, for example, up to 30:70, up to 20:80, or up to 10:90. For example, the lower limit for the molar ratio of water to methanol may be, for example, 0.05:99.95, 0.1:99.9, 1 :99, 2:98, 3:97, 4:96; or 5:95. Suitable ranges for the molar ratio may be, for example, 1:99 to 30:70; 1 :99 to 20:80; 1 :99 to 10:90; or 2:98 to 10:90.

[0068] The hydrogen used in the process may be derived from any suitable source. Non-limiting examples of processes which may provide a source of hydrogen that may be used in the process of the present invention include synthesis gas generation processes; the hydrolysis of water; and various other chemical processes, such as, for example, ethane crackers, styrene manufacture and catalytic reforming.

[0069] Carbon monoxide used in the process may likewise be derived from any suitable source. Nonlimiting examples of processes which may provide a source of carbon monoxide that may be used in the process of the present invention include synthesis gas generation processes; the reduction of metal oxides; and various other chemical processes, such as, for example, the high temperature reaction of air or oxygen with a carbonaceous material (for example coal).

[0070] The feed stream may be provided at elevated temperature. For example, the feed stream may have a temperature in the range of 200-500°C, such as 200-450°C, or 200-400°C, or 200- 350°C, or 200-300°C, or 250-500°C, or 250-450°C, or 250-400°C, or 250-300°C, or 300-500°C, or 300-450°C, or 300-400°C.

[0071] Preferably, the decomposition of methanol is performed with a conversion efficiency of methanol of at least 30%, e.g., at least 40%, or at least 50%, or at least 60%, or at least 65%, or at least 70%, or at least 75%. By “conversion efficiency” we mean the weight percentage of methanol in the product stream as a percentage of the weight of methanol in the feed stream.

[0072] Due to the consumption of methanol in the reaction, the product stream preferably includes no more than 75 mol% methanol, e.g., no more than 60 mol% methanol, no more than 50 mol% methanol, or no more than 25 mol% methanol (the mol% being calculated as a percentage of the whole product stream).

[0073] Preferably, the product stream comprises at least 20 mol% total of CO and H2, e.g., at least 35 mol%, or at least 50 mol%, or at least 65 mol%. Without wishing to be bound by theory, methanol decomposition under these conditions is expected to generate two moles of H2per mole of CO. Accordingly, in various embodiments as otherwise described herein, the first product stream has a molar ratio of hydrogen to carbon monoxide in the range of 0.5:1 to 5:1 , e.g., 1:1 to 3:1 , or 1.5:1 to 2.5:1 , or 1.5:1 to 3.5:1.

[0074] Preferably, the product stream comprises no more than 20 mol% of methane e.g. no more than 15 mol% methane, no more than 10 mol% methane, no more than 5 mol% methane, no more than 3 mol% methane, no more than 2 mol% methane, or no more than 1 mol% methane.

[0075] Preferably, the product stream comprises no more than 20 mol% of CO2, e.g. no more than 15 mol% CO2, no more than 10 mol% CO2, no more than 5 mol% CO2, no more than 3 mol% CO2, no more than 2 mol% CO2, or no more than 1 mol% CO2.

[0076] Preferably, the product stream comprises no more than 20 mol% of DME, e.g. no more than 15 mol% DME, no more than 10 mol% DME, no more than 5 mol% DME, no more than 3 mol% DME, no more than 2 mol% DME, or no more than 1 mol% DME.

[0077] Preferably, the product stream comprises no more than 20 mol% of methyl formate, e.g. no more than 15 mol% methyl formate, no more than 10 mol% methyl formate, no more than 5 mol% methyl formate, no more than 3 mol% methyl formate, no more than 2 mol% methyl formate, or no more than 1 mol% methyl formate. Preferably, the decomposition of methanol is performed with high selectivity for CO over other carbon products (i.e. with minimal formation of side-products including methane, CO2, DME and methyl formate) - that is with high carbon product selectivity for CO. When referring to “carbon product selectivity” of the decomposition process for a particular component, we mean the space time yield (STY) of the component as a percentage of the STY for all carbon-containing products from the methanol decomposition, subtracting the contribution from any components not derived from methanol decomposition (for example, since carbon monoxide is added to the feed stream then the contribution from this is subtracted from the carbon monoxide in the product stream). In this disclosure, STY is reported as the grams of product produced per kilogram of catalyst per hour (space time yield weight, or STYW), although those skilled in the art will recognise that the carbon product selectivity is a percentage which is independent of the particular units used for the STY.

[0078] Preferably, the decomposition of methanol is performed with a carbon product selectivity of at least 50% for CO, e.g., at least 60%, or at least 70%, or at least 80%, or at least 90% for CO.

[0079] Preferably, the decomposition of methanol is performed with a carbon product selectivity of no more than 20% for methane e.g., no more than 15%, or no more than 10%, or no more than 5%.

[0080] Preferably, the decomposition of methanol is performed with a carbon product selectivity of no more than 20% for CO2, e.g., no more than 15%, or no more than 10%, or no more than 5%.

[0081] Preferably, the decomposition of methanol is performed with a carbon product selectivity of no more than 20% for dimethyl ether (DME), e.g., no more than 15%, or no more than 10%, or no more than 5%.

[0082] Preferably, the decomposition of methanol is performed with a carbon product selectivity of no more than 20% for methyl formate, e.g., no more than 15%, or no more than 10%, or no more than 5%.

[0083] Particularly preferred are methods which are performed with a carbon product selectivity of greater than 60% for CO and less than 40% for methane, more preferably less than 70% for CO and less than 30% for methane.

[0084] Reactor type

[0085] The reaction zone of the present invention can conveniently be any reactor, multiple reactors, such as a series of reactors, or a part thereof, wherein the process of the present invention occurs.

[0086] Suitable reactors which may be used in the process of the present invention include adiabatic bed, multi-tubular, fluidised bed, spinning basket and buss loop, and heat exchanger reactors. When more than one reactor is used, the reactors may be arranged either in series or in parallel. For reactors utilised in series, heat exchangers and / or intercoolers and / or additional reactant and / or recycle of intermediates can be employed in between successive reactors to control the reaction temperature. In one embodiment of the present invention, the process is performed in at least two adiabatic reactors in series.

[0087] An example embodiment is shown in schematic view in FIG. 1. Here, in process 100 a crude methanol stream 102 is optionally combined with a feed of one or more further gases 104 to form a first feed stream 106 which is delivered into reactor 110. Reactor 110 includes a methanol decomposition reaction zone in which with methanol decomposition catalyst 112 is contacted with the first feed stream 106 and product stream 120 is formed. Here, product stream 120 is conducted from the methanol decomposition reaction zone, and unreacted methanol is substantially separated from the product stream (e.g., at least 50%, at least 75%, at least 90% or at least 95% unreacted methanol is separated) and is recycled to the first feed stream 106 via methanol recycle 108.

[0088] Processing of the product stream

[0089] Preferably the method involves separating components from the product stream. In particular, the method preferably comprises separating CO and H2from the product stream, optionally separating CO and H2independently.

[0090] Preferably, at least a portion of the product stream is recycled to the feed stream. For example, preferably at least a portion of methanol is separated from the first product stream and recycled to the feed stream.

[0091] Optionally, at least a portion of the CO2is separated from the product stream. The CO2may be recycled to the feed stream or may be subjected to further processing. For example, the CO2may be separated and used as the feed stream for a reverse water-gas shift (reverse WGSR) to form carbon monoxide and water.

[0092] Optionally, at least a portion of the methane is separated from the product stream. The methane may be recycled to the feed stream or may be subjected to further processing. For example, the methane may be separated and used as the feed stream for a methane reforming process (such as steam reforming or autothermal reforming) to generate further hydrogen.

[0093] Optionally, the CO and H2are stored for further use. Alternatively, the CO and H2may be used as a feedstock for further processing, such as the Fischer-Tropsch reaction to produce hydrocarbons (as described in the applicant’s earlier application WO 2024 / 033867).

[0094] Follow-on reactions

[0095] Due to the advantageous compatibility of the methods of the present invention with follow-on processes which take the products of methanol decomposition and use them as the feedstock for further use, the present invention envisages use of the method of the first aspect to generate feedstocks for further processes.

[0096] In particular, the present invention also provides a process for performing an integrated Fisher- Tropsch synthesis, the process comprising: providing a first feed stream comprising methanol, H2and CO, wherein the molar ratio of H2to CO in the first feed stream is between 1 :5 and 5:1; contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2and CO in a method according to the first aspect of the invention; optionally providing a second feed stream comprising H2and at least a portion of the CO of the first product stream; and contacting the first product stream or, optionally, the second feed stream, with a Fischer- Tropsch catalyst to perform a Fischer-Tropsch synthesis to provide a second product stream comprising Cs+ hydrocarbons.

[0097] The Fischer-Tropsch step of the method may be carried out in the manner taught in the applicant’s earlier application WO 2024 / 033867.

[0098] The temperature of the Fischer-Tropsch synthesis can suitably be in the range of 200-400 °C, such as 200-300 °C, or 210-400 °C, or 210-300 °C, or 220-400 °C, or 220-300 °C. For example, the temperature of the Fischer-Tropsch synthesis is in the range of 200-250 °C, such as 200-240 °C, or 200-230 °C, or 200-220 °C, or 210-250 °C, or 210-240 °C, or 210-230 °C, or 220-250 °C, or 220-240 °C, or 230-250 °C. The pressure of the reaction may suitably be in the range from 10-50 barg, such as 20-50 barg, or 25-50 barg, or 10-40 barg, or 20-40 barg, or 25- 40 barg or 10-35 barg, or 20-35 barg, or 25-35 barg. For example, the contacting of the first product stream or second feed stream with the Fischer-Tropsch catalyst may be performed at a pressure in the range of 20-40 barg.

[0099] The Fischer-Tropsch catalyst may be selected by the person of ordinary skill in the art. In various embodiments as otherwise described herein, the Fischer-Tropsch catalyst comprises cobalt, iron, rhodium, ruthenium, or a combination thereof (e.g., comprises cobalt or iron). In particular embodiments, the Fischer-Tropsch catalyst comprises cobalt in an amount in the range of 2 to 30 wt.%, e.g., in the range of 5 to 25 wt.%, or in the range of 8 to 20 wt.%, calculated as Co(0), as a weight percentage of the Fischer-Tropsch catalyst. In particular embodiments, the Fischer-Tropsch catalyst comprises iron in an amount in the range of 15 to 95 wt.%, e.g., 25 to 95 wt.%, or 30 to 90 wt.%, calculated as Fe(0). In various embodiments as otherwise described herein, the Fischer-Tropsch catalyst further comprises manganese (e.g., comprises manganese in the amount of 0.1 to 15 wt.%, or 1 to 10 wt.%).

[0100] In various embodiments as otherwise described herein, the Fischer-Tropsch catalyst is a supported catalyst, wherein the support comprises at least one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide, magnesium oxide, and zinc oxide (e.g., comprises at least one of titanium oxide, aluminum oxide, and silicon oxide). For example, in particular embodiments, the support is a titanium dioxide support, or is an alumina support, or is a silica support. In various embodiments, the support is a shaped particle, e.g., an extrudate. The catalyst can be prepared using methods conventional in the art.

[0101] Suitably, the Fischer-Tropsch catalyst is activated prior to use. The Fischer-Tropsch catalyst may be activated by reductive activation, in the manner described above in relation to the methanol decomposition catalyst.

[0102] Suitably, the methanol decomposition catalyst is different to the Fischer-Tropsch catalyst.

[0103] The contacting of the first product stream / second feed stream with the Fischer-Tropsch catalyst and the contacting of the first feed stream with the methanol decomposition catalyst may be performed in the same plant. This can be, e.g., within different beds in the same reactor, or in different reactors. In such embodiments, the two processes may be integrated together to provide efficient transformation of methanol to hydrocarbons.

[0104] Suitably, the first reaction zone comprises a first reactor in which the methanol decomposition catalyst is disposed, and wherein the second reaction zone comprises a second reactor in which the Fischer-Tropsch catalyst is disposed. The first reaction zone comprises a first catalyst bed in which the methanol decomposition catalyst is disposed, and the second reaction zone comprises a second catalyst bed in which the Fischer-Tropsch catalyst is disposed. Optionally, the first catalyst bed and the second catalyst bed are disposed within the same reactor, e.g., in catalyst stacks or catalyst bed sections. In such situations, the reactor may be held at a temperature and pressure to achieve efficient decomposition of methanol and efficient Fischer-Tropsch synthesis. As demonstrated in the examples below, this may be, for example, a temperature in the range of 200-400°C, in particular around 300-350°C.

[0105] An example of such an arrangement is shown in Figure 2. Here, first feed stream 221 is provided to stacked bed reactor 225, which includes a methanol decomposition reaction zone 220 (here, a first bed of the stacked-bed reactor that includes the methanol decomposition catalyst 223) and a Fischer-Tropsch reaction zone 230 (here, a second bed of the stacked-bed reactor that includes the Fischer-Tropsch catalyst 233). The first feed stream 221 is contacted with the methanol decomposition catalyst 223 to provide a first product stream 222 that includes CO and H2. The first product stream is provided to the Fischer-Tropsch reaction zone as second feed stream 231 , which is contacted with Fischer-Tropsch catalyst 233 to provide a second product stream 232 that includes C5+ hydrocarbons. Here, at least a portion of the C5+ hydrocarbons of the second product stream is conducted to hydroprocessing unit 260, where it is hydroprocessed to provide an end product stream 265. Here, at least a portion of H2 of the first product stream is separated and conducted to the hydrotreating unit 260 via stream 262. H2can also be provided to the hydrotreating unit in the portion of the second product stream that is conducted to the hydrotreating unit. PreReactions

[0106] The feed stream comprises methanol, hydrogen and CO. These components may be provided by any suitable method.

[0107] In some embodiments the water-gas shift reaction may be used to generate H2by reacting carbon monoxide with water. Suitable conditions are known in the art. Advantageously, at least or more than 10%, such as at least 15% or at least 20% of the hydrogen used in the methanol decomposition reaction may be generated by the water-gas shift reaction.

[0108] In some embodiments, the methanol may be generated by hydrogenation of CO2. Suitable conditions are known in the art.

[0109] In some embodiments, the CO may be generated through a reverse water-gas shift reaction. Suitable conditions are known in the art.

[0110] EXPERIMENTAL EXAMPLES

[0111] Catalysts were prepared and tested according to the method of the invention.

[0112] Example 1

[0113] A catalyst having 2.5 wt.% platinum on a titania support was produced by impregnation. 1.168 g of platinum nitrate solution (17 wt.% Pt) and 10 g of titania (TiO2) was added to a round bottom flask. To this 30 mL of de-ionized water was added, and the mixture stirred at 400 rpm at room temperature. After 4 hours the temperature was increased to 80 °C to evaporate water. Once the water had evaporated, the sample was dried further in an oven at 60°C for 18 hours. After drying, the catalyst was ground using a pestle and mortar, and sieved to select particles having a size of 500 pm or less using a Fisherbrand™ Stainless Steel Test Sieve. The catalyst was then calcined by ramping the temperature from ambient temperature to 120°C at 10°C / min, holding at 120°C for 2 hours, ramping the temperature to 500°C at 2°C / min, holding at 500°C for a further 4 hours, and then allowing to cool to ambient temperature. Subsequent to calcining, the catalyst was sieved using a Fisherbrand™ Stainless Steel Test Sieve to select particles between 100-200 pm.

[0114] The catalyst was loaded into a 16-channel parallel fixed-bed stainless steel reactor system. Each stainless steel reactor (300 mm in length; 3 mm external diameter; 2 mm internal diameter) housed a 25 mg bed of catalyst (having particle size fraction of 100 to 200 microns diameter) loaded on top of a 6 cm deep bed of an inert material (carborundum). The reactor volume above the catalyst was also packed with carborundum. The reactor was set-up in a down-flow configuration. Each reactor was maintained at a temperature of 60-400 °C and at a total pressure of 10 barg throughout the reactions, according to the scheme set out in Table 1 below. Different feeds were employed to determine the impact on the yield of carbon monoxide and hydrogen whilst maintaining a GHSV of 165,000 IT1. The effluent stream from each reactor was diluted with inert gas (nitrogen) and was periodically analysed by online gas chromatography to determine the yield of carbon monoxide and hydrogen product.

[0115] The reactor conditions used are set out in steps 1-15 in Table 1 below, with steps 1-8 serving as an activation step. The effect of the addition of carbon monoxide was assessed by assessing the products obtained in steps 14 and 15.

[0116] Table 1

[0117] Example 2

[0118] A catalyst having 2.5% copper on a ceria support was produced by impregnation. 0.950 g of copper nitrate solution and 10 g of ceria (CeO2) was added to a round bottom flask. To this 30 mL of de-ionized water was added, and the mixture stirred at 400 rpm at room temperature. After 4 hours the temperature was increased to 80 °C to evaporate water. Once the water had evaporated, the sample was dried further in an oven at 60°C for 18 hours. After drying, the catalyst was ground using a pestle and mortar, and sieved to select particles having a size of 500 pm or less using a Fisherbrand™ Stainless Steel Test Sieve. The catalyst was then calcined by ramping the temperature from ambient temperature to 120°C at 10°C / min, holding at 120°C for 2 hours, ramping the temperature to 500°C at 2°C / min, holding at 500°C for a further 4 hours, and then allowing to cool to ambient temperature.

[0119] The catalyst was loaded into a reactor and tested following the same procedure as Example 1.

[0120] Example 3

[0121] A commercially-available copper zinc oxide catalyst (T-2130, available from Slid Chemie) was used, having the composition: 33 wt.% CuO and 66 wt.% ZnO. This catalyst was chosen as a suitable comparative catalyst since it is the most preferred methanol decomposition catalyst type highlighted in the applicant’s earlier application WO 2024 / 033867. It is also known for use in methanol synthesis from syngas, and hence is expected to be a suitable methanol decomposition catalyst based on the principle of microscopic reversibility.

[0122] The catalyst was loaded into a reactor and exposed to the conditions detailed in Table 1 above, with steps 1-8 serving as an activation step. The effect of the addition of carbon monoxide was assessed by comparing steps 14 and 15.

[0123] Results

[0124] The results of the experiments are summarised in Table 2 and shown in Figures 3-5.

[0125] Table 2

[0126] As can be seen, the addition suppressed formation of methane and carbon dioxide in all experiments. This result was unexpected since, as explained in the summary of the invention, it was known that carbon monoxide and hydrogen are the starting materials for the production of methane and carbon dioxide side-products. Thus, it was anticipated that including carbon monoxide alongside hydrogen in the feed stream would lead to a significant increase in sideproduct formation, particularly since the hydrogen and carbon-dioxide accounted for over 80 mol% of the feed.

[0127] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0128] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0129] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0130] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0131] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0132] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%. REFERENCES

[0133] A number of publications are cited above in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. Full citations for these references are provided below. The entirety of each of these references is incorporated herein. 1) WO 2024 / 033867

[0134] 2) US 4,716,859

[0135] 3) US 6,541 ,142

[0136] 4) US 9,833,773

[0137] 5) Usami, et al., “Catalytic methanol decomposition at low temperatures over palladium supported on metal oxides.” Appl. Cat. A 171(1): 123-130 (1998)

[0138] 6) Hargreaves, J.S.J. and Ormsby, G. Catalysis 2007, 20. 107-121.

Claims

CLAIMS1. A method for decomposing methanol, the method comprising: providing a first feed stream comprising methanol, H2and CO, wherein the molar ratio of H2to CO in the first feed stream is between 1 :5 and 5:1; contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2and CO.

2. A method according to claim 1, wherein the molar ratio of H2to CO in the first feed stream is up to 3: 1 .

3. A method according to any one of the preceding claims, wherein the molar ratio of H2to CO in the first feed stream is at least 1 :3.

4. A method according to any one of the preceding claims, wherein the methanol comprises up to 0.05 mol% water.

5. A method according to any one of the preceding claims, wherein the contacting is carried out at a temperature of at least 150°C, or at least 200°C, or at least 300°C.

6. A method according to any one of the preceding claims, wherein the contacting is carried out at a pressure of at least 5 barg.

7. A method according to any one of the preceding claims, wherein the methanol decomposition catalyst comprises at least one of platinum, copper, nickel and palladium supported on a support.

8. A method according to claim 7, wherein the at least one of platinum, copper, nickel and palladium is present in an amount of in the range of 0.5 to 10% by weight of the methanol decomposition catalyst, based on the total weight of the methanol decomposition catalyst.

9. A method according to any one of the preceding claims, wherein the methanol decomposition catalyst comprises one or more transition metals selected from Groups 6-12 of the periodic table supported on a support, the support comprising titania or ceria or a mixed oxide comprising a mixture of titania and ceria.

10. A method according to any one of the preceding claims, which shows:(i) a methane selectivity of less than 10 wt.%, based on the total weight of the products;and / or(ii) a CO2 selectivity of less than 10 wt.%, based on the total weight of the products; and / or(iii) a dimethyl ether (DME) productivity of less than 60 g / kg(cat) / h.

11. A method according to any one of the preceding claims, wherein the first feed stream comprises at least 5 mol% methanol.

12. A process for performing an integrated Fisher-Tropsch synthesis, the process comprising: providing a first feed stream comprising methanol, H2and CO, wherein the molar ratio of H2to CO in the first feed stream is between 1 :5 and 5:1; contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2and CO in a method according to any one of claims 1 to 11 ; optionally providing a second feed stream comprising H2and at least a portion of the CO of the first product stream; and contacting the first product stream or, optionally, the second feed stream, with a Fischer- Tropsch catalyst to perform a Fischer-Tropsch synthesis to provide a second product stream comprising C5+ hydrocarbons.

13. Use of CO to reduce, minimise or eliminate the formation of at least one side-product during a methanol decomposition process, the methanol decomposition process comprising providing a first feed stream comprising methanol and H2, and contacting the first feed stream with a methanol decomposition catalyst to decompose at least a portion of the methanol to form a first product stream comprising H2and CO.

14. The use according to claim 13, wherein the CO is used as part of the first feed stream and molar ratio of H2to CO in the first feed stream is between 1:3 and 3:1.

15. The use according to claim 13 or claim 14, wherein the at least one side-product is methane, CO2, and / or dimethyl ether (DME).

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