Field of the invention

The invention relates to a process for the production of methanol, to a related plant and to a related use.

Background of the invention

In the oil-and-gas industry, it is regularly of interest to convert hydrocarbon fractions of petroleum having relatively high boiling points into more valuable products like gasoline, olefins and the like. A so-called fluid catalytic cracking unit (FCCll) allows for such a conversion. In an FCCll, a feedstock is regularly heated to a high temperature and pressurized to a moderate pressure, and is then brought into contact with a powdered catalyst in a reactor section. In the reactor section, the catalyst cracks long-chain molecules of the hydrocarbon fractions having relatively high boiling points into shortchain molecules which are then collected as a vapor. However, the cracking reactions produce some carbonaceous material (coke) that deposits on the catalyst and significantly reduces the catalyst reactivity. In order to maintain a continuous process, the catalyst must therefore be regenerated. For the regeneration, the catalyst is transferred from the reactor section to a regenerator section of the FCCll. Air, and hence oxygen (O2), is regularly fed to the regenerator section to burn off the deposited coke which yields regenerated catalyst. The regenerated catalyst is then recirculated to the reactor section.

The regeneration by burning the deposited coke results in fumes which, in addition to nitrogen from the air, regularly comprise carbon monoxide (CO), carbon dioxide (CO2), sulfur oxides (SO _X ), nitrous oxides (NOx), ammonia (NH3) and hydrogen cyanide (HCN). All these gaseous components of the fumes, to the exclusion of N2, are toxic and environmentally unfriendly and need to be removed from the fumes before emitting the fumes to the atmosphere. In this context, especially CO and CO2 pose a massive problem because of the typically generated high amounts thereof. For CO2, some technical solutions for avoiding an emission thereof to the atmosphere in order to reduce the carbon footprint have already been developed, and quite a number of new technical solutions are currently under development. With some of these technical solutions, CO2 can be captured from the process and can then subsequently be stored, for example stored underground.

Further, CO is often produced by the regeneration in addition to CO2 because a complete oxidisation of the coke deposited on the catalyst to CO2 already in the regenerator section of the FCCll could lead to an overheating of the regenerator section. However, the CO is particularly toxic and environmentally unfriendly and should not be emitted to the atmosphere. Therefore, in some current FCCUs, the CO is converted into CO2 by oxidisation in a subsequent conversion stage. This regularly requires feeding of additional air to an oxidation zone of this subsequent conversion stage in which the CO is converted into CO2, and sometimes further requires feeding of additional fuel gas to such an oxidation zone. The required CO conversion leads to increased costs and yields additional CO2 which additionally needs to be captured and eventually stored. This leads to further costs for transport of the CO2 and its storage. Moreover, no value is generated from the CO and/or the CO2 produced by the FCCUs.

In particular, little efforts have been made so far to valorise the fumes from an FCCU, for example by converting them into products of higher quality. Generally, a product of higher quality is methanol (MeOH) which is a key product in the chemical industry. MeOH is in particular used for producing other chemicals like formaldehyde, acetic acid and plastics. According to the International Renewable Energy Agency (IRENA), around 98 million tonnes MeOH are produced per annum. Hence, it is desirable to find new sources of MeOH as well as new processes for synthesising MeOH.

However, in the context of FCCUs, potential processes for synthesising MeOH have been considered only rarely. EP 0 101 878 A2 describes inter alia a process in which carbon monoxide rich flue gas stemming from a catalyst regeneration is combined with a hydrogen rich gas product stream of an adjacent hydrocarbon conversion operation to provide a syngas product which can be converted to methane and/or methanol. The flue gas is however not separated into gas streams of different carbon oxide contents which could thereafter be treated individually. Further, it is not foreseen to employ any other hydrogen than the hydrogen obtained in the hydrocarbon conversion operation. Moreover, the product stream of the hydrocarbon conversion operation naturally contains additional gases apart from hydrogen which may impair the conversion to methane or methanol making the conversion less efficient, and/or which may require additional separation steps making the entire process less economic. Overall, there remains a general desire for an improved process for the production of methanol.

Problem underlying the invention

It is an object of the present invention to provide a process for the production of methanol which at least partially overcomes the drawbacks encountered in the art.

It is in particular an object of the present invention to provide a process for the production of methanol which allows to valorise fumes stemming from an FCCLI.

It is furthermore an object of the present invention to provide a process for the production of methanol which is more economic and/or lowers the required CO2 storage capacities for an FCCLI regeneration and/or runs in a safe mode.

It is additionally an object of the present invention to provide a process for the production of methanol which reduces the overall carbon footprint.

It is also an object of the present invention to provide a use which at least partially overcomes the drawbacks encountered in the art.

It is also an object of the present invention to provide a plant which at least partially overcomes the drawbacks encountered in the art.

Disclosure of the invention

Surprisingly, it has been found that the problem underlying the invention is overcome by processes, a plant and a use according to the claims. Further embodiments of the invention are outlined throughout the description.

Subject of the invention is a process for the production of methanol comprising the following steps: a) feeding a stream 1 comprising O2 to a regenerator section of a fluid catalytic cracking unit, wherein the regenerator section comprises coked catalyst, b) regenerating the coked catalyst with O2 fed in step a), thereby producing a stream 2 comprising CO and CO2, c) separating stream 2 at least into a CO-rich stream 3, which comprises > 75 mol% of CO, and a CO2-rich stream 4, which comprises > 75 mol% of CO2, wherein the CO2-rich stream 4 is at least partially recycled in the process and is co-fed in step a) to the regenerator section, wherein the at least partially recycled CO2-rich stream 4 has a temperature of 75-200°C, d) feeding H2 to the CO-rich stream 3, and e) converting H2 fed in step d) and CO of the CO-rich stream 3 into MeOH.

Logically, steps a), b), c), d) and e) are carried out in the given order, i.e., first step a), thereafter step b), thereafter step c), thereafter step d) and thereafter step e). However, additional steps before or after each of steps a), b), c), d) and e) may also be comprised by the process according to the present invention.

As used herein, a fluid catalytic cracking unit (FCCll) used in the process according to the invention is an FCCll as understood in the art. Such an FCCll regularly comprises a reactor section and a regenerator section which are in fluid connection, and which typically have two fluid connections with each other for a circulation of catalyst or catalyst particles.

As used herein, a catalyst is a catalyst as understood in the art. The catalyst is employed in the reactor section of the FCCll for cracking long-chain hydrocarbons comprised by a feedstock which is sent to the reactor section into shorter-chain hydrocarbons. An exemplary catalyst may comprise a zeolite, a matrix, a binder and a filler. The zeolite is catalytically active and may be a faujasite-type zeolite. The catalyst may comprise the zeolite, preferably a faujasite-type zeolite, in an amount of 15 to 50 wt.%, based on the total weight of the catalyst. The matrix is preferably made from alumina (AI2O3) and/or silica (SiC>2), and the matrix may also be catalytically active. The binder is preferably made from silica sol. The filler is preferably made from kaolin. The catalyst is preferably in the form of a fine powder (fine catalyst powder; or powdered catalyst). Such a fine catalyst powder may preferably have a bulk density of 0.80 to 0.96 g/cm ³ , a particle size distribution ranging from 10 to 150 pm and/or an average particle size of 60 to 100 pm.

Over time, carbonaceous material deposits on the catalyst in the reactor section. Such a carbonaceous material (or carbon containing material) is herein also referred to as “coke”, and a catalyst having such carbonaceous material or coke deposited thereon is also referred to herein as “coked catalyst”. The catalyst reactivity of a coked catalyst is impaired, i.e., the catalyst becomes less catalytically active. The catalyst is therefore regularly sent to the regenerator section of the FCCll, so that the regenerator section of the FCCll comprises coked catalyst.

In step a), a stream 1 comprising O2 is fed to the regenerator section. In the regenerator section of the FCCll, the coke deposited on the catalyst is then burned in step b) with the aid of the O2 fed in step a) as a component of stream 1 to give at least CO and CO2 which are comprised by a stream 2. In other words, the carbon deposited on the coked catalyst is oxidised to CO and CO2. Stream 2 (initially, i.e., without any subsequent treatment thereof) preferably has a temperature of 700-800°C and/or a gauge pressure of 100- 300 kPa.

In the subsequent step c), stream 2 is separated or split into at least two streams. Generally, a separation unit can be used for separating stream 2 in step c) into at least two streams. One of the at least two streams is stream 3 which is a CO-rich stream which comprises > 75 mol% of CO. Accordingly, as used herein, a CO-rich stream is a stream which has a higher CO-concentration, or C(QQ), than CO2-concentration, or C(QQ ₂ ). Hence, for stream 3 the equation C(QQ) > C(CQ ₂ ) is true. The other one of the at least two streams is stream 4 which is a CO2-rich stream which comprises > 75 mol% of CO2. Accordingly, as used herein, a CO2-rich stream is a stream which has a higher CO2-concentration than CO-concentration. Hence, for stream 4 the equation ^C (CO ₂ ) ^{> C} (CO) ' ^{s true} - Herein, concentrations of gases or compounds in streams are regularly given in mol%. Hence, the relation between CO-concentration and CO2- concentration in stream 3 can also be expressed as mol%(CO) > mol%(CO2), while the relation between CO-concentration and CC>2-concentration in stream 4 can also be expressed as mol%(CC>2) > mol%(CO). Stream 3 (initially, i.e., without any subsequent treatment thereof) is preferably gaseous and/or preferably has a temperature of 25-75°C and/or a gauge pressure of 1-20 kPa. Stream 4 (initially, i.e., without any subsequent treatment thereof) is preferably liquid.

Further, the CC>2-rich stream 4 is at least partially recycled in the process and is co-fed in step a) to the regenerator section. The CC>2-rich stream 4 which is at least partially recycled in the process (the at least partially recycled CC>2-rich stream 4; co-fed in step (a)) has a temperature of 75-200°C. Further, the CC>2-rich stream 4 which is at least partially recycled in the process preferably has a gauge pressure of about 200-500 kPa. The regeneration of the catalyst in the regenerator section regularly creates heat with a danger of overheating the regenerator section. As the CO2 is fed to the regenerator section, the CO2 acts as a cooling medium (or heat sink) which can help to avoid an overheating, thereby increasing the safety of the inventive process and/or reducing the need for cooling energy to be applied to the regenerator section from the outside. This safety effect is particularly pronounced when stream 1 is substantially free of N2 which could otherwise act as a cooling medium. In other words, the safety effect is particularly pronounced when stream 1 is composed of substantially pure O2. However, it has been surprisingly found that partially recycling CO2 of CC>2-rich stream 4 also to stream 3 (optional) does not impair the formation of MeOH in step e) which enhances the application range of the inventive process in existing equipment. It is also possible that recycled CC>2-rich stream 4 comprises minor amounts of CO (<20 mol%). In this case a complete separation of CO and CO2 is not required in step c) which can reduce the OPEX and makes the inventive process more economic.

In this context, it is crucial that the CO2-rich stream 4 comprises > 75 mol% of CO2 because only at a significantly enhanced CO2 level, the cooling effect of the at least partially recycled CO2 in the regenerator section reaches a desired level which allows for preventing an undesired and ultimately dangerous overheating of the regenerator section. At the same time, it is also crucial that the CO2-rich stream 4 which is at least partially recycled to the regenerator section has a temperature of 75-200°, preferably of 100- 150°C. This is because the regeneration in the regenerator section typically takes place at temperatures of up to 800°C and regularly within the range of 700 to 780°C. Hence, the CC>2-rich stream 4 recycled to the regenerator section needs to be of lower temperature in order to act as a heat sink within the regenerator section. It has been found that the prevention of undesired and ultimately dangerous overheating of the regenerator section is actually achievable when the recycled CC>2-rich stream 4 has a temperature of not more than 200°C. Thereby, the temperature difference between the recycled CO2 and the operation temperature of the regenerator section is large enough to achieve the desired cooling effect even at rather low residence times of the fed streams (or process streams) in the regenerator section. At the same time, the recycled CO2 stems from the regenerating reactions in the regenerator section and thus originally has a high temperature. Subsequently in the process, this temperature may drop partly automatically, but may also require active cooling and hence cooling energy to lower it such that the recycling to the regenerator section achieves the desired cooling by the recycled CO2. In this respect, it has been found sufficient for the recycled CO2 to have a temperature of not lower than 75°C when recycled to the regenerator section. In this way, an unnecessarily high investment of cooling energy can be avoided and/or additional cooling steps and equipment can be minimized. As a result, an advantageous balance between heat sink characteristics of the recycled CO2 on the one hand and reduced need for an active cooling of that CO2 is achieved. This balance is particularly pronounced when the CO2- rich stream 4 which is at least partially recycled to the regenerator section has a temperature of 100-150°.

In the subsequent step d), hydrogen (H2) is fed to the CO-rich stream 3. Thereby external H2 is added to stream 3, i.e., the H2 is not produced by the FCCll, and is in particular not produced in the reactor section or the regenerator section of the FCCll. Rather, the H2 comes from an external source, for example from water electrolysis, steam methane reforming (SMR), partial oxidation (POX) or auto-thermal reforming (ATR).

In the subsequent step e), the previously fed H2 and the CO of the CO-rich stream 3 (i.e., the CO contained in stream 3) are reacted with each other to yield MeOH. In other words, a carbon monoxide hydrogenation is performed which gives methanol according to the following reaction: CO + 2H2 — > CH3OH. Generally, a methanol production unit can be used for performing the carbon monoxide hydrogenation to give MeOH. Step e) is regularly carried out in the presence of a catalyst, more specifically a catalyst which lowers the activation energy of the reaction of CO and H2 to methanol. Various catalysts can be used in such a methanol production unit for realizing the desired MeOH formation. Preferred catalysts comprise copper and/or zinc and/or aluminium, and more preferably contain from 55 to 65 wt. % of CuO and/or from 20 to 35 wt. % of ZnO and/or from 5 to 20 wt. % of AI2O3. Such catalysts can lead to an improved efficiency of the conversion of H2 and CO into MeOH, making the inventive process more economic. It is preferred that step e) is performed at a temperature ranging from 200 to 300°C and/or at an absolute pressure ranging from 3.5-10 MPa. Such process conditions can lead to an improved efficiency of the conversion of H2 and CO into MeOH, making the inventive process more economic.

The streams of the process according to the present invention are mostly gaseous streams. However, even if not explicitly mentioned, water (H2O) is regularly present in the steps and streams of a process according to the present invention. The water may also be present in gaseous form, or may be (partially) condensed. Accordingly, the streams of the process according to the present invention may be only partially gaseous streams. Additionally, some streams like in particular stream 4 can also be liquid streams.

The process according to the present invention converts highly poisonous CO, which is regularly considered a waste product of low quality, into MeOH, a chemical of much higher quality. The process according to the present invention thereby allows to valorise fumes stemming from an FCCLI. Further, with the conversion of CO into MeOH, there is no need for an oxidisation of CO to CO2, nor a need for a subsequent capture and storage of the thereby produced CO2. Accordingly, costs associated with such steps can be avoided which makes the process more economic. Additionally, less CO2 is generated by the process so that less CO2 storage capacities are required. Moreover, the CO is recovered from the process in the form of MeOH so that neither the CO nor CO2 produced therefrom is emitted by the process to the environment, thereby reducing the overall carbon footprint.

It is preferred that in a process according to the present invention, between steps d) and e) unsaturated hydrocarbons comprised by CO-rich stream 3 are hydrogenated with hydrogen (H2) into saturated hydrocarbons. Depending on the feed of the FCCLI stream 2 typically further comprises unsaturated hydrocarbons, regularly olefins and/or acetyls, especially ethylene and propylene. It has been found that after the separation into CO-rich stream 3 and CO2-rich stream 4, such unsaturated hydrocarbons are predominantly present in the CO-rich stream 3. In contrast, the CO2-rich stream 4 is substantially free of unsaturated hydrocarbons, e.g., contains <0.1 mol% unsaturated hydrocarbons. Unsaturated hydrocarbons are often poisons for a catalyst over which MeOH is regularly synthesized in step e). Accordingly, when comprised unsaturated carbons are hydrogenated and hence converted into saturated hydrocarbons before step e), the efficiency of a catalytic conversion of CO and H2 into MeOH in step e) can be improved. In this respect it is particularly preferred that substantially all hydrocarbons comprised by CO-rich stream 3 are hydrogenated with hydrogen (H2) into saturated hydrocarbons, especially such that after the hydrogenation CO-rich stream 3 contains <0.1 mol% unsaturated hydrocarbons. Such a substantially complete hydrogenation of unsaturated hydrocarbons in CO-rich stream 3 further improves the efficiency of the subsequent MeOH synthesis.

It is preferred that in a process according to the present invention, stream 1 and in particular the overall inventive process is substantially free of nitrogen (N2). As used herein, “substantially free of nitrogen” means that trace amounts, typically < 1 mol%, of N2 might still be present. Trace amounts of N2 regularly depend on the technology used for providing stream 1. In order to achieve that stream 1 is substantially free of N2 it is particularly preferred to use i) O2 which is commercially available as stream 1, in which case stream 1 is composed of substantially pure O2 (as used herein, “substantially pure O2” means that trace amounts, typically < 1 mol%, of other gases might still be present), ii) O2 which comes from an air separation unit (ASU) as stream 1, in which case the N2 contained in the air is effectively separated from the O2 contained in the air so that stream 1 is composed of substantially pure O2, and/or iii) O2 which comes from an electrolysis of water, in which case stream 1 is composed of substantially pure O2.

It is also preferred that in a process according to the present invention, the at least partially recycled CC>2-rich stream 4 is substantially free of nitrogen (N2). In this way, any nitrogen potentially contained in stream 2 can remain in the CO-rich stream 3 so that there is no need to separate such N2 from CO in stream 2. This is advantageous because a separation of N2 from CO is regularly difficult to achieve and would require unnecessary energy and/or equipment.

It is known that in a carbon monoxide hydrogenation for synthesizing methanol, as in step e) of the inventive process, the presence of N2 can impair the efficiency of the hydrogenation and/or can lower the MeOH yield. By using a stream 1 which is substantially free of N2 already in step a) of the inventive process, the presence of N2 in step e) can be avoided. Accordingly, a higher efficiency of the conversion and a better MeOH yield can be achieved in step e) of the inventive process. As a result, stream 1 and in particular the overall inventive process being substantially free of N2 can further contribute to the advantages of the inventive process, in particular to the valorisation of FCCll fumes, to the economics of the process, to the reduction of required CO2 storage capacities and to the reduction of the overall carbon footprint. These advantages are particularly pronounced when O2 according to any of i), ii) and iii) above is used for stream 1. In addition, when O2 which comes from an ASU is used as stream 1 , further cost savings may be achieved because freely available air can be used for generating the required O2. Similarly, when O2 which comes from an electrolysis of water is used as stream 1 , further cost savings may be achieved because freely available or at least cheap water can be used for generating the required O2. Additionally, when O2 which comes from an electrolysis of water is used as stream 1 , hydrogen will simultaneously be produced which can advantageously be used elsewhere, or which may particularly advantageously be fed in step d) and used in step e).

More specifically, it is particularly preferred that in a process according to the present invention, the H2 fed in step d) and used in step e) is previously produced by an electrolysis of H2O. Such a production of H2 by an electrolysis of H2O avoids any generation or emission of carbon oxides, especially CO2, thereby being particularly environmentally friendly. Consequently, the MeOH produced in step e) is also particularly environmentally friendly, and the overall footprint of the inventive process is reduced. Additionally, no CO2 is generated by such an electrolysis of H2O for producing the H2, so that overall less CO2 needs to be separated, leading to reduced costs, and consequently also less CO2 storage capacities are required.

It is thus particularly preferred that in a process according to the present invention, the O2 comprised by stream 1 and/or the H2 fed in step d) is previously produced by an electrolysis of H2O, wherein it is more preferred that the O2 comprised by stream 1 and the H2 fed in step d) are previously produced by an electrolysis of H2O. It is in particular preferred that the O2 comprised by stream 1 and the H2 fed in step d) are previously produced by the same electrolysis of H2O. O2 and H2 produced by an electrolysis of H2O are regularly considered “green”, i.e., no carbon oxides are generated or emitted to the atmosphere by their production. Accordingly, when the O2 comprised by stream 1 and/or the H2 fed in step d) is previously produced by an electrolysis of H2O, an advantageously low carbon footprint of the inventive process can be achieved. The carbon footprint can be particularly low when both, the O2 and the H2 are previously produced by an electrolysis of H2O. Further, when the O2 and the H2 are previously produced by the same electrolysis of H2O, only one electrolytic cell is required which can lower the capital expenditure (CAPEX) as well as the operational expenditure (OPEX). Accordingly, the inventive process can become more economic.

Generally, an electrolysis of water, or electrochemical water splitting, uses electricity to decompose water into oxygen and hydrogen gas. The electrolysis is regularly performed in an electrolytic cell which comprises two electrodes, namely an anode and a cathode, between which an electric field is applied. For this, the anode and the cathode regularly comprise electroconductive material, especially metal, coated metal, carbon cloth, graphite felt, carbon fibre composite, carbon loaded polymer, or graphite. Between the anode and the cathode, a membrane is sandwiched. When operating the electrochemical cell, electrons (e") are given from the cathode to hydrogen cations to form hydrogen gas, and on the other hand electrons are given from the water to the anode to form oxygen gas. Accordingly, H2 is produced at the cathode according to the following equation:

2 H ⁺ (aq) + 2e H ₂ (g)

At the same time, O2 is produced at the anode according to the following equation:

2 H ₂ O(/ O ₂ (g) + 4 H ⁺ (aq) + 4e“

The overall cell reaction is then as follows:

2 H ₂ O(/) 2 H ₂ (g) + O ₂ (g)

The efficiency of the electrolysis may be advantageously increased through the addition of an electrolyte like a salt, an acid or a base and/or may be advantageously increased through the use of electrocatalysts.

It is preferred that in a process according to the present invention, the electrolysis of H2O is performed by one of alkaline electrolysis (AEL), proton exchange membrane electrolysis (PEMEL) and solid oxide electrolysis (SOEL), more preferably by solid oxide electrolysis (SOEL). When the electrolysis of H2O is performed by one of the mentioned specific electrolyses, already existing equipment can be used which reduces the CAPEX, making the inventive process more economic.

It is preferred that in a process according to the present invention, the electrolysis of H2O is performed using a renewable energy (electricity originating from a renewable source), wherein the renewable energy is preferably selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat, more preferably generated from sunlight or wind. This is preferred for the electrolysis of H2O which yields O2 which itself is fed in step a) as a component of stream 1 to the regenerator section of the FCCll and/or for the electrolysis of H2O which yields H2 which itself is fed in step d) to the CO-rich stream 3. It is more preferred that the electrolysis of H2O which yields O2 and the electrolysis of H2O which yields H2 are both performed using a renewable energy, wherein the renewable energy is preferably selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat. It is more preferred that the electrolysis of H2O which yields O2 and the electrolysis of H2O which yields H2 are the same electrolysis which is performed using a renewable energy, wherein the renewable energy is preferably selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat. By using a renewable energy, especially renewable energy selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat, no conventional power plants like gas power plants, coal power plants or nuclear power plants need to be involved. This can lead to an advantageous reduction of the carbon footprint of the inventive process.

It is preferred that in a process according to the present invention, electrolysed H2O is preheated in an electric boiler using renewable energy, wherein the renewable energy is preferably selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat, more preferably from energy generated from sunlight or wind. Such a preheating can improve the efficiency of the electrolysis of H2O, while using an environmentally friendly energy source. The inventive process can thereby become more economic and can have a reduced carbon footprint. It is also contemplated that the electrolysed H2O is pre-heated using heat comprised by stream 2, which can also improve the efficiency of the electrolysis of H2O such that the inventive process becomes more economic and has a reduced carbon footprint.

As afore-said, a separation unit may generally be used for separating stream 2 in step c). It is preferred that in a process according to the present invention, a cryogenic separation unit, a pressure swing adsorption unit and/or a selective absorption process is used for separating stream 2 in step c), more preferably a cryogenic separation unit.

A cryogenic separation unit is herein also referred to as a low temperature phase change separation unit (see for example, Berstad et al., J. Int. Acad. Refrig. Vol. 36, No. 5 (2013), 1403-1416; IEAGHG, 2011. Rotating Equipment for Carbon Dioxide Capture and Storage. IEAGHG report 2010/07). A commercial example of a CO2 separation means is the Air Liquide Cryocap®. In a low temperature phase change separation unit CO2 is condensed, i.e., gaseous CO2 is converted into liquid CO2, to give a condensed fraction. This condensed fraction corresponds to CC>2-rich stream 4. At the same time, the CO remains mostly gaseous, to give an uncondensed fraction. This uncondensed fraction corresponds to CO-rich stream 3. With a low temperature phase change separation unit, the CO and the CO2 can be separated from each other in a particularly effective manner. In other words, stream 3 can become a particularly pure CO-stream (having a particularly high CO-concentration, or mol%(CO)), and stream 4 can become a particularly pure CO2-stream (having a particularly high CO2-concentration, or mol%(CO2)). This can enhance the effectiveness of the subsequent conversion of the CO contained in CO-rich stream 3 into MeOH.

A pressure swing adsorption (PSA) unit according to the present invention is a unit which allows to perform at least one and preferably more than one (i.e., repeated) cycle(s) of PSA. The PSA unit thus regularly comprises at least two columns which typically contain an absorbent, and regularly comprises more than two columns, especially four to twelve columns. Further, the at least two columns can be individually, and normally alternatingly, fed with fluids and in particular gases. Further, such fluids and in particular gases can individually, and normally alternatingly, be withdrawn from the PSA unit. The PSA unit may further comprise a compressor to feed the at least two columns individually, and normally alternatingly, with pressurized gases. A pressure swing adsorption unit according to the present invention also encompasses a vacuum pressure swing adsorption (VPSA) unit, which further comprises a vacuum pump for generating a vacuum inside the PSA unit to withdraw gases contained in the PSA unit, in particular gases adsorbed by an absorbent. It is preferred that in a PSA unit according to the present invention, absorbents comprising carbon, in particular activated carbon or carbon molecular sieves, or oxide absorbents, in particular zeolites, are contained. With a PSA unit, the CO and the CO2 can be separated from each other in a particularly effective manner so that stream 3 can become a particularly pure CO-stream (having a particularly high CO-concentration, or mol%(CO)), and stream 4 can become a particularly pure CO2-stream (having a particularly high CO2-concentration, or mol%(CO2)). This can enhance the effectiveness of the subsequent conversion of the CO in CO-rich stream 3 into MeOH.

It is preferred that in a process according to the present invention, the CO2-rich stream 4 is at least partially sent to a CO2 storage facility. In this way, the CO2 which is generated in the regenerator section and which is at least partially recycled does not pile up in the process, but a steady state is achieved in which excess CO2 is removed from the process while the cooling effect of the partially recycled CO2-rich stream 4 on the regenerator section is maintained. The CC>2-rich stream 4 which is at least partially sent to a CO2 storage facility preferably has a temperature of 20-75°C and/or a gauge pressure of 3-5 MPa. The CO2 storage facility may preferably be a geological storage facility. In general, geological storage of CO2 involves injecting captured CO2 into rock formations deep underground. In this way the CO2 is permanently removed from the atmosphere which helps to reduce the overall carbon footprint. Alternatively, or additionally, the CO2 storage facility may preferably comprise one or more containers. Such one or more containers are preferably configured for transportation thereof on a ship, a train or a truck. Transportation of the CO2 through piping is also contemplated. The use of containers in the CO2 storage facility can allow for a greater flexibility of the CO2 storage, and may even allow for a reuse of the captured CO2 at a different site remote from the site of the FCCLI.

Optionally the CO2-rich stream 4 is additionally fed to stream 3 prior to step e), i.e., the CO2-rich stream 4 is optionally split and is partly recycled and co-fed in step a) to the regenerator section and is further partly fed to stream 3 prior to step e). The CO2-rich stream 4 which is at least partially fed to stream 3 preferably has a temperature of 75- 200°C and/or a gauge pressure of about 300-500 kPa.

It is preferred that in a process according to the present invention, heat (or heat energy) is recovered from stream 2 in a heat exchanger or in a waste heat boiler after step b) and prior to step c). As afore-mentioned, the regeneration of the catalyst in the regenerator section regularly creates heat, sometimes excessive heat. Such heat is preferably recovered and can be used elsewhere, for example for heating the reactor section of the FCCLI or for heating an electrolytic cell, or can be used to generate steam in a waste heat boiler which steam can also be used elsewhere. Due to the at least partial recycling of the CC>2-rich stream 4 to the regenerator section, heat and in particular excessive heat generated within the regenerator section is absorbed by the CO2 which then becomes part of stream 2. In the preferred heat exchanger (waste heat boiler), the absorbed heat is recovered and can be valorised elsewhere in the process. Accordingly, the recycling of CO2 allows for an improved heat recovery and adds to the self-supporting characteristics of the process. Preferably, the heat is used for heating an electrolytic cell in which H2O is electrolyzed and wherein the resulting O2 is used as stream 1 and/or wherein the resulting H2 is fed and used in steps d) and e), more preferably wherein the resulting O2 is used as stream 1 and wherein the resulting H2 is fed and used in steps d) and e). By recovering the heat, the overall process for the production of MeOH can become more economic. Further, downstream of the heat exchanger or the waste heat boiler additional units for further treatment of stream 2, for example a filtering unit, a scrubbing unit, a cryogenic separation unit or a pressure swing adsorption unit may be arranged. Such additional units might be heat sensitive. By recovering heat after step b) and prior to step c), stream 2 is cooled down and heat sensitive units downstream of the heat exchanger or the waste heat boiler are protected, which enhances the safety of the inventive process. After having passed the heat exchanger or the waste heat boiler stream 2 preferably has a temperature of 200-300°C and/or a gauge pressure of 5-20 kPa.

It is preferred that in a process according to the present invention, stream 2 is filtered after step b) and prior to step c). Stream 2 can for example be filtered with cartridge filters and/or bag filters, and stream 2 is preferably filtered with bag filters. Commercially available bag filters which can be used in the inventive process are CataFlex® bag filters. Generally, as a filtering unit for filtering out catalytic particles an electrostatic precipitator (ESP) may be used. Potential residual catalyst particles present in stream 2 are often electronegative and can be filtered out by the ESP in which an electric field is generated. However, stream 2 comprises CO which can form an ignitable mixture with air which can result in fires and explosions. The electric field of the ESP may lead to sparks which can initiate such fires and explosions. It is therefore particularly preferred that no electrostatic precipitator is used in the inventive process. Further, with the use of bag filters, especially instead of a not-used ESP, for filtering out the residual catalyst particles, the inventive process can run in a safer mode. After having passed the filtering unit, preferably the bag filters, stream 2 preferably has a temperature of 150-300°C and/or a gauge pressure of 5- 20 kPa.

It is preferred that in a process according to the present invention, stream 2 is treated with an alkaline solution after step b) and prior to step c), wherein the alkaline solution preferably comprises NaOH. The alkaline solution is regularly an aqueous alkaline solution. The treatment is preferably performed in a scrubbing unit, or scrubber, and can remove SO _X and/or HCN contained in stream 2. These substances are hazardous and removing them from stream 2 can enhance the safety of the inventive process. SO _X and HCN, respectively, each together with H2O of the aqueous alkaline solution form acids so that a neutralization with the alkaline solution occurs and removable salts are formed. For example, when the alkaline solution comprises NaOH, the SO _x will typically be converted into sodium sulfate (NaSO4). Further, when the alkaline solution comprises for example NaOH, another resulting salt is sodium cyanide (NaCN). The NaCN can for example be removed with an absorbing resin, typically followed by a waste water treatment. Alternatively, or additionally, the NaCN can for example be removed by partial oxidation, for example using peroxide. After having been treated with the alkaline solution, stream 2 preferably has a temperature of 25-75°C and/or a gauge pressure of 1-20 kPa.

It is preferred that in a process according to the present invention, stream 2 is treated to remove sulfur-containing compounds, more preferably to remove H2S, COS and/or CS2. This treatment is made before step e) and may be made after step b) and prior to step c). Alternatively, this treatment may be made in step c). In particular, it is preferred that in step c) a further stream comprising H2S is formed and is separated from CO-rich stream 3 and CO2-rich stream 4. Sulfur-containing compounds, especially H2S, COS and/or CS2, and in particular H2S, are often poisons for a catalyst over which MeOH is regularly synthesized in step e). Accordingly, when those poisons are removed from the process before step e), the efficiency of a catalytic conversion of CO and H2 into MeOH in step e) can be improved.

It is preferred that in a process according to the present invention, stream 2 is treated to remove nitrogen-containing compounds, more preferably to remove nitrogen oxide (NOx) and/or NH3 and/or remaining HCN. This treatment is made before step e) and may be made after step b) and prior to step c). Alternatively, this treatment may be made in step c). In particular, it is preferred that in step c) a further stream comprising NH3 is formed and is separated from CO-rich stream 3 and CO2-rich stream 4. Nitrogencontaining compounds, especially NO _X and/or NH3, and in particular NH3, are often poisons for a catalyst over which MeOH is regularly synthesized in step e). Accordingly, when those poisons are removed from the process before step e), the efficiency of a catalytic conversion of CO and H2 into MeOH in step e) can be improved.

It is particularly preferred that in step c) a further stream comprising H2S and NH3 is formed and is separated from CO-rich stream 3 and CO2-rich stream 4. In this way, both these catalyst poisons are efficiently removed prior to the methanol synthesis in step e) which improves the efficiency of the latter.

It is preferred that in a process according to the present invention subsequent to (or after) step b) heat is recovered from stream 2 in a heat exchanger or in a waste heat boiler as described herein, that stream 2 is subsequently filtered, preferably with bag filters, as described herein, that subsequently stream 2 is treated with an alkaline solution preferably comprising NaOH as described herein and that subsequently step c) follows. It is preferred that in a process according to the present invention, stream 1 comprises

> 20 mol% of O2, more preferably > 50 mol% of O2, still more preferably > 75 mol% of O2, even more preferably > 90 mol% and most preferably 100 mol% of O2 (corresponding to substantially pure O2 as defined herein). With the increasingly higher concentrations of O2, the regeneration in step b) becomes increasingly more efficient, making the overall process more economic.

It is preferred that in a process according to the present invention, CO-rich stream 3 comprises > 90 mol% of CO and more preferably > 95 mol% of CO. With the increasingly higher concentrations of CO, the conversion of H2 and CO into MeOH in step e) becomes increasingly more efficient, making the overall process more economic.

It is preferred that in a process according to the present invention, CO2-rich stream 4 comprises > 90 mol% of CO2, more preferably > 95 mol% of CO2, still more preferably

> 99 mol% of CO2 and most preferably > 99.5 mol% of CO2. With the increasingly higher concentrations of CO2, the lowering of the carbon footprint, especially by storing the CO2, and/or the effects of recycling the CO2 within the inventive process can become increasingly more pronounced. In particular, the higher the molar percentage of the CO2- rich stream 4 is, the better the cooling effect of its at least partially recycled portion in the regenerator section becomes.

It is preferred that in a process according to the present invention, stream 1 comprises

> 75 mol% of O2, CO-rich stream 3 comprises > 75 mol% of CO, and CO2-rich stream 4 comprises > 70 mol% of CO2. It is still more preferred that in a process according to the present invention, stream 1 comprises > 90 mol% of O2, CO-rich stream 3 comprises

> 90 mol% of CO, and CO2-rich stream 4 comprises > 90 mol% of CO2. With the increasingly higher concentrations of O2, the regeneration in step b) becomes increasingly more efficient, making the overall process more economic. Simultaneously, with the increasingly higher concentrations of CO, the conversion of H2 and CO into MeOH in step e) becomes increasingly more efficient, making the overall process more economic. Also simultaneously, with the increasingly higher concentrations of CO2, the lowering of the carbon footprint, especially by storing the CO2, and/or the effects of recycling the CO2 within the inventive process can become increasingly more pronounced. Disclosed herein is also methanol obtainable by (or obtained by) a process as described herein. The preferred embodiments of the process described herein including the claims are likewise preferred for this methanol in an analogous manner. Such methanol contributes to the valorisation of fumes stemming from an FCCLI. Such methanol allows to do away with any oxidisation of CO to CO2, and with any subsequent capture and storage of the thus formed CO2, thereby reducing costs and making the methanol and its production process more economic. Additionally, the methanol reduces the generation of CO2 and hence reduces the required CO2 storage capacities. Moreover, the methanol binds the initially formed CO so that neither the CO nor CO2 produced therefrom is emitted to the environment, thereby reducing the overall carbon footprint.

Subject of the invention is also a plant comprising a fluid catalytic cracking unit, a separation unit and a methanol production unit, wherein the plant is configured for running a process as described herein. The preferred embodiments of the process described herein including the claims are likewise preferred for this inventive plant in an analogous manner. Such a plant according to the present invention allows for a formation of MeOH and hence allows for a valorisation of fumes stemming from its fluid catalytic cracking unit. Such a plant no longer requires any means for an oxidisation of CO to CO2, and may also no longer require any means for a subsequent capture and storage of such CO2, both leading to reduced CAPEX. Accordingly, the plant is more economic. Moreover, the plant ultimately procedures no CO, but rather MeOH. As a result, no CO nor CO2 produced therefrom is emitted by the plant to the environment, thereby reducing the overall carbon footprint of the plant.

Subject of the invention is also a use of methanol obtained by (or via) a process as described herein as fuel in waterborne transport. Waterborne transport is the transport of passengers and/or cargo via waterways, especially via oceans, rivers and canals. Fuel in waterborne transport is especially a fuel which is used for vessel propulsion. As used herein, a vessel is a vessel within the meaning of Article 5ter Paris Convention for the Protection of Industrial Property. Such a vessel is generally a watercraft and is in particular a ship, a yacht, a freighter, a containership, a gas tanker, an oil tanker, or the like. The methanol obtained by a process as described herein is a low carbon fuel. The requirements for fuel used in waterborne transport become constantly more severe, and respective fuel shall be produced at lower CO2 emissions and/or should lead to lower CO2 emissions per produced energy quantum when actually burnt. As the process described herein generally reduces CO2 emissions and valorises intermittently produced CO by converting it into methanol, the thereby produced methanol regularly meets the requirements for fuel to be used in waterborne transport and its use for such applications is advantageous in that it lowers the carbon footprint of the waterborne transport.

Any use of methanol described herein may also be considered as a corresponding method of using such methanol.

Brief description of the drawings

Fig. 1 schematically shows a first exemplary embodiment of an inventive plant and an inventive process running therein.

Fig. 2 schematically shows a second exemplary embodiment of an inventive plant and an inventive process running therein.

Fig. 3 schematically shows a third exemplary embodiment of an inventive plant and an inventive process running therein.

Fig. 4 schematically shows a fourth exemplary embodiment of an inventive plant and an inventive process running therein.

Fig. 5 schematically shows a fifth exemplary embodiment of an inventive plant and an inventive process running therein.

Fig. 6 schematically shows a sixth exemplary embodiment of an inventive plant and an inventive process running therein.

Exemplary embodiments

First exemplary embodiment

The first exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 1. While various details of the plant and the process are described below, the description thereof is not comprehensive and the plant can have various other units, devices, components and the like, and the process can have additional steps and streams. With stream 1 shown in Fig. 1 substantially pure O2 (purchased) is fed to a fluid catalytic cracking unit (FCCll), more specifically to the regenerator section of the FCCll (regenerator section not separately shown). Additionally, N2 is fed to the regenerator section of the FCCll as an inert gas (not shown). The hydrocarbon feed of the FCCU is crude oil which primarily contains long-chain hydrocarbons. The long-chain hydrocarbons are cracked in the FCCU in the presence of catalyst particles so that the product of the FCCll contains a mixture of hydrocarbons of shorter chain length. The cracking results in coked catalyst particles which are sent to the regenerator section for regeneration. In the regenerator section, the coked catalyst particles are regenerated by burning off the coke with the fed O2. The fumes from the regenerator section of the FCCll form stream 2 which leaves the FCCll and contains CO and CO2 as well as H2O. Depending on the feed of the FCCU stream 2 typically further contains sulfur oxides (SO _X ; in particular sulfur dioxide (SO2) and sulfur trioxide (SO3)) and hydrogen cyanide (HCN). Stream 2 exiting the FCCU has a temperature of 780°C. The composition of steam 2 leaving the FCC and its temperature are shown for illustration purposes in a separate box in Fig. 1 indicted by reference numeral 2d , but the box does not represent a unit of the plant or a process step. The same is true for the boxes indicated by reference numerals 2c2, 2c3 and 2c4, and the dotted lines merely indicate for which point of the described process compositions and temperatures of stream 2 are presented.

In the next step some heat of stream 2 is recovered. For this, stream 2 is sent to a waste heat boiler (“Boiler) which is fed with boiler feed water (“BFW”). In the waste heat boiler, the heat of stream 2 heats up the boiler feed water and transforms the same into steam (“Steam”) which exists the waste heat boiler and is used in the planet or elsewhere (not shown). The thereby cooled stream 2 exits the waste heat boiler and has a composition and temperature as indicated by 2c2. In comparison to the composition and temperature indicated by 2d, it is seen that no change of the composition of stream 1 occurs in the waste heat boiler, but its temperature drops down to 200°C. Accordingly, heat equivalent to a temperature difference of 580°C has been utilized to generate steam which can be used at a different location of the plant, for example for heating the unshown reaction section of the FCCU. The plant and the process running therein thereby both become at least partly self-supporting.

In the next step stream 2 is filtered. For this, stream 2 is sent to a filtering unit (“Filter”). In this exemplary embodiment the filtering unit is equipped with CataFlex® bag filters which filter out the residual catalyst particles present in stream 2. Otherwise, there is no change in the composition of stream 2, and the temperature of stream 2 remains the same, as seen from the compositions and temperatures indicated by 2c2 and 2c3, respectively. After collection of the residual catalyst particles, these can be re-introduced into the FCCU which adds to the self-supporting characteristics of both, the plant and the process running therein. In the next step stream 2 is subjected to a scrubbing treatment in a scrubbing unit (“Scrubber”). To the scrubbing unit, an aqueous solution of sodium hydroxide (NaOH) is fed. Stream 2 then passes through the aqueous NaOH solution. The SO _X react with the water of the aqueous NaOH solution to the corresponding acids and are then neutralized by the NaOH to form respective sodium salts which are scrubbed from stream 2. Similarly, the HON is also neutralized by the NaOH to give sodium cyanide (NaCN). The sodium cyanide is removed from the scrubber unit with the aid of an ion exchange rein (“Resin”). After the scrubbing of SO _X and the removal of NaCN, the remaining waste water is passed to the waste water treatment (“WWT”). Additionally, the scrubbing treatment leads to a further lowering of the temperature of stream 2 which drops to 20 to 50°C. On the other hand, neither CO nor CO2 are affected when passing through the aqueous NaOH solution and remain in stream 2 as shown by 2c4. With the scrubbing treatment, the hazardous substances SO _X and HCN are removed from the plant and the process running therein, respectively, and the safety of both is thereby enhanced.

In the next step stream 2 is separated into two streams, namely stream 3 and stream 4. For this, stream 2 is sent to a cryogenic separation unit (“Cryogenic separation”). In this exemplary embodiment, an Air Liquide Cryocap® is used as such a cryogenic separation unit. The separation leads to a CO-rich stream 3 and a CO2-rich stream 4. In this exemplary embodiment the CO2-rich stream 4 is sent to a geological storage (“Storage”) and is thereby constantly removed from the environment which reduces the carbon footprint of both, the plant and the process running therein.

In the next step CO-rich stream 3 is sent to a methanol generating unit (“MeOH unit”). Additionally, hydrogen (H2) is fed to the methanol production unit and hence ultimately to stream 3. The fed H2 is reacted in the methanol production unit with the CO contained in CO-rich stream 3 in the presence of a catalyst to yield methanol (MeOH). The methanol can be used in various chemical processes and is a high-quality product so that the fumes stemming from the regenerator section of the FCCll have been valorised by both, the plant and the process running therein.

Second exemplary embodiment

The second exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 2. While various details of the plant and the process are described herein, the description thereof is not comprehensive and the plant can have various other units, devices, components and the like, and the process can have additional steps and streams.

The second exemplary embodiment has basically all features of the first exemplary embodiment. However, the substantially pure O2 fed to the fluid catalytic cracking unit (FCCll) is not purchased, but comes from an air separation unit (“ASU”). Here, air is fed to the air separation unit and is separated into a substantially pure O2 stream and a substantially pure N2 stream (trace amounts of other gases contained in the air are present in the two streams, but can be neglected). The inert N2 is vented to the atmosphere, while the reactive O2 is sent as stream 1 to the regenerator section of the FCCll. The use of air as the source for the O2 which is fed to the FCCll makes both, the plant and the process running therein, more economic.

Further, a part of stream 4 is sent to a geological storage (“Storage”) as in the first exemplary embodiment which reduces the carbon footprint of both, the plant and the process running therein. Additionally, another part of stream 4 is recycled back and is cofed to the regenerator section. In schematic Fig. 2, the recycled part of stream 4 is combined with stream 1 prior to entering the FCCll, but it is also envisaged that the recycled part of stream 4 and stream 1 are separately fed into the FCCU. The CO2 thereby fed to the regenerator section of the FCCU acts as a cooling medium and helps to avoid an overheating of the regenerator section. The safety of both, the plant and the process running therein, is thereby increased.

Third exemplary embodiment

The third exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 3. While various details of the plant and the process are described herein, the description thereof is not comprehensive and the plant can have various other units, devices, components and the like, and the process can have additional steps and streams.

The third exemplary embodiment has basically all features of the first exemplary embodiment. However, the substantially pure O2 fed to the fluid catalytic cracking unit (FCCU) is not purchased, but comes from an electrolytic cell (Electrolytic cell) in which water (H2O) fed to the cell is electrolyzed by solid oxide electrolysis to yield so-called green O2 and so-called green H2. The yield of the green O2 is larger than required for the process so that part of the produced green O2 is sent to other units for use thereof. The remaining part of the green O2 is used as stream 1 and is fed to the regenerator section of the FCCLI. The yield of the green H2 is also larger than required for the process so that part of the produced green H2 is sent to other units for use thereof. The remaining part of the green H2 is fed to the methanol production unit as the H2 required for the formation of MeOH by reaction with the CO contained in CO-rich stream 3. By the use of green O2 as feed for the regenerator section and the use of green H2 as feed for the methanol production unit the carbon footprint of both, the plant and the process running therein, is reduced.

Further, a part of stream 4 is sent to a geological storage (“Storage”) as in the first exemplary embodiment which further reduces the carbon footprint of both, the plant and the process running therein. Additionally, another part of stream 4 is recycled back and is co-fed to the regenerator section. In schematic Fig. 3, the recycled part of stream 4 is combined with stream 1 prior to entering the FCCLI, but it is also envisaged that the recycled part of stream 4 and stream 1 are separately fed into the FCCLI. The CO2 thereby fed to the regenerator section of the FCCLI acts as a cooling medium and helps to avoid an overheating of the regenerator section. The safety of both, the plant and the process running therein, is thereby increased.

Fourth exemplary embodiment

The fourth exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 4. While various details of the plant and the process are described herein, the description thereof is not comprehensive and the plant can have various other units, devices, components and the like, and the process can have additional steps and streams.

As shown in Fig. 4, an oxygen-containing feed is fed to the regenerator section of a fluid catalytic cracking unit (to the FCC regeneration). In the regenerator section, a coked catalyst is present which is regenerated by burning the coke. The resulting flue gas contains various components, in particular CO2, CO, H2O, O2, N2, Ar, H2, COS, CS2, H2S, SOx, HCN, NH3, NOx, Ci, C2, C5+, and catalyst (catalyst particles). The flue gas is subsequently used to generate steam in a waste heat boiler (WHB) which is fed with fresh boiler feed water (BFW). Subsequently, dust (foremost catalyst particles, especially metalbased catalyst particles) is removed from the flue gas using a filter. The removed dust is disposed, and the filtered flue gas is sent to a scrubber. The scrubber is fed with caustic water to remove especially sulfur oxides. Waste water (WW) generated by the scrubbing is sent to a purge treatment unit (PTU) and thereafter to waste water treatment (WWT). The scrubbed flue gas is subsequently compressed and washed with water, and the thereby generated waste water is sent to a sour water stripper (SWS) and afterwards to waste water treatment (WWT). The washed flue gas is sent to a hydrolysis unit for conversion of COS and CS2 to CO2 and H2S and conversion of HCN to NH3 + CO and thereafter enters a separation unit. In the separation unit, a selective absorption process is performed to separate the flue gas into various streams. More specifically, the flue gas is separated into a CO2-rich stream, which contains more than 90 mol% CO2 (here about 99 mol% CO2), a CO-rich stream, which contains more than 90 mol% CO, an H2S-rich stream, which contains more than 90 % of all H2S recovered from stream 2, and some waste water which is sent to the sour water stripper (SWS). The H2S-rich stream further contains CO2 and minor amounts of COS, CS2, HCN, NH3, NOx and SOx and is sent to a sulfur recovery unit.

After leaving the separation unit, the CO-rich stream is blended with additionally fed H2, and the resulting blend is compressed and sent to a methanol unit for synthesizing CH3OH from CO and H2 over a catalyst. Produced CH3OH is withdrawn from the methanol unit as the desired major product of the process. By-products of the methanol synthesis are fusel oil, an off-gas containing CO, H2, O2, N2, Ar, and Ci, and some waste water which contains a minor amount of methanol. The waste water together with the minor amount of methanol is recycled back to the separation unit.

Further, after leaving the separation unit, the CO2-rich stream is split into two CO2-rich sub-streams. A first CO2-rich sub-stream is sent to a compression and purification unit (CPU) and is subsequently sent to storage for finally removing part of the produced CO2 from the process. In this way, a piling-up of CO2 in the process is avoided. A second CC>2-rich sub-stream is recycled back to the FCC regeneration so that generated CO2 is partially recycled in the process. The recycled CC>2-rich sub-stream has a temperature of 75-200°C, preferably 120°C, and cools down the FCC regeneration such that an undesired overheating of the regenerator section of the fluid catalytic cracking unit is avoided.

Calculations have shown that recycling CO2, in particular substantially pure CO2, having a temperature of 120°C, allows to run an FCC regeneration at around 700°C and hence at the lower end of the temperature range of 700 to 780°C regularly required for decoking the FCC catalyst. This reduces the need for additional cooling of the regenerator section and increases the safety of the entire process.

Fifth exemplary embodiment

The fifth exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 5. The fifth exemplary embodiment has basically all features of the fourth exemplary embodiment, but no hydrolysis unit is foreseen in this embodiment. In addition to the fourth exemplary embodiment, a hydrogenation unit is arranged downstream of the separation unit. The CO-rich stream and additional H2 are fed to this hydrogenation unit. The CO-rich stream contains some minor amounts of unsaturated hydrocarbons, in particular ethylene and propylene. These unsaturated hydrocarbons are hydrogenated in the hydrogenation unit so that a poisoning of the catalyst in the methanol unit by such unsaturated hydrocarbons is prevented.

Sixth exemplary embodiment

The sixth exemplary embodiment of the inventive plant and the inventive process running therein is shown in Fig. 6. The sixth exemplary embodiment has all features of the fourth exemplary embodiment, including the hydrolysis unit. In addition to the fourth exemplary embodiment, a hydrogenation unit is arranged downstream of the separation unit like in the fifth embodiment. Also in the sixth embodiment, the CO-rich stream and additional H2 are fed to the hydrogenation unit. The CO-rich stream contains some minor amounts of unsaturated hydrocarbons, in particular ethylene and propylene. These unsaturated hydrocarbons are hydrogenated in the hydrogenation unit so that a poisoning of the catalyst in the methanol unit by such unsaturated hydrocarbons is prevented.

Lists of reference signs and abbreviations

1: stream 1

2: stream 2

2d : first composition and temperature of stream 2

2c2: second composition and temperature of stream 2

2c3: third composition and temperature of stream 2

2c4: fourth composition and temperature of stream 2 3: stream 3

4: stream 4

ASU: air separation unit

BFW: boiler feed water

CPU: compression and purification unit

FCC: fluid catalytic cracking

FCCU: fluid catalytic cracking unit

PTU: purge treatment unit

SRU: sulfur recovery unit

SWS: sour water stripper

WHB: waste heat boiler

WW: waste water

WWT : waste water treatment

Further disclosure

The present invention further provides the following items:

1. A process for the production of methanol comprising the following steps: a) feeding a stream (1) comprising O2 to a regenerator section of a fluid catalytic cracking unit, wherein the regenerator section comprises coked catalyst, b) regenerating the coked catalyst with O2 fed in step a), thereby producing a stream (2) comprising CO and CO2, c) separating stream (2) at least into a CO-rich stream (3) and a CO2-rich stream (4), d) feeding H2 to the CO-rich stream (3), and e) converting H2 fed in step d) and CO of the CO-rich stream (3) into MeOH.

2. The process according to item 1, wherein stream (1) is substantially free of N2.

3. The process according to any of the preceding items, wherein the O2 comprised by stream (1) and/or the H2 fed in step d) is previously produced by an electrolysis of H2O.

4. The process according to item 2 and/or item 3, wherein the electrolysis of H2O is performed using a renewable energy, wherein the renewable energy is preferably selected from energy generated from sunlight, wind, rain, tides, waves and/or geothermal heat.

5. The process according to any of the preceding items, wherein for separating stream (2) in step c) a cryogenic separation unit and/or a pressure swing adsorption unit is used, preferably a cryogenic separation unit.

6. The process according to any of the preceding items, wherein the CC>2-rich stream (4) is at least partially sent to a CO2 storage facility.

7. The process according to any of the preceding items, wherein the CC>2-rich stream (4) is at least partially recycled in the process and is co-fed in step a) to the regenerator section and/or is fed to stream (3) prior to step e), and is preferably co-fed in step a) to the regenerator section.

8. The process according to any of the preceding items, wherein after step b) and prior to step c) heat is recovered from stream (2) in a heat exchanger or in a waste heat boiler.

9. The process according to any of the preceding items, wherein after step b) and prior to step c) stream (2) is filtered, and is preferably filtered with bag filters.

10. The process according to any of the preceding items, wherein after step b) and prior to step c) stream (2) is treated with an alkaline solution, wherein the alkaline solution preferably comprises NaOH.

11. The process according to any of the preceding items, wherein stream (1) comprises > 20 mol% of O2, preferably > 50 mol% of O2.

12. The process according to any of the preceding items, wherein CO-rich stream (3) comprises > 50 mol% of CO, preferably > 75 mol% of CO.

13. The process according to any of the preceding items, wherein CO2-rich stream (4) comprises > 50 mol% of CO2, preferably > 75 mol% of CO2.

14. Methanol obtainable by a process according to any of the preceding items. 15. A plant comprising a fluid catalytic cracking unit, a separation unit and a methanol production unit, wherein the plant is configured for running a process according to any of items 1 to 13, or configured for producing methanol according to item 14.