Process for the production of carboxylic acids and carbonyl compounds by utilizing carbon dioxide-rich feedstock

Abstract

Process to produce carboxylic acids and carbonyl compounds comprising the steps of: a) producing a syngas by means of a short contact time catalytic partial oxidation process which uses a feedstock comprising a mixture of carbon dioxide included in natural gas and other gases, and / or carbon dioxide captured from gaseous streams, said carbon dioxide being from 5 to 50% v / v of said mixture; and air, oxygen, air enriched with oxygen, and optionally steam; b) using said syngas for the production of a compound selected from the group consisting of carboxylic acids, alcohols, carbonyl compounds and carbonates. Also described is an apparatus to carry out the process.

Description

[0001] PROCESS FOR THE PRODUCTION OF CARBOXYLIC ACIDS AND CARBONYL COMPOUNDS BY UTILIZING CARBON DIOXIDE-RICH FEEDSTOCK

[0002] The present invention relates to a process for the production of carboxylic acids, carbonates, carbonyl compounds and alcohol species and other products obtained with process solutions including the production and use of synthesis gas having low hydrogen vs. carbon monoxide ratios obtained by utilizing carbon dioxide-rich feedstock. The invention also relates to an apparatus for carrying out this process.

[0003] BACKGROUND OF THE INVENTION

[0004] The CO2 concentration in the atmosphere has overcome, in 2016, the 400 ppm after having remained between 100 ppm and 300 ppm for thousands of years before, during and after the industrial revolution periods.

[0005] The reduction of greenhouse gases (GHG) concentration, whose main components are CO2 and methane, is crucial and requires a systemic approach for an efficient use of the primary energy sources in which the percentage of renewable energy needs to be increased while the share of fossil sources need to be reduced.

[0006] From another perspective, CO2 is also a synthon but being a highly stable molecule, its transformations require a relevant energy input and / or complex biological cycles.

[0007] The present invention provides innovative solutions for utilizing CO2 in the synthesis gas production and subsequently for utilizing the produced syngas for chemicals and fuels production.

[0008] PRIOR ART

[0009] Currently, the synthesis gas (syngas) with low H2 vs CO ratios is obtained with steam-CO2 reforming technologies utilizing large amounts of CO2 and often referred to as dry reforming technologies. These technologies are limited in their operation windows by carbon formation reactions.

[0010] As mentioned above, in steam-CO2 reforming, particularly in high pressure conditions, the occurrence of carbon formation reactions onto the catalyst surfaces cause limitations in the operation conditions; these limitations particularly affect the possibility of lowering or avoiding the steam content in the reactant mixtures while operation in low steam vs carbon (moles of carbon in the hydrocarbon feedstock) would be particularly advantageous for producing synthesis gas with low H2 vs CO ratios.

[0011] In other words, the production processes utilizing steam-CO2 reforming and particularly dry reforming are limited by thermodynamic and kinetic affinity towards carbon formation reactions occurring at the surfaces of the catalytic species. Steam-CCh reforming and dry reforming [1] are also examined as a possible solution for defining carbon capture and utilization processes as well as other processes which utilize CO2 as synthon, such as: i) the urea synthesis [2] particularly from blue NH3, ii) the methanol synthesis from direct hydrogenation of CO2 [3] and iii) the CO2 methanation to synthetic natural gas (SNG) [4] and liquid hydrocarbons [5].

[0012] CH4+ C02= 2C0 + 2 H2AH0= 247.3 kJ / mol [1]

[0013] 2 NH3+ C02= NH2CONH2 + H20 AH0= - 133.5 kJ / mol [2]

[0014] 3 H2+ C02= CH3OH + H20 AH0= - 48 kJ / mol [3]

[0015] C02+ 4 H2= CH4+ 2H2O AH0= - 164 kJ / mol [4] n C02+ (4n+2) H2= CnH2n+2 + 2n H20 [5]

[0016] However, except for the urea production [2], the other pathways still appear as rather inefficient. Indeed, direct hydrogenation of CO2 into methanol [3], into synthetic natural gas [4], and synthetic liquid hydrocarbons [5] still show mayor thermodynamic limitations and relatively low selectivity features.

[0017] Concerning the production of CO-rich syngas by steam-CCh reforming and / or dry reforming, it is reported that this process is affected by the possible deactivation of the catalysts due to the carbon formation reactions [6-9] particularly at the industrially relevant pressures between 15 - 40 bar.

[0018] 2 CO = CO2+ C AH0= - 171 kJ / mol [6]

[0019] CO + H2= H2O + C AH0= 131 kJ / mol [7]

[0020] CH4= 2 H2+ C AH0= 75 kJ / mol [8]

[0021] CnHm (g) = olefins (g) = coke (s) [9]

[0022] Reactions [6-9] are the primary sources of carbon that can be divided into three typologies: i) whisker carbon, ii) gum (encapsulating carbon), and iii) pyrolytic carbon.

[0023] Gum formation and pyrolytic carbon are especially associated with the presence of hydrocarbons with more than two carbon atoms in the feedstock and can be avoided by removing these molecules with a pre-reformer unit upstream dry reforming.

[0024] Instead, the production of whisker carbon can only be avoided by operating in condition having a low thermodynamic affinity towards this species that once formed bring to the catalyst pellet destruction and to the plant shut down due to the necessity of avoiding that the heat flow from the furnace not adsorbed by the endothermic reactions leads to tubes overheating and fracturing.

[0025] Therefore, one of the primary tasks in the development of a steam-CCh reforming and / or dry reforming processes, is the careful theoretical and experimental analysis of the allowed carbon free operating conditions.

[0026] Significant research has been conducted for limiting, with appropriate catalysts definition, the carbon formation reactions. However, whisker carbon formation remains primarily dictated by thermodynamics instead of kinetics and its avoidance can be obtained only in limited operation conditions.

[0027] Nickel, cobalt, and noble metal catalysts, among others, have been extensively studied as potential catalysts for steam-CCh reforming and dry reforming, with nickel being the most investigated system, as this is, cost-wise, the most attractive catalyst.

[0028] Noble metal catalysts are also utilized since they typically have a lower kinetic affinity for carbon formation and a higher activity for steam and CO2 reforming reactions.

[0029] In addition, it is noted that the CO2 consumption features in steam-CCh and dry reforming is limited by the emissions determined by the heating furnaces. Indeed, the CO2 reforming reaction [1] requires ca. 22% of enthalpy more than steam reforming

[0010] and this heat is currently provided in heating furnaces with reactions such as

[0011]

[0030] CH4+ H2O = 3H2+ CO AH0= +206 kJ / mole

[0010]

[0031] CH4+ 2O2+ 4N2= CO2+ 2H2O + 4N2AH0= -802 kJ / mole

[0011]

[0032] Since the heat transferred into the reaction inside the reforming tubes is roughly the 50% of the heat released by the combustion reactions

[0011] , it can be estimated that per any CO2 molecule consumed with reaction [1] ca 0.6 CO2 molecules would be produced when the reaction heat is provided by burning CH4molecules.

[0033] Despite these difficulties, steam-CO2 reforming processes in which some steam addition prevents the above-mentioned carbon formation reactions have been defined and commercialized, while pure dry reforming is not currently commercialized.

[0034] In conclusion, it is mentioned that TOPSOE has developed a process solution in which a hot CO2 containing stream is added to the synthesis gas produced by a steam reformer operating at low steam vs. carbon ratios. In this way a CO2 enriched synthesis gas is transformed in a subsequent Adiabatic POst Converter (APOC) reactor in conditions in which the thermodynamic affinity towards the carbon formation reactions is greatly reduced. Indeed, in the APOC reactor the CO2 is transformed with a reverse water gas shift reaction into CO and H2O. The use of the APOC provides then a method for tailoring a synthesis gas composition in a wide range of H2 vs CO ratio minimizing the risk of carbon formation.

[0035] In view of the foregoing, there is the need of innovative process and technology solutions that overcome the steam-CO2 reforming and the dry reforming drawbacks related to the occurrence of carbon formation reactions.

[0036] SUMMARY OF THE INVENTION

[0037] An aspect of the present invention is a process to produce carboxylic acids and carbonyl compounds, alcohols and other compounds through the production and use of a low hydrogen vs carbon monoxide synthesis gas comprising the steps of: a) producing a syngas by means of a short contact time catalytic partial oxidation process which uses a feedstock comprising an organic component and an inorganic component, wherein: i) said organic component is a mixture comprising carbon dioxide included in one or more of natural gas, associated gases, off-gases of industrial chemistry and / or refining activities, blast furnace gases, coke oven gases and direct reduction gases produced in the reduction of iron ores, biogas and carbon dioxide captured from gaseous streams, said carbon dioxide being from 5 to 50% v / v of said mixture; ii) said inorganic component comprises one or more of air, oxygen, and air enriched with oxygen, and optionally steam; iii) said oxygen is obtained from electrolysis of water or from air; and iv) said short contact time catalytic partial oxidation process is carried out in a reactor on a catalytic bed comprising a portion with truncated cone geometry operated at a gas hourly space velocity from 15,000 to 500,000 h1; v) said syngas has a hydrogen / CO ratio from 0.5 to 2; b) using said syngas for the production of a compound selected from the group consisting of carboxylic acids, alcohols, carbonyl compounds and carbonates.

[0038] Another aspect of the invention is an apparatus for producing synthetic hydrocarbon compounds with the process defined above, comprising a short contact time catalytic partial oxidation reactor including a first portion having a cylindrical shape consisting of an inlet a mixing zone and a thermal shield zone, a second portion containing a catalytic bed having a truncated cone shape, and a third portion having a cylindrical shape with a diameter greater than the diameter of said first cylindrical portion, followed by a second thermal shield zone, wherein: a) in said second portion having the shape of a truncated cone the upper base is smaller than the bottom base; b) said upper base of said truncated cone is joined to said first cylindrical portion and said bottom base is joined to said third cylindrical portion; and c) the external angle (a) of said truncated cone at the upper base is lower than 85° and preferably lower than 75°.

[0039] The term “short contact time catalytic partial oxidation” (SCT-CPO) has a well-defined meaning either in the scientific, technical, and patent literature. As used in the present invention, however, certain aspects are quite specific for what concerns the combination of the characteristics of the reactor and the operation conditions.

[0040] DETAILED DESCRIPTION OF THE INVENTION

[0041] The apparatus according to the present invention overcome the drawbacks of the prior art by utilizing short contact time - catalytic partial oxidation (SCT-CPO) reactors with a catalytic bed having a truncated cone geometry placed between thermal shields.

[0042] This reactor configuration, an appropriate choice of the catalyst composition and shape and an appropriate selection of operation conditions does not determine the occurrence of the carbon formation reactions at the catalyst surfaces also in the presence of large amounts of CO2 in the reactant mixture.

[0043] Indeed, it has also been found that with the utilization of the SCT-CPO reactor solutions here described, the presence of the CO2 inside the reactant molecules mixture, does not determine the occurrence of carbon formation reactions onto the catalysts surfaces but also inhibits the occurrence of radical reactions in the gas phase that, particularly in high pressure conditions, lead to unsaturated hydrocarbon formation that can further aggregate and decompose producing carbonaceous deposits.

[0044] Hence in the SCT-CPO systems, here described the carbon formation reactions observed in steam-C02 reforming and dry reforming cannot be originated.

[0045] It is stressed the point that only with the adopted and here described reactor solutions, we have found that: i) the presence of CO2 in the reactant mixture inhibits the propagation of the unselective radical reactions inside the reactant / product gaseous mixture progressing inside the SCT-CPO reactor while ii) the CO2 participates, mainly through the reverse water gas shift reaction (RWGS), the heterogeneous chemistry inside the catalytic bed after that relevant amounts of hydrocarbons have been already transformed into synthesis gas.

[0046] Other CPO reactor solutions utilizing tubular and fixed bed reactors, fluidized bed, moving beds, or bubbling bed reactors cannot be applied in the conditions here described.

[0047] The SCT-CPO technology is described in numerous patent documents, including WO2016016257 (Al), WO2016016256 (Al), WO2016016253 (Al), W02016016251 (Al), WO 2011151082, WO 2009065559, WO 2011072877, US 2009127512, WO 2007045457, WO 2006034868, US 2005211604, WO 2005023710, WO 9737929, EP 0725038, EP 0640559.

[0048] Extensive technical and scientific literature has been produced on SCT-CPO and mentioned, for example in:

[0049] ^‘Issues in H2 and synthesis gas technologies for refinery, GTL and small and distributed industrial needs”; Basini, Luca, Catalysis Today, 106 (1-4), p. 34, Oct 2005

[0050] “Fuel rich catalytic combustion: Principles and technological developments in short contact time (SCT) catalytic processes”; Basini, L.; Catalysis Today, 117 (4), 384-393; DOI: 10.1016 / j.cattod.2006.06.043 Published: 15 October 2006

[0051] “Natural Gas Catalytic Partial Oxidation: A Way to Syngas and Bulk Chemicals Production | IntechOpen”; G. laquaniello, E. Antonetti, B. Cucchiella, E. Palo, A. Salladini, A. Guarinoni, A. Lainati and L. Basini; http: / / dx.doi.org / 10.5772 / 48708

[0052] “Short Contact Time Catalytic Partial Oxidation (SCT-CPO) for Synthesis Gas Processes and Olefins Production”; L.E. Basini, A. Guarinoni, Ind. Eng. Chem. Res. 2013, 52, 17023-17037; https: / / doi.org / 10.1021 / ie402463m.

[0053] We have found that the utilization of specific SCT-CPO reactors and operation conditions improves the possibility of transforming CO2 rich stream into a CO rich syngas for producing chemical and fuels completely avoiding the occurrence of conditions in which the carbon formation reactions are produced either for kinetics or thermodynamic reasons.

[0054] Moreover, we have found that, inside the SCT-CPO reactor according to the invention, the CO2 is transformed mainly through the RWGS reaction after that the gaseous hydrocarbons and the oxygen containing flows have been largely converted into a mixture of H2 and CO. In this way within the same SCT-CPO reactor, it is possible to produce the same result that would be obtained by combining the steam-CO2 reforming or dry reforming and APOC reactors.

[0055] It is also mentioned that this technology requires moderate pre-heating of the reactant mixtures, and this pre-heating can be achieved by recovering the heat obtained by cooling the produced synthesis gas avoiding the utilization of fire heaters and hence avoiding the CO2 emissions that this use would produce.

[0056] The use of the specific solutions for SCT-CPO reactors and operation conditions provides a unique mean for obtaining CO rich syngas production suitable for chemical and / or other products by integrating substantial amounts of CO2 into the final products.

[0057] More specifically we have found that the SCT-CPO technology solutions here described allow the utilization of hydrocarbon feedstock also including relevant amounts of CO2 in a wide range of pressure conditions (1 - 80 ATM and preferentially between 5 - 35 ATM) without incurring in the carbon formation reactions. Moreover, we have found that the here described solutions allow the operation of SCT-CPO reactors with a moderate pre-heating of the reactants that can be provided with gas-gas heat exchangers recovering the heat from the produced synthesis gas.

[0058] In this way the syngas can be produced, by utilizing the CO2 as a synthon, with a very low H2 vs CO ratio suitable for chemical processes such as, the synthesis of the acetic acid, the hydroformylation of olefins, the production of other chemicals such as the Methylene Diphenyl Diisocyanate (MDI), Methyl Methacrylate (MMA), Dimethyl Carbonate (DMC) Dimethyl Ether (DME).

[0059] The invention is described also with reference to the accompanying drawings, wherein:

[0060] Fig. 1. (A) Qualitative drawing of the enthalpy / temperature contributions determined by reactions [1],

[0010] and [12-14] occurring along a tubular reactor including a fixed catalytic bed operated at low mass flow velocity; the solid line represents the total enthalpy variation.

[0061] (B) Qualitative drawing of the enthalpy / temperature contributions determined by reactions [1],

[0010] and [12-14] occurring along a truncated cone geometry including a fixed catalytic bed operated at high mass flow velocity; the solid line represents the total enthalpy variation

[0062] Fig. 2. Scheme of the internal zones of a SCT-CPO reactor with a truncated cone reaction zone with elements on the geometry of the truncated cone zone

[0063] Fig. 3. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for the acetic acid synthesis through methanol carbonylation. In this case some CO is separated with a dedicated pressure swing adsorption (PSA) unit for obtaining a synthesis gas stream with a methanol module ca. 2 v / v, useful for methanol production while, the separated CO is utilized for methanol carbonylation

[0064] Fig. 4. Describes a process scheme for integrating CO2 rich streams into acetic acid through the intermediate production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v). The scheme includes two SCT-CPO reactors (A) and (B) operating in parallel. The components of the syngas produced by reactor (B) are separated and the H2 containing stream is added to the syngas produced by reactor (A) for achieving a composition suitable for the methanol synthesis, while the CO is used for the following methanol carbonylation step Fig. 5. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for the acetic acid synthesis through methanol carbonylation. In this case some H2 provided by steam electrolysis can be added to the synthesis gas for achieving a methanol module ca. 2 v / v useful for the methanol synthesis, while the CO useful for methanol carbonylation is obtained from CO2 and H2 by utilizing an electrified reverse water gas shift (E-RWGS) reactor

[0065] Fig. 6. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for the acetic acid synthesis through methanol carbonylation. In this case some H2 provided by steam electrolysis is added to the synthesis gas for achieving a methanol module ca. 2 v / v useful for the methanol synthesis, while the CO useful for methanol carbonylation is obtained from CO2 electrolysis performed with a solid oxide electrolysis cell (SOEC)

[0066] Fig. 7. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for the DMC synthesis through the oxidative methanol carbonylation. In this case some CO is separated with a pressure swing adsorption unit for obtaining a synthesis gas stream with a methanol module ca. 2 v / v, while the separated CO is utilized for methanol carbonylation

[0067] Fig. 8. Describes a process scheme for integrating CO2 rich streams into DMC through the intermediate production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v). The scheme includes two SCT-CPO reactors (A) and (B) operating in parallel. The components of the syngas produced by reactor (B) are separated and the H2 containing stream is added to the syngas produced by reactor (A) for achieving a composition suitable for the methanol synthesis, while the CO is used for the following oxidative carbonylation step

[0068] Fig. 9. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for DMC production through the oxidative carbonylation of methanol. In this case some H2 provided by steam electrolysis is added to the synthesis gas for achieving a methanol module ca. 2 v / v useful for the methanol synthesis, while the CO useful for methanol carbonylation is achieved from CO2 and H2 by utilizing an electrified reverse water gas shift (E- RWGS) reactor

[0069] Fig 10. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) useful for the DMC synthesis through methanol oxidative carbonylation. In this case some H2 provided by steam electrolysis is added to the synthesis gas for achieving a methanol module ca. 2 v / v useful for the methanol synthesis, while the CO useful for methanol carbonylation is achieved from CO2 electrolysis inside an SOEC

[0070] Fig. 11. Describes a process scheme for integrating CO2 rich streams into the production, via SCT-CPO, of a syngas with low H2 vs CO ratios useful for the hydroformylation of alkenes (in this case propene) for producing (A) the corresponding aldehyde (in this case n-butyraldehyde) and (B) the corresponding oxo-alcohol (in this case n-butanol)

[0071] The thermo-chemical properties of the reaction environment produced in short contact time conditions during the SCT-CPO in a heterogeneous catalytic fixed bed reactor fed with a premixed CH4, Steam, CO2 and O2 stream, can be discussed considering the system composed by the by equations [1], [8], [10-12]

[0072] CH4+ 2O2= CO2+ 2H2O AH° = -803.0 kJ / mol

[0012]

[0073] CH4+ ‘ / 2 O2= CO + 2 H2AH0= -38 kJ / mol

[0013]

[0074] CO + H2O = CO2+ H2AH° = - 41.0 kJ / mol

[0014]

[0075] CH4+ CO2= 2CO + 2 H2AH0= 247.3 kJ / mol [1]

[0076] CH4+ H2O = 3H2+ CO AH0= +206 kJ / mole

[0010]

[0077] Clearly the exothermic total oxidation reaction

[0012] would have highest probability to be localized at the beginning of the bed, while the endothermic steam-CO2 reforming [1] and

[0010] and the mildly exothermic (WGS) reactions

[0014] would have the highest probability of occurring in following zone. Noteworthy by increasing the reaction temperature above 830 °C reaction

[0014] is shifted on the left side and a slightly endothermic reverse water gas shift (RWGS) reaction is favoured together with steam-CO2 reforming [1] and

[0010] .

[0078] Moreover, we found that the extent and the localization of these reactions was greatly affected by physical and chemical factors. Total combustion

[0012] has been found be the most competitive reaction on noble metal base (Rh, Ru, Ir, Pt, Pd) catalysts at "low temperature" (T<750 °C) and high O2 partial pressure. These are typically the conditions produced at the beginning of the catalytic beds in tubular reactors operated at “high” contact time values (above 1 s). In these cases, we found that the thermal profiles of the reaction environments are determined by the strongly exothermic reaction

[0012] with a minor contribution of reactions

[0014] and

[0014] , followed by the strongly endothermic steam-CCh reforming reactions [1] and

[0010] . These conditions originate very large axial temperature gradients and moreover, the energy release associated to total combustion also determines the propagation of the heterogeneous reactions into the gaseous phase originating a rather unselective radical chemistry leading to unsaturated molecules and soot formation.

[0079] Indeed, we have found that with tubular reactors the catalytic partial oxidation reactions cannot be performed at high pressures since reaction

[0012] cannot be controlled and propagate reactions into the gaseous phase with the risk of flame ignition and producing radical reactions leading to the formation of unsaturated hydrocarbons and soot.

[0080] Instead, it has been found that the solid catalyst temperatures can reach values higher than 1000 °C while the gas remains relatively cool by utilizing a reaction environment geometry that allows to reduce the contact time at the entrance of the catalytic bed to few milliseconds and that allows the expansion of the reaction volume when the temperature and the mole flow increases due to the progressing of the reaction. This effect is obtained by adopting a truncated shape geometry of the catalytic bed and catalyst geometrical features that allow to reduce the pressure drop inside the reaction zone.

[0081] Accordingly, it has been found that in these short contact time conditions, the methane conversion largely depends on the O2 / C ratios while is almost unaffected by the addition of steam and CO2. This addition instead modifies the H2 / CO ratios in the produced synthesis gas clearly indicating that the reactivity is largely determined by the direct partial oxidation

[0013] and by the RWGS reaction

[0014] .

[0082] Figure 1 shows qualitative pictures of the Enthalpy / Temperature profiles obtained at (A) low mass velocity, high contact time, tubular geometry of the catalytic bed and (B) high mass velocity, short contact time, truncated cone geometry of the catalytic bed.

[0083] Figure 2 shows the main zones of the SCT-CPO reactor including a truncated cone reaction zone.

[0084] The cylindrical first portion includes a mixing inlet zone and a first thermal shield pre-heating zone.

[0085] The central second portion includes a reaction zone,

[0086] The cylindrical third portion includes a second thermal shield and a reactor exit zone.

[0087] The angle a shown in Figure 9 is clearly lower than 85° and preferentially comprised between 75° and 30°.

[0088] The other geometrical features namely the: i) truncated cone inlet radius Rl, ii) the truncated cone exit radius R2, iii) the truncated cone length L and the catalytic bed filling are designed for allowing pressure drop values (AP) inside the catalytic bed between 0.1 and 10 ATM and preferentially between 0.5 and 5 ATM.

[0089] To this purpose the ratios R1 / R2 have to be comprised between 0.9 and 0.1 and preferentially between 0.8 and 0.4 and the shapes of the filling of the catalyst bed need to be defined for minimizing the pressure drop conditions by utilizing pelletized or monolith structures and their combinations.

[0090] It has also been noted that the existence of a non-thermal equilibrium between the gas and the solid phases and this has been explained considering that the chemical heat generated at the surfaces and emitted by radiation, is absorbed, and scattered much better by the solid than by the gaseous phase and is transferred along the catalytic bed from the hotter towards the cooler points smoothing the solid surface temperatures.

[0091] The main experimental observations on the thermo-chemical properties of the SCT environments, performed after optimization of the reaction environment characteristics, are synthesized as follows: i) the temperature of the solid phase raises steeply at the beginning of the bed and the temperature profiles are smoothed through radiative and conduction mechanisms in the axial and radial directions; ii) temperature differences are originated between the gas and the solid phases; iii) part of the surface temperatures results higher than the adiabatic temperatures; iv) gas temperatures are always lower than the adiabatic temperatures and gradually increase from the entrance to the exit of the bed

[0092] It has also been found that part of the reaction heat is transferred towards the incoming reactants inside the first thermal shield zone and in this way a reactant pre-heating internal to the reactor is also achieved.

[0093] In the following we describe process schemes based on the possibility of utilizing such a SCT-CPO reactor for treating a gaseous hydrocarbon feedstock containing relevant amounts of CO2 (between 1 - 50 % v / v and preferentially between 5 - 35% v / v) also at high pressure (between 1 - 60 ATM and preferentially between 5 - 35 ATM) without incurring in the carbon formation reactions. Moreover, since SCT-CPO requires a moderate pre-heating (between 50 - 450 °C and preferentially between 150 and 400 °C), this can be provided with gas-gas heat exchangers recovering the heat from the produced synthesis gas.

[0094] More in detail it is specified that the gaseous hydrocarbon stream could be constituted by methane, natural gas, acid gas, natural gas liquids, well head gas, refinery and chemical plants off gases including pyrolysis gases, biogas and combinations thereof.

[0095] Accordingly, in the described process solutions, the CO2 emissions are mainly related to the E.E. consumption required for: i) compressing the feedstock (compression energy that would be required for any syngas production technology), ii) for obtaining the O2 flow with an Air Separation Unit (ASU), iii) in some cases, for performing steam and CO2 electrolysis and in some others for operating an electrified reverse water gas shift reactor (E-RWGS)

[0096] Noteworthy, when steam electrolysis is included in the process architectures here described, not only the H2 stream participate to the process flows but also the co-produced O2 streams are utilized by the SCT-CPO reactor, and this increases the energy efficiency of the overall solutions.

[0097] The scheme described in Figure 3 describes a solution for producing acetic acid from a CO2 rich hydrocarbon stream by producing, via SCT-CPO, a synthesis gas with a low H2 vs CO ratio (ca. 1 v / v) and by treating the obtained synthesis gas with a CO removal unit for producing a stream with a composition suitable for the methanol synthesis and hence with a methanol module M = (H2-CO2) / (CO+CO2) v / v ca. 2 and a CO stream. This last is utilized for methanol carbonylation for producing Acetic Acid with commercial technologies such those mentioned in Table 1.

[0098] Table 1

[0099] In this scheme, as mentioned above, the CO2 emissions are mainly related to the E.E. consumption required for compressing the feedstock (compression energy that would be required for any syngas production technology) and for obtaining the O2 flow.

[0100] If it is assumed, for the purpose of this discussion, that: i) the simplified reactivity features are described by eq.

[0015] by utilizing a CH4+CO2 mixture in which the CO2 content corresponds to 30% v / v, and ii) the O2 flow would be produced with an Air Separation Unit (ASU) in a scenario in which carbon intensity for E.E. production will vary between 50 gCCh / kWh - 200 gCCE / kWh (current EU emissions range).

[0101] The emissions would vary between 0.03 - 0.12 mole of emitted CO2 per mole of consumed CO2 and would allow a strong reduction with respect to the CO2 emissions associated to the heating furnaces of the dry reforming units (ca. 0.6 moles of emitted CO2 per mole of consumed CO2 by considering reactions [1]] and

[0012] ).

[0102] CH4+ 0.56 02 + 0.43 CO2= 1.45 H2+ 1.43 CO + 0.55 H2O AH0= - 47.04 kJ / mole

[0015] The scheme of Figure 4 describes instead solutions for integrating CO2 rich streams into acetic acid molecules. The scheme includes the production, via SCT-CPO, of a syngas with low H2 vs CO ratios (H2 / CO ca 1 v / v) with two SCT-CPO reactors (A) and (B) operating in parallel.

[0103] The components of the syngas produced by reactor (B) are separated and the H2 containing stream is added to the syngas produced by reactor (A) for achieving a composition suitable for the methanol synthesis, while the CO is used for the following methanol carbonylation and the achievement of acetic acid molecules.

[0104] The scheme of Figure 5 describes solutions for integrating CO2 rich streams into acetic acid molecules by adjusting the synthesis gas composition produced with SCT-CPO by adding an H2 flow produced by steam electrolysis obtained with Alkaline Electrolysis (AE), Polymer Membrane Electrolysis (PEME) but also with Solid Oxide Electrolysis Cells (SOEC).

[0105] In this case the associated O2 production is utilized in the SCT-CPO reactor combined, if it is the case, with the O2 produced by an ASU. Clearly the contribution of the H2 and O2 addition obtained with electrolysis need to be evaluated as function of the associated electric energy consumption and of the amount of CO2 included in the SCT-CPO feedstock.

[0106] The scheme also considers the possibility of producing a CO rich stream from CO2 and H2 with an electrified reverse water gas shift reactor (E-RWGS) with solutions such those described in S. De Sarkar, K. Aasberg-Petersen, T.S. Christensen, P.M. Mortensen, “Conversion of CO2 and H2 to synfuels”; WO 2022 / 079098 Al. Indeed, quite recently it has been estimated that the electrification of the RWGS reactor would allow the production of CO rich mixtures avoiding the CO2 emissions of the same reactors utilizing heating furnaces thus allowing the definition of CO2 sink processes.

[0107] As in Figures 3 and 4 also in the scheme of Figure 5, the MeOH and the CO streams are then combined for producing Acetic Acid with methanol carbonylation technologies.

[0108] The scheme described in Figure 6 is also based on the possibility of SCT-CPO of treating a gaseous hydrocarbon feedstock with relevant amounts of CO2 also at high pressure (e.g., 30 barg) without incurring in the soot formation reactions an on the moderate pre-heating of the reactants avoiding the fire heaters CO2 emissions. As in the process scheme of Figure 5 the composition of the syngas is adjusted for achieving the methanol module M ca. 2 v / v by adding an H2 flow produced by steam electrolysis obtained with Alkaline Electrolysis (AE), Polymer Membrane Electrolysis (PEME) but also with Solid Oxide Electrolysis Cells (SOEC). However, differently from the scheme of Figure 5 the scheme of Figure 6 considers the possibility of producing a CO rich stream with an SOEC fed with a CO2 stream. As in Figures 3 -5 the MeOH and the CO streams are then combined for producing Acetic Acid with methanol carbonylation technologies.

[0109] The schemes of Figures 7 - 10 include the same solutions described in Figures 3 - 6 but in this case the methanol and the CO streams are produced for feeding methanol oxidative carbonylation reactions for obtaining DMC.

[0110] The schemes of Figure 11 include the same solutions of Figure 3 for producing a syngas with a H2 vs CO ratio of 1.0- 1.5 v / v integrated in an hydroformylation process (A) for oxoaldehyde productions and (B) for oxo-alcohols productions.

Claims

CLAIMS1. Process to produce carboxylic acids and carbonyl compounds comprising the steps of: a) producing a syngas by means of a short contact time catalytic partial oxidation process which uses a feedstock comprising an organic component and an inorganic component, wherein: i) said organic component is a mixture comprising carbon dioxide included in one or more of natural gas, associated gases, off-gases of industrial chemical or refining activities, and blast furnace gases, coke oven gases, direct reduction gases produced in the reduction of iron ores activities, biogas and carbon dioxide captured from gaseous streams, said carbon dioxide being from 5 to 50% v / v of said mixture; ii) said inorganic component comprises one or more of air, oxygen, and air enriched with oxygen, and optionally steam; iii) said oxygen is obtained from electrolysis of water or from air; iv) said short contact time catalytic partial oxidation process is carried out in a reactor on a catalytic bed comprising a portion with truncated cone geometry operated at a gas hourly space velocity from 15,000 to 500,000 h1; v) said syngas has a hydrogen / CO ratio from 0.5 to 2; b) using said syngas for the production of a compound selected from the group consisting of carboxylic acids, alcohols, carbonyl compounds and carbonates.

2. Process according to claim 1, wherein said alcohol of said step b) is methanol.

3. Process according to claim 2, wherein said methanol is fed to a reactor for the carbonylation of methanol to produce carboxylic acids and carbonyl compounds.

4. Process according to claim 1, wherein said synthesis gas is fed to an olefins hydroformylation reactor for producing aldehyde compounds.

5. Process according to claim 4, wherein said aldehyde compounds are fed to a hydrogenation reactor for producing corresponding alcohols.

6. Process according to any claim 1-5, wherein said syngas has a hydrogen / CO ratio from 0.7 to 1.5, preferably from 0.8 to 1.3.

7. Process according to any claim 1-6, wherein said oxygen from air of said step a)ii) is obtained by means of a method selected from cryogenic air separation, vacuum pressure swing adsorption, membrane separation8. Process according to any claim 1 - 7, wherein said oxygen of said step a)ii) is obtained from both air and from electrolysis of water.

9. Process according to any claim 1-8, wherein said syngas produced in said step a) is treated in a pressure swing adsorption unit to separate a portion of said CO, and said separated portion of CO is fed to said carbonylation reactor of said step c).

10. Process according to any claim 1-9, wherein said feedstock of said step a) is pre-heated by means of a method selected from: a) recovering heat from the produced syngas with gas-gas heat exchangers, b) transferring to the feedstock inside the reactor part of the reaction heat before the feedstock reaches the reaction zone.

11. Process according to any claim 1-10, wherein said syngas is produced in two separate short contact time catalytic partial oxidation reactors operating in parallel, with the syngas produced in one of said two reactors which is treated to separate hydrogen and CO, and with the hydrogen which is mixed to the syngas produced in the other short contact time catalytic partial oxidation reactor and fed to said step b) for the synthesis of methanol, and the CO is fed to said step c) to produce carboxylic acids and carbonyl compounds.

12. Process according to any claim 1-11, wherein syngas is produced also in a reverse water gas shift reactor which uses a feedstock comprising a mixture of hydrogen and carbon dioxide, and wherein the CO contained in said syngas is produced said reverse water gas shift reactor is used to produce carboxylic acids and carbonyl compounds.

13. Process according to claim 12, comprising a Solid Oxide Electrolysis Cells (SOEC) fed with a stream containing carbon dioxide and producing a stream containing CO which is used to produce said carboxylic acids and carbonyl compounds.

14. Process according to any claim 1 - 13, wherein said carboxylic acid is acetic acid.

15. Process according to any claim 1 - 13, wherein said carbonyl compound is dimethyl carbonate.

16. Apparatus for producing carboxylic acids and carbonyl compounds with the process according to any claim 1-15 comprising a short contact time catalytic partial oxidation reactor containing a catalytic bed comprising a first portion having a cylindrical shape, a second portion having the shape of a truncated inverted cone and a third portion having a cylindrical shape with a diameter greater than the diameter of said first cylindrical portion, wherein: a) in said second portion having the shape of a truncated inverted cone the upper base is smaller than the bottom base;b) said upper base of said truncated inverted cone is joined to said first cylindrical portion and said bottom base is joined to said third cylindrical portion; and c) the external angle (a) of said truncated cone at the upper base is lower than 80°.

17. Apparatus according to claim 16, wherein said upper base of said catalytic bed having the shape of a truncated inverted cone has a diameter R1 and said bottom base has a diameter R2, wherein the ratio R1 / R2 is from 0.9 to 0.1, preferably from 0.8 to 0.4.

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