Process for producing fuels from waste by converting olefins from methanol to propylene (MTP)

Abstract

A process for producing hydrocarbons, usable as fuels, from industrial, agroforestry, urban waste and derivatives thereof, with high sustainability and lower CO2 emissions, given the same energy, with respect to the equivalent fuels of fossil origin, by means of a series of subsequent conversions in which first a syngas is produced,, obtained by gasification of waste with oxygen at high temperature, which is purified and adjusted in composition by modulating the H2 / CO ratio and then converted into methanol. The methanol obtained is in turn catalytically converted into light olefins by means of methanol -to- propylene (MTP) technology; such olefins are catalytically converted by oligomerization in order to obtain a hydrocarbon mixture comprising an ultra-light fraction (C1 and C2 ), a light fraction (C3 and C4), a fraction with a boiling range from 60 to 300°C, and a fraction with a boiling temperature above 300°C to be used for product separation and fractionation treatments.

Description

PROCESS FOR PRODUCING FUELS FROM WASTE BY CONVERTING OLEFINS FROM METHANOL TO PROPYLENE (MTP)Summary of the invention

[0001] The present invention relates to a process and an apparatus for producing gasoline and jet fuel from waste, preferably urban and / or industrial waste and derivatives thereof, as better clarified in the continuation of the description .Field of the invention

[0002] More precisely, the invention falls within the field of waste valorization by means of gasification technology aimed at producing synthesis gas (or syngas) ; said syngas is in turn transformed into methanol which is then reacted under suitable conditions to produce light olefins; the olefins thus obtained are oligomerized, and possibly hydrogenated, to produce hydrocarbon fractions, in particular gasolines and let fuels, useful in the transport field .Background art

[0003] The conversion of waste of different types aimed at producing sustainable fuels, particularly intended for air transport, is the subject of several research and development activities, especially in view of the progressive reduction in the use of petroleum-derived fuels so as to reduce C02emissions and greenhouse gas .

[0004] Several laws adopted in different countries promote, in fact, the conversion of waste and scraps to produce sustainable fuels, in perfect harmony with the criteria of a new circular approach to the economy, aimed at reducing or eliminating the residues and at fully valorizing the resources .

[0005] For example, patent WO 2018 / 066013 Al describes a process and a plant for producing waste-derived synthesis gas orwaste-derived fuel, such as refuse-derived fuel (RDF ) ; the synthesis gas, which can be used as a raw material for Fisher- Tropsch plants, methanol or ammonia, is thus originated from partially renewable sources, avoiding the consumption of raw materials of fossil origin such as natural gas, petroleum or coal for the production thereof; in fact, RDF has a renewable material content of about 35 / 40% by weight .

[0006] Patent EP 3433341 Bl describes a process and a plant for producing synthesis gas, obtained by gasifying agricultural, industrial or urban waste, in which the synthesis gas is treated in a single purification line in order to modulate the C0 / H2 / C02ratios so as to make them optimal for the transformation into methanol .

[0007] The first studies for the transformation of methanol into hydrocarbons (methanol to hydrocarbons - MTH) date back to 1970 at the Mobil laboratories; during these studies, Mobil researchers discovered the possibility of converting methanol into gasoline using ZSM-5 zeolite as a catalyst and developing the related process (methanol to gasoline - MTG) claimed in patent US 3928483 A.

[0008] Later, the process of converting methanol into olefins (MTO - methanol to olefins; Chang, C . D . Catal . Rev . 1984, 26(3-4) , 323-345) was again claimed by Mobil research .

[0009] In essence, these two processes allowed the production of fuels or petrochemical intermediates starting from methanol instead of petroleum .

[0010] More recently, UOP has developed MTO technologies using a microporous silicoaluminophosphate, namely SAPO-34, as a catalyst (PT Barger, BV Vora, PR Pujado, Q Chen - Studies in Surface Science and Catalysis, Volume 145, 2003, Pages 109-114) .

[0011] The Dalian Institute of Chemical Physics (DICP) has also developed the technology (DMTO) for producing olefins frommethanol up to a commercial scale using SAPO-34 as a catalyst ( Liu, Z . M. ; Qi, Y. Bull . Chin . Acad . Sci . 2006, 21(5) , 406- 408) .

[0012] MTO technologies produce mixtures of ethylene and propylene with high yields, with molar ratios of ethylene yield to propylene yield between 0.75 and 1.5.

[0013] Lurgi company has developed the technology for the transformation of methanol to propylene (MTP) , again using ZSM-5 zeolite as a catalyst for the conversion of methanol but aiming to maximize the yield of propylene (Koempel, H . ; Liebner, W. Stud . Surf . Sci . Catal . 2007, 167, 261-267) .

[0014] The methanol-to-olef in conversion reaction catalyzed by zeolites is characterized by the co-production of water; in particular, the presence of water in the reaction medium has a positive role in limiting the formation of carbon on the catalyst, extending the life thereof .

[0015] Some studies then show the positive role of water in attenuating the deactivation of the SAPO-34-based catalyst for coking (A. G . Gayubo et al . ; Studies in Surface Science and Catalysis, Volume 126, 1999, Pages 129-136) .

[0016] For this reason, the feed of methanol-to-olef in (MTO) conversion reactors generally consists of a mixture of methanol and a variable percentage of water, even up to 30%.

[0017] Both MTO and MTP technologies allow obtaining high conversions of methanol; in both cases, the effluent from the conversion stage contains olefins, water, unreacted methanol, unreacted dimethyl ether (DME ) which is generally formed during the methanol-to-olefin conversion steps, and to a lesser extent saturated and aromatic hydrocarbons .

[0018] The difference between the two technologies, MTO and MTP, lies in the different composition of the obtainable olefins .

[0019] By way of example, the material balance and the typical yields of olefins and hydrocarbons of the "methanol-to- olefin" (MTO) technology can be inferred from patent US 7138557 B2 and are given in table 1 below.Yields from the MTO conversion zoneSelectivity (Mass - % Component Equivalent Methanol)Methane 0.85Ethylene 33.50Ethane 0.65Propylene 44.50Propane 0.30Butylene 9.5Butane 0.01C5 +5.00Coke 2.85Unreacted methanol 0.50DME 1.05Other (H2, CO, C02, Dienes) 1.29Total 100.00TabLe 1 - YieLds from the MTO conversion zone

[0020] Methanol-to-propylene (MTP) technology has much higher yields in propylene (71%) and lower yields in ethylene (1.6%), however featuring a higher yield in C4+ (24.6%) ("Methanol to Olefins", Report No . 261, November 2007, SRI Consulting, Menlo Park, California) .

[0021] Generally, in the MTO process there is also a formation of dimethyl ether (DME) , an intermediate which remains in the effluent to a small extent .

[0022] Both MTO and MTP technologies are characterized by very complex separation trains downstream of the reaction stages, in order to produce high purity ethylene and propylene(polymer grade) .

[0023] The first separation stage for both technologies is represented by a quencher where the hydrocarbon fraction is separated from water; specifically, hydrocarbons exit the quencher in the vapor phase while water condenses .

[0024] In the aqueous phase, methanol also accumulates and is recovered and recycled in the reaction .

[0025] Instead, DME partially passes to the aqueous phase with methanol and partially exits with the hydrocarbon fraction .

[0026] The hydrocarbon vapor phase is compressed in a multistage compressor, with intermediate ref rigeration; a two-phase condensate is obtained from which water is separated, which is recycled to the quencher, while the non-condensed hydrocarbons, in both the liquid phase and the vapor phase, pass to the distillation section .

[0027] Given the considerable sensitivity of modern polymerization catalysts to the presence of oxygenated compounds, acetylenes and dienes, the fact that the elimination of these contaminants must be particularly scrupulous in the hydrocarbon fraction separation step is problematic .

[0028] As for DME, the need to separate it and recycle it at the beginning of the methanol conversion process is mainly dictated by the need to increase the overall yields of the process .

[0029] In MTO and MTP technologies, DME recovery is generally carried out by means of a plurality of stages of washing the hydrocarbon fraction with suitable solvents, such as water and methanol or methanol, for example .

[0030] For example, patent US 4587373 A describes a method and an apparatus for recovering DME from the effluent and recycling it in the reaction, however, during this recovery operation, small amounts of olefins remain dissolved in DME andthese dissolved olefins are the main cause of deactivation of the zeolitic catalyst .

[0031] Patent US 7138557 B2 describes a different method for the selective recovery of DME adapted to avoid the previously described drawback of olefin entrainment by means of a series of subsequent separations; namely, such a method has the disadvantage of requiring a multiplicity of operations (stripping and purification stages) to avoid olefin entrainment at the beginning of the methanol conversion process .

[0032] Patent US 8058498 B2 describes a method for separating DME from the hydrocarbon fraction, produced during the MTP reaction stage, by means of extractive distillation .

[0033] Patent US 9505684 B2 describes a process in which a hydrocarbon mixture, generated by the MTP reaction stage and containing ethylene, propylene, propane, butane and butenes, as well as higher hydrocarbons and a significant amount of DME, is treated in a specific column for the separation and recovery of DME from the hydrocarbon fraction by means of a rectification column from the head of which a fraction rich in propylene comes out, with small amounts of ethane and ethylene practically free of DME; from the bottom, a fraction rich in butanes and butenes and higher hydrocarbons comes out while a propane fraction rich in DME is taken from an intermediate plate.

[0034] MTO and MTP technologies are generally used in plants intended for the production of polymers in which the hydrocarbon fraction, after the recovery of DME, is fractionated according to a different scheme depending on whether both "polymer grade" ethylene and propylene are to be produced, or only "polymer grade" propylene.

[0035] In the case of MTP technology, the typical hydrocarbon fraction separation train consists of at least one de-ethanizer to separate the light components (C2-) to bevalorized as a fuel gas; the de-ethanizer is generally followed by a de-propanizer associated with a splitter of the C3fraction the function of which is to separate pure propylene and propane .

[0036] This is then followed by a de-butanizer to separate the butane fraction (C4) from the heavier hydrocarbon fractions (C5 +) .

[0037] The C4fraction and propane can be recycled to the MTP reactor or valorized as an LPG ( Liquefied Petroleum Gas) , while the heavier hydrocarbon fraction (C5 +) is valorized as a gasoline.

[0038] The features for the gasoline obtained from MTP are reported in Table 2.PropertiesDensity at 15°C kg / m3740 - 790Reid Vapor Pressure at 37°C bar 0.45 - 0.70Octane number RON 90 - 95CompositionParaffines and Naphthenes %wt 20 - 30Olefins %wt 30 - 60Aromatics %Wt 15 - 50Benzene %Wt < 0.1Total sulfur components ppm wt < 0.1TabLe 2 - Features of gasoLine from MTP

[0039] The use of propylene as a raw material adapted to produce fuels and chemical products by means of an oligomerization reaction is also known .

[0040] Oligomerization was discovered and developed by UOP in 1935, for the production of the so-called polymer gasolines .

[0041] The oligomerization reaction, catalyzed by supported phosphoric acid (SPA) , allows producing a mixture mainly consisting of propylene trimers and tetramers which can be used as gasoline or as intermediates for producing detergents(Christopher P . Nicholas, Applied Catalysis A: General, Volume 543, 2017, Pages 82-97) .

[0042] Patent US 4150062 A describes a light olefin oligomerization process for obtaining gasoline by using zeolitic catalysts .

[0043] Similarly, in the "Mobil Olefine to Gasoline and Distillate" (MOGD) process, propylene and butenes are converted into gasoline and diesel fuel by oligomerization using a ZSM-5 zeolite catalyst (S . A. Tabak, F . 3 . Krambeck, W. E . Garwood, AIChE Journal, vol . 32 (1986) , 1526-1531) .

[0044] Patent US 5149896 A describes a process for the oligomerization of olefins, in particular containing propylene, by means of an amorphous silica-alumina gel catalyst, which is characterized by the presence of pores in the mesoporous region (Studies in Surface Science and Catalysis, Vol . 84, pp . 85-92) .

[0045] Patent US 5342814 A describes an extruded catalyst based on amorphous silica-alumina and active in the reaction of oligomerization of propylene to gasoline and jet fuel and the related preparation method .

[0046] Patent US 5498811 A describes an oligomerization process of C3-C4mixtures rich in olefins (propylene and butenes ) aimed at producing oligomers from which a gasoline fraction with a boiling range of 80-175°C, a jet fuel fraction with a boiling range of 175-300°C, and a diesel fuel fraction with a boiling point above 300°C can be separated, and in which the jet fuel fraction, after hydrogenation, has a freezing point lower than -60°C and a smoke point of 38 mm .

[0047] Moreover, the use of a catalyst based on amorphous silica-alumina for the oligomerization of C4olefins is described by the Institut Francais du Petrole (Studies in Surface Science and Catalysis, Volume 44, 1989, Pages 167-174) with the production of gasoline and jet fuel; for the productionof diesel fuel, the catalyst used is a zeolite (Mordenite) .Task of the invention

[0048] The invention aims to overcome the limitations of the prior art by providing an integrated process for the production of fuels, in particular gasoline and jet fuel, from waste the transformation of which into the final product is obtained by means of a sequence of subsequent conversions, each of which is aimed at providing the reagent stream in the best possible conditions to obtain an optimal yield of the desired products, maximizing the conversion of waste into synthesis gas and minimizing C02emissions into the environment as well as minimizing the number of treatments required, and thus the energy consumption, to obtain the desired products .Suggested solution

[0049] The suggested solution is a process in which waste is first gasified at high temperature to obtain a raw syngas which is converted into methanol; the methanol obtained is then transformed into olefins from which, utilizing an oligomerization treatment, gasoline and middle distillates are obtained .

[0050] Middle distillates are then hydrogenated to obtain jet fuels .

[0051] In the preferred embodiment described, the transformation of methanol into olefins occurs by means of an MTP technology, characterized by a predominant production of propylene and a negligible yield of ethylene.List of figures

[0052] A better understanding of the invention will be achieved by means of the following detailed description and with reference to the accompanying drawings, which show a preferred embodiment thereof merely given by way of a non-limiting example .

[0053] In the drawings :Figure 1 shows a block diagram of the process according to the present invention;Figure 2 shows a block diagram corresponding to Figure 1 in which all the treatment units are shown .Detailed description of the invention

[0054] The present invention relates to an integrated process aimed at producing fuels from waste, in particular intended for the production of jet fuels .

[0055] The use of an alternative source, characterized by a high degree of sustainability, with respect to fossil sources (petroleum or natural gas ) , allows producing fuels characterized by a lower overall emission of C02into the environment .Process

[0056] According to the invention, the process comprises the following steps :1. Conversion (100) of waste into syngas and purification thereof;2. Adjustment of the composition (200) of the syngas obtained;3. A step of conversion of syngas into methanol (300) ;4. A step of catalytic conversion of methanol into olefins (400) ;5. A step of catalytic olefin conversion (500) to obtain gasoline and middle distillates;6. A step of separating the light components from the heavy components (600) present in the oligomerized stream;7. A step of treating the heavy fraction (700) aimed at obtaining and fractionating the products .

[0057] Optionally, a water electrolysis unit (1000) can be present, from which a stream of 02and a stream of H2are obtained .

[0058] Additionally, a fuel gas treatment unit (1100) can bepresent .

[0059] Each of the steps indicated above, both the essential and the optional ones, can consist of one or more processing trains operating in parallel, depending on the potential of the plant .Feed

[0060] The feed entering the process according to the invention consists of industrial, agroforestry and urban waste, and derivatives thereof .

[0061] An indicative, but not limiting, list comprises :1. Urban solid waste;2. RDF ( refused derived fuel) , fuel obtained from urban waste;3. Plasmix, the mixture of plastic waste from separate collection, after separation of recyclable plastics;4. Scraps and waste from plastic processing;5. Straw, corn stalks, cobs;6. Forestry cuttings and residues;7. Sawdust and wood chips;8. Sludges from the purification of urban and / or industrial water .

[0062] The feed entering the process according to the invention can also be a combination of the waste listed above .Syngas production (100)

[0063] According to the invention, the syngas production step comprises the following steps :1. Gasification (110) of the waste to give synthesis gas (or syngas) ;2. A first purification (120) of the synthesis gas aimed at eliminating particulate matter, metals and acidic and / or basic components :3. A step of compressing (140) the raw syngas;4. A second purification (160) of the compressed syngas forcompletely removing the metals still contained and HC1;5. A sulfur removal step (180) .Gasification (110)

[0064] The conversion of waste by high-temperature gasification (110) occurs in a fixed-bed reactor by injecting pure 02, optionally added with natural gas (CH4) , at various points of the reactor itself, so as to conveniently control the temperature gradient inside the reactor .

[0065] The 02sent to the reactor can be produced in various manners, by both an air separation unit (ASU) and an electrolysis unit (1000) , for example .

[0066] More in detail, the injection of 02is such as to allow having :• in the lower part of the gasifier, the fusion of the inert material with temperatures above 1400°C;• in the middle part, the products of partial oxidation of the carbon matrix forming the waste, above the conversion bed with temperatures of 600 / 700°C;• in the upper part, the stabilization zone with temperatures between 1100°C and 1200°C, where methane, heavy hydrocarbons and tar are converted into CO and C02.

[0067] The synthesis gas ( raw syngas) thus obtained from the waste indicated above and in the operating modes described above has a volume ratio H2 / C0 generally between 0.8 and 1.2, more preferably equal to 0.9, and a C0 / C02ratio between 3.5 and 4 and still contains a whole series of pollutants which must be removed before any catalytic treatment downstream of the gasification .First impurity removal, step _ ( 120)

[0068] The main pollutants that must be removed are HC1,H2S, COS, NH3and the various metals .

[0069] In the preferred but not limiting embodimentdescribed, the separation of the pollutants occurs in multiple subsequent steps by conveniently providing, in terms of pressure and temperature, the syngas stream for each treatment .

[0070] According to the invention, the syngas coming out of the gasification step (100) enters the first impurity removal step (120) in which HC1 and metals are eliminated; such an impurity removal step (120) comprises in series, as shown in Figure 2 : a . first a wash with water (121) ; b . an acid wash (122) ; c . a wash with soda (123) ; d . a removal of possible solid entrainments (124) obtained by means of an electrostatic precipitator (WESP) ; e . a step of adjusting the temperature achieved by cooling (125) and heating (126) the purified stream; f . a syngas storage (127) aimed at stabilizing the fluctuations in the flow rate of the synthesis gas which are related to the operating modes of the reactor and, in the case of multiple processing trains of the sections upstream of the syngas storage step (127) , aimed at ensuring a stabilization of the syngas compositions before the conversion treatments downstream of said storage (127) .Raw syngas compression _ (140)

[0071] The syngas from the storage (127) is sent to a gas compression station (140) .

[0072] Said compression step allows the syngas to be brought to optimal conditions to carry out the subsequent and further deep purification steps, in addition to have a suitable pressure for the subsequent processing steps .Second purification step (160)

[0073] The syngas thus compressed is directed to a secondpurification step (160) in which possible entrainments of HC1 and metal particulates are eliminated .SuLfur and nitrogen compound removal. (180)

[0074] The second purification (160) is followed by a step of converting and removing sulfur and nitrogen components (180) in which COS and NH3are hydrolyzed and H2S is converted to elemental sulphur .

[0075] The elemental sulphur thus obtained is removed from the stream, thus obtaining a highly purified syngas .Composition adjustment (200)

[0076] According to the invention, the step of adjusting the H2 / C0 ratio comprises the following steps :1. A step of adjusting the H2 / C0 ratio (220) ;2. A step of removing any C02(240) possibly present;

[0077] The purified syngas from the previous purification step (180) is sent to a composition adjustment section (220) to reach the so-called methanol index (H2 / C0 ratio) equal to 2 / 2.1.

[0078] In order to obtain this value, a part of CO can be converted into C02and H2by catalytic reaction with H20 by means of the well-known Water Gas Shift, WGS, technology (221) and then the C02present can be removed .

[0079] Alternatively, it is possible to adjust the H2 / C0 ratio by merely mixing (222) the syngas with the hydrogen (H2) obtained in the water electrolysis section (1000) .C02removal. _ (240)

[0080] The syngas with a suitable composition for methanol synthesis is sent to a C02removal unit (240) , where said separation occurs by means of a conventional or chemical solvent-based system, for example amine, or with Pressure Swing Adsorption (PSA) .

[0081] The recovered C02can be used to inertize thegasification system .Conversion of syngas into methanoL (300)

[0082] According to the invention, the step of converting the syngas into methanol comprises the following steps, as shown in Figure 2 :1. A purified syngas compression step (320) ;2. Conversion of the compressed syngas into methanol (340) ;3. A step of purifying the produced methanol (360) .Syngas compression (320)

[0083] The syngas obtained, from the C02removal zone (240) , is sent to a compression step (320) to reach the pressure of 80 / 90 barg at which the methanol synthesis reactor operates . MethanoL synthesis _ (340)

[0084] The compressed syngas from step (320) is converted into methanol (340) ; by way of example, but not of limitation, the methanol synthesis process used can be like the conventional one suggested by 3M or Air Liquide, characterized by a relatively low conversion per step and by a significant recycling .

[0085] Hydrogen (H2) is recovered from the off-gas of the synthesis reactor (340) and is recycled at the head of the reactor .MethanoL purification (360)

[0086] The methanol produced in the previous step (340) needs to be purified (360) in a two- or three-column system to obtain the required degree of purity.CataLytic conversion of methanoL to oLefins (400)

[0087] The present invention provides that the step of converting methanol to olefins (400) comprises the following steps, as shown in Figure 2 :1. Catalytic conversion of methanol to olefins (420) by means of Methanol-to-Propylene (MTP) technology;2. Cooling and separation of the effluent from the synthesis reactor by means of a quencher (440) ;3. Compression and purification of the gaseous phase (460) exiting the quencher (440) .MTP - MethanoL to PropyLene (420)

[0088] The methanol produced during the previous synthesis stage (300) is transformed into light olefins, mainly C2, C3and C4, by means of a catalytic reaction with on molecular sievebased catalysts, such as zeolites or microporous crystalline silicoaluminophosphates, for example .

[0089] In the preferred but not limiting embodiment described, the conversion technology (420) used is selected from those which predominantly produce propylene (Methanol to Propylene, MTP) .

[0090] Processes are known for converting olefins to predominantly produce propylene; among these, it is useful to mention MTP® technology licensed by Air Liquide- Lurgi and DTP® licensed by 3GC-Mitsubishi Chemicals .

[0091] The MTP reaction is characterized by a first stage of dehydrating methanol to DME, followed by the main reaction stage, where the methanol / water / DME mixture is reacted with a zeolite-based catalyst, for example modified ZSM-5, to form a mixture of hydrocarbons, rich in propylene and other olefins .

[0092] The reactor is adiabatic with a fixed bed and the catalyst placed in layers on the catalytic beds; normally, the technology involves two reactors (twin reactors ) or several reactors, operating alternately, i . e . , while one is regenerating, the other(s ) is / are operating .

[0093] The reaction occurs within a temperature range from 400 to 450°C at a pressure between 1.5 and 2 barg; the catalyst deactivation is caused by the deposition of tar and coke; for this reason, the regeneration is carried out by sending amixture of impoverished air onto the catalytic bed, previously evacuated from reagents and products, so as to cause a controlled combustion of any tar and coke deposits .

[0094] In this step, the control of combustion and relative temperature is highly accurate in order to avoid thermal stresses and phenomena of structural degradation of the catalyst .

[0095] The mixture exiting the reactor contains about 40% of water (H20) by weight, the aliquot of unreacted methanol (CH3OH) (less than 1%) and a few thousand ppm of DME (C2H60) ; the remaining part consists of olefinic, paraffinic and aromatic hydrocarbons ranging from methane (CH4) to C8and beyond . Quencher (440)

[0096] The mixture exiting the methanol-to-olefin conversion reactor described above is conveniently cooled by means of a quencher (440) aimed at condensing most of the water; a significant part of water and soluble organic fraction in the aqueous phase, mainly methanol, and contained in said stream is thus separated .OLefin compression (460)

[0097] The gaseous phase exiting the quencher (440) is then sent to compression (460) , followed by a cooling and condensation step, aimed at further separating the rest of water and methanol contained in said gaseous stream .

[0098] The result is a hydrocarbon mixture mainly consisting of olefins in which, however, unconverted DME is still present . De-hexanizer (480)

[0099] The olefin production step comprises a gasoline separation step; in this case, a de-hexane column (480) is inserted on the hydrocarbon fraction separated from the water during the first compression stages (460) , downstream of the olefin production stage (420) by methanol-to-propylene (MTP)conversion; the gasoline fraction produced in the olefin production step (420) is thus preliminarily recovered and corresponds to about 10-15% of the hydrocarbons produced .

[0100] This gasoline is characterized by a content between 15 and 50% of aromatics, almost exclusively xylenes (benzene less than 0.1%) and can be added to the gasoline fraction produced during the subsequent oligomerization step (520) .Catalytic oLefin conversion (500)

[0101] In the preferred embodiment described, the stream consisting of (olefinic, paraffinic and aromatic) hydrocarbons and unreacted DME, which can be defined as a "reaction crude", is sent to a catalytic conversion reactor .Reaction crude buffer tank (510)

[0102] In the preferred embodiment described, the stream defined as a "reaction crude" is conveyed to a buffer tank (510) the function of which is to allow the optimal modulation of the flow rates for subsequent treatments .OLigomerization (520)

[0103] According to the invention, said catalytic conversion of the reaction crude is obtained by oligomerization (520) , without the need to separate propylene from the other olefins and the other hydrocarbons, and without having to separate the DME; moreover, it is not necessary to introduce a stage of selective hydrogenation of acetylenes, which stage must generally be introduced instead for producing pure olefins .

[0104] By means of such an oligomerization reaction, olefins are converted into a hydrocarbon mixture comprising an ultralight fraction (Ci and C2) , a light fraction (C3and C4) , a fraction with a boiling range approximately from 60 to 175°C, a fraction with a boiling range approximately from 175 to 300°C, and a heavy fraction with a boiling point above 300°C .

[0105] The relative amounts and the compositional featuresof these fractions obviously depend on the catalyst and on the operating conditions adopted .

[0106] The oligomerization reaction is carried out with heterogeneous catalysis, i . e . , with a solid acid catalyst .

[0107] Moreover, the operating conditions for the development of this reaction are selected in a temperature and pressure range such as to ensure that the reaction medium is in a mixed gas-liquid phase; said temperature range is from 50 to 300°C, while the respective pressure range is from 10 to 70 barg .

[0108] Moreover, in order to optimize said oligomerization step, the temperature and weight hourly space velocity (WHSV) parameters the value of which, corresponding to the ratio of the mass flow rate of olefins alone to the mass of catalyst, is generally between 0.2 and 4 h- 1, are selected as a function of the catalyst used, so as to obtain a practically total conversion of propylene ( >90%) , in order to avoid expensive recovery and recycling operations thereof .

[0109] As for the solid acid catalyst, this can be selected, for example, from phosphoric acid, for example solid phosphoric acid (SPA) , supported on diatomaceous earth; crystalline microporous silicoaluminates, for example, zeolites, characterized by medium, large or extra-large pores; amorphous silica-aluminas .

[0110] Under the operating conditions described and with the use of the catalysts indicated above, all the olefins present, not only propylene, are converted by oligomerization and isomerization, but with different reactivities .

[0111] By way of indication, in the case of the SPA catalyst, the reactivity of olefins for the oligomerization reaction qualitatively follows the following order (from the most reactive to the least reactive) :isobutene methyl-pentenes n-butene propylene n-pentenes

[0112] Reactivity further decreases for higher olefins : hexenes, heptenes, octenes, etc .

[0113] Moreover, ethylene is characterized by a low reactivity under these operating conditions and with these catalysts .OLigomerization catalyst

[0114] According to a preferred embodiment of the invention, the catalyst is selected from the family of amorphous silica- aluminas and in particular the mesoporous ones, including silicoaluminates belonging to the different families of silica- aluminas synthesized using surfactants as micellar templates and characterized by an ordered porous system such as the M41S and in particular MCM-41 family, for example, or even FSM-16, HMS, SBA, MSI) and KIT-1 (Journal, of MoLecuLar Catalysis A: Chemical 134, 1998. 145-157; Chemical Society Reviews, 2013, 42, 3956- 3976) , or silicoaluminates with a disordered porous system obtained with sol-gel synthesis in the presence of clusters as templates, such as MSA, ERS-8 and MMM, for example (Microporous and Mesoporous Material 44-45 (2001), 733-744) .

[0115] Even more preferred is mesoporous amorphous silica- alumina MSA, synthesized as described in Studies in Surface Science and Catalysis, 1994, 84, 85-92.

[0116] When the catalyst used is a mesoporous amorphous silica-alumina, such as MSA, for example, at temperatures preferably between 120 and 250°C, a hydrocarbon mixture is obtained, which contains gasoline (with a boiling point between 60-175°C) , middle distillates, in particular kerosene (boilingtemperature between 175-300°C) and diesel fuel (boiling temperature above 300°C) , in addition to a fraction of LPG (liquefied petroleum gas essentially consisting of C3-C4hydrocarbons) .OLigomerization reactor

[0117] The oligomerization reaction is preferably carried out continuously in an adiabatic fixed catalytic bed reactor with one or more catalytic beds, or in a reactor of the shell and tube type with the catalyst loaded into the tubes .

[0118] This olefin oligomerization process, carried out using an amorphous silica-alumina-based catalyst, such as mesoporous amorphous silica-alumina (MSA) , for example, does not result in the formation of significant amounts of aromatic hydrocarbons unlike similar processes which use zeolites, such as ZSM-5, as a catalyst, except for the aliquot of aromatics already present in the feed from the MTP.

[0119] In any case, the presence of aromatics in the hydrocarbon mixture produced by the MTP reaction stage and fed to the oligomerization does not negatively affect the performance of mesoporous amorphous silica-alumina such as MSA.

[0120] Under these operating conditions, however, the aromatics participate in the reaction by interacting with the olefins and producing alkylaromatics which are distributed in the different product fractions, being indicatively divided in gasolines with the C n- aromatics and in middle distillates with the Ci 2+ aromatics .

[0121] Particularly preferred for the oligomerization stage in the present invention is the adiabatic reactor, consisting of two or more catalytic beds, with the possibility of feeding portions of the recycled gasoline, possibly mixed with part of the fresh feed, at the beginning of each bed (split feed) , so as to better control the exothermicity of the reaction .

[0122] Moreover, the presence of an optional gasoline separation step, obtained by means of a de-hexane unit (480) , placed upstream of said olefin conversion step (500) , causes the hydrocarbon mixture produced during the oligomerization (520) o be practically free of aromatic hydrocarbons .Component separation (600)

[0123] The step of separating the light components (600) is aimed at separating the ultra-light fraction (Ci and C2) and the light fraction (C3and C4) from the heavy fraction contained in the effluent from the oligomerization reactor (520) .

[0124] In the preferred embodiment described, said separation occurs by means of a series of distillation columns (620, 640) , obtaining light effluents which are more specific in terms of composition .

[0125] Alternatively, the separation of the light components can occur by means of a simple flash (660) , thus obtaining a more heterogeneous gaseous effluent in terms of composition . De-ethanizer (620)

[0126] In the preferred embodiment described, the effluent from the oligomerization reactor (520) is sent to a first deethane column (620) where the hydrocarbons C2_ are recovered at the head and are valorized to a fuel gas or can be recycled to the methanol-to-olef in conversion step (400) , while the stream from the bottom of the de-ethane column (620) is sent to a subsequent treatment .De-butanizer (640)

[0127] The liquid effluent from the de-ethanizer column (620) is directed into a second de-butanizer column (640) , which separates unreacted propylene, propane, butanes and unreacted butenes at the head from a stream containing the heavier fractions exiting the bottom of the column and sent to subsequent treatments .

[0128] The fraction exiting the head of the column and containing said C4_ components is partially recycled to the olefines production stage (400) or valorized to liquefied petroleum gas ( LPG) .

[0129] In turn, the LPG fraction can be recycled, in whole or in part, to the oligomerization stage (520) as a function of the content of unconverted olefins .FLash _ (660)

[0130] In an alternative embodiment of the present invention, the stage of separating and recycling the light components (600) consists of a simple flash (660) of the effluent from the oligomerization reactor (520) ; therefore, a flash column (660) replaces the two de-ethane and de-butane columns and operates at a temperature between 10 to 50°C .

[0131] The choice of the operating conditions of the flash is a function of the vapor pressure at 37.8°C (EN 13016-01) of the gasoline, which depends on seasonality.

[0132] In this case, the gaseous fraction exiting said flash column (660) mainly consists of C4_ hydrocarbons, including unreacted C3and C4olefins, and can be recycled, in whole or in part, to the MTP reaction stage or can be valorized, in whole or in part, as a fuel gas .

[0133] Any compression and recycling to the oligomerization reactor is considered depending from the present content of unconverted olefins .

[0134] The liquid phase exiting said flash column (660) contains the heavier fractions and is sent to treatment . Separation of heavy components (680)

[0135] The effluent from the bottom of the de-butane column (640) , or possibly from the flash column (660) , is sent to a column in which the separation of the heavy components (680) is carried out; in particular, in this column, the gasolinefraction is separated at the head (boiling range from 60 to 175°C) and the middle distillates are recovered from the bottom (boiling range above 175°C) .

[0136] According to the invention, in order to increase the yield of middle distillates, the gasoline exiting the head of the heavy component separation column (680) is recycled, in whole or in part, to the oligomerization reactor (520) .

[0137] The fraction of gasoline not recycled to the oligomerization step (520) is marketed as such or blended with other gasoline fractions produced in the process, for example that recovered in the de-hexane unit (480) .Heavy fraction treatment (700)

[0138] The middle distillates exiting the bottom of the heavy component separation column (680) are hydrogenated, according to the usual modes, to saturate the olefinic double bonds, trying however to avoid the hydrogenation of the aromatic rings .MiddLe distiL Late buffer tank (710)

[0139] The effluent from the bottom of the column in which the separation of the heavy components (680) is carried out is conveyed into a buffer tank (710) which allows the modulation of the flow rate for the subsequent treatment steps .Hydrogenation (720)

[0140] The hydrogenation step (720) is typically carried out continuously in a trickle bed reactor by feeding middle distillates and hydrogen at a pressure between 15 and 30 bar and a temperature between 50 and 200°C, at a weight hourly space velocity (WHSV) corresponding to the ratio of the mass flow rate of the middle distillate to the amount of catalyst, between 1 and 6 h- 1.

[0141] The hydrogenation catalyst is selected from one or more group VIII metals (e . g . , Pt, Pd or Ni) supported onconventional supports (e.g. , activated carbon, alumina) .

[0142] Preferably, the reactor is adiabatic with catalytic beds; the exothermicity of the reaction is controlled therein by recirculating part of the hydrogenated product, after cooling, between the catalytic beds and, if required, also at the head of the reactor .Sp Litter (740)

[0143] After the hydrogenation reaction, the effluent exiting the reactor (720) is cooled and the unreacted hydrogen is separated from the hydrocarbon phase in a separator (740) .

[0144] Hydrogen is recycled to the hydrogenation reactor (720) with the addition of a make-up.StabiLizer (760)

[0145] The hydrocarbon phase obtained is partially recycled to the reactor (720) and partially sent to a stabilizer column (760) where the light hydrocarbons, produced by hydrogenolysis, are separated from the heavier hydrocarbon fraction .Product distiLLation and fractionation _ (780)

[0146] The stream exiting the bottom of the stabilizer column (760) is sent to a distillation column (780) adapted to separate gasoline, jet fuel and diesel fuel .

[0147] The light hydrocarbons, exiting the head of the stabilizer column (760) , are valorized as a fuel gas .

[0148] The gasoline, produced during the hydrogenation step (720) and recovered by means of the distillation column (780) , is added to the gasoline produced during the oligomerization and recovered in the column in which the separation of the heavy components (680) is carried out and that produced in the MTP stage and possibly recovered in the de-hexanizer (480) .

[0149] let fuel is valorized as such or in a mixture with other jet fuels of different origin .

[0150] Diesel fuel is valorized to diesel alone or in amixture with other diesel fuels of different origin .

[0151] Optionally, the diesel fuel separated from the jet fuel after hydrogenation may be valorized to fuel for the waste gasification stage, thus reducing the consumption of natural gas .ELectroLysis (1000)

[0152] As mentioned, optionally a water electrolysis unit (1000) can be present, from which a stream of 02, usable for the gasification, and a stream of H2, usable for the correction od the H2 / C0 ratio of syngas (200) and for the hydrogenation of the middle distillates (720) , are obtained .

[0153] The presence of the electrolysis unit (1000) , and therefore the availability of H2, allows minimizing if not completely eliminating the emission of C02into the atmosphere, thus allowing the modulation of the H2 / C0 ratio by simply adding H2and avoiding the conversion of CO into H2and C02and hence the production of carbon dioxide to be removed and treated .FueL gas treatment unit (1100)

[0154] According to the invention, the fuel gas produced in the various steps of the process, in particular in the steps of methanol synthesis (340) , oligomerization (520) and hydrogenation (720) , is recoverable and convertible into carbon monoxide (CO) and hydrogen (H2) by means of known technologies; the stream thus obtained can be further used to adjust the H2 / C0 ratio .

[0155] In particular, the fuel gas recovered :• from the methanol synthesis reactor (340) ;• from the head of the de-ethanizer (620) and mainly consisting of hydrocarbons C2_ (methane, ethane and ethylene) ;• optionally from the head of the flash (660) and consisting of hydrocarbons C4-, including unreacted propylene and butenes;• from the head of the stabilizer (760) , placed downstream ofthe hydrogenation step (720) and mainly consisting of paraffins C4_; can be converted into hydrogen (H2) and carbon monoxide (CO) with a technology chosen from steam reforming or partial oxidation, preferably catalytic partial oxidation (CPO) ; or it can be valorized to fuel for the waste gasification stage, thus reducing the consumption of natural gas .

[0156] The synthesis gas thus obtained, characterized by a H2 / C0 ratio greater than 2, is conveniently mixed with the syngas produced during the gasification (110) to obtain a stream entering the methanol synthesis step (300) which has a suitable final H2 / C0 ratio (i . e . , equal to 2-2.1) .Mater treatment unit (1200)

[0157] Optionally, the streams of waste water from the various sections can be treated in one or more water treatment units (1200) ; the recovered water, depending on the final features, may thus be conveniently recycled in the different sections of use (i . e . , 120, 221, 1000) .

[0158] In the preferred, but not limiting, embodiment described, the water treatment units are two in number (1200A, 1200B) ; such units recover water from different sections of the plant making it suitable for recycling in the process .Advantages

[0159] A first advantage of the invention can be found in the possibility of valorizing waste by converting it into fuels and therefore avoiding the use of fossil fuels for the production thereof .

[0160] In this sense, the jet fuel produced has a low carbon footprint and can be considered as a sustainable aviation fuel (SAF) .

[0161] A second advantage is that, in the presence of an electrolysis unit (1000) , it is possible to minimize if notcompletely eliminate C02emissions into the atmosphere.

[0162] Moreover, in the presence of said electrolysis unit (1000) , jet fuel, gasoline and diesel fuel produced may be considered E-Fuel, limited to the portion corresponding to the electrolytic hydrogen obtained from renewable electricity.

[0163] A further advantage of the invention can be found in the fact that there is no need to separate propylene from the other olefins and other hydrocarbons; moreover, dimethyl ether (DME) does not require any separation from the feed intended for oligomerization (500) .

[0164] In fact, these components are not harmful for the subsequent steps of conversion into fuels .

[0165] Moreover, the fuel gases produced in the various steps are valorized and reused in the plant to optimize the entire processing cycle, thus maximizing the fuel yield .

[0166] A further advantage is related to the quality of the products obtained : by way of example, the gasoline obtained by mixing the olefine fraction with that produced in the MTO stage has a research octane number (RON) between 92 and 96; similarly the jet fuel, after hydrogenation, has a freezing point lower than -60°C, while the smoke point for the jet fuel obtained is about 40 mm; such features cause the jet fuel to not require further treatments to be marketed .

Claims

CLAIMS1. A process for producing hydrocarbons usable as fuels from industrial, agroforestry, urban waste and derivatives thereof, with high sustainability and lower C02emissions, given the same energy, compared to equivalent fuels of fossil origin, characterized by the following steps :• Production of a syngas (100) , obtained by gasification of waste with oxygen at high temperature, and purification thereof;• Adjustment of the composition (200) of said purified syngas by modulating the H2 / C0 ratio in the syngas from the previous step;• Conversion (300) of the syngas, coming out of the composition adjustment step (200) , into methanol;• Catalytic conversion of the methanol thus obtained into olefins (400) aimed at obtaining light olefins by means of methanol to propylene (MTP) technology, said step comprising a separation of the gasolines produced by a de-hexane column (480) ;• Catalytic olefin conversion (500) by oligomerization of the stream coming out of the previous step of converting methanol into olefins (400) , aimed at forming a hydrocarbon mixture, comprising an ultra-light fraction (C2and C2) , a light fraction (C3and C4) , a fraction with a boiling range between 60 and 300°C, and a fraction with a boiling temperature above 300°C;• Separation of the light components from the heavy components (600) of the hydrocarbon mixture from the previous step of catalytic olefin conversion (500) , said separation being such as to obtain a gaseous stream, or fuel gas, comprising an ultra-light fraction (C2and C2) , a light fraction (C3and C4) , and a liquid stream containing the heavy fractions;• Treatment (700) of the heavy fraction aimed at separating gasoline, jet fuel and a residue mainly consisting of dieselfuel, wherein the step of separating the gasolines by means of a de-hexane column (480) allows the removal of the gasoline fraction, also containing a high percentage of aromatics, from the subsequent olefin conversion steps, and wherein the gasoline recovered respectively :• in the heavy component separation step (680) ;• in the product distillation and fractionation step (700) ;• in the gasoline recovery step by means of a de-hexane column (480) , is recycled, in whole or in part, in the oligomerization reactor (520) to increase the yield in middle distillates; the remaining part being directly marketable .

2. The process according to the preceding claim characterized in that said waste comprises alone or in combination with one another : municipal solid waste, refuse- derived fuel (RDF ) , agroforestry waste, urban and / or industrial water purification sludges, biomass, the mixture of plastic waste from separate collection after the separation of recyclable plastics and mixtures thereof .

3. The process according to one or more of the preceding claims characterized in that it further comprises a water (H20) electrolysis unit (1000) for producing hydrogen (H2) and oxygen (02) .

4. The process according to claim 1 characterized in that said syngas production step (100) comprises the following steps :• Gasification (110) of the waste at high temperature in the presence of pure oxygen (02) to obtain syngas;• First purification (120) of the syngas from thegasification (110) aimed at removing HC1 and metals;• Compression (140) of the syngas from the first purification step (120) ;• Second purification step (160) of the compressed syngas aimed at removing any traces of HC1 and metals still present in the compressed syngas;• Conversion and removal of sulphur and nitrogen compounds (180) in which COS and NH3are hydrolyzed and H2S is converted into elemental sulphur which is then separated .

5. The process according to claim 4 characterized in that the oxygen (02) used for said gasification step (110) comes from an air fractionation unit .

6. The process according to claim 4 characterized in that the oxygen (02) used for said gasification step (110) comes from the electrolysis unit (1000) .

7. The process according to claim 1 characterized in that said composition adjustment unit (200) receives the purified syngas exiting from the second purification step (160) to obtain a H2 / C0 ratio, or methanol index, equal to 2 / 2.1, said step comprising the following steps :• Adjustment of the H2 / C0 ratio (220) ;• Removal of C02(240) .

8. The process according to claim 7 characterized in that said adjustment of the H2 / C0 ratio (220) is obtained by means of a water gas shift, or WGS, unit (221) , wherein a part of carbon monoxide (CO) is catalytically converted into carbon dioxide (C02) and hydrogen (H2) by reaction with water (H20) .

9. The process according to claim 7 characterized in that said adjustment of the H2 / C0 ratio (220) is obtained by adding hydrogen (H2) from the electrolysis unit (1000) , thus avoiding the further production and consequent release of C02into the atmosphere .

10. The process according to claim 7 characterized in that said removal of C02(240) occurs by means of a conventional amine system or with pressure swing adsorption (PSA) .

11. The process according to claim 1 characterized in that said step of converting the syngas into methanol (300) comprises the following steps :• compression (320) of the purified syngas at a pressure of 80 / 90 barg;• conversion of the compressed syngas into methanol (340) ;• purification of the produced methanol (360) by means of a two- or three-column system .

12. The process according to claim 1, characterized in that said production of olefins (400) comprises the following steps :• catalytic conversion of methanol (420) into light olefins, mainly C2, C3and C4by means of methanol to propylene (MTP) technology, with production of water and dimethyl ether (DME) ;• cooling and separation of the effluent from the synthesis reactor by means of a quencher (440) aimed at condensing the majority of the water and at separating the latter and the soluble organic fraction, including the unreacted methanol and part of the DME, in the aqueous phase from the gaseous hydrocarbon phase;• compression and purification by cooling the gaseous phase (460) exiting the quencher (440) aimed at further separating the water and methanol contained in the gaseous stream from the hydrocarbon mixture mainly consisting of olefins .

13. The process according to claim 12 characterized in that said catalytic conversion of methanol (420) into olefins occurs by means of a catalytic reaction with catalysts based on molecular sieves such as zeolites or microporous crystalline silicoaluminophosphates .

14. The process according to claim 1 characterized in that said catalytic olefin conversion step (500) is obtained by oligomerization (520) of the stream consisting of olefinic, paraffinic, aromatic hydrocarbons and unreacted DME, and carried out with heterogeneous catalysis in a range of temperatures and pressures such as to ensure that the reaction medium is in a mixed gas-liquid phase, said range being from 50 to 300°C and from 10 to 70 barg, with weight hourly space velocity (WHSV) values between 0.2-4 h- 1, and wherein the olefins are converted into a hydrocarbon mixture comprising an ultralight fraction (Ci and C2) , a light fraction (C3and C4) , a fraction with a boiling range from 60 to 175°C, a fraction with a boiling range from 175 to 300°C, and a heavy fraction with a boiling point above 300°C, without the need to separate propylene from the other olefins and the other hydrocarbons, and without having to separate DME from the incoming stream .

15. The process according to claim 14 characterized in that the catalyst used in the oligomerization step (520) is selected from diatomaceous earth-supported phosphoric acid (SPA) , crystalline microporous silicoaluminates (zeolites ) , or amorphous silica-aluminas .

16. The process according to claim 15 characterized in that said catalyst used in the oligomerization step (520) and chosen from amorphous silica-aluminas is selected from the family of mesoporous ones, including silicoaluminates belonging to the different families of silica-aluminas synthesized using surfactants as micellar templates and characterized by an ordered porous system, such as the M41S family and in particular MCM-41, or even FSM-16, HMS, SBA, MSU and KIT-1, for example, or silicoaluminates with a disordered porous system obtained by sol-gel synthesis in the presence of clusters as templates, such as MSA, ERS-8 and MMM, for example .

17. The process according to claim 1 characterized in that said step of separating the light components from the heavy components (600) of the hydrocarbon mixture from the previous catalytic olefin conversion step (500) , aimed at obtaining a gas stream, or fuel gas, comprising the ultra-light fraction (Ci and C2) , a light fraction (C3and C4) , is carried out by means of a de-ethane column (620) and a de-butane column (640) so as to obtain two streams containing the ultra-light fraction (Ci and C2) from the de-ethane column and the light fraction (C3and C4) from the de-butane column, respectively .

18. The process according to claim 1 characterized in that said step of separating the light components from the heavy components (600) of the hydrocarbon mixture from the previous catalytic olefin conversion step (500) , aimed at obtaining a gas stream, or fuel gas, comprising the ultra-light fraction (C2and C2) , a light fraction (C3and C4) , is carried out by means of a flash column (660) operated at a temperature between 10 and 50°C, thus obtaining a single gaseous phase comprising the ultra-light fraction (C2and C2) and the light fraction (C3and C4) .

19. The process according to one or more of claims 1 to 18 characterized in that the effluent from the bottom of the debutane column (640) or from the flash column (660) is sent to a column in which the separation of the heavy components (680) is carried out, from which the gasoline fraction is separated at the head (boiling range from 60 to 175°C) and the middle distillates are recovered from the bottom (boiling range above 175°C) .

20. The process according to claim 1 characterized in that the middle distillate fraction from the heavy component separation column (680) is sent to a treatment step (700) comprising the following steps :• hydrogenation (720) ;• separation of unreacted hydrogen (H2) (740) ;• stabilization (760) of the effluent from the splitter (740) by removing the light components;• distillation (780) of the effluent from the stabilizer (760) and fractionation of the products .

21. The process according to claim 20 characterized in that mainly gasoline, jet fuel and diesel fuel come out from said distillation step (780) .

22. The process according to one or more of the preceding claims characterized in that the fraction exiting from the debutanizer (640) and mainly containing the C4_ components is partially or totally recycled to the olefin production stage (400) ; the remaining part being valorized to LPG .

23. The process according to one or more of the preceding claims characterized in that the LPG fraction, recovered from the de-butanizer (640) , can be recycled, in whole or in part, to the oligomerization stage (520) as a function of the content of unconverted olefins .

24. The process according to one or more of the preceding claims characterized in that the gas produced in the various steps of the process and mainly recovered :• from the methanol synthesis reactor (340) ;• from the head of the de-ethanizer (620) , said gas mainly consisting of hydrocarbons C2_ (methane, ethane and ethylene) ;• optionally from the head of the flash (660) , said fuel gas consisting of hydrocarbons C4_, including unreacted propylene and butenes;• from the head of the stabilizer (760) , placed downstream of the hydrogenation step (720) , said gas mainly consisting of paraffins C4_; is converted into carbon monoxide (CO) and hydrogen (H2) in aspecific fuel gas treatment step (1100) , and wherein the effluent from said fuel gas treatment section (1100) is characterized by a H2 / C0 ratio greater than 2 and is conveniently mixed with the syngas produced during the gasification (110) to obtain a stream entering the methanol synthesis step (300) having a final H2 / C0 ratio equal to 2-2.1.

25. The process according to claim 24 characterized in that said fuel gas conversion step (1100) occurs by means of a steam reforming unit .

26. The process according to claim 24 characterized in that said fuel gas conversion step (1100) occurs by means of a partial oxidation unit .

27. The process according to one or more of the preceding claims characterized in that the diesel fuel exiting from the distillation step (780) is valorized either as a fuel in the waste gasification stage (110) or as a diesel fuel, alone or in a mixture with other diesel fuels .

28. The process according to one or more of the preceding claims characterized in that the jet fuel exiting from the distillation step (780) is marketed as a fuel as such or in a mixture with other jet fuels of other origin .

29. The process according to one or more of the preceding claims characterized in that the aqueous streams from the various conversion steps and separated from the organic fraction are sent to a water treatment step (1200) aimed at purifying and recycling water .

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