Process for manufacturing a fertilizer and fertilizer

Description

1 / 26 “PROCESS FOR MANUFACTURING A FERTILIZER AND FERTILIZER” Field of invention

[001] In general, the invention relates to a fertilizer product composition for use in agriculture, viticulture, arboriculture, horticulture, and / or forestry. In a particular aspect, the invention relates to a fertilizer product (for example, in solid form, in powder form, in grain form or in granule form) containing urea or ammonium nitrate and also a zeolite filler. Technological histories

[002] In the field of fertilizer products, there is a growing drive for innovation, linked to the constant environmental and social pressure on farmers regarding the use of synthetic products, but also to the growing awareness of the essential role of the relationship between soil microorganisms and plants: this is what characterizes sustainable agriculture.

[003] In the context of this document, the term "fertilizer product" is used to designate a substance or mixture of substances intended to be applied to plants or their rhizosphere in order to supply plant nutrients, a substance or mixture of substances comprising at least one fertilizer. The term "fertilizer" designates, in the context of this document, a substance or mixture of substances intended to supply plant nutrients to improve their growth and increase the yield and / or quality of a crop. There are different categories of nutrients. Petition 870250093644, dated 10 / 13 / 2025, p. 9 / 35 2 / 26

[004] The macroelements (or macronutrients) are nitrogen (N), phosphorus (P), and potassium (K).

[005] Calcium (Ca), sulfur (S) and magnesium (Mg) are considered secondary elements.

[006] Trace elements include iron (Fe), manganese (Mn), molybdenum (Mo), copper (Cu), boron (B), zinc (Zn), and others.

[007] Fertilizers are also divided into different categories. Fertilizers that provide only one of the three macroelements (N, P, or K) are considered simple fertilizers. Compound fertilizers are those that contain several nutrients, including at least one macroelement. Binary fertilizers combine two macroelements (NP, NK, or PK fertilizers), and ternary fertilizers combine all three macroelements (NPK fertilizers).

[008] Agriculture is the main source of nitrous oxide (N2O) emissions, primarily due to the use of synthetic nitrogen-based fertilizers. Agricultural activities generate, on average, 30 kg of excess nitrogen per hectare of farmland per year. One of the main problems causing these surpluses seems to be related to the low efficiency of absorption and use of the supplied nitrogen. Specifically, it is believed that only about 50% to 60% of the nitrogen supplied by a fertilizer product is absorbed by the crop on average (Sylvester-Bradley R, Kindred DR. Analyzing cereal nitrogen responses to prioritize routes for improving nitrogen use efficiency. J Exp. Bot. 2009; 60(7):1939-51. doi: 10.1093 / jxb / ERP116. Epub 2009 23 Petition 870250093644, dated 10 / 13 / 2025, page 10 / 35 3 / 26 April. PMID: 1939538). Part is lost through leaching, causing pollution of surface and groundwater. Another portion is volatilized in the form of nitrous oxide (N2O), a greenhouse gas (GHG) with a radiative power 298 times stronger than CO2.

[009] It is clear that there is potential for GHG mitigation through the reduction of the use of synthetic fertilizer products, in combination, firstly, with rigorous supply management and, secondly, with the implementation of techniques capable of reducing nitrogen losses and increasing the effectiveness of nitrogen supplied to crops.

[0010] Ammoniacal nitrogen can be naturally retained in the clay-humus complex of the soil, represented by its CEC (cation exchange capacity), which varies considerably depending on the soil.

[0011] However, the use of synthetic chemical fertilizers for decades, without parallel supplies of organic matter, has contributed to the depletion of humus in many soils and, therefore, to the decrease in the clay-humus complex. This results in a net reduction in CEC and an increase in nitrogen loss through the mechanisms mentioned above.

[0012] In addition, besides economic losses, the 50% of nitrogen not used by plants causes serious environmental damage, such as groundwater pollution and greenhouse gas (GHG) emissions.

[0013] It is therefore desirable to reduce nitrogen losses.

[0014] Document CN1078225A describes a compound of Petition 870250093644, dated 10 / 13 / 2025, page 11 / 35 4 / 26 zeolite and ammonium nitrate. The zeolite content is 10-40% (by mass) and the ammonium nitrate content is 60-90% (by mass). The zeolite is reduced to powder (particle size ranging from 0.15 mm to 0.28 mm) and mixed with ammonium nitrate in the desired mass ratio to produce granules in a granulator. Most granules (80%) have a size of 1 to 4 mm. According to the document, the compound would allow a 15.6% reduction in fertilizer product costs without loss of productivity.

[0015] EP 1 379 558 A1 refers to a urea-based fertilizer coated with zeolite. The mass ratio between zeolite and urea is between 6:1 and 0.5:1, preferably between 2.2:1 and 1.2:1. Preferred zeolites are analcime, chabazite, laumontite, phillipsite, faujasite, clinoptilolite, and mordenite. According to EP 1 379 558 A1, bentonite may be added to the granules to improve granule plasticity during granulation.

[0016] US 5,676,729 A describes urea particles containing a mineral filler which may, inter alia, be zeolite. According to this document, the mineral filler may be added to molten urea and the resulting mixture is then converted into granules, aggregates or pellets.

[0017] Zeolites are crystalline aluminosilicates with the general empirical formula: Mx / n[(AlO2)x(SiO2)y]-wH2O where M represents a cation with valence n, w is the number of water molecules, the ratio y / x represents the molar ratio between Si and Al and is greater than or equal to 1, and the part in parentheses indicates the composition of the microporous skeleton. A Petition 870250093644, dated 10 / 13 / 2025, p. 12 / 35 5 / 26 The presence of Al3+ in the micropore skeleton (in locations that would otherwise be occupied by Si4+) results in a negative charge that is compensated by the M cations in the interstices of the skeleton.

[0018] Natural zeolites have a variable adsorption capacity for ammonium ions, which can range from about 3 to 30 mg / g. However, it should be noted that the degree of adsorption of ammonium by natural zeolite is reduced after heating it to 200°C and above, and is reduced proportionally to the temperature, being reduced by almost half above 500°C. Elevation to high temperatures can destroy adsorption sites, blocking pores through micropore aggregation and modifying surface functional groups (Wang, S., Zhu, ZH, 2006. Characterization and environmental application of an Australian natural zeolite for basic dye removal from aqueous solution. J. Danger. Mater. 136 (3), 946-952, and also Xu, Y., Liu, S., Guo, X. et al. Methane activation without the use of oxidants over Mo / HZSM-5 zeolite catalysts. Catal. Lett. 30, 135-149 (1994)).Given that the synthesis reactions of various types of nitrogen fertilizers are exothermic reactions, using temperatures that can reach up to 250°C, the zeolite used in the synthesis of nitrogen fertilizers will have its ammonium ion adsorption capacity reduced.

[0019] Although the state of the art includes synthetic fertilizers based on ammonium nitrate or urea containing zeolite, the fertilizers in question are not effective in preventing ammonium ion losses. General description of the invention Petition 870250093644, dated 10 / 13 / 2025, page 13 / 35 6 / 26

[0020] A first aspect of the invention relates to a process for manufacturing a fertilizer product. The process involves adding (incorporating) a modified zeolite, doped with sodium (sodium ion Na+), calcium (calcium ion Ca2+) or potassium (potassium ion K+), as a filler to a nitrogen-based fertilizer.

[0021] Another aspect of the invention relates to a fertilizer product composed of a nitrogen-based fertilizer to which a modified zeolite doped with sodium, calcium or potassium has been added. The modified zeolite may, in particular, be doped with sodium and calcium, sodium and potassium, calcium and potassium or sodium, calcium and potassium.

[0022] Zeolite modified by doping with sodium, calcium, or potassium has a higher and faster adsorption capacity for NH4+ ions than the same zeolite before modification. The use of modified zeolite obtained by doping with sodium is particularly preferred, as it allows compensating for the degradation of the adsorption capacity of ammonium ions that untreated zeolite suffers when exposed to high temperatures.

[0023] The zeolite used may be in the form of a powder with a size (average diameter or D50 diameter) of 1 μm to 1000 μm, preferably 1 μm to 500 μm, more preferably 20 μm to 500 μm, even more preferably 50 μm to 400 μm and most preferably 100 μm to 200 μm. Unless expressly stated otherwise in this text, all particle size measurements (e.g., D50 diameter) are based on measurements obtained by laser particle size analysis in accordance with ISO 13320:2020. Petition 870250093644, dated 10 / 13 / 2025, p. 14 / 35 7 / 26 based on the Fraunhofer diffraction pattern (diameters corresponding to equivalent spherical volumes). The zeolite micronization process can be dry or wet, using an air jet or ball mill or any other type of mill.

[0024] Zeolite (before doping modification) can be either natural or synthetic. Zeolite is an aluminosilicate with a nanoporous structure. The voids are connected to each other and are initially occupied by cations and water molecules. Cations and water molecules are mobile within the structure, allowing for ion exchange on the one hand, and reversible partial dehydration on the other. Many zeolites are listed in various families. Clinoptilolite (lamellar-monoclinic zeolite) and chabazite (hexagonal-cubic zeolite) are considered particularly efficient in this context due to their content of exchangeable cations (Ca, K, and Na) and their cation exchange capabilities. Synthetic zeolites also exist, but in the context of the invention, natural zeolites are preferred, especially those from deposits selected for their purity.Preferably, the term zeolite denotes a natural zeolite selected from the analcime family, such as analcime, polucite, wairakite, bellbergite, bikitaite, boggsite and brewsterite; the chabazite family, such as chabazite, willhendersonite, cowlesite, dachiardite, edingtonite, epistilbite, erionite, faujasite, ferrienite and herschelite; the gismonde family, such as amicite, garronite, gismonde, gobbinite, gmelinite, gonnardite and goosecreekite; the harmotome family, such as harmotome, philphisite and wellsite; the heulandite family. Petition 870250093644, dated 10 / 13 / 2025, page 15 / 35 8 / 26 such as clinoptilolite, heulandite, laumonite, levyne, mazzite, merlinoite, montesommite, mordenite and maricopaite; the natrolite family, such as mesolite, natrolite, skolecite, offretite, paranatrolite, paulingite and perlialite; the stilbite family, such as barrerite, stilbite, stellerite, thomsonite, tschernichite and yugawaralite; sodic daquiardite; and tetranatrolite. More preferably, the term zeolite denotes clinoptilolite, chabazite, phillipsite, ferrierite, mordenite or erionite. More preferably, zeolite comprises or consists of clinoptilolite. It should be noted that natural zeolite may contain impurities, for example, quantities of feldspar, illite or quartz. Natural zeolite preferably comprises at least 40% (mass / mass), more preferably at least 60% (mass / mass), and even more preferably at least 80% (mass / mass) of pure zeolite.

[0025] Modified zeolite can represent between 2% and 98% by mass of the fertilizer product, preferably 20% to 40% by mass of the fertilizer product, and even more preferably 30% to 40% by mass of the fertilizer product, in order to have a maximum ammonium ion retention effect without significantly reducing the nitrogen content of the fertilizer product.

[0026] Nitrogen-based fertilizer may include, for example, ammonium nitrate, urea, ammonium sulfate, or ammonium sulfonate. Nitrogen-based fertilizer may be a single fertilizer. Alternatively, nitrogen-based fertilizer is a compound fertilizer based on nitrogen and one or more elements chosen from phosphorus, potassium, sulfur, magnesium. Petition 870250093644, dated 10 / 13 / 2025, page 16 / 35 9 / 26 and calcium, not excluding the presence of other nutrients.

[0027] The addition step may involve mixing the modified zeolite with an aqueous solution or a fusion of ammonium nitrate or urea.

[0028] The process may involve the formation of an aggregate of ammonium nitrate or urea and the coating of the aggregate with ammonium nitrate or urea, supplemented with modified zeolite and, optionally, one or more other adjuvants. The fertilizer product may thus be presented in the form of granules consisting of ammonium nitrate or urea in their core (e.g., ammonium nitrate or urea) and a coating of the mixture of nitrogen-based fertilizer and modified zeolite, as well as, optionally, one or more other adjuvants.

[0029] The process may also include granulation of the nitrogen-based fertilizer supplemented with modified zeolite. The fertilizer product may therefore be in granular form.

[0030] The process may include the production of modified zeolite. Modified zeolite can be produced by impregnating zeolite (natural or synthetic) with a solution containing sodium, calcium or potassium ions, for example, a solution of sodium nitrate (NaNO3), sodium hydroxide (NaOH) and / or sodium chloride (NaCl), calcium nitrate (Ca(NO3)2) or potassium nitrate (KNO3).

[0031] Modifying zeolite by impregnating it with a sodium, calcium, or potassium-based solution improves its adsorption capacity and the adsorption rate of NH4+ ions. Modifying zeolite by impregnating it with a sodium-based solution (preferably a sodium nitrate solution) Petition 870250093644, dated 10 / 13 / 2025, page 17 / 35 10 / 26 sodium) improves its NH4+ ion adsorption capacity at high temperatures, which is advantageously applicable to the manufacture of nitrogen-based fertilizers. Impregnation of zeolite increases its cation exchange capacity and can also increase the volumetric ratio of zeolite mesopores, promoting the adsorption of ammonium NH4+ ions and improving its heat resistance.

[0032] Zeolite is formed from a microporous aluminosilicate skeleton, and the valence electrons of the oxygen atoms are not balanced in the tetrahedron, making it negatively charged. Positively charged cations tend to be captured in the interstices of the microporous skeleton. These cations are weakly bound to the aluminosilicate and are therefore exchanged relatively easily. This cation exchange mechanism in zeolite plays an important role in ammonium adsorption, as the cations released by the zeolite are replaced by NH4+ ions.

[0033] Different zeolites may have different selectivities with respect to different cations. The selectivity of a zeolite for a cation M can be denoted α(M). Most natural zeolites have a(NH4+) > a(K+) > a(Sr+) > a(Na+) > a(Ca2+).

[0034] The modification of zeolite (preferably initially a natural zeolite) involves doping with sodium, calcium or potassium ions, so that these ions can be exchanged for the ammonium ion NH4+, for which the zeolite has a greater affinity in relation to the ion with which it was doped.

[0035] Cation doping is preferentially Petition 870250093644, dated 10 / 13 / 2025, p. 18 / 35 11 / 26 selected based on the zeolite, so that the selectivity of the zeolite for the ammonium ion NH4+ is greater than the selectivity for cation doping. Depending on the type of zeolite chosen, the preferred cation for doping may vary between Na+, Ca2+, or K+.

[0036] Because Na+ ions are typically the weakest bound to zeolite compared to K+, Mg2+, Ca2+, and Cu2+, sodium doping is currently considered the most preferred.

[0037] By modifying the zeolite (during doping), the cations naturally present in the interstices of the zeolite micropore skeleton are replaced by dopant ions, for example, Na+ ions. These can then be exchanged for ammonium ions NH4+. It can be observed that Na+, Ca2+ and K+ ions give the modified zeolite a greater ion exchange capacity and thus improve the adsorption of ammonium ions.

[0038] The production of modified zeolite (preferably sodium-doped zeolite) optionally, but preferably, involves drying and / or calcining the zeolite after impregnation. Calcination can be carried out at a temperature in the range of 300°C to 800°C. It should be noted that calcination of unmodified (undoped) zeolite greatly reduces its ammonium ion adsorption capacity. On the other hand, modified zeolite, preferably zeolite modified by impregnation with a nitrate-based solution, for example, sodium nitrate, calcium nitrate or potassium nitrate, has improved capabilities in the case of heat treatment, notably calcination. Modified zeolite has Petition 870250093644, dated 10 / 13 / 2025, page 19 / 35 12 / 26 good heat resistance from a calcination process and a synthetic fertilizer manufacturing process.

[0039] The mesopore volume and specific surface area of ​​zeolite are factors that can affect its ammonium adsorption capacity. Nitrate salts (e.g., sodium nitrate, calcium nitrate, or potassium nitrate) are known to decompose and release oxygen gas at high temperatures. This gas release can destroy some of the zeolite's micropores and create larger pores. The pore structure of zeolite can therefore be modified to increase its NH4+ ion adsorption capacity, notably by impregnation with NaNO3, followed by a calcination step.

[0040] A sodium nitrate solution is therefore more preferably chosen to dope the zeolite with sodium, as the heat treatments and / or high-temperature reactions (which occur during fertilizer synthesis) decompose the sodium nitrate, release oxygen, destroy some of the zeolite's micropores, and create larger pores. More particularly, heat treatment of sodium nitrate-doped zeolite further increases the adsorption capacity and adsorption rate of NH4+ ions in the zeolite compared to those of untreated doped zeolite.

[0041] The invention combines zeolite modified by doping with sodium, calcium, or potassium and a nitrogen-based fertilizer in a fertilizer product. It should be noted that the zeolite is present in the composition as an active filler. The zeolite, therefore, cannot be considered a simple excipient but actively contributes to the effectiveness of the fertilizer product. The combination of zeolite and Petition 870250093644, dated 10 / 13 / 2025, page 20 / 35 13 / 26 nitrogen-based fertilizer effectively produces a synergistic effect on the composition of the fertilizer product.

[0042] The use of this fertilizer product allows for a reduction in the amount of fertilizer applied to the soil or plants, while simultaneously preventing crop yield loss. The presence of zeolite also reduces water requirements.

[0043] When applied to the soil, the zeolite in the fertilizer product limits nitrogen leaching through reversible retention. The fertilizer product allows nutrients, particularly nitrogen, to be retained near the roots, reinforcing the CEC, induced by the high CEC of the modified zeolite. As a result, the fertilizer product also reduces nitrous oxide (N2O) emissions. Brief description of the drawings

[0044] Other details and features of the invention will become apparent from the detailed description of certain advantageous embodiments presented below, for illustrative purposes, with reference to the accompanying drawing, which shows: Fig. 1: A schematic flowchart of a manufacturing process for a fertilizer product according to an embodiment of the invention. Detailed description of the invention

[0045] In a preferred aspect, the present invention relates to the manufacture of a synthetic fertilizer product composed of a nitrogen-based fertilizer and a zeolite modified by impregnation with a sodium, calcium or potassium-based solution as a filler.

[0046] Zeolite modified by impregnation with a Petition 870250093644, dated 10 / 13 / 2025, page 21 / 35 14 / 26 Sodium-based solution may or may not be calcined. Calcination of the zeolite after impregnation is preferably carried out in the temperature range of 300 to 550°C, for example, at (approximately) 400°C.

[0047] The sodium-based solution may include an aqueous solution of sodium nitrate (NaNO3), an aqueous solution of sodium hydroxide (NaOH), or an aqueous solution of sodium chloride. The concentration of the sodium-based solution is preferably in the range of 0.1 to 10 mol / l. A NaNO3 solution at a concentration between 0.1 mol / l and 10 mol / l, preferably between 1 mol / l and 5 mol / l, for example, 3 mol / l, has been considered effective for impregnation. The duration of impregnation may depend on the concentration and temperature (room temperature is preferred) and is, for example, between 2 and 48 hours.

[0048] Impregnation-modified zeolite has a higher and faster ammonium ion adsorption capacity than the zeolite (usually a natural zeolite) that served as the starting material.

[0049] Modifying zeolite by doping with sodium (sodium ions) improves its ammonium adsorption capacity at high temperatures, which is an advantage for mixing with molten nitrogen-based fertilizers. Doping zeolite also allows increasing its cation exchange capacity, promoting NH4+ adsorption.

[0050] Nitrogen-based fertilizer may comprise or consist of, for example, ammonium nitrate (AN) or calcium ammonium nitrate (CAN), urea, ammonium sulfate or ammonium sulfonate or other complex fertilizer. Petition 870250093644, dated 10 / 13 / 2025, page 22 / 35 15 / 26

[0051] The fertilizer product may be in the form of granules of homogeneous composition or of grains comprising a core coated with the mixture comprising the nitrogen-based fertilizer and the modified zeolite.

[0052] Modified zeolite (doped with sodium) is compatible with current manufacturing processes for fertilizer products and fertilizers. The fertilizer product can be manufactured using a solution or a molten mass of ammonium nitrate, ammonium sulfate, ammonium sulfonate, or urea, to which the modified zeolite is added as a filler. The mixture can then be granulated or used to coat an aggregate (e.g., urea or ammonium nitrate).

[0053] The manufacture of a sodium-doped modified zeolite may include one or more of the following options or operations: • Zeolite may comprise or consist of clinoptilolite; • Zeolite can be crushed to obtain a particle size between 100 and 200 μm; • After grinding, the zeolite can be passed through an oven at (approximately) 200°C for 10 to 40 minutes, for example, 20 minutes; • preparation of a sodium nitrate (NaNO3) solution, for example, at 3 mol / L; • Impregnation of the zeolite with a sodium nitrate solution at room temperature for 10 to 72 hours, for example, 24 hours; • Zeolite can then be collected by filtration and Petition 870250093644, dated 10 / 13 / 2025, p. 23 / 35 16 / 26 heat treated, for example, calcined at (about) 400°C in a furnace for 2 hours and then cooled to room temperature.

[0054] All operations can be carried out at neutral pH. The calcination temperature of the impregnated zeolite of (approximately) 400°C is considered advantageous, as sodium nitrate begins to decompose at approximately 380°C. Impregnation of a zeolite, particularly clinoptilolite, as described above, has proven to be a viable method for significantly improving the efficiency of ammonium adsorption by the zeolite. Impregnation with a NaNO3 solution, followed by calcination, also increases the sizes and volumes of the mesopores in the zeolite.

[0055] The manufacturing process of a fertilizer product according to the invention may include one or more of the following operations: • produce a molten mass of ammonium nitrate or urea by either process and incorporate modified zeolite (doped with sodium), calcined or uncalcined, optionally followed by a granulation phase; • To manufacture an aggregate of ammonium nitrate or urea followed by coating (in one or more layers) of the aggregate with a mixture consisting of a nitrogen-based fertilizer, modified zeolite and, optionally, one or more other adjuvants (e.g., binders, etc.); • Mix ammonium nitrate or urea with a feedstock containing modified zeolite and, optionally, one or more other adjuvants (e.g., binders, etc.), followed by granulation in a granulator; • mix ammonium nitrate or urea with one or more Petition 870250093644, dated 10 / 13 / 2025, p. 24 / 35 17 / 26 other macroelements (P and / or K) and / or with one or more secondary elements (Ca, Mg, S, Si, etc.) and also with a charge containing modified zeolite and, optionally, one or more other adjuvants (e.g., binders, etc.), followed by granulation in a granulator.

[0056] Various substances can be used as adjuvants, for example, as an adhesive agent: lignosulfites, molasses, resins, etc., as a binder: calcium bentonite, etc., during granulation or as a coating at the end of granulation to form a protective layer that will prevent moisture reabsorption and clumping (lignosulfonates, etc.).

[0057] Synthetic nitrogen-based fertilizer is generally manufactured using ammonia. This is obtained by combining atmospheric nitrogen and hydrogen from natural gas or, more recently, from the hydrolysis of water, and is the basic starting material for the entire synthetic nitrogen-based fertilizer industry. When combined with carbon dioxide, ammonia allows the production of urea, while ammonium nitrate is obtained by reacting ammonia with nitric acid.

[0058] Urea can be manufactured using various processes (Stamicarbon, Snam Progetti, Chemico, Mitsui Toatsu, Montedison or CPI). The urea synthesis processes (H2N-CO-NH2) use the same starting materials: ammonia and carbon dioxide. The finishing operations (granulation) are similar for all processes, and the quality of the granules depends on the amount of impurities, mainly biuret (HN(CONH2)2), in the urea.

[0059] Ammonium nitrate (AN) fertilizers and Petition 870250093644, dated 10 / 13 / 2025, page 25 / 35 18 / 26 Calcium ammonium nitrate (CAN) can be produced from ammonium nitrate, which is optionally mixed with a feedstock. There are several manufacturing processes for ammonium nitrate (NH4NO3) (Kaltenbach, Stamicarbon, SBA, ICI, C and I, Montedison, Uhde, Fisons and Stengel) that utilize various combinations of neutralization, evaporation, drying and finishing methods. Solid ammonium nitrate (AN) is produced in the form of pure grains, crystals or granules, or it is mixed with one or more other fertilizers to form a complex fertilizer. Calcium ammonium nitrate (CAN), a mixture of limestone (CaCO3) or lime (CaO) and ammonium nitrate, is a nitrogen-based fertilizer consisting of 20% to 30% nitrogen, depending on the amount of calcium component added.

[0060] If zeolite is used in its natural, unmodified state as a filler, it will not be effective in terms of adsorbing ammonium ions. Ammonium nitrate or urea solutions or melts are at high temperatures (between 100°C and 200°C, or more) when fillers are incorporated. At these temperatures, contact with natural zeolite will reduce its adsorption rate of NH4+ ions, as described previously. The residual adsorption capacity may become insufficient to justify the use of zeolite as a filler.

[0061] Sodium-doped zeolite has been found to have a greater capacity for adsorbing ammonium ions and is even more resistant to the high temperatures encountered during the manufacture of nitrogen-based fertilizers. Surprisingly, modified zeolite, particularly the Petition 870250093644, dated 10 / 13 / 2025, page 26 / 35 19 / 26 Zeolite modified by impregnation with a sodium nitrate solution, exhibits even an enhanced ammonium ion adsorption capacity when exposed to these temperatures, for example, during a calcination step.

[0062] Modified zeolite can reversibly retain a greater number of cations supplied by a nitrogen-based fertilizer. In this way, it is possible to obtain a more uniform distribution of NH4+ ions over time and thus obtain more uniform nitrification with NO3- that can be directly assimilated by plants. This reduces nitrogen losses through leaching, denitrification, and volatilization. In the context of the invention, the modified zeolite represents an active load in the fertilizer product, in that it actively contributes to cation exchange with plants and increases its effectiveness.

[0063] Since heat increases the adsorption capacity of modified zeolite, particularly zeolite modified by impregnation with a sodium nitrate solution, a calcination step at temperatures between 300°C and 800°C after sodium doping is considered advantageous. Calcination can further improve the performance of impregnation-modified zeolite. The ideal calcination temperature may depend on the type of zeolite used. High calcination temperatures or molten nitrogen-based fertilizers may have the effect of increasing pore size and thus facilitating ammonium diffusion into the porous structure.

[0064] The zeolites that are particularly suitable for the invention are clinoptilolite and chabazite. The best results were obtained with clinoptilolite, which has a Petition 870250093644, dated 10 / 13 / 2025, page 27 / 35 20 / 26 has a high natural affinity for ammonium ions and whose performance can be further improved by doping with sodium (notably by impregnation), optionally followed by a calcination step.

[0065] If the fertilizer product contains an ammonium-based fertilizer, the ammonium must be converted into nitrate ions (NO3-) to be absorbed by plant roots. The modified zeolite binds the ammonium ion and thus prevents excessively rapid nitrification, which leads to the loss of nitrate ions (which are very mobile) by leaching.

[0066] If the fertilizer product contains a urea-based fertilizer, the urea must be hydrolyzed to ammonium by soil enzymes (ureases). The hydrolysis of urea temporarily induces a very sharp increase in pH in the vicinity of the fertilizer granule. The physicochemical equilibrium between ammonium in the soil solution and gaseous ammonia is shifted in favor of the latter, resulting in nitrogen losses through ammonia volatilization. This volatilization will be mitigated by the modified zeolite, which will not only have an effect on the reversible retention of the ammonium ion, to provide the gradual formation of nitric nitrogen through the oxidation of the ammonium ion over time, but will also delay the hydrolysis of urea to ammonia. Example 1 (modified zeolite)

[0067] Clinoptilolite was impregnated with a NaNO3 solution, after which the solids were collected by filtration and calcined.

[0068] Previously, the selected zeolite was Petition 870250093644, dated 10 / 13 / 2025, p. 28 / 35 21 / 26 crushed to obtain a particle size between 100 and 200 μm (D50 of approximately 150 μm), followed by 20 minutes in an oven at 200°C.

[0069] An aqueous solution of NaNO3, 3 mol / L (moles per liter), was prepared. Crushed zeolite was impregnated with this solution at room temperature in a stirrer for 24 hours. The zeolite was then collected by filtration and calcined at 400°C (673 K) in a furnace for 2 hours and then cooled to room temperature. The entire operation was performed at neutral pH. The calcination temperature of the impregnated zeolite was set at 400°C (673 K) because sodium nitrate begins to decompose at about 653 K. Tests to determine the NH4+ adsorption capacity of natural zeolite and modified zeolite were performed using a) a low-dose ammonium solution (200 mg / l, solution A) and b) a high-dose ammonium solution (> 1000 mg / l, solution B). In the example, it was found with solution A that the mass of NH4+ absorbed per unit mass of adsorbent was 14.4 mg / g for the natural zeolite and increased to 20.6 mg / g after the modification, that is, an increase of 43%.With solution B, the mass of NH4+ absorbed per unit mass of adsorbent was 23.9 mg / g for the natural zeolite and increased to 32.5 mg / g after modification, representing a 36% increase. It should be noted that tests to determine the NH4+ adsorption capacity of natural zeolite and zeolite modified with a given ammonium solution must be carried out under the same conditions of temperature, pH, and incubation time for both natural and modified zeolite. It was found that the NH4+ adsorption rate of... Petition 870250093644, dated 10 / 13 / 2025, pp. 29 / 35 22 / 26 modified zeolite was always significantly higher than that of natural zeolite (for the same ammonium solution and under the same conditions of temperature, pH and duration).

[0070] In another test, carried out with natural chabazite zeolite impregnated in a 3 mol / L NaNO3 solution after thermal treatment, the mass of NH4+ absorbed per unit mass of adsorbent was 12 mg / g for natural zeolite. After treatment, the value increased to 16.3 mg / g, representing an increase of 35%.

[0071] The modified zeolite charge can be added directly to the molten urea or ammonium nitrate solution before granulation, or it can be used to coat urea or ammonium nitrate aggregates during granulation. Example 2 (urea and modified zeolite granules)

[0072] Urea was produced from ammonia and carbon dioxide. The process comprised a first stage of ammonium carbamate synthesis and a second stage of thermal decomposition of ammonium carbamate into urea. Both stages occurred under a pressure of 140 to 250 bar.

[0073] The urea obtained was in the form of an aqueous solution with a concentration of about 70% to 80% (mass / mass). This was converted by vacuum evaporation of the water into a mass called “molten urea.”

[0074] Molten urea granulation was carried out in a rotary disc granulator, but other processes can also be used, for example, fluidized bed granulation. Modified zeolite was added to the molten urea at the beginning of the granulation phase. The granules obtained can be bagged directly and / or stored at Petition 870250093644, dated 10 / 13 / 2025, pages 30 / 35 23 / 26 bulk.

[0075] A “horizontal thin-film dryer” can be used, in which zeolite and any other adjuvants can be added through a separate inlet from that which supplies the urea. Liquid compounds can be injected through the dryer rotor. The components are mixed as they pass through the dryer to form the final product. Example 3 (ammonium nitrate and modified zeolite granules)

[0076] Ammonium nitrate can be produced by neutralizing 45-65% by weight of nitric acid with ammonia according to the reaction NH3 + HNO3 □ NH4NO3. Neutralization preferably takes place in stainless steel reactors. An ammonium nitrate solution with a concentration of 98% to 99.5% can be obtained. This concentrated ammonium nitrate solution can then be introduced into the granulator.

[0077] There are several processes for the production and granulation of ammonium nitrate, all of which can be carried out within the context of the present invention. Common granulation processes include high-recycling processes (e.g., Pugmill, Spherodizer, Drum) and low-recycling processes (e.g., Fluidized Bed, Pan, Fluidized Drum), in which the recycling rate is defined as the amount of material that returns to the granulator relative to the amount of products manufactured.

[0078] The modified zeolite feedstock and any other ingredients can then be incorporated into the ammonium nitrate. For this purpose, the molten concentrated ammonium nitrate can first be mixed with the zeolite feedstock. Petition 870250093644, dated 10 / 13 / 2025, pages 31 / 35 24 / 26 and then granulated.

[0079] The proportion of modified zeolite filler used according to the invention influences the timing of the release of nitrogen contained in the fertilizer product. The higher the proportion of modified zeolite, the greater the retarding effect.

[0080] In Pugmill type installations, molten ammonium nitrate and modified zeolite feedstock can be added directly to the granulator in fixed proportions or added to a mixing device before granulation, which allows increasing or decreasing the residence time of the molten ammonium nitrate and feedstock before introduction into the granulator. This makes it possible to adapt to changes in the reactivity of the modified zeolite feedstock or to variable concentrations (always possible in the case of using natural starting materials).

[0081] The fertilizer product containing ammonium nitrate and a modified zeolite charge may contain, for example, 20% to 30% (mass / mass) nitrogen, depending on the amount of modified zeolite added. Example 4 (complex fertilizer and modified zeolite granule)

[0082] A complex nitrogen-based fertilizer comprises nitrogen and at least one other macroelement (P and / or K) and / or at least one other nutrient (e.g., Mg, Ca, S, B, Mn, etc.).

[0083] Each granule contains all the nutrients, unlike mixed fertilizers.

[0084] A complex fertilizer can be manufactured from ammonium nitrate. Modified zeolite can be Petition 870250093644, dated 10 / 13 / 2025, pp. 32 / 35 25 / 26 added along with the other nutrients to the ammonium nitrate solution before granulation. The mixing and granulation processes can be the same as in the previous examples.

[0085] Mixed fertilizers, generally urea-based, are manufactured by mixing granules of different compositions. One or more fertilizer products according to the invention can be combined (possibly also with other fertilizers) to form a mixed fertilizer. Example 5 (coated grain)

[0086] In the aggregation technique, a molten mass of ammonium nitrate or urea is pumped to the top of a tower to form droplets that solidify as they fall. Aggregation was once the preferred process for producing urea or ammonium nitrate-based fertilizers. However, the resulting granules can be small and / or have low density.

[0087] To improve quality, the resulting granules can be coated with a mixture of ammonium nitrate or urea and modified zeolite, or simply with modified zeolite. In this way, it is possible to obtain a granule with the desired nitrogen content and with sufficient diameter and density for high-quality spreading. The aggregate coating technique is known, but the application of a coating containing modified zeolite is not.

[0088] Although particular realizations have been described in detail, a person skilled in the art will appreciate that various modifications and alternatives to them Petition 870250093644, dated 10 / 13 / 2025, pages 33 / 35 26 / 26 can be developed in light of the general teaching provided by the present invention disclosure. Consequently, the specific arrangements and / or processes described herein are intended to be provided for illustrative purposes only, without intending to limit the scope of the invention, which is determined by the scope of the appended claims. Petition 870250093644, dated 10 / 13 / 2025, pp. 34 / 35

Claims

1 / 3 CLAIMS 1. Process for manufacturing a fertilizer, characterized by: - ​​adding a modified zeolite, doped with sodium, calcium or potassium, as a filler to a nitrogen fertilizer.

2. Process according to claim 1, characterized in that the nitrogen fertilizer comprises ammonium nitrate or urea.

3. A process, according to any one of claims 1 or 2, characterized in that the nitrogen fertilizer is a compound fertilizer based on nitrogen and one or more elements chosen from phosphorus, potassium, sulfur, magnesium, and calcium.

4. Process, according to any one of claims 1 to 3, characterized in that the addition step comprises mixing the modified zeolite with a molten mass of ammonium nitrate or urea.

5. A process according to any one of claims 1 to 4, characterized in that it comprises forming a granule of ammonium nitrate or urea and coating the granule with ammonium nitrate or urea added to modified zeolite and, optionally, one or more other adjuvants.

6. A process, according to any one of claims 1 to 4, characterized in that the nitrogen fertilizer added to the modified zeolite is subjected to granulation.

7. Process, according to any one of claims 1 to 6, characterized in that it comprises the production of modified zeolite, the production of the modified zeolite comprising impregnating the zeolite with a solution containing sodium, calcium or potassium ions, for example, a solution of sodium nitrate, sodium hydroxide and / or sodium chloride, calcium nitrate or potassium nitrate.

8. Process according to claim 7, characterized in that the production of the modified zeolite comprises drying the zeolite after impregnation.

9. Process, according to any one of claims 7 or 8, characterized in that the production of the modified zeolite includes calcination of the zeolite after impregnation.

10. Process according to claim 9, characterized in that the calcination is carried out at a temperature in the range of 300 °C to 800 °C.

11. Process, according to any one of claims 1 to 10, characterized in that the modified zeolite is a sodium-doped zeolite.

12. Process, according to any one of claims 1 to 10, characterized in that the modified zeolite is a calcium-doped zeolite.

13. Process, according to any one of claims 1 to 10, characterized in that the modified zeolite is a potassium-doped zeolite.

14. Fertilizer, characterized by comprising a nitrogen fertilizer to which a modified zeolite, doped with sodium, calcium or potassium, has been added.

15. Fertilizer, according to claim 14, characterized in that the nitrogen fertilizer comprises ammonium nitrate or urea. Petition 870250085546, dated 09 / 22 / 2025, page 10 / 12 3 / 3 16. Fertilizer, according to any one of claims 14 or 15, characterized in that the nitrogen fertilizer is a compound fertilizer based on nitrogen and one or more elements chosen from phosphorus, potassium, sulfur, magnesium and calcium.

17. Fertilizer, according to any one of claims 14 to 16, characterized in that it is in the form of granules comprising in its core an ammonium nitrate or urea granule and an ammonium nitrate or urea coating, with the addition of modified zeolite and, optionally, one or more other adjuvants.

18. Fertilizer, according to any one of claims 14 to 16, characterized in that it is in granular form.

19. Fertilizer, according to any one of claims 14 to 18, characterized in that the modified zeolite is a sodium-doped zeolite.

20. Fertilizer, according to any one of claims 14 to 18, characterized in that the modified zeolite is a calcium-doped zeolite.

21. Fertilizer, according to any one of claims 14 to 18, characterized in that the modified zeolite is a potassium-doped zeolite. Petition 870250085546, dated 09 / 22 / 2025, p. 11 / 12

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