WO2015197887A1 - Carbonaceous particles and materials with optimised properties, methods for the production thereof, and applications of the same - Google Patents

Abstract

The method for the production of said particles and materials comprises electrospraying or electrospinning a mixture of at least one type of carbonaceous precursor and at least one type of chemical agent, preferably a precursor of phosphorous species, said carbonaceous precursor being functionalised with phosphorus homogeneously by means of dissolution in an appropriate solvent in suitable proportions and conditions, said method comprising between 1 and 3 additional steps compared to those of electrospraying or electrospinning which, in turn, encompass up to 6 different processes and which are carried out, according to the individual case, in either a single inert or oxidising atmosphere, or in up to three different atmospheres. The invention also relates to the carbonaceous particles and materials obtained by means of any of the variants of the method, to applications of said particles, and to said carbonaceous materials.

Description

 CARBON PARTICLES AND MATERIALS WITH

 OPTIMIZED PROPERTIES, PROCEDURES FOR OBTAINING, AND APPLICATIONS OF THE SAME TECHNICAL SECTOR

The present invention falls within the scope of man-made materials, particularly those of a carbonaceous nature, as well as the procedures for obtaining said materials and their applications.

STATE OF THE TECHNIQUE

Due to their unique chemical, mechanical, electrical and magnetic properties, carbon fibers or other fibrillar structures (membranes / meshes / networks) are currently used in numerous applications of extraordinary technological and industrial importance. Thus, in addition to acting as very light reinforcement components in a multitude of special products of superior quality and / or luxury (military, aerospace, automobile, sports, etc.), when activated and present an adequate porosity these materials receive great interest in catalysis, in adsorption and absorption beds and / or separation processes, in the electrodes of fuel cells, supercapacitors and batteries, in gas storage, nanoelectronics, composite materials, and any other application where materials with a high material are required specific surface On the other hand, the possibility of preparing interconnected fibrillar assemblies or frameworks in the form of membranes, meshes or networks has aroused great interest, in addition, for other applications, such as (bio) sensors or tissue engineering in biomedicine or military industry.

However, despite its great potential for numerous applications, the actual use of carbon fibers and fibrillar structures depends largely, in addition to their properties and performance, on the cost of production processes. In this sense, the high cost of carbonaceous carbonaceous petroleum precursors, mainly poly-acrylonitrile (PAN) and breasts, and their processing stages greatly limit a wider and / or widespread use of these materials. As a consequence, there is great interest and great efforts are being made at the research level to reduce the manufacturing costs of carbon fibers through the use of cheaper precursors and / or simpler and cheaper preparation processes and, at the same time , less pollutants.

 Among the different alternatives, the use of natural polymers such as lignocellulosics (lignin, hemicellulose, cellulose) or resins, as abundant, renewable, and low-cost carbonaceous precursors, is an advantageous and promising approach. In this way, the development of high value-added by-products by biomass-related industries, such as bio-refineries or paper industries, could be a great opportunity to reduce their associated environmental costs and impacts.

Particularly, the preparation of carbon fibers from lignin has been known since the mid-1960s. As with other carbonaceous precursors, the preparation of carbon fibers from lignin basically requires a spinning process, followed by a heat treatment to stabilize and subsequently carbonize them. Since lignin alone cannot be spun to obtain fibers, Kubo et al proposed the conversion of lignin into functional polymers by an appropriate method of wood separation (S. Kubo, Y. Uraki and Y. Sano, Coal 1998, 36, No. 7-8, pp. 1119-1124). Among the conventional spinning methods, the obtaining of fibers by extrusion of the rounded precursor (melt extrusion) (US7678358B2) clearly stands out, so that the vast majority of research work has been aimed at improving and optimizing the fusibility of lignins and its extrusion process. In general, the strategies have been the optimization of the process of extraction and / or purification of more suitable lignins or the chemical modification and / or mixing with other polymers (binders) that are capable of producing fibers by thermal extrusion (DA Baker, TG Riáis , J. Appl. Polym. Sci. 2013, 130 (2), 713-728). However, despite having been more studied, these melt extrusion processes have 3 major disadvantages: (i) the diameter of the fibers is limited by the sealing of the extrusion nozzles, so that it is difficult to reduce the diameter of the fibers below 20 um; (ii) the use of additional stages of purification, mixing with polymers, additional chemical treatments and / or heat treatments necessary to obtain an optimal round considerably increase the number of stages and the duration and overall cost of the process; and (iii) the strategies that favor the fusion of lignin for In the extrusion process, they generally also favor the fusion of the fibers during the carbonization stage, so that they hinder and / or slow down the previous stabilization stage at the same time.

 The use of a simple and versatile production technique, such as electro-spinning, is an advantageous and promising approach to the preparation of lignin fibers (ES2326455B2; R. Ruiz-Rosas, J. Bedia, M. Lallave, IG Loscertales, A. Barrero, J. Rodríguez-Mirasol, T. Cordero, Carbon, 2010, 48 (3), 696-705). Thus, electro-spinning solves a large part of the problems associated with the melt-extrusion method, since it allows the manufacture at room temperature of micro and sub (micro) lignin fibers directly in a single step and without the addition of polymers or chemical treatments . In addition, the electro-spinning of lignin solutions has several advantages over the most common precursors, such as PAN, because in addition to being cheaper, the high solubility of lignin in common volatile solvents avoids solvent recovery processes that make the process more expensive .

Regardless of the spinning method, the preparation of carbon fibers is largely limited by the thermal fusibility of the polymeric fibrillar precursors during the carbonization stage. This is because the glass transition temperature of most polymeric precursors is well below the carbonization temperature. Consequently, polymeric fibers normally require a stabilization pretreatment to prevent their melting / "softening" and preserve their fibrillar shape during the carbonization stage. The most commonly used method for stabilizing fibrillar precursors is oxidative thermal stabilization in the presence of air (oxidative thermostabilization), in which a series of reactions that occur with a slow increase in temperature, increase the glass transition temperature to greater speed than the system temperature itself, so that the material remains in its vitreous state during its heating. The rigidity acquired during this process then allows the precursor to be heated to the carbonization temperature without experiencing melting. However, despite being a simple method, stabilization of fibrillar precursors is an additional stage that requires very slow heating (several days) to temperatures of 200-250 ° C and, therefore, greatly slows down and makes the production of carbonaceous fibrillar materials (DA Baker, TG Riáis, J Appl Polym. Sel 2013, 130 (2), 713-728). The thermal stability / fusibility of the precursors, as well as the conditions necessary to carry out their stabilization, depend mainly on their chemical composition, which is ultimately determined by the nature of the precursor in question and the method of obtaining / extracting / purifying . Thus, since it is already considerably oxidized, lignin can be oxidatively thermo-stabilized potentially at much higher speeds than breasts or PAN. However, stabilization of lignin fibers requires still very low heating ramps, typically 0.05-0.08 ° C / min, followed by prolonged times (typically 36 h) at the stabilization temperature (200-250 ° C) (R Ruiz-Rosas, J. Bedia, M. Lallave, IG Loscertales, A. Barrero, J. Rodríguez-Mirasol, T. Cordero, Carbon, 2010, 48 (3), 696-705). Despite its importance, the vast majority of studies on the preparation of carbon fibers from lignin focus on facilitating and / or optimizing your spinning process and proposing strategies to increase its mechanical properties. Thus, unlike PAN and Breas, for which numerous stabilization strategies have been proposed, fewer studies are aimed at improving / optimizing, accelerating or avoiding the stabilization stage of lignin fibers. Fundamentally, the strategies are based on (i) the design of new routes of extraction and / or purification of lignins (more suitable) with higher glass transition temperatures (lignin Alcell) or with more suitable molecular fractions (WO2012112108A1; WO2013112100A1); (ii) the incorporation of certain polymers that favor the spinning process and at the same time improve the stabilization stage, such as poly (ethylene terephthalate) (PET) (S. Kubo and JF Kadla J. Polym. Environ. 2005, 13 (2), 97-105) or poly (ethylene oxide) (PEO) (S. Hu, Y.-L. Hsieh, J Mater. Chem. A 2013, 1, 1 1279-1 1288; I. Dallmeyer , LT Lin, Y. Li, F. Ko, JF Kadla, Macromol. Mater. Eng. 2013, 298, 1-12); <iii) heat treatments of pyrolytic lignins prior to the spinning process (W. Qin, JF Kadla, J Appl. Polym. Sel 2012, 126, E203-E212); (iv) chemical treatments (HC1 1- 6 M at 100 ° C between 2 and 6 h) to eliminate certain fractions (PEG) of lignin (J. Lin, S. Kubo, T. Yamada, K. Koda, Y. Uraki, BioResources 2010, 7 (4), 5634-5646). However, the use of additional physical, chemical and / or thermal treatments of purification and / or modification, or mixing with other slaughter polymers considerably increases the time, the number of stages and the cost of the process. The possibility of simply using a stabilizing agent / molecule for different types of lignin has been proposed by Poeppel et al., Who carry out the incubation / impregnation of the precursors, before or after the melt spinning stage (melt-extrusion ), with several crosslinking molecules ("crosslinkers") to allow stabilization without melting up to 2 ° C / min (EP2644758A1). However, the stabilization method is completely different, since it refers exclusively to the use of molecules with structure:

and requires an incubation stage at relatively low temperatures (0-20 ° C) and a pre-stabilization stage between 20-60 ° C for 10-60 min, prior to the main at 240-260 ° C. On the other hand, the effect of H ₃ P0 ₄ as a stabilizing promoter was suggested by Chenevey et al, who patented a method / process for preparing stabilized acrylic fibers or films by incorporating a stabilizing agent (elP0 ₄ between several options) previous spinning stage (solution extrusion), followed by oxidative stabilization stage between 200-350 ° C (US4002426A). However, the process is described exclusively for acrylic fibers, whose chemical composition and polymerization, stabilization and carbonization mechanisms are very different from that of natural polymers. In addition, in both cases the spinning method and, therefore, the dimensions and other final properties of the resulting materials are completely different from those claimed herein.

During the carbonization stage at high temperatures and in the absence of oxygen (inert atmosphere), a chemical decomposition of the carbonaceous precursors occurs along with a restructuring / ordering of the carbon atoms to give rise to ordered domains of aromatic rings. The degree of ordering increases with temperature and heat treatment time. In the case of lignin fibers prepared by electro-spinning, in addition, the increase in temperature during the carbonization stage produces a considerable development of microporosity and, therefore, an increase in its specific surface area to values of 1100-1200 m ² / g at 900 ° C (Ruiz-Rosas, J. Bedia, M. Lallave, IG Loscertales, A. Barrero, J. Rodríguez-Mirasol, T. Cordero. Carbon, 2010, 48 (3), 696-705). Despite getting these areas relatively high, to show good performance in a multitude of applications, a larger surface area, adequate porosity and / or the presence of heteroatoms or functional groups that greatly affect the surface chemistry of carbonaceous materials are normally required. In this sense, by increasing the temperature during heat treatments to carry out the carbonization process, the elimination of heteroatoms and functional groups is favored. Obtaining fibers and fibrillar structures activated or with a high development of porosity and / or rich surface chemistry has been extensively studied. Said properties have been conventionally obtained by a chemical activation step after impregnation of the precursor in fibrillar form with a suitable agent (NaOH, KOH, H3PO4, ZnCl ₂ , etc.) or physical activation of the carbonized fibers, consisting of passing a gas inert (C0 ₂ ) or oxidant (water vapor) at high temperatures (800-900 ° C). Through these treatments, activated carbon fibers (FCAs) have been prepared with areas (2000-3000 m ² / g) that match or exceed those of activated carbon in granular form or powder, but in addition to being prepared by other methods and having dimensions much larger require additional stages of impregnation-drying and / or physical activation, and larger amounts of activating agent. In the particular case of melt-extrusion spun lignin, FCAs have been obtained by steam activation of H ₂ 0 at 900 ° C of up to 3000 m ² / g, matching those of other FCAs prepared from other precursors and, Therefore, demonstrating the potential of lignin for the preparation of such materials. However, in addition to using a different spinning method and obtaining fibers with diameters between 3 and 4 times greater than those claimed herein, to obtain such porosity developments they used an additional activation stage, at elevated temperatures, and with a physical mechanism totally different from those claimed here.

Regarding the effect of H ₃ PO4 during the carbonization stage, Moore et al. proposed a method / process of carbonization of carbonaceous fibrillar precursors (in general) treated with H ₃ P0 ₄ or derivatives, in which they act as catalysts for the pyrolytic transformations during carbonization and as agents that improve the physical properties and yield of the final carbonaceous materials (US3527564A) .. On the other hand, De La Pena et al. patented a method / process of preparing CA fibers or films from the carbonization and subsequent activation of cellulose fibers in an inert atmosphere between 200 and 1100 ° C (both stages), in which, prior to activation, the cellulosic or carbonized material is impregnated with a compound that it contains boron atoms and another with phosphorus atoms, so that impregnation increases the activation speed and, therefore, reduces the activation time, to achieve areas above 700 m ² / g (maximum reflected, 1629 m ² / g) (JMD De La Pena, RA Roberts US5202302 1993). In this case, however, in addition to not including the specific electro-spinning process (with its requirements and peculiarities), the activation and carbonization are carried out as two different stages and an effect on the activation speed is described that has nothing to do with the thermo-oxidative stabilization process to avoid the fusion of thermoplastic fibrillar materials.

More recently, Baker proposes a very general method / process of preparing AC fibers from natural and / or renewable precursors, including mixing said precursors with a chemical activating agent (chemical activation), its fiber spinning process ( co-spinning) and its heat treatment to carry out carbonization and activation in a single stage (US 2007/0142225 Al). In the detailed description he talks about electro-spinning as a possible technique and proposes lignin and H ₃ P0 ₄ as his "preferred" examples. The inventor indicates 3 effects of H ₃ P0 ₄ : low temperature carbonization promoter (400-500 ° C), flame retardant increasing carbon yield and assistant (favoring) of the extrusion process, in addition to mentioning that the fact using lower temperatures and the possibility of carbonizing and chemically activating in one stage (always in an inert atmosphere) means shorter energy and processed savings. However, in addition to not claiming any of the foregoing, the inventor proposes a prophetic example ("Prophetic example") with preferred lignin / H ₃ P0 ₄ impregnation ratios from 1 / 0.5 to 1/3, and conventional extrusion and / or melt extrusion as spinning techniques. That is, the inventor describes processes and effects and proposes impregnation relations (conventional and well studied) and other experimental conditions (traditional and best known methods for preparing fibers) that are easily deduced from the state of the art to obtain activated carbon fibers. prepared from natural precursors, trying to cover all the possible properties that one can think or imagine: materials with a pore size distribution from 2 to 100 nra or predominantly microporous, mesoporous or macroporous, and containing a wide variety of heteroatoms incorporated to the carbonaceous structure and at least one dispersed metal (Pt, Pd, Ni, Fe, Cr, Ti) over the entire structure of said fibers. In this sense, although the author also tries to talk about the electro-spinning process and the lignin and H ₃ P0 ₄ , as preferred examples, the impregnation ratios that it proposes are exactly those that do not allow and disable the electrowinning and thermostabilization process (at least, based on the procedure proposed here and the knowledge of its inventors) . For this reason, the author probably does not provide any details of this synthesis procedure or its operating conditions. Any expert in the field would fail to try to deduce how to do it because he would test the conditions that, based on his knowledge, lead to observe the effects of chemical activation with H ₃ P0 ₄ . On the other hand, it does not describe any novel effect of H P0 ₄ in the stages of stabilization or oxidation resistance (or anything related to controlled gasifications in the presence of 0 ₂ ) and, when it claims the functionalization of carbonaceous structures, it only talks about N and S and that it does it exclusively from heterocyclic molecules, which attracts a lot of attention due to the widely known incorporation of P in the activation processes with H ₃ P0 ₄ ..

The participation of the electro-spinning method in the preparation of activated carbon fibers has been less explored. Sakurai et al. they have patented activated carbon fibers with pores between 0.1 and 200 nm and a diameter below 1000 nm, the method for manufacturing them and their application in supercapacitors and fuel cells (EP1666649A1). Said method consists of electro-spinning of PAN fibers or melt-extrusion of oil or mesophase with a plasticizing agent, which is then removed, to obtain fibers with diameters below 1000 nm, a stabilization stage in an oxidizing atmosphere, a carbonization stage and a final stage of physical activation with H ₂ 0 (v) or chemical with alkaline species. Although it claims activated carbon fibers with specific surface areas between 100 and 50,000 m ² / g, the largest reporting area is 2200 m ² / g for very mesoporous 100 nm fibers (43% of the total pore volume) prepared at from a PAN mixture: KOH = 1: 5 (800 ° C, 30 min). On the other hand, with physical activation with H ₂ 0 (v) (850 ° C, 1 h), it obtains 1300 m ² / g for a 100 nm fiber and the Pitch mixture: KOH = 1: 5 (800 ° C, 30 min) obtains 980 m ² / g for a 200 nm fiber. Despite allowing high degrees of activation in fibers with such a small diameter, the method uses other precursors and plasticizing agents to (by elimination during heat treatment) reduce the size of the fibers and, on the other hand, the activation processes are a posteriori (after the electrowinning stage), allowing much larger amounts of agent activator, so to obtain materials with properties similar to those claimed here, they not only require a greater number of stages but also a greater consumption of reagents (plasticizers and activators) that should make the overall process more expensive. In addition, since the chemical and physical activation processes they use are different from those of the present invention, the materials have different textural properties (pore size distribution) and cannot take advantage of the stabilization or oxidation resistance effects that Here they claim.

 In other works (X. Xu, J. Zhou, L. Jiang, G. Lubineau, Y. Chen, X.-F. Wu, R. Piere Mater. Lett. 2013, 109, 175-178; N. Sasaki US 2012/0251925) the preparation of porous carbon nanofibers, with high surface area, is reported by electrospinning and formulations containing lignin and cellulose. In these cases other polymers facilitating the electro-spinning are added or as main components (such as PAN) or inorganic species (such as transition metals), but again lignin is not electro-spun with any chemical (specific) precursor, with phosphorus species that affect the oxidation reactions that the precursor undergoes during its thermal transformation.

On the other hand, the introduction of an activating agent in the precursor solution subjected to electro-spinning has recently been studied. Mainly, in these works, the introduction of H ₃ P0 ₄ has been studied to facilitate graffiti and therefore increase the mechanical properties of the fibers (JH Kim, B. Bajaj, SJ Yoon, SH Kim, JR Lee, Compos Res. 2013, 26 (3), 160-164) or to introduce functional phosphorus groups (X. Yan, Y. Liu, X. Fan, X. Jia, Y. Yu, X. Yang, J. Power Sources 2014, 248 (15) 745-751). However, the stabilizing and / or oxidation resistance potential of phosphorus species directly introduced homogeneously into the fibers through the electrowinning process has not been observed or reported in these works (or in any other), probably due to The enormous influence of the carbonaceous precursor (for example, the properties of a natural polymer such as lignin, with a high oxygen content, are totally different from those of a synthetic one such as PAN). Finally, there are only two works that describe lignin electro-spinning with an activating agent. First, the use of alkaline hydroxides (NaOH, KOH) was proposed as an activating agent (S. Hu, Y.-L. Hsieh, J Mater. Chem. A 2013, 1, 11279-11288). Although it is possible to develop the porosity in the resulting material, on the one hand, the lignin used in this work is _" modified" and at least required 10% plasticizer polymer (PEO) to carry out the electrowinning process; and on the other hand, these activating agents do not improve the stabilization process, do not increase the resistance to oxidation (they should even decrease it) and surface areas above 1400 m ² / g are not achieved. The other work consists of a summary of a poster communication to a congress (R. Berenguer, J. Rodríguez-Mirasol, T. Cordero UBIOCHEM (4th International Workshop of COAST Action CM0903, 14-16 October 2013, Valencia (Spain)) that discloses a process for preparing carbon fibers by electrospinning solutions of lignin Alcell in ethanol in the presence of H ₃ PO ₄ , followed by successive stages of stabilization and carbonization (conventional method), in oxidizing and inert atmosphere, respectively, of the fibers of lignin obtained.The work focuses on taking advantage of the known effect of chemical activation with H ₃ PO ₄ (in an inert atmosphere) to produce materials with a high specific surface area, exactly what was claimed in the above-mentioned Baker patent (US 2007 / 0142225 Al), but the authors do not describe how they do it. Again, neither this document nor Baker's patent describes the key ideas of the procedure requested for tempt how it is to simplify the preparation of the carbonaceous materials with the claimed size and porosity, nor that the functionalization with phosphorus species affects the oxidation reactions that occur during the heat treatment of the precursors. On the other hand, the carbon fibers described in this document are not affected by the novel effects of the patent application. That is to say, they do not suffer the processes of "assisted" stabilization in various atmospheres or carbonization in an oxidizing atmosphere (avoiding total combustion and allowing partial gasification and, therefore, the direct activation of the materials), which confer some exclusive properties to the carbonaceous materials claimed in the patent application, such as the greater degree of control in the partial fusion of the fibers, a greater surface area, a microporous structure with a greater contribution of mesopores, or a greater content in surface phosphorus that confer them a high acidity and greater resistance to chemical and electrochemical oxidation. Very important, both this document and Baker's patent, aimed at producing the known effect of chemical activation with H3PO4, involve the use of experimental preparation conditions that either impede the process of electro-spinning and / or fiber stabilization or they do not allow observing the effects of stabilization promotion (both in an inert and oxidizing atmosphere) or Total gasification resistance during carbonization at high temperatures in the presence of oxygen, which are claimed in this patent. That is, only the uniform and homogeneous functionalization with phosphorus species proposed in this patent, based on proportions of carbonaceous precursor and precursor of specific phosphorus species (proportions lower than those described in the prior art, and which according to this state of the art would not produce any relevant effect, so that an expert in the field would not be inclined to try to test) is the one that allows to solve the technical problem and simplify and reduce the time, cost and repercussions Environmental preparation of these materials.

The reactivity of various precursors and carbonaceous materials with oxygen has been extensively studied in the literature, mainly for the introduction of oxygenated groups or to study and optimize their oxidation resistance. Oxidation by oxygen (air) is an exothermic reaction whose reaction rate is difficult to control. As a result, and unlike physical activation with C0 ₂ or water vapor, molecular oxygen (air) consumes the carbonaceous materials from the outside, without penetrating into the carbonaceous material and, therefore, without significantly developing or even decreasing its porosity. However, activation by oxygen (air) can be carried out at low temperatures (usually at T <500 ° C) or by successive stages of oxygenation-carbonization after an initial stage of. However, and unlike the effect of the present invention, in these conditions very significant activations are not achieved and, at higher / higher temperatures, the result is a rapid consumption of the carbonaceous material, which is more pronounced the smaller the size / particle / fiber diameter and / or by increasing its specific surface area (its reactivity).

The preparation of activated carbon fibers with high oxidation resistance is of great importance for several of its applications, such as catalysis or electrochemistry. In this sense, it is widely known that the presence of halogenated, boron and phosphorus groups increase the resistance against oxidation of carbonaceous materials (JM Rosas, R. Ruiz-Rosas, J. Rodríguez-Mirasol, T. Cordero. Coal 2012, 50, 1523-1537) and have been widely used as flame retardants (US3294489A). Thus, some authors have proposed / patented some carbon fibers with high oxidation resistance and their method of preparation. Saito et al. claimed joint introduction of different compounds of Zn and / or Ca (≥ 100 ppm) and P and / or B (> 50 ppm) at any stage / stage of the global process of preparing carbon fibers from acrylic fibers, resulting in high mechanical and oxidation resistance, so that during a 3-ha treatment 500 ° C, the fibers suffered a decrease in mass <20 wt% (US4197279A). However, the patent is only directed to acrylic fibers and does not contemplate the advantages of the electrowinning method for introducing the agent directly into materials of reduced dimensions, nor that of allowing controlled gasification at elevated temperatures in atmospheres containing 0 ₂ .

On the other hand, several authors have observed that impregnation with H ₃ P0 ₄ increases the carbonization yield and the degree of activation with C0 ₂ of Nomex-derived fibers. Fukuda et al. patented a process of preparing activated carbon fibers from cellulose fibers impregnated with phosphorus compounds (0.5 to 20% wt.) which, after a heat treatment at 200-350 ° C, were subjected to an activation stage between 450-1000 ° C in an atmosphere containing at least 5% H ₂ 0 (v) until the mass loss was between 65 and 95% (US3969268A). These authors propose that the phosphorus compound significantly favors / promotes activation with H ₂ 0 (v), shortening the time required for activation. However, and as we mentioned, the introduction of this type of P groups has not been applied / studied to allow / improve / control the development of the porosity of carbonaceous materials in the presence of gases containing 0 ₂ , (even less, to high temperatures and not directly during the carbonization stage).

 As can be seen from this extensive bibliography, despite the advantages of the electro-spinning method for the preparation of lignin fibers or other polymeric precursors of natural origin with diameters much smaller than those obtained by other techniques, the overall process up to Obtaining carbonaceous fibrillar materials still requires a very slow thermostabilization stage (without the help of additional stages of modification and / or post-impregnation of some stabilizer). Very important, the conventional preparation of these materials means that stabilization is carried out very slowly in the presence of air in an oven or stove and carbonization in an inert atmosphere in an oven that reaches higher temperatures.

When the stabilization stage is finished, the oxidizing atmosphere must be completely evacuated with an inert gas to be able to carbonize it without producing total gasification (combustion) of the material. Technically this is an important problem, because the process must be stopped to change / purge the atmosphere for a while (especially if the oven does not cool) and / or take the material to another oven with another atmosphere. The possibility of carrying out the two processes in the same atmosphere and / or facilitating the stabilization process, then, would greatly reduce the time, cost, and complexity of manufacturing carbonaceous materials with micro and nanometric dimensions. On the other hand, the materials obtained do not directly show the necessary properties to have a sufficient and / or comparable added value, so they need additional stages of activation, gasification and / or functionalization that, in addition to slowing down, increase the consumption of reagents and complexity and make the process more expensive, can compromise the fibrillar structure. In addition, regardless of the cost of the overall process, there are no carbonaceous fibrillar materials obtained from lignin with unique properties and / or with superior performance for a given application. All these disadvantages limit its commercialization and application on an industrial scale. Consequently, obtaining fibers and other carbonaceous fibrillar structures with advanced properties and, therefore, of high added value, from lignin and / or other renewable resources through faster and simpler / direct processes constitute great challenges that, if totally or partially surpassed / achieved, would suppose enormous environmental benefits and a considerable reduction of the costs of its manufacture, favoring or making possible its commercialization and application on an industrial scale.

On the other hand, regardless of the precursor and the activation process used to develop its textural properties, the extent and degree of activation of the fibrillar carbonaceous material depend largely on its diameter, so that to obtain areas of the order of 2000-3000 m ² / g fibers with sufficiently wide diameters (above 5-10 microns) are normally required, in addition to high amounts of activating agent. Consequently, it is very difficult to obtain activated carbon fibers with diameters between hundreds of nanometers and 5 microns and at the same time show surface areas above 1500 m ² / g (so far, the only one known by the authors of The present invention is the one mentioned above by Sakurai, which achieves 2200 m ² / g fibers from PAN fibers and its subsequent activation with KOH).

DESCRIPTION OF THE INVENTION The present invention, which comes to respond and solve the problems indicated above and not resolved in the state of the art, relates to carbonaceous fibrillar materials of optimized properties, among other carbonaceous fibrillar materials with high specific surface and oxidation resistance , to the procedures for obtaining said particles or materials of optimized properties, as well as to applications of said particles or materials and / or their obtaining procedures.

 Thus, an object of the present invention relates to processes for obtaining particles and carbonaceous materials of optimized properties from a mixture of at least one carbonaceous precursor and at least one chemical agent.

 One aspect of said first object of the invention relates that the carbonaceous precursor is of natural origin, obtained either from biomass (for example, by pyrolysis or liquefaction of natural organic compounds) or from plant origin (for example, resins, lignins , etc.) of fossil origin (for example, breas, PAN, etc.). In an embodiment of said object of the invention the carbonaceous precursor is lignin, pitch or resin. In one embodiment of said object of the invention the carbonaceous precursor is Alcell lignin type (that is, extracted by the Alcell method), although it can be lignin extracted by methods other than Alcell that employ appropriate organic solvents, such as alcohols, acids organic (for example, formic acid, acetic acid, etc.), phenol, cresols, ethyl acetate, amines and their oxides, ketones, dioxane, or DMSO.

 One aspect of said first object of the invention relates that the carbonaceous precursor is synthetic, such as PBO, nylon, kevlar, etc.

 One aspect of said object of the invention refers to the mixture comprising a single type of carbonaceous precursor, for example only lignin type, only resin type, only pitch type, although it can comprise, for example, several types of lignins or several types of resins or several types of breas. In one embodiment of said aspect of the invention, the mixture comprises more than one type of carbonaceous precursor, that is, for example, a mixture of lignin precursors and / or resin precursors and / or pitch precursors, although it may comprise in turn, for example, various types of lignins and / or various types of resins and / or various types of breasts.

One aspect of said first object of the invention relates to the fact that the chemical agent allows to accelerate and / or optimize the stabilization stage. In an embodiment of said aspect of the invention the chemical agent is an inorganic acid or base with a dehydrating character such as phosphoric acid and derivatives, sulfuric acid, hydrochloric acid, nitric acid, methane sulfonic acid, aromatic sulfonic acid, carboxylic acids and alcohols, etc., as well as their corresponding salts or esters. Accelerating the stabilization stage of the fibrillar structures in inert or oxidative conditions, prior to their carbonization stage, allows to avoid the fusion / collapse of the fibrillar structure, and on the other hand, control the degree of widening and / or fusion interconnection of the fibrillar structures to give rise to three-dimensional frameworks, by controlling the experimental conditions of said stabilization process, such as heating rate (mainly), temperature and stabilization time, air concentration, etc. Examples of such chemical species are H3PO4, ...

 One aspect of said first object of the invention relates to the fact that the chemical agent allows to induce, accelerate and / or optimize the process of direct chemical activation during the carbonization stage, and thereby allows to modulate and optimize its textural, structural and / or properties. or chemical In one embodiment of said aspect of the invention the chemical agent is an inorganic acid such as phosphoric and its derivatives (for example, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphine, phosphine), sulfuric acid, nitric acid, or salts thereof. .

One aspect of said first object of the invention relates to the fact that the chemical agent increases oxidation resistance and / or allows a partial gasification process during or after the carbonization stage, to modulate and optimize its textural, structural and / or properties. or chemical In one embodiment of said aspect of the invention the chemical agent is a compound comprising phosphorus (phosphoric, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphonic, phosphine or its salts, polyphosphates, polyphosphonates or phosphonium salts, phosphines and oxides salts phosphine) or boron (boric acid, boric oxide, borax, sodium metaborate, sodium tetraborate, lithium metaborate, lithium pentaborate, lithium tetraborate, potassium metaborate, potassium tetraborate). Other compounds that comprise (and can introduce) phosphorus would be phosphorothioic triamide, phosphoric triamide, triamide Ν, Ν ', Ν''- trimethylphosphoric, diamide (chloromethyl) phosphonotionic, trimethyl phosphate, triethyl phosphate, diethyl methylphosphoramidate, diethyl ethyl phosphoramidate, diethyl diamide methylphosphonic, and mixtures thereof (found in some patents to increase the flame retardant effect)

 - - R '

 G = -OR, i.

 L = alkyl radicals (1 to 4 at. Of C), halogenated alkyl radicals (1 to 4 at. Of C) z = o, s

One aspect of said first object of the invention refers to the mixture comprising a single type of carbonaceous precursor and a single type of chemical agent. In one embodiment of said aspect of the invention the mixture comprises more than one type of carbonaceous precursor and a single type of chemical agent. In one embodiment of said aspect of the invention the mixture comprises a single type of carbonaceous precursor and more than one type of chemical agent. In one embodiment of said aspect of the invention the mixture comprises more than one type of carbonaceous precursor and more than one type of chemical agent.

One aspect of said first object of the invention relates to a mixture of lignin (Alcell) and H ₃ P0 ₄ , consisting of the dissolution of lignin / H ₃ P0 ₄ mixtures in an appropriate solvent, in this case ethanol, where the proportion of lignin in the mixture varies between 25% to 99% by mass of the mass of H ₃ P0 ₄ , where the proportion of lignin in the solution varies between 10% and 90% by mass of the solvent mass; where the solution thus obtained is stirred and heated at the same time, at a constant volume for a sufficient time to dissolve the possible carbonaceous precursor agglomerates and chemical agent and distribute them homogeneously in the mixture (at least 2 h and preferably 5 h). One aspect of said first object of the invention relates to a lignin / H3PC> 4 mixture, where lignin is extracted by methods other than Alcell, which use organic solvents such as alcohols, organic acids (formic acid, acetic acid), phenol, cresols, ethyl acetate, amines and their oxides, ketones, dioxane and DMSO among others, in solvents suitable for manufacturing at ambient temperature lignin fibers, such as ethanol, propanol, acetone, H ₂ 0, etc.

 A second object of the invention relates to the fact that the process for obtaining particles and carbonaceous materials of optimized properties comprises either the electro-spray of the mixture of at least one carbonaceous precursor and at least one chemical agent (for obtaining carbonaceous particles) either electro-spinning of said mixture (for obtaining carbonaceous materials, particularly carbonaceous fibrillar materials). In an embodiment of said aspect of the invention the electrospray or the electrowinning is carried out at room temperature. An embodiment of said aspect of the invention optionally comprises the addition of electrospray or electro-spin facilitating polymers.

One aspect of said first object of the invention relates to the fact that the process for obtaining particles and carbonaceous materials of optimized properties comprises, having as a starting point the product of the electrospray or the electrowinning of the mixture of at least one carbonaceous precursor and the less a chemical agent, a heating stage using a single atmosphere comprising the processes of stabilization, chemical activation and carbonization. In one embodiment of said aspect the atmosphere would be an inert atmosphere (N ₂ ). In another embodiment of this aspect the atmosphere would be an oxidizing atmosphere (N ₂ mixtures / 0 ₂ with up to 5% 0 _2). In one embodiment of this aspect of the invention in an oxidizing atmosphere (mixtures N _{2/0 2} with up to 5% 0 ₂₎ the method further process stabilization, chemical activation and carbonization, comprise a process of partial gasification .

Another aspect of said first object of the invention relates to the fact that the process for obtaining particles and carbonaceous materials of optimized properties comprises, having as a starting point the product of the electrospray or the electrowinning of the mixture of at least one carbonaceous precursor and the less a chemical agent, a stabilization stage and a carbonization stage. In an embodiment of said aspect of the invention, said stabilization and Carbonization are performed in different atmospheres. In one embodiment of this aspect of the invention, the stabilization step is performed in an oxidizing atmosphere (air or any mixture N _{2/0 2),} and the carbonization step, which comprises a prior chemical activation process, is performed in an inert atmosphere (N ₂ ). In one embodiment of said aspect of the invention, the stabilization stage is carried out in an inert atmosphere (N ₂ ), and the carbonization stage, comprising a prior chemical activation process and a subsequent partial gasification process, is performed in an atmosphere. oxidant (mixture N _2/0 up to 5% 0 _2). In one embodiment of this aspect of the invention, the stabilization step is performed in an oxidizing atmosphere (air or any mixture N _{2/0 2),} and the carbonization step, comprising a prior chemical activation process, in an oxidizing atmosphere different from that used for the stabilization step (i.e., any mixture N _{2/0 2} different from that used for the stabilization step).

Another aspect of said first object of the invention relates to the fact that the process for obtaining particles and carbonaceous materials of optimized properties comprises, having as a starting point the product of the electrospray or the electrowinning of the mixture of at least one carbonaceous precursor and the less a chemical agent, a stabilization-carbonization stage and a subsequent partial gasification stage. In an embodiment of said aspect of the invention, said stabilization-carbonization and partial gasification steps are performed in different atmospheres. In one embodiment of this aspect of the invention, the stabilization step-carbonization is performed in an inert atmosphere (N _2), and the step of partial gasification is performed in an oxidizing atmosphere (mixtures N _{2/0 2} to 5 % in 0 ₂ ). In one embodiment of this aspect of the invention, the steps of stabilization and carbonization-stage partial gasification is performed in an oxidizing atmosphere (N ₂ mixtures / 0 ₂ with up to 5% 0 _2).

Another aspect of said first object of the invention relates to the fact that the process for obtaining particles and carbonaceous materials of optimized properties comprises, having as a starting point the product of the electrospray or the electrowinning of the mixture of at least one carbonaceous precursor and the less a chemical agent, three successive stages of stabilization, carbonization and partial gasification. In an embodiment of said aspect of the invention, said steps are performed in different atmospheres. In an embodiment of said aspect of the invention, the stabilization stage is performed in an oxidizing atmosphere (air or any N2 / O2 mixture); the carbonization stage, comprising a previous stage of chemical activation, is carried out in an inert atmosphere (N ₂ ); and the partial gasification stage is carried out in an oxidizing atmosphere (N2 / O2 mixtures with up to 5% in 0 ₂ ).

 In an embodiment of said first object, prior to, where appropriate, a stage of partial gasification, the particles or the fruit resulting from stages prior to initiating a new heating process are allowed to cool for the realization of said stage of partial gasification

 Another aspect of said first object of the invention relates to the use of a device, similar to that described in ES2326455A1, so that the mixture of at least one carbonaceous precursor and at least one chemical agent, duly dissolved by means of a suitable solvent, is forced through a capillary tube located inside another capillary tube concentric with it; where an appropriate solvent is forced through the annular space between the two tubes; where, when applying a potential difference between the capillary tubes (connected to the same potential) and a reference electrode, an electrified meniscus is formed consisting of the conical meniscus of the precursor solution and a surrounding solvent layer; where downstream of the electrified meniscus a coaxial jet is formed consisting of the jet of the solution surrounded by the solvent layer; where the distance between the end of the inner capillary and the reference electrode varies between 1 mm and 1 m; where the potential difference applied between both electrodes varies between IV and 100 kV; where the flow rates of the solution and the solvent circulating in the capillaries are between 0.001 ml / h and 10000 ml / h; where the diameter of the coaxial jet is between 900 microns and 5 nanometers.

Another aspect of said first object of the invention relates to the use of a device, similar to that described in ES2326455A1, so that the mixture of at least one carbonaceous precursor and at least one chemical agent, duly dissolved by means of a suitable solvent, is forced through the intermediate annular space left by three capillary tubes located concentrically; where an inert liquid is forced through the innermost tube, which does not change phase during the process; where an appropriate volatile solvent is forced through the annular space between the two outermost tubes; where when applying a potential difference between the capillary tubes (connected to the same potential) and a reference electrode a meniscus is formed electrified with a structure in which the conical meniscus of the precursor solution is surrounded by a solvent layer and contains inside it the meniscus of inert liquid; where the jets emanating from the vertices of the menisci give rise to a coaxial jet of three liquids in which the precursor solution surrounds the inert liquid and is in turn surrounded by a solvent layer; where the distance between the end of the inner capillary and the reference electrode varies between 1 mm and 1 m; where the potential difference applied between both electrodes varies between IV and 100 kV; where the flow rates of the solution and the solvent circulating in the capillaries are between 0.001 ml / h and 10000 ml / h; where the diameter of the coaxial jet is between 900 microns and 5 nanometers.

 Another aspect of said first object of the invention relates to the use of a device, similar to that described in ES2326455A1, where the inert liquid is replaced by another (polymer, sol-gel, etc.) capable of solidifying, so as to obtain Coaxial fibers formed by a polymeric or ceramic material surrounded by a lignin layer.

A second object of the present invention relates to particles and carbonaceous materials of optimized properties obtained by any of the variants of the process, and from any of the variants (precursors, chemical species, mixture thereof), which constitute the first object of the invention. An embodiment of this aspect of the invention relates to carbonaceous fibrillar materials, particularly porous carbonaceous fibrillary materials. Fibrillar materials can have a degree of widening and / or show a degree of interconnection determined by controlling the experimental conditions of the stabilization process, such as heating rate (mainly), temperature and stabilization time, air concentration , etc. Fibrillar materials can be rigid, hollow or coaxial. Fibrillar materials can be linear or branched and / or with specific surface areas between 100 and 4000 m ² / g, mainly microporous or mesoporous or with a certain distribution of micropores and mesopores, with O contents of up to 30% and P of up to 15%, and a high resistance to thermal oxidation (up to 600 ° C) and electrochemical (up to 1.6 V against a reference electrode Ag / AgCl / Cl- (sat.) in a solution of H ₂ SO ₄ ) An embodiment of this aspect of the invention relates to nanoparticles. An embodiment of this aspect of the invention relates to submicroparticles. An embodiment of this aspect of the invention relates to microparticles.

 A third object of the present invention relates to the application of said particles and materials that constitute the second object of the present invention, for example as adsorbents, catalysts, catalyst support and / or electrodes in supercapacitors, batteries, fuel cells, sensors and / or other electrochemical applications.

In accordance with the above general description, the invention relates, among others, to a process in which mixtures of carbonaceous precursors with chemical species, such as H ₃ P0 ₄ , are electrowelled, which, once homogeneously dispersed in the electro-spun composite , have adequate properties to accelerate, simplify and / or improve the various stages of conversion of electro-spun precursors into their corresponding carbonized products (stabilization, carbonization, chemical and / or physical activation (gasification)). Thus, by means of the new procedure claimed here, it is not only accelerated or simplified, reducing the consumption of activating reagent and / or the number of stages, the global manufacturing process of carbonaceous fibrillar structures, but also, materials are obtained carbonaceous fibrils with advanced and / or unique properties (as a whole).

The electro-spinning of precursor / chemical-chemical mixtures is carried out at room temperature and without polymeric additives, using a coaxial device similar to that claimed in a previous invention (ES2326455B2). However, both the properties of the precursor mixture and of the electro-spun and / or finally carbonized composite material, as well as the experimental conditions of the electrowinning process and the subsequent thermal stages, are totally novel and unique. Due to the presence of chemical species, which increase the concentration and usually with acid-base, redox, etc. properties, the mixed solutions have relatively high viscosities and conductivities that require precise control of the operating conditions (relatively high flow rates and voltages. ) to allow an electrowinning process that, therefore, is limited exclusively to mixtures with low proportions of said chemical species (from 1% of the amount of the carbonaceous precursor and up to 60 or 70%, usually up to about 50% of the amount of carbonaceous precursor). In the process claimed herein, the electro-spinning produces fibrillar materials composed of very small dimensions (diameters up to 5 μπι) and, being homogeneously mixed with the carbonaceous precursors, the chemical species directly produce 3 effects in the polymer precursor conversion process. yarns in their corresponding final carbonaceous structures: (i) they allow to accelerate (up to 50 times) and / or optimize (allowing a greater variety of conditions and / or reducing the temperature) the stabilization stage totally avoiding or improving the control of the fusion / partial swelling of said structures; and / or (ii) allow said structures to be chemically activated directly during the carbonization stage at different temperatures (450-1100 ° C, preferably 500-1000 ° C); and (iii) increasing its resistance to oxidation, allows partially and controlled gasification at high temperatures ((450-1100 ° C, preferably 500-1000 ° C), and under different oxidizing atmospheres with 0 ₂ , said materials during or after the carbonization stage at different temperatures ((450-1100 ° C, preferably 500-1000 ° C).

As a result of the above effects, in addition, the versatility with which the manufacture of carbon fibrillar materials from the electro-spinning technique can be carried out is considerably expanded. Thus, in the process claimed here, the thermal transformation of the electro-spun composite materials (precursors) into their corresponding carbonaceous structures can be carried out in 1-3 stages through 6 different processes according to the following modalities: (i) a single stage stabilization-carbonization using a single, inert atmosphere (N ₂₎ or oxidizing (mixtures N _{2/0 2);} (ii) two steps consisting of a step of stabilization-carbonization in an inert atmosphere (N _2), followed by a subsequent additional step of partial gasification controlled oxidizing atmosphere (N ₂ mixtures / 0 _2); (iii) two successive stages of stabilization and carbonization carried out in different atmospheres (inert + oxidant or oxidant + inert); and (iv) three successive stages of stabilization, carbonization and activation - partial gasification carried out in various atmospheres (inert + oxidizer + oxidant (mixture N _{2/0 2)).}

The object of the present invention is also the carbonaceous fibrillar materials resulting from carrying out the process that constitutes the first object of the invention in any of its variants, having not been described in the state of the art to obtain said physicochemical properties together by other techniques and / or procedures. According to its morphology and dimensions, fibrillar materials carbonates can be linear or branched and / or interconnected, and have diameters between 100 nm and 5 μπι. On the other hand, through the appropriate choice of experimental conditions, the introduction of stabilizing chemical species allows to control the degree of softening / partial fusion of the fibrillar structures at wider temperature intervals and at considerably higher heating rates, giving rise to various structures interconnected three-dimensional and its carbonaceous replicas. According to its structure, the materials can be simple (rigid) or hollow, although they can also be of the coaxial type, in which the carbonaceous material covers or is coaxially coated by another different material, which can be interchangeably of the carbonaceous, polymeric or ceramic. According to their textural properties, the materials can be microporous (pore diameter between 0.7 - 2.0 nm) (with volumes up to 1.5 crnVg), mesoporous (2.0 - 50 nm) (volumes up to 0.5 cm / g) or present a certain distribution of pore sizes that give them a high specific surface area from 500 to 3000 m ² / g. Based on their chemistry and reactivity, carbonaceous fibrillar materials can incorporate various heteroatoms or functionalities of the precursors themselves and / or chemical species or of the reactive atmosphere, such as oxygen (from 0.01 to 30%) and phosphorus (from 0.1 to 15%) , with acid-base, oxide-reduction (redox), complexing, exchangers, promoters of conductivity, catalytic activity, oxidation resistance, etc. For various applications. In particular, the materials have a certain tensile and / or deformation resistance (mechanical properties) and a high resistance to oxidation, withstanding temperatures of up to 600 ° C in the presence of air, after gasification. In addition, the composite fibrillar materials claimed herein can be additionally doped with catalytic or conductive particles (metallic, ceramic, carbonaceous) or other microstructured or nanostructured materials, the object of which is the modification of the structure and final properties of the carbon fibrillar structures obtained from the precursor / chemical species mixtures.

Although some of the effects on the stabilization, activation, simplification of stages and on the properties of the final fibrillar materials could be expected or deductible from their properties and / or the state of the art of the preparation of carbonaceous materials, they are totally novel for being considerably magnified, advantageous and / or never reported effects from relatively small quantities of chemical species, which not only limit the viability and make exclusive the electro-spinning process that is claimed here, but is distributed homogeneously throughout the structure (external and internal) of fibrillar structures of very small dimensions, at micro- and sub-micrometric scales, and very accessible to the atmospheres in which they react .

Although the inclusion of activating and / or promoter species for oxidation resistance, such as H ₃ P0 ₄ , in the lignin solution electrowinning process may seem easily deductible from the state of the art, the process claimed herein presents Great inventive activity for several very important aspects:

 A) First, against the previous invention of electroign spinning of lignin solutions (ES2326455B2):

(i) in which it is claimed (third claim) that "the lignin solution is doped with catalytic particles or other nanostructured materials to modify the properties of the carbon fibers obtained from the thermal treatment of those of lignin," the present The invention claims the mixing or doping of the precursor with chemical species that not only affect the final properties of the carbon fibers, but also actively participate and decisively affect the stabilization and carbonization stages. Among these superior or advantageous effects, never observed, it should be noted that these species considerably reduce the time (from 3 days 11 hours to 1 h 30 min, about 50 times) and the stabilization temperature (from 200 to 150 ° C); simplify the number of stages and the amount of activating agent, so that the processes of stabilization, chemical activation, carbonization and / or physical activation can be carried out during the same heating stage; and, therefore, reduce the cost (energy, economic and / or pollution) of the overall manufacturing process; and, at the same time, the processes of chemical and physical activation (in the presence of controlled quantities of 0 ₂ at high temperatures) during or after gasification give rise to structures with significantly larger surface areas (up to 3000 m ² / g compared to 700 m ² / g in the absence of these species) and with a greater variety of textural and chemical properties, such as the presence of surface phosphorus groups that significantly increase oxidation resistance.

(ii) the behavior and preparation of lignin + ethanol + phosphoric solutions claimed herein is different from that of lignin + ethanol solutions (of the previous invention) in terms of concentration, viscosity and electrical conductivity, etc., in a manner that the experimental conditions of electro-spinning (flow rate, voltage, distance collector tip, etc.) are different and more different the higher the proportion of H3PO4.

 (iii) after evaporation of ethanol, electrowinged lignin / phosphoric fibers behave in a completely different way from pure lignin (of the previous invention) in terms of heating rate, stabilization and carbonization temperatures , chemical stability, etc.

B) Second, although the activating effect and other properties of H3PO4 in the preparation and characteristics of activated carbons have been extensively studied, those observed in stabilization, chemical activation and increased oxidation resistance in the procedure that Here it is claimed they are again completely new. Whereas the known effects of H3PO4 are only significant when the precursor / H ₃ P0 ₄ ratio is equal to or greater than 1/1 (1/2, 1/3, etc.) and that said mixtures cannot be electro-spun (by the great instability of the Taylor cone) nor stabilized without the fibrillar structures collapsing by fusion, the novelty of the procedure claimed here is based on the electro-spinning of precursor / H ₃ P0 ₄ mixtures with small amounts of H ₃ P0 ₄ (up to 1 /0.5 at most) which, unlike what you would expect, produce a very noticeable effect because the dimensions of the fibers are very small and the H ₃ P0 ₄ is very well distributed throughout the fiber and very accessible to the gaseous atmosphere reactive In this way, the very limitation of the electro-spinning method for electro-spinning lignin / H ₃ P0 ₄ mixtures with impregnation ratios that are considered minimal to obtain appreciable effects, is what has allowed to reveal that only when the dimensions of the precursor material are reduced to values close to or below the few microns and when the chemical species is homogeneously distributed, not only for its external part but also for its entire internal structure (both requirements exclusively feasible by the procedure claimed here), then it has been possible to observe magnified effects (much higher effects despite using much lower amounts) of the chemical species, introduced in small quantities by said method and using specific experimental conditions.

C) That said, although there are works and inventions where the stabilization of lignin fibers with certain chemical species or other precursors (acrylics) is studied, even with estudia0 ₄ , these have been carried out by the method of extrusion. Thus, both the nature of the precursor / H ₃ P0 ₄ mixture and the spinning method are very different, so that the process and the effects and properties claimed herein are completely different and hardly deductible from the foregoing. And it is that the procedure that is claimed here is the only one that so far poses and has been able to successfully carry out the electrowinning of lignin mixtures with H ₃ P0 ₄ and / or its transformation into carbonaceous materials. To do this, if phosphoric is not used in the appropriate amounts and / or if the experimental conditions during the electrowinning, stabilization and carbonization stages are not carried out exactly as stated here, neither the resulting materials nor the materials can be obtained. news / advantages of the manufacturing process. All these considerations are proof of the great difficulty and inventive activity of the claimed process.

D) Finally, the present invention describes the advanced properties obtained together in the carbonaceous fibrillar materials, the obtaining of which by other methods has not been described in the state of the art. Said amalgam of properties consists of fibrillar diameters of the order of a few microns or less, high surface areas of up to 3000 m ² / g, and a rich surface chemistry with varying percentages of phosphorus that considerably increase its resistance to oxidation. Considering that reducing the diameter of the fibers is more complicated to post-activate them significantly and / or functionalize them without breaking or breaking them down; that the post-impregnation of fibrillar materials of small dimensions with a certain chemical species after the electrowinning and / or stabilization or carbonization stage entails the destruction of the fibers and / or a less homogeneous and exclusively external distribution, respectively, and by therefore, less efficient of said species; The inventive activity is that only the process claimed here, in which the chemical species dissolves and disperses homogeneously in small proportions with the carbonaceous precursor before the electrowinning process and, therefore, before shaping the small dimensions of the materials, allows to benefit and optimize the effects of the chemical species to obtain the claimed materials.

BRIEF EXPLANATION OF THE FIGURES

Figure 1. SEM images of linear (a) and branched (b) lignin fibers Figure 2. Evolution of the heating rate and SEM images of the as-spun and stabilized lignin fibers at 0.05 ° C / min and 1 ° C / min (rounds-optical microscope) and those of 1 / 0.3 as-spun and stabilized at 0.05 ° C / min and 1 ° C / min, 3 ° C / min 4-5 ° C / min.

Figure 3. Activated isotherm-1 / 0.3 (after carbonization) compared to that of lignin without P

Figure 4. Stability + Gasification (TG) and gasification isotherm - 1 / 0.3 compared to that of lignin without P

Figure 5. XPS functionalization of P (2p): The resulting carbonaceous materials have strongly anchored phosphorus surface groups (1-3 wt% P -XPS) and high oxygen content (5-20 wt% 0 -DTP).

DETAILED DESCRIPTION OF THE INVENTION

The present invention claims a method that allows the manufacture of various carbonaceous fibrillar materials with high specific surface and oxidation resistance by electro-spinning and subsequent thermal transformation of composite materials formed by carbon precursors (majority component: lignin, breas and other derivatives of the pyrolysis of natural organic waste, as well as resins of plant origin) and a chemical stabilizing agent to accelerate the stabilization stage and / or capable of inducing a chemical activation process during the carbonization stage and which, increasing the resistance against oxidation / gasification at high temperatures, allow a controlled partial gasification of the carbonaceous fibers in the presence of gases containing oxygen during or after the carbonization stage, to reduce the duration and simplify its global manufacturing process and, at the same time, modulate and optimize their property It is textural, structural and / or chemical.

The preparation of homogeneous solutions of carbonaceous precursor and chemical agent or, what is the same, the uniform functionalization of the carbonaceous precursor with said chemical agent, is very important to be able to satisfactorily carry out the electrowinning stage For example, for mixtures lignin / H ₃ P0 ₄ , an appropriate amount of H ₃ P0 _{4 is added} on a given mass of lignin and, in turn, an appropriate volume of solvent, such as ethanol, is poured onto the mixture previous lignin / H ₃ P0 ₄ . The mixture is then heated, at constant volume, under magnetic stirring at temperatures below the boiling point of the solvent. Stirring can be performed at different speeds (recommended between 25 and 500 rpm), and is strictly necessary for a sufficient time (a minimum of 2 h is recommended) to dissolve the possible precursor and chemical agent agglomerates and obtain a homogeneous mixture, while that heating is required due to the difficulty of obtaining a viscous solution of lignin at room temperature.

 The concentration and nature of the precursor, chemical species and solvent (composition) of the solutions determine its viscosity and conductivity, very important properties that greatly affect the feed flow of the mixture and / or the stability and properties of the Taylor cone, which in Ultimately, they will determine both the success of the electrowinning process and the advantages in the subsequent thermal stages and the properties of the resulting materials. Consequently, the precise control of both parameters, viscosity and conductivity, is of vital importance for the process claimed here, and to a greater extent, considering the great influence of chemical species on these parameters.

Because it is the major component, the viscosity of the solution depends mainly on the concentration of the carbonaceous precursor. However, the nature and concentration of the chemical agent can play a very important role. Thus, solid chemical agents (KOH, NaOH, ZnCl ₂ ) and certain liquids (H ₃ P0 ₄ 85wt%. = 47 cP (20 ° C); H ₂ S0 ₄ 98wt%. = 20.5 cP (20 ° C) ; HN0 ₃ 68wt%. = 2.6 cP (20 ° C)) considerably increase the viscosity of the solution, while common solvents decrease it (H ₂ 0 = 1,002 cP (20 ° C); Ethanol = 1,201 cP ( 20 ° C); Acetone = 0.324 cP (20 ° C)). In particular, the presence of H ₃ P0 ₄ greatly increases the viscosity of lignin-ethanol solutions so that its priming / feeding to the electrowinning system must be carried out quickly after stirring, when they are still hot, thus taking advantage of its lower viscosity with the temperature and facilitate its movement through the ducts and needles of reduced diameter. The solutions are then cooled rapidly to room temperature, but increasing their viscosity does not prevent or hinder the controlled flow of the mixture due to inertia. acquired after the initial impulse. On the other hand, the conductivity of the solution is determined mainly by the nature of the volatile solvent, but, likewise, the addition of some chemical agents (acids and bases above all) can greatly affect and condition the stability of the Taylor cone and , consequently, the properties of the fibers.

 Regarding the electro-spinning process, the solutions must show a minimum electrical conductivity to deform the solution and generate the Taylor cone, while the concentrations of precursor and chemical agent must be appropriate for, on the one hand, achieving viscosity and molecular interlacing necessary and that the mixture can be spun, and on the other, to maintain a stable Taylor cone that allows continuous ejection of a jet of solution that is transformed into fibers. In this sense, increasing the concentration of H3PO4 considerably increases the conductivity of the mixed solution and, in parallel, the instability and whiplash of the Taylor cone, which begins to be considerable for lignin / t PC ^ mixtures with a 1 / 0.5 ratio . For higher proportions of H3PO4 the electrowinning process is not feasible (the viscosity and conductivity of the solution are so high that a sufficient voltage cannot be applied so that the electro-hydrodynamic forces deform the meniscus, and the fiber formation process it is interrupted) and even while obtaining some short fibers, its heating during the stabilization stage causes the softening of H3PO4 phases that melt and destroy the fibrillar structure. The maximum value of viscosity and / or conductivity depends on the nature and concentration of carbonaceous precursor and chemical agent, so the electro-spinning of different mixtures requires a specific knowledge of each precursor system / chemical agent / solvent.

Considering all these factors, for the first electrowinning stage of the process object of the invention, the proportion of solvent versus precursor, for example ethanol vs. lignin, can vary between 40% and 60% of the total mass (of both) and the proportion of chemical agent against precursor, for example of H3PO4 against lignin, between 1% to 50% of the total mass, which implies lignin / HsPC (1 / x) impregnation ratios with x = 0.01-0.5. However, and within the range of compositions above, the concentration of chemical agent should be that necessary to induce the desired stabilization, activation and oxidation resistance effect. Said concentrations and / or compositions of the solutions lignin + ethanol + H3PO4, With specific viscosities and electrical conductivities, necessary to carry out the electrowinning process successfully, they have not been reported and cannot be deduced from the state of the art in the electrowinning technique or in the preparation of carbonaceous materials with H ₃ P0 ₄ , for which they are claimed in the present invention. For higher proportions of solvent, the concentration of the precursor and chemical species decrease and its molecules are not able to remain cohesive and produce a continuous fibrillar material before the applied voltage. In this case, the solution is atomized in the form of electrospray to give rise to compound spherical particles precursor / chemical agent with diameters similar to those of the fibers. For example, for mixtures lignin / H ₃ P0 ₄ / ethanol this happens for percentages of ethanol greater than 60% (with respect to lignin) and the amount of H ₃ P0 ₄ does not exceed 15% of that of lignin, increasing the percentage of ethanol with that of chemical species.

The electro-spinning of the precursor / chemical agent mixtures is carried out at room temperature and without polymeric additives by means of a coaxial device similar to that claimed in a previous invention (ES2326455B2). The precursor / chemical agent mixture prepared according to the method claimed herein is fed through the internal needle and a flow of solvent with low boiling point, typically ethanol, with a flow rate of between 1% and 50% is passed through the external (normally 10%) of the solution of the mixture, to avoid solidification of the Taylor cone. In general, and due to its higher viscosity, it is necessary to increase the flow rate and the voltage to be able to electro-spin solutions with increasing amounts of chemical agent. In the particular case of lignin / H ₃ P0 ₄ mixtures, the increase in viscosity induced by H ₃ P0 ₄ leads to an increase in the flow necessary to electrowire the solution, being narrow (usually around ± 0.5 ml / min) the interval of flows that enable this process. For example, for a mixture with lignin ratio / H ₃ P0 ₄ = 1 / 0.15, the appropriate solution flow rate is around 3 ml / min and for a mixture 1 / 0.3, about 4 ml / min, approximately double that in the absence of phosphoric. On the other hand, the increase in viscosity and flow entail the need to use higher voltages to generate the Taylor cone. For the previous cases, for example, voltages of 20-22kV and 24-26 kV are needed, respectively, when the distance between the needle and the collector is 30 cm.

Finally, the great influence of the viscosity and the conductivity of the solution on the electrodynamic forces during the electrowinning process considerably affect, in turn, the morphological / structural properties of the resulting fibrillar materials. Thus, said structures have diameters between 100 and 5 μπι (Fig. 2), increasing with the increase in the viscosity of the precursor solutions. On the other hand, the instability of the Taylor cone and the whiplash phenomenon, promoted with the increase of the conductivity of the solution and the applied voltages, favor the curvature, the curl, the shortening, the branching and / or the dispersion of diameters of the fibers (Fig. 1). Regarding its composition, and once dry after the complete evaporation of the solvent, the precursor / chemical species compound fibrillar structures have similar percentages of the chemical species used to prepare the solutions. For example, once electro-spun, lignin / H ₃ P0 ₄ fibers prepared from a solution with a 1 / 0.3 ratio, have a high percentage of phosphorus with a high percentage of oxygen (around 30% mass of oxygen) from the high oxygen content in the molecular structure of lignin and the presence of H ₃ P0 ₄ . Furthermore, and according to the process of the present invention, the chemical species efficiently introduced into the fibrillar structures of the carbonaceous precursor (lignin, breas and other derivatives of the pyrolysis of natural organic waste, as well as resins of plant origin) allows accelerating and / u optimize the stabilization stage and / or directly induce a chemical activation process and / or allow partial gasification (with gases containing oxygen) during or after the carbonization stage of said structures to reduce the duration and simplify their manufacturing process global and, at the same time, modulate and optimize the textural, structural and / or chemical properties of the final carbonaceous materials. Therefore, the electro-spun composite fibrillary materials claimed herein are totally exceptional and novel, different from those of other inventions and / or works of the state of the art.

In addition to other types of lignin and various lignocellulosic residues, the electro-spinning of mixtures with chemical species claimed here can be carried out with other carbonaceous precursors, such as resins of plant origin, breasts or derivatives of the pyrolysis of natural organic waste, adjusting their rheological properties (viscosity and conductivity), and other volatile solvents other than ethanol, as propanol, acetone, H ₂ 0, etc. or mixture thereof. On the other hand, both the manufacturing advantages and the novel effects and properties that are claimed here for carbonaceous fibrillar structures, from electrohydrodynamic processing of precursor / chemical species mixtures, can be extended to other conformations and / or combinations Thus, and by using a coaxial configuration and dilute solutions of the precursor / chemical species mixtures, spherical carbon particles can be obtained (and after subsequent heat treatments); while by means of a triaxial configuration device, hollow or coaxial carbonaceous fibrillar structures can be obtained, only by passing an inert sacrificial liquid or other solution or gel of a material capable of solidifying (polymers, sol-gel, etc.) through the concentric needle inside. Finally, the different materials in fibrillar, tubular, coaxial and particular form, obtained from the electrohydrodynamic processing of precursor / chemical species mixtures that are claimed here, can be additionally doped (and directly in a single stage) with particles (metallic, ceramic, carbonates), functionalities and / or their precursors, to modify and / or optimize the structural, mechanical, conductive, chemical properties (catalytic activity, stability, etc.) of the final carbonaceous materials.

After the electrowinning stage, the fibrillar-shaped precursor / chemical species composites are transformed into carbonaceous structures at elevated temperatures. Due to the thermoplastic nature of the precursors, the conservation of their fibrillar structure requires a previous stage of thermo-oxidative stabilization. The process is carried out in a conventional oven or oven in the presence of air, heating from 60 ° C to moderate temperatures (250 ° C maximum). During this stage, the presence of stabilizing chemical species, such as H ₃ P0 ₄ , homogeneously distributed throughout the fibrillar structure of the carbonaceous precursor, promotes various reactions of dehydration, oxidation and cross-linking between the oxygenated groups of the precursor polymer molecules, stabilizing its fíbrilar structures. In particular, the unique properties of electro-spun lignin / H ₃ P0 ₄ composites, with proportions of H ₃ P0 ₄ of at least 10%, allow very fast heating ramps, up to 3 ° C / min, and temperatures to be used of very low stabilization, up to 150 ° C, maintained for 1 h, without compromising the original fibrillar structure and giving rise to linear fibrillar structures (Figure 2). Compared to the stabilization process in the absence of stabilizing chemical species (0.05-0.08 ° C / min up to 200 ° C + 36 h) (Figure 2), this means an extraordinary reduction in time (from 3 days 11 hours to 1 h 30 min, about 50 times) and the temperature (from 200 to 150 ° C) of stabilization and, therefore, of the time, economic costs and pollution associated with the global process. In addition, the stabilizing effect H3PO4 is such that, with oxygen-rich precursors (such as lignin), it allows the stabilization process to be carried out even in an inert atmosphere, such as that used in the carbonization process and, obviously, in atmospheres with different oxygen contents.

On the other hand, the stabilizing effect of H ₃ P0 ₄ also allows higher heating rates to be used, between 4-6 ° C / min (processes up to 100 times faster), but in this case the fibers soften and undergo a certain degree of widening and / or partial fusion, giving rise to interconnected fibers and, therefore, three-dimensional structures (mesh type) (Figure 2). Again, said structures and / or the control in their degree of interconnection cannot be achieved so quickly in the absence of stabilizing agent due to the low glass transition temperature of these polymeric precursors, which melt completely at these heating rates. Accordingly, in the present invention not only the electro-spinning stage of the composite material with the appropriate amount and nature of the stabilizing agent is claimed, but also a rapid stabilization method that allows control of the degree of interconnection and / or dimensional of the fibrillar structures during its stabilization stage in the presence of the stabilizing agent, by controlling the experimental conditions of said process, such as heating rate (mainly), temperature and stabilization time, air concentration, etc. Once carbonized, these interconnected structures are of great interest for use as electrodes or electrocatalyst supports for different electrochemical applications. As chemical agents to accelerate and / or optimize the stabilization step, inorganic acids and bases can be used with dehydration such as phosphoric acid and derivatives, sulfuric acid, hydrochloric acid, nitric acid, methane sulfonic acid, aromatic sulfonic acid, carboxylic acids and alcohols, etc., as well as their corresponding salts or esters.

After stabilization, the carbonization of the fibrillar materials is carried out in an oven by heating them in an inert atmosphere to high temperatures (500-1000 ° C) and using much faster heating ramps (around 10-20 ° C / min ), without the electro-spun structures seeing their fibrillar structure compromised. During the carbonization process, a rearrangement of carbon atoms occurs to give rise to aromatic ring sheets (graphitization) and the evolution of different volatile compounds and carbonaceous and / or oxygenated groups with structure development porous In addition, in the process claimed here, the presence of chemical species with activating properties, such as those of H3PO4, favor decomposition processes producing an extra development of porosity. In the particular case of fibrillar materials prepared using lignin as a precursor, carbonization at 900 ° C in an inert atmosphere in the presence of only an initial 30% mass of H3PO4 results in linear or interconnected carbonaceous fibrillar structures (depending on the velocity of the stabilization stage) with a surface area around 1300-1400 m / g, approximately twice that in the absence of said activating agent (Figure 3). Considering that to obtain a similar development of porosity from lignin powder (that is, unprocessed lignin by the electrowinning step of the process claimed herein), at least an initial 80% of H3PO4 is needed, it can again be affirmed that The magnified activating effect of the H3PO4 claimed in the present invention is completely novel. In addition, although there is a work in which lignin has been electrowinned with other activating agents such as NaOH or KOH (S. Hu, Y.-L. Hsieh, J. Mater. Chem. A 2013, 1, 11279-11288), both the mechanism of the activation reactions and the final resulting properties (mainly in terms of the type and distribution of the porosity) are completely different and specific to the activating agent (A. Linares-Solano, MA Lillo-Ródenas, JP Marco-Lozar, M. Kunowsky, AJ Romero-Anaya, Inter. J. Ener. Environ. Econ. 2012, 20 (4), 59-91), so that the magnified effects, and resulting properties in the aforementioned materials with reduced dimensions and Optimum distribution of the activating agent of the present invention are completely novel.

On the other hand, the process of carbonization of the fibrillar materials stabilized in an inert atmosphere leads to a development of the porosity lower (up to 1100 m ² / g) to that of the stabilized ones in the presence of air or other atmospheres with oxygen (as a consequence of the lower oxygen uptake in the form of leaving groups during the heat treatment), but still greater than that achieved in the absence of activating agent and, in addition, obtaining it directly after said stabilization in the presence of the same inert atmosphere. This preparation of carbonaceous, linear or interconnected fibrillar materials, in which a chemical species is introduced to induce a stabilization process in an inert atmosphere and to be able to carry out a carbonization process directly without changing the atmosphere, is also completely exclusive of the present invention As chemical agents for the direct chemical activation process during the carbonization stage (which is claimed here), various inorganic acids such as phosphoric and their derivatives (for example, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphine, phosphine) can be used ), sulfuric acid, nitric acid, or its salts. For example, due to the presence of 10-30 wt.% Of H ₃ P0 ₄ , during the carbonization stage (in N ₂ ) the chemical activation of the lignin fibers occurs, so that the fibrillar structures obtained increase its specific surface area between 100-800 m / g with respect to the same pure lignin fibers (Figure 3).

In addition to the chemical activation induced during the carbonization stage, the presence of a chemical agent such as H ₃ P0 ₄ , and / or in the form of different types of phosphorus functionalities, increases the oxidation resistance of the carbonaceous transformation precursor, so that the carbonization process can be carried out in oxidizing atmospheres (containing up to 5-10% in 0 ₂ , depending on the temperature, treatment time, diameter of the fibers) also up to high temperatures (500-1000 ° C ) without producing total uncontrolled gasification (combustion) of the fibrillar materials (Figure 4a) (yields 5-30%). Thus, the high resistance to oxidation induced by this type of chemical species allows to partially gasify (in a controlled manner, according to time, temperature, the amount of chemical species introduced, the percentage of oxygen) the carbonaceous fibrillar materials during the stage of carbonization and thus produce another extra development of porosity. In particular, for fibrillar materials prepared from lignin as a precursor and only an initial 30% mass of H ₃ P0 ₄ , carbonization at 900 ° C in N2 / O2 atmospheres with 3-4% at 0 ₂ results in Linear or interconnected carbonaceous fibrillar structures (depending on the speed of the stabilization stage) with a surface area in the volume of 2000-2300 mg, approximately triple that in the absence of said activating agent (Figure 3). Increasing the degree of gasification increases the average pore size, thereby increasing the proportion of mesopores. The great novelty of this effect that is claimed here is that at high temperatures (usually above 450 ° C), and in the absence of the species or functionalities promoting oxidation resistance), the reaction of 0 ₂ (even in small proportions) with carbonaceous materials (and their precursors) it is produced very quickly and in an uncontrolled manner, so that it does not allow controlling the development of porosity and / or consumes the material in a short time, especially in small-sized materials and older exposed area (more reagents). Since the development of porosity induced by gasification controlled with 0 ₂ is different (in mechanism and induced properties) from that produced by other physical activation agents, such as, for example, steam of H ₂ 0 or C0 ₂ , the operation of which is feasible at high temperatures (800-1000 ° C), and since it cannot normally be carried out at temperatures even above 450 ° C, the process of the present invention is considered totally novel and unique in order to carry out this type of reaction , with development of specific porosity of 0 ₂ , at high temperatures in materials with fibrillar structure of small dimensions. In addition, and since in the process claimed here the stabilization step can be carried out with atmospheres containing different percentages of 0 ₂ , the carbonization process can also be carried out under these conditions directly by increasing the temperature following stabilization. . This implies a process of great novelty of the present invention in which, without changing the atmosphere, the stabilization, chemical activation, carbonization and partial gasification processes controlled with 0 ₂ can be carried out progressively and simultaneously, with the corresponding reduction in the time, energy consumption and pollution (associated with said consumption) to produce carbonaceous fibrillar materials with advanced properties that are also claimed in the present invention.

On the other hand, the increase in oxidation resistance induced by the chemical species claimed here can not only be used during the heating of the carbonization stage, but certain phosphorus functionalities (up to 15% mass) are strongly retained. in the carbon structure (they remain after thorough washing in water at 60 ° C - (Figure 5) and also induce an increase in oxidation resistance after carbonizing the fibrillar materials (Figure 4b). For example, for fibrillar materials prepared to from lignin as a precursor and only 30% mass initial H ₃ P0 ₄ of, carbonized at 900 ° C in an atmosphere N _{2/0 2} 0 3-4% in ₂ gasification does not begin until temperatures above 600 ° C (Figure 4b) Accordingly, the high oxidation resistance claimed in the present invention to carry out controlled gasification with 0 ₂ at high material temperatures It is fibrillar of small dimensions can be carried out not only during the carbonization stage, but also, subsequently after said process as an additional stage. As chemical agents to increase the resistance to oxidation and / or allow a partial gasification process during or after the carbonization stage, phosphorus-containing compounds (phosphoric, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphine, phosphine or their compounds can be used salts, polyphosphates, polyphosphonates or phosphonium salts, phosphines and phosphine oxides) or boron (boric acid, boric oxide, borax, sodium metaborate, sodium tetraborate, lithium metaborate, lithium pentaborate, lithium tetraborate, potassium metaborate, potassium tetraborate ).

 Other compounds containing (and may introduce) phosphorus would be phosphorothioic triamide, phosphoric triamide, triamide Ν, Ν ', Ν' '- trimethylphosphoric, diamide (chloromethyl) phosphonotionic, trimethyl phosphate, triethyl phosphate, diethyl methylphosphoramidate, diethyl ethylphosphoramide, diethyl methylphosphonic diamide, and mixtures thereof (found in some patents to increase the flame retardant effect)

 - - '

G = -OR, A *

 L = alkyl radicals (1 to 4 at. Of C), halogenated alkyl radicals (1 to 4 at. Of C) z = o, s

Considering the different advantageous effects of chemical species in the process of stabilization, chemical activation and oxidation resistance that are claimed in the present invention, and the consequent great versatility of experimental conditions (heating rates, temperatures, times and atmospheres) a When it is possible to carry out the stabilization and carbonization processes, the thermal process of transformation of the fibrillar precursors into the corresponding carbonaceous fibrillar structures can be carried out in 1 to 3 stages (2 to 4 stages for the overall process, considering the previous electrowinning stage) through 6 different processes according to the following modalities: a) 1 stage: a single stage of heating using a single atmosphere:

- inert (N ₂ ), comprising the processes of stabilization + chemical activation + carbonization.

- oxidising (mixtures N _{2/0 2} with up to 5% 0 ₂₎ comprising stabilization processes + chemical activation + + partial carbonization gasification.

b) 2 stages: a stabilization stage followed by a carbonization stage, carried out in different atmospheres:

- oxidising (air or any mixture N _{2/0 2)} + inert (N _2), the stabilization process (oxidant) + chemical activation comprising (inert) + carbonization (inert).

- inert (N ₂₎ + oxidant (mixture N _{2/0 2} with up to 5% 0 ₂₎ stabilization processes (inert) + chemical activation (oxidant) + carbonization (oxidant) + partial gasification comprising (oxidant) respectively.

c) two steps: two steps consisting of a step of stabilization-carbonization in an inert atmosphere (N ₂₎ (mode (a)), followed by a subsequent step of partial gasification in an oxidizing atmosphere (mixtures N _{2/0 2} up 5% in 0 ₂ ).

d) 3 stages: three successive stages of stabilization, carbonization and partial gasification carried out in different atmospheres, stabilization processes (oxidant (air or any mixture N _{2/0 2))} + chemical activation comprising (inert) + carbonization ( inert) + partial gasification (oxidant (mixture N _{2/0 2} with up to 5% 0 _2)), respectively.

Claims

Process for obtaining particles and carbonaceous materials with optimized properties characterized by comprising the electrospray or electro-spinning of a mixture of at least one type of carbonaceous precursor and at least one type chemical agent, said chemical agent affecting the chemical reactivity of said carbonaceous precursor during its heat treatment of stabilization and carbonization.

Method according to the preceding claim characterized in that the at least one type of chemical agent included in the mixture for the homogeneous functionalization of the carbonaceous precursor is a chemical agent suitable for accelerating and / or optimizing the stabilization step.

 Process according to the preceding claim characterized in that the at least one type of chemical agent is an inorganic acid or base with a dehydrating character, for example phosphoric acid and derivatives, sulfuric acid, hydrochloric acid, nitric acid, methane sulfonic acid, aromatic sulfonic acid , carboxylic acids and alcohols, as well as their corresponding salts or esters.

Method according to claim 1 characterized in that the at least one type of chemical agent included in the mixture for the homogeneous functionalization of the carbonaceous precursor is a chemical agent suitable for inducing, accelerating and / or optimizing the process of direct chemical activation during the stage of carbonization. Process according to the preceding claim characterized in that the at least one type of chemical agent is an inorganic acid, such as phosphoric and its derivatives (for example, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphonic, phosphine), sulfuric , nitric, or its salts.

Process according to claim 1, characterized in that the at least one type of chemical agent included in the mixture for the homogeneous functionalization of the carbonaceous precursor is a chemical agent suitable for increasing oxidation resistance and / or allowing a partial gasification process during or after the carbonization stage.

Process according to the preceding claim characterized in that the at least one type of chemical agent is a compound comprising (a) phosphorus, for example phosphoric, metaphosphoric, pyrophosphoric, phosphorous, phosphonic, phosphonous, phosphine, phosphine or its salts, polyphosphates, polyphosphonates or phosphonium salts, phosphines and phosphine oxides, phosphorothioic triamide, phosphoric triamide, triamide Ν, Ν ', Ν''- trimethylphosphoric, diamide (chloromethyl) phosphonotionic, trimethyl phosphate, triethyl phosphate, diethyl methylphosphoramidate, diethyl ethyl phosphoramidaphthiophosphide, diethyl mixtures from them; or (b) boron, for example boric acid, boric oxide, borax, sodium metaborate, sodium tetraborate, lithium metaborate, lithium pentaborate, lithium tetraborate, potassium metaborate, potassium tetraborate.

 Method according to any one of the preceding claims, characterized in that the electrospray or electro-spinning of said mixture is carried out at room temperature.

 9. Method according to any of the preceding claims characterized in that it comprises the addition of electroplating or electrowinning facilitating polymers.

 Method according to any one of the preceding claims characterized in that it comprises a single stage, of heating, using a single atmosphere and said stage comprising the processes of stabilization, chemical activation and carbonization.

11. Method according to the preceding claim characterized in that the heating step is carried out in an inert atmosphere (N ₂ ).

12. The process of claim 10 wherein the heating step is performed in an oxidizing atmosphere (N ₂ mixtures / 0 ₂ with up to 5% 0 _2).

 13. Method according to the preceding claim characterized in that the heating step further comprises a partial gasification process.

 14. Method according to any of the preceding claims 1 to 9 characterized in that it comprises two stages, a stabilization stage and a carbonization stage, which are carried out in different atmospheres.

15. Method according to the preceding claim wherein the stabilizing step is performed in an oxidizing atmosphere (air or any mixture N _{2/0 2),} and the carbonization step, which comprises a prior chemical activation process, is performed in an inert atmosphere (N ₂ ).

16. Method according to claim 14 characterized in that the stabilization stage is carried out in an inert atmosphere (N ₂ ), and the carbonization stage, comprising prior chemical activation process and a subsequent process of partial gasification is performed in an oxidizing atmosphere (mixtures Ν _{2/0 2} to 5% 0 _2).

17. The process of claim 14 wherein the stabilizing step is performed in an oxidizing atmosphere (air or any mixture N _{2/0 2),} and the carbonization step, comprising a prior chemical activation process, in an oxidizing atmosphere different from that used for the stabilization step (any mixture N _{2/0 2} different from that used for the stabilization step).

18. Method according to any of the preceding claims 1 to 9 characterized in that it comprises two stages, a stabilization-carbonization stage and a subsequent partial gasification stage.

19. Method according to the preceding claim characterized in that the stabilization-carbonization step is performed in an inert atmosphere (N _2), and the step of partial gasification is performed in an oxidizing atmosphere (N ₂ mixtures / 0 ₂ to 5 % in 0 ₂ ).

20. The process of claim 18 wherein the steps of stabilization-carbonization and partial gasification is performed in an oxidizing atmosphere (N ₂ mixtures / 0 ₂ with up to 5% 0 _2).

 21. Method according to any one of the preceding claims 1 to 9 characterized in that it comprises three stages, a stabilization-carbonization stage and a subsequent partial gasification stage.

 22. Method according to the preceding claim characterized in that said three stages are carried out in different atmospheres.

23. Method according to the preceding claim wherein the stabilizing step is performed in an oxidizing atmosphere (air or any mixture N _{2/0 2);} the carbonization stage, comprising a previous stage of chemical activation, is carried out in an inert atmosphere (N ₂ ); and the step of partial gasification is performed in an oxidizing atmosphere (N ₂ mixtures / 0 ₂ with up to 5% 0 _2).

24. Method according to any of claims 13, 16, 18, 19, 20, 21, 22 or 23 characterized in that, prior to the stage or the partial gasification process, the particles or the fruit resulting from stages are allowed to cool to room temperature previous.

25. Method according to any of the preceding claims characterized in that the at least one type of carbonaceous precursor included in the mixture is of synthetic origin, such as for example PBO, nylon or kevlar.

 26. Process according to any one of claims 1 to 24 characterized in that the at least one carbonaceous precursor type is of natural origin, said carbonaceous precursor (a) obtained from biomass, for example by pyrolysis or liquefaction of natural organic compounds; (b) of plant origin, for example resins or lignins; or (c) of fossil origin, for example breas or PAN.

 27. Method according to the preceding claim characterized in that the at least one carbonaceous precursor of plant origin is of the resin type, comprising one or more kinds of resins.

 28. A method according to claim 26, characterized in that the at least one carbonaceous precursor of plant origin is of the lignin type, comprising one or more classes of lignins.

29. Method according to the preceding claim characterized in that the at least one carbonaceous precursor of plant origin of the lignin type comprising lignin obtained by the Alcell method.

 30. The method according to claim 28, characterized in that the at least one carbonaceous precursor of plant origin of the lignin type comprising lignin obtained by a method other than the Alcell method using suitable organic solvents, such as alcohols, organic acids (for example, acid formic, acetic acid, etc.), phenol, cresols, ethyl acetate, amines and their oxides, ketones, dioxane, or DMSO.

31. A method according to claim 29 characterized in that it comprises a mixture of lignin obtained by the Alcell method as well as H ₃ P0 ₄ as a chemical agent, consisting of the dissolution of a lignin / H ₃ P0 ₄ mixture in a suitable solvent, where the proportion of lignin in the mixture varies between 25% to 99% by mass of the mass of H ₃ P0 ₄ , and where the proportion of lignin in the solution varies between 10% and 90% by mass of the solvent mass .

32. Method according to the preceding claim characterized in that the suitable solvent is ethanol.

33. Method according to claim 30 characterized in that it comprises a mixture of lignin not obtained by the Alcell method as well as H ₃ P0 ₄ as agent chemical, consisting of dissolving a lignin / H ₃ P0 ₄ mixture in a suitable solvent such as ethanol, propanol, acetone or water.

 34. A method according to any one of claims 1 to 24 characterized in that it comprises a mixture of two or more types of carbonaceous precursors and at least one type of chemical agent,

 i. said two or more types of carbonaceous precursors comprising (a) one or more classes of lignin carbonaceous precursors according to claims 29 or 30, in addition to one or more classes of resin-type carbonaceous precursors and / or one or more kinds of type precursors pitch; (b) one or more kinds of carbonaceous resin precursors, in addition to one or more classes of carbonaceous lignin precursors according to claims 29 or 30 and / or one or more kinds of pitch precursors; or (c) one or more kinds of pitch type precursors, in addition to one or more classes of carbonaceous resin type precursors and / or one or more classes of lignin type precursors according to claims 29 or 30; Y

 ii. said at least one type of chemical agent according to any of claims 2 to 7.

 35. A method according to any one of claims 1 to 24 characterized in that it comprises a mixture of at least one type of carbonaceous precursor and two or more types of chemical agents,

 i. said at least one type of carbonaceous precursor according to any one of claims 25 to 30; Y

ii. said two or more types of chemical agents comprising (a) a type of chemical agent according to claims 2 or 3, in addition to a type of chemical agent according to claims 4 or 5 and / or a type of chemical agent according to claims 6 or 7; (b) a type of chemical agent according to claims 4 or 5, in addition to a type of chemical agent according to claims 2 or 3 and / or a type of chemical agent according to claims 6 or 7; or (c) a type of chemical agent according to claims 6 or 7, in addition to a type of chemical agent according to claims 2 or 3 and / or a type of chemical agent according to claims 4 or 5.

36. A method according to any one of claims 1 to 24 characterized in that it comprises a mixture of two or more types of carbonaceous precursors and two or more types of chemical agents,

 i. said two or more types of carbonaceous precursors comprising (a) one or more classes of lignin carbonaceous precursors according to claims 29 or 30, in addition to one or more classes of resin-type carbonaceous precursors and / or one or more kinds of type precursors pitch; (b) one or more kinds of carbonaceous resin precursors, in addition to one or more classes of carbonaceous lignin precursors according to claims 24 or 30 and / or one or more kinds of pitch type precursors; or (c) one or more kinds of pitch type precursors, in addition to one or more classes of carbonaceous resin type precursors and / or one or more classes of lignin type precursors according to claims 29 or 30; Y

 ii. said two or more types of chemical agents comprising (a) a type of chemical agent according to claims 2 or 3, in addition to a type of chemical agent according to claims 4 or 5 and / or a type of chemical agent according to claims 6 or 7 (b) a type of chemical agent according to claims 4 or 5, in addition to a type of chemical agent according to claims 1 or 2 and / or a type of chemical agent according to claims 6 or 7; or (c) a type of chemical agent according to claims 6 or 7, in addition to a type of chemical agent according to claims 2 or 3 and / or a type of chemical agent according to claims 4 or 5.

37. Method according to any one of claims 1 to 36 characterized in that it comprises the use of a device according to that described in patent document ES2326455A1, such that the mixture of at least one carbonaceous precursor and at least one chemical agent, duly dissolved by a suitable solvent is forced through a capillary tube located inside another capillary tube concentric with it; where an appropriate solvent is forced through the annular space between the two tubes; where, when applying a potential difference between the capillary tubes (connected to the same potential) and a reference electrode, an electrified meniscus is formed consisting of the conical meniscus of the precursor solution and a surrounding solvent layer; where downstream of the electrified meniscus a coaxial jet consisting of the jet of the solution is formed surrounded by the solvent layer; where the distance between the end of the inner capillary and the reference electrode varies between 1 mm and 1 m; where the potential difference applied between both electrodes varies between IV and 100 kV; where the flow rates of the solution and the solvent circulating in the capillaries are between 0.001 ml / h and 10000 ml / h; where the diameter of the coaxial jet is between 900 microns and 5 nanometers.

 38. Method according to any one of claims 1 to 36 characterized in that it comprises the use of a device according to that described in patent document ES2326455A1, such that the mixture of at least one carbonaceous precursor and at least one chemical agent, duly dissolved by a suitable solvent is forced through the intermediate annular space left by three capillary tubes located concentrically; where an inert liquid is forced through the innermost tube, which does not change phase during the process; where an appropriate volatile solvent is forced through the annular space between the two outermost tubes; where by applying a potential difference between the capillary tubes (connected to the same potential) and a reference electrode an electrified meniscus is formed with a structure in which the conical meniscus of the precursor solution is surrounded by a solvent layer and contains inside the meniscus of inert liquid; where the jets emanating from the vertices of the menisci give rise to a coaxial jet of three liquids in which the precursor solution surrounds the inert liquid and is in turn surrounded by a solvent layer; where the distance between the end of the inner capillary and the reference electrode varies between 1 mm and 1 m; where the potential difference applied between both electrodes varies between IV and 100 kV; where the flow rates of the solution and the solvent circulating in the capillaries are between 0.001 ml / h and 10000 ml / h; where the diameter of the coaxial jet is between 900 microns and 5 nanometers.

 39. Method according to the preceding claim characterized in that the inert liquid is replaced by another, for example a polymer or a sol-gel, etc., capable of solidifying.

 40. Particles and carbonaceous materials with optimized properties obtained by a method according to any of the preceding claims.

41. Use of optimized property particles and carbonaceous materials obtained by a method according to any one of claims 1 to 39 as adsorbents, catalysts, support of catalysts and / or electrodes in supercapacitors, batteries, fuel cells, sensors and / or other electrochemical applications.