Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
  • B01J31/006—Catalysts comprising hydrides, coordination complexes or organic compounds comprising organic radicals, e.g. TEMPO
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
  • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
  • B01J31/06—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing polymers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
  • C01B15/01—Hydrogen peroxide
  • C01B15/022—Preparation from organic compounds
  • C01B15/023—Preparation from organic compounds by the alkyl-anthraquinone process
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
  • D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/22—Other features of pulping processes
  • D21C3/222—Use of compounds accelerating the pulping processes

Definitions

• the present invention relates to novel supported anthraquinone catalysts, processes for their preparation, and their uses, in particular for kraft cooking of wood chips.
• the largest pulp production uses the kraft process as a cellulose extraction method. Based on the use of sodium hydroxide solution and sodium sulphide, the kraft process is today the universal process for the production of chemical pulp. This has many advantages such as a low level of residual lignin and good mechanical and physico-chemical properties of the fibers. This process is also self-sufficient in energy and allows a reduction in reagent consumption with regeneration of inorganic reagents.
• the kraft process has significant disadvantages: low yields (about 45%) because some hemicelluloses and cellulose is degraded; formation of volatile sulfur derivatives, responsible for olfactory nuisances ....
• anthraquinone in catalytic amount has proved to be very effective in improving soda and kraft cooking. It allows both to improve the yield of cellulosic pulp and to speed up delignification. Despite this efficacy, the non-regeneration of anthraquinone and its high cost are currently unfavorable for widespread industrial use. There is therefore a need for effective catalysts for cooking wood kraft, which can be recycled.
• the present invention therefore aims to provide new anthraquinone catalysts especially for kraft cooking wood.
• the present invention also aims to provide new fully recyclable anthraquinone catalysts.
• the present invention also aims to provide effective anthraquinone catalysts for wood kraft cooking and to improve the efficiency of this process.
• the present invention relates to a supported anthraquinone catalyst, comprising a polymeric support containing on the surface at least one anthraquinone unit, said supported anthraquinone catalyst being capable of being obtained by radical polymerization of a reaction mixture comprising:
• At least one at least one difunctional crosslinking agent selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, di (ethylene glycol) dimethacrylate, compounds comprising an alkyl chain, interrupted by one or more groups; (CH 2 ) k O) m with 2 ⁇ k ⁇ 5, 1 ⁇ m ⁇ 3, substituted in position a or ⁇ by at least one acrylate, methacrylate, vinyl or styrenic function, and mixtures thereof;
• n is an integer ranging from 1 to 5.
• the present invention also relates to a process for the preparation of a supported anthraquinone catalyst as defined above, by radical polymerization of a reaction mixture comprising:
• At least one at least difunctional crosslinking agent as defined above is at least one at least difunctional crosslinking agent as defined above;
• At least one anthraquinone styrenic monomer of formula (I) as defined above at least one anthraquinone styrenic monomer of formula (I) as defined above.
• the anthraquinone catalyst according to the invention is obtained according to a process well known to those skilled in the art, radical polymerization. This process is carried out by growth and propagation of macroradicals. These macroradicals, with a very short life time, recombine irreversibly by coupling or disproportionation.
• Such a process consists of a chain polymerization which involves radicals as active species. It includes priming, propagation, termination and chain transfer reactions.
• the first step of such a method consists in the generation of so-called primary radicals using a free radical initiator as defined below.
• the method used may be a so-called "controlled” or "living” radical polymerization process, which is also a process well known to those skilled in the art.
• controlled radical polymerization mention may be made, for example, of the RAFT (reversible addition-fragmentation chain transfer) or NMRP (nitroxide-controlled radical polymerization) methods.
• the polymerization is carried out in a mold by simple heating.
• the reaction mixture is as defined above and comprises one or more monomers including a crosslinking agent, one or more porogens and an initiator.
• the catalyst is obtained in the form of a monolith which is purified with a more volatile solvent to remove the heavier blowing agents and reagents unreacted.
• Monomers used to prepare the catalysts include styrene.
• the above-mentioned reaction mixture comprises from 10% to 30% by weight of styrene relative to the total weight of the reaction mixture.
• the weight content of styrene in the reaction mixture is between 15% and 25%, and preferably between 20% and 25%.
• the polymerization process is initiated by addition of a polymerization initiator (or initiator).
• a polymerization initiator or initiator.
• These initiators are called “free radical initiators”.
• thermal initiators redox or initiators for controlled radical polymerization.
• the thermal initiators are chosen from initiators that generate the radicals by thermal decomposition.
• examples include organic peresters (t-butylperoxypivalate, t-amylperoxypivalate, t-butylperoxy-2-ethylhexanoate, etc.); organic compounds of the azo type, for example azobisamidinopropane hydrochloride, azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile, etc.); inorganic and organic peroxides, for example hydrogen peroxide, benzoyl peroxide and butyl peroxide.
• the initiator used is an organic peroxide or an organic compound of azo type.
• an initiator is preferably benzoyl peroxide or azobisisobutyronitrile (AIBN), and is preferably AIBN.
• redox initiators for which the production of radicals results from a redox reaction.
• redox initiator systems such as those comprising oxidizing agents, such as binders (especially ammonium or alkali metal persulfates, etc.); chlorates and bromates (including inorganic or organic chlorates and / or bromates); reducing agents such as sulphites and bisulphites (including inorganic and / or organic sulphites or bisulfites); oxalic acid and ascorbic acid as well as mixtures of two or more of these compounds.
• the above-mentioned reaction mixture comprises from 0.1% to 5% by weight of initiator relative to the total weight of the reaction mixture.
• the content by weight of initiator in the reaction mixture is between 0.5% and 3%.
• the reaction medium also comprises at least one crosslinking agent.
• This crosslinking agent is an at least difunctional agent.
• this crosslinking agent is a compound comprising an alkyl chain interrupted by one or more groups - ((CH 2 ) k O) m with 2 ⁇ k ⁇ 5, 1 ⁇ m ⁇ 3, the (s) said group (s) being substituted in the ⁇ or ⁇ position by at least one acrylate, methacrylate, vinyl or styrenic function.
• a crosslinking agent according to the invention comprises, for example, at least two functions, chosen in particular from the acrylate, methacrylate, vinyl and styrene functional groups.
• the crosslinking agent according to the invention comprises at least two vinyl functional groups or at least two (meth) acrylate functional groups.
• the crosslinking agent is a crosslinking agent selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, di (ethylene glycol) dimethacrylate, and mixtures thereof.
• the crosslinking agent according to the invention is di (ethylene glycol) dimethacrylate.
• the aforementioned reaction mixture comprises from 10% to 30% by weight of crosslinking agent relative to the total weight of the reaction mixture.
• the content by weight of crosslinking agent in the reaction mixture is between 12% and 25%, and preferably between 15% and 20%.
• the reaction mixture also comprises at least one porogenic agent, and preferably at least two porogenic agents.
• the blowing agent is chosen from compounds in which the catalyst is insoluble and in which the styrene-containing anthraquinone monomers of formula (I) are soluble at the temperature of the process of the invention.
• the blowing agents do not react during the polymerization but participate in the formation of pores. They remain trapped in the pores, surrounded by the polymer mass until the end of the reaction. Their volume fraction is related to porosity. According to one embodiment, the boiling point of these compounds is higher than the polymerization temperature.
• the blowing agent is selected from the group consisting of toluene, long chain alcohols comprising at least 10 carbon atoms, and preferably from 10 to 20 carbon atoms, long chain alkanes comprising at least less than 10 carbon atoms, and preferably from 10 to 20 carbon atoms, oligomers of ethylene glycol and mixtures thereof.
• oligomer of ethylene glycol refers in the context of the present invention to a compound consisting of at least two ethylene glycol units.
• Such a compound can be represented for example by the formula H- (OCH 2 CH 2 ) i -OH, i being an integer greater than or equal to 2, and preferably less than 4.
• the anthraquinone supported catalyst according to the invention is obtained by the aforementioned method comprising the implementation of a mixture of at least two porogenic agents.
• the blowing agent is a mixture of at least two compounds selected from the group consisting of toluene, long-chain carbon alcohols comprising at least 10 carbon atoms, long-chain alkanes of at least 10 atoms of carbon and oligomers of ethylene glycol.
• the reaction mixture comprises dodecanol and / or toluene as a blowing agent.
• the blowing agent is a mixture of dodecanol and toluene.
• the above-mentioned reaction mixture comprises from 10% to 60% by weight of porogenic agent (s) relative to the total weight of the reaction mixture.
• the content by weight of agent (s) porogen (s) in the reaction mixture is between 30% and 60%, and preferably between 50% and 60%.
• the reaction mixture according to the invention also comprises at least one monomer of formula (I) as defined above.
• This monomer is a monomer of the anthraquinone family.
• n is 2.
• the aforementioned reaction mixture comprises less than 10% by weight of anthraquinone styrene monomer of formula (I).
• the content by weight of styrenic monomer anthraquinone of formula (I) in the reaction mixture is between 0.01% and 10%, and preferably between 5% and 10%.
• the aforementioned reaction mixture comprises:
• crosslinking agent in particular di (ethylene glycol) dimethacrylate, relative to the total weight of the reaction mixture;
• porogen preferably a mixture of dodecanol and toluene, relative to the total weight of the reaction mixture
• the catalysts according to the invention are supported catalysts which comprise a polymeric support containing on the surface at least one anthraquinone unit.
• This anthraquinone unit is derived from the aforementioned monomer of formula (I).
• These catalysts thus comprise a support of polymeric nature on which anthraquinone units are grafted.
• the anthraquinone catalysts supported according to the invention comprise from 5% to 20%, preferably from 8% to 1%, by weight of anthraquinone relative to the total weight of supported anthraquinone catalyst.
• the catalysts according to the invention are in particular in the form of monoliths.
• Monoliths are porous and solid materials formed in one piece. According to the invention, they are polymeric (organic) in nature.
• the catalysts according to the invention can also be designated as “macroporous rigid organic monoliths", or as monolithic anthraquinone catalysts or as monolithic catalysts.
• the monolithic catalysts according to the invention are different from the catalysts usually used in emulsion, namely in the form of particles.
• the Catalysts according to the invention are not in the form of particles but of monoliths as indicated above.
• These monoliths consist of several grains (microspheres) aggregated in the form of clusters (aggregates of grains) and have pores whose size is highly dependent on the composition of the polymerization mixture (reaction mixture). "Pores” are irregular voids formed between and in clusters. They are interconnected and form channels that allow the monolith to be penetrated in its depth by solutes and solvents.
• the catalysts obtained according to the invention are therefore porous materials consisting of pores of varying shapes and sizes.
• the pores are classified according to their size in three categories:
• mesopores with dp0 res between 2 nm and 50 nm mesopores with dp0 res between 2 nm and 50 nm
• the catalyst of the invention is a mesoporous monolith.
• the porous structure of monoliths can be evaluated using several techniques among which:
• SEM scanning electron microscopy
• TEM transmission electron microscopy
• AFM atomic force microscopy
• the average pore diameter of the catalysts in the dry state can vary from 5 nm to 10 nm as measured by the BET method (as detailed in the experimental section below) and from 50 nm to 300 nm as measured by mercury porosity (as detailed in the experimental section below).
• the monolithic catalysts according to the invention take the form of the polymerization reactor (tube or column), the latter may consist of different materials: glass, steel, silicone, synthetic polymers, ....
• the catalysts of the invention may have several geometric shapes, such as cylinders or balls. According to a preferred embodiment, the catalysts of the invention have a cylindrical shape.
• the diameter of the monoliths synthesized can be between 10 micrometers for example for chromatographic columns and 25 millimeters or even up to 200 millimeters for example for reaction media.
• the supported anthraquinone catalyst has a specific surface area, determined by the BET method, greater than or equal to 20 m 2 / g, and preferably between 20 and 200 m 2 / g.
• the pore surface associated with that of the grains per unit mass represents the specific surface area of the porous material.
• the main contribution to the specific surface comes from micropores and then mesopores. The more micropores there are, the greater the specific surface area.
• Macropores have a negligible contribution to the specific surface but allow the liquid to circulate inside the monolith at a relatively low pressure. They are the ones that will support the hydraulic or electroosmotic flow in the monolith and allow convective mass transfer.
• the anthraquinone catalysts supported according to the invention have interesting mechanical properties.
• the Young's modulus of these catalysts can be between 100 MPa and 400 MPa.
• the Young's modulus characterizing the elastic behavior of the material was estimated by considering the monolith in rectangular form of width and height equal to 10 mm and length between supports of 35 mm.
• the catalysts according to the invention also have the advantage of being able to be recycled, that is to say that they can be used at least once again after a first use, and this while retaining their catalytic properties. They can advantageously be reused several times after their first use. Preferably, they are recycled, that is to say reused, for at least 4, even 5 or even 6 times.
• This recyclability character is particularly advantageous especially with respect to conventional catalysts in the form of particles.
• the present invention also relates to the use of the supported anthraquinone catalyst as defined above, for catalyzing the kraft or alkaline cooking of wood or lignocellulosic biomass.
• Alkaline cooking of wood is the simplest alkaline cooking method, in which the wood is treated with an aqueous solution of sodium hydroxide at a temperature between 150 ° C and 170 ° C. At the end of cooking, the black liquor containing dissolved organic and inorganic derivatives is concentrated by evaporation and burned. The residue obtained is the sodium carbonate which will be converted into sodium by caustification with calcium hydroxide. This process makes it possible to isolate the cellulose fibers after removal of a large part of the lignin and hemicelluloses.
• the kraft process also known as the sulphate process, is a process in which sodium sulphate is used as a chemical in the regeneration of the cooking liquor. This process is used today in most paper mills which are easily recognizable thanks to the smell given by volatile sulfur compounds formed during cooking.
• the wood chips are treated at a temperature of 160 ° C. to 180 ° C. (8-9 bar pressure) for 2 to 3 hours in a chemical reactor called digester in the presence of an aqueous solution of sodium hydroxide (NaOH) and sodium sulphide (Na 2 S) called "white liquor”.
• a chemical reactor called digester in the presence of an aqueous solution of sodium hydroxide (NaOH) and sodium sulphide (Na 2 S) called "white liquor”.
• black liquor contains mainly inorganic salts and organic compounds consisting of lignin and polysaccharides obtained by degradation but also small amounts of extractives. During this cooking, the lignin is dissolved releasing the cellulosic fibers.
• the present invention also relates to a process for the preparation of a cellulosic pulp, comprising a kraft or alkaline cooking step of wood chips or of lignocellulosic biomass at a temperature of between 130.degree. 180 ° C for a period of 30 minutes to 120 minutes, in the presence of water, supported anthraquinone catalyst as defined above, and an aqueous solution of sodium hydroxide and / or sodium sulfide.
• the invention therefore also relates to the implementation of the sodium process or kraft process mentioned above with the catalyst according to the invention.
• This process consists in bringing wood chips or lignocellulosic biomass with water, said catalyst and an aqueous solution of sodium hydroxide and / or sodium sulphide (depending on the applied technology).
• the content by weight of active alkali namely the weight content of sodium hydroxide and sodium sulphide, expressed in equivalent grams of NaOH or Na 2 O, is between 9% and 26% by weight. relative to the total weight of dry wood (wood chips or lignocellulosic biomass).
• the sulfide S corresponding to the existing sulfur content defined as the ratio between sodium sulphide and active alkali, ranges from 25% to 35%.
• the dilution factor ranges from 3 to 4.5 (the dilution factor represents the ratio between the total amount of water (sum of the water contained in the wood plus the volume of white liquor) and the amount of dry wood).
• the content of anthraquinone catalyst according to the invention is less than 0.5% by weight relative to the weight of dry wood used.
• the use of the catalysts according to the invention is particularly advantageous in the context of the kraft process because the yields are improved compared to a kraft process with the anthraquinone catalysts according to the state of the art.
• these catalysts make it possible to use a lesser amount of reagents (sodium hydroxide and sodium sulphide) compared to the kraft processes with the anthraquinone catalysts according to the state of the art.
• the present invention also relates to a process for preparing hydrogen peroxide, comprising a step of hydrogenation of the supported anthraquinone catalyst as defined above, followed by a step of oxidation with oxygen in the air.
• the reagents used are commercially available from Sigma-Aldrich.
• This example relates to the preparation of the monomer of the following formula:
• the first step is a Diels-Alder reaction between myrcene and naphthoquinone which leads to the formation of 2- (4-methyl-pent-3-enyl) anthraquinone, 1A.
• This product was synthesized by the company "Resinic and Terpenic Derivatives”.
• Myrcene and naphthoquinone are solubilized in toluene or a mixture of toluene and butanol.
• the solution is heated at 90 ° C until the reagents are consumed.
• the aromatization is carried out by following by adding 50% sodium or potassium hydroxide solution while maintaining the mixture at 70 ° C while bubbling oxygen. After evaporation of the solvents the 1A derivative is obtained with a yield greater than 90%.
• the synthesis protocol has been described by Cazeils (Synthesis of new paper-based cooking catalysts: study of their mechanisms of action, Thesis No. 3477, Bordeaux 1 University, 2007).
• the second stage of monomer synthesis is the epoxidation of the double bond of the anthraquinone side chain followed by an oxidative cleavage of the aldehyde epoxide (electrophilic opening of the epoxide).
• the last step is the Wittig reaction of the aldehyde with 4-vinylbenzyltriphenylphosphonium chloride in the presence of a phase transfer agent.
• the second step is to synthesize 2- [2-3,3-dimethyl-oxiranyl) anthraquinone (1 B).
• the method further comprises an intermediate step of synthesizing 4-vinylbenzyltriphenylphosphonium chloride (1 E).
• the last step of the process is the synthesis of 2- [4- (4-vinyl-phenyl) -but-3-enyl] -anthraquinone (1 D).
• the general scheme of the polymerization reaction for the synthesis of the anthraquinone catalysts according to the invention is represented below.
• the table below indicates the amounts of the reagents used for the synthesis of St-DVB-AQ monoliths with a diameter of 10 mm according to this example (monolith with divinylbenzene as crosslinking agent).
• the reaction mixture composed of styrene, crosslinking agent (DVB, EGDMA or DEGMDA), toluene, dodecanol, AQwittig and AIBN purified in ethanol at 50 ° C and recrystallized at 0 ° C
• the reaction medium is homogenized under ultrasound at 50 ° C.
• the medium is drawn under vacuum and then immersed in an oil bath heated at 70 ° C. for 24 hours.
• the monolith is carefully extracted from the contacted tube with liquid nitrogen and then washed with 700 mL of THF in soxhlet for about 8 hours to remove the porogens and unreacted monomers. After purification, it is dried under vacuum at 200 ° C for 12 hours.
• the synthesis yield is determined by an indirect method by UV-Visible spectrometry.
• the extraction solvent is concentrated to determine, by UV spectrometry, the unreacted AQwittig monomer in order to determine the AQ functionality of the monolith.
• the monolith is analyzed in UV, GC, SEM, BET and PIM.
• AIBN is purified by crystallization in ethanol. After dissolving 5 g of AIBN in 50 mL of ethanol at 50 ° C, the solution is immediately filtered and the filtrate is cooled to 0 ° C. The AIBN crystallizes rapidly and the crystals obtained by filtration are dried under vacuum at room temperature and kept in a bottle protected from light.
• the above detailed example relates to the preparation of monoliths from divinylbenzene as a crosslinking agent but has also been applied identically with EGDMA or DEGDMA crosslinking agents using the same amounts of reagents. number of moles.
• the extraction solvent is concentrated to determine, by UV spectrometry, unreacted AQwittig monomer to determine the anthraquinone (AQ) functionality of the monolith.
• the assay of grafted QA is performed by an indirect assay by evaluating the amount of unreacted QA.
• the AQwittig has a characteristic band at 327 nm which makes it possible to go back up after a calibration to the non-grafted concentration of AQ.
• the amount AQwittig grafted is the difference between the initial amount and the amount dosed.
• UV-Vis spectrometry Determination of the monomer AQwittig
• UV-Visible Assays are performed with Perkin Elmer Lambda Apparatus
• the grafted anthraquinone is assayed by UV-Visible absorption in the following washing mixture: the THF solvent used for the purification of the monoliths, diluted in dichloromethane. After determining the absorbance at 327 nm of the solution, the amount of QA is determined based on pre-calibration with AQwittig solutions of known concentrations. The linearity of the calibration makes it possible to apply the Beer-Lambert law:
• I is the optical path length (the thickness of the quartz cuvette of 1 cm)
• the gravimetric efficiency (Y) in AQwittig is determined by making the ratio between the grafted mass and the mass introduced at the beginning.
• the grafted QA (T AQ ) rate is determined after calculating the remaining mass (m r ) of AQwittig according to the following equations:
• V m initial ⁇ TM r - 100 (%)
• Grafted QA ( TQA ) on monoliths is between 8 and 11% AQ per gram of monolith.
• the graft yield (Y) of grafted AQwittig, determined by UV, is greater than 99% in the case of the three types of monoliths.
• ATG was performed using a Shimadzu model TGA-50TA. About 10 mg of product is placed on a platinum boat and then heated to 500 ° C., with a gradient of 10 ° C./min, under a nitrogen or oxidizing (air) atmosphere.
• the apparatus used is a MTS QTest25 Elite tensile machine with a maximum force of 25 kN. It makes it possible to calculate the Young's modulus using a TestWorks 4 software. The measurements were performed on cylindrical samples (radius 10 mm, height 40 mm) with an initial compression speed imposed at 1 mm / min. . The length between the supports is equal to 35 mm. 3. Morphology of monoliths
• the morphology of the monolithic catalysts can be analyzed according to various techniques described below.
• the internal structure of the monoliths was visualized with a scanning electron microscope type JOEL JMS-6700 Field Emission between 2-5 kV.
• the dry monoliths were first metallized with a layer of gold deposited for 20 seconds with a JOEL-JFC-1200 Fine Coater, to facilitate the evacuation of electrons to the surface.
• Sample sections with a thickness of 50 and 75 nm are made on ultramicrotome ultracut E (Leica) using a diamond knife at a speed of 1 mm / sec floating on water. These sections are deposited on 600 mesh copper grids with fine hexagonal bars and are observed under a microscope.
• Nitrogen adsorption porosimetry Monolith porosity (BET) The specific surface area of monoliths was measured by nitrogen adsorption at 77K with a Micrometrics ASAP2100 device, assuming that the surface of a single nitrogen molecule is from 16.2 to. The samples are degassed and dried under vacuum at 120 ° C for 24 hours before each measurement. By monitoring the pressure, the number of adsorbed molecules is determined and an adsorption isotherm is obtained which makes it possible to calculate the specific surface using the BET model (Brunauer, Emmett, Teller) based on the analytical calculation of the isotherms of adsorption determined experimentally. This method measures the (multimolecular) adsorption and nitrogen desorption on the surface of the monolith during its cooling with liquid nitrogen and allows to deduce the porosity from the isotherms.
• BET Monolith porosity
• adsorption equilibrium For a given temperature, the relationship between the amount of adsorbed gas (mass or volume) and its pressure is called adsorption equilibrium isotherm. It expresses the thermodynamic equilibrium between the gas phase and the solid phase.
• the shape of the adsorption isotherms gives indications on the characteristics of the material.
• six adsorption isotherm curves are described (Rouquerol, F. Llewellyn, P. Rouquerol, J. Luciani, L. Denoyel, R. Engineering Techniques 2003, P1050).
• the type II adsorption isotherm is characteristic of a multimolecular adsorption and it is obtained with non-porous or macroporous adsorbents on the surface of which the adsorbed layer gradually thickens.
• the type IV adsorption isotherm is obtained with mesoporous adsorbents in which a capillary condensation occurs.
• the desorption of the condensed nitrogen by capillarity in the mesopores is not reversible: a hysteresis of the desorption is generally observed with respect to the adsorption.
• the adsorption isotherms of type III and V are observed in the case of the adsorption of water vapor by a hydrophobic surface. They are much rarer for materials with weak adsorbent / adsorbable interactions.
• the BET method makes it possible to determine in the dry state the total porosity of a monolith: micropores, mesopores and macropores.
• Porosimetry by mercury intrusion Porosity of monoliths (PIM)
• Mercury intrusion porosimetry is used to characterize the pore size distribution and porosity of macroporous materials. The measurements are carried out on a Micrometrics AutoPore IV 9500 device on samples whose mass is between 0.4 and 1 g.
• the volume of non-wetting mercury (the contact angle of mercury, Q Hg , is generally between 1 10 and 160 ° depending on the surfaces considered) penetrates into the pores of the sample (under vacuum) as a function of the applied pressure mercury.
• the diameter of the pore in which the mercury can penetrate is inversely proportional to the applied pressure: the smaller the pores, the greater the need for high pressure (Krajnc, P. Leber, N., Stefanec, D .; , S. Podgornik, A. Journal of Chromatography A 2005, 1065, (1), 69-73).
• the cylindrical pore model and the variation of the intrusion volume as a function of the pressure make it possible to calculate the average pore diameter.
• the porosity of the DEGDMA-based monolith is not measurable by the PIM technique due to the absence of mercury penetration. This monolith does not exhibit macroporosity. According to the results obtained by PIM measurement for EGDMA or DVB-based monoliths, these two types of monoliths present macropores with, in addition, mesopores in the case of the EGDMA-based monolith.
• the cooking is carried out using the rotary digester of Smurfit Kappa Cellulose Pine.
• the maritime pine peeling wood in the form of chips, is sorted using sieves of different sizes to use fractions of diameter 7 mm and thickness 4 mm.
• the digester is an autoclave consisting of six shells, which are immersed in an oil bath.
• the dryness is measured in an oven at 105 ° C for 24 hours on 200 g of damp wood.
• each shell 450 g of wood chips (expressed in dry) are introduced including 180 g (40%) of thickness 4 mm and 270 g (60%) of diameter 7 mm.
• the cooking conditions are different depending on the value of the targeted kappa index.
• the example was carried out for a targeted kappa index of 25.
• the white liquor is taken from the factory (industrial laundry).
• Active alkali total amount of sodium hydroxide and sodium sulphide expressed in equivalent grams of NaOH or Na 2 0
• sulphidity corresponding to the existing sulfur content defined as the ratio of sodium sulphide to active alkali
• the active alkali content used in cooking varies between 9-22% and the sulphidity between 25-30%.
• the dilution factor of 3.5 represents the ratio between the total amount of water contained in a shell (the sum between the water of the wood, the volume of white liquor and the filler) and the quantity of dry wood.
• the digester rotated without the shells is preheated to 80 ° C. At this temperature, shells filled with wood, liquor, water and in some cases with the catalyst are introduced. For example, for an alkali of 20%, in a control shell is introduced about 360 g wet wood thickness 4 mm, 520 g wet wood diameter 7 mm, 770 mL of white liquor active alkali of 1 16 g / Na 2 0 and 380 mL of water.
• the shells are cooled down by immersing them in cold water.
• shells with monoliths they are recovered and kept in the black liquor.
• the chips are prewashed overnight, defibrated for 2 minutes, washed and dewatered; pulp is obtained at the end of this series of operations.
• the yield is calculated by weighing taking into account the dryness of the dough on 50 g.
• a quantity of 50 g of the recovered paste is diluted in 2.5 L of water and defibrated for 10 minutes.
• a sheet is made using the Noble Wood form with one liter of the diluted suspension. After drying the sheet on the Noble and Wood drier at 120 ° C to constant weight, the dry weight of the sheet is determined by weighing. This then makes it possible to calculate the volume necessary to take a gram of dough to measure the kappa index.
• the kappa index of the dough which measures the degree of delignification of an unbleached dough, the following procedure was used.
• the kappa number is obtained by oxidation of the residual lignin in the presence of a precise volume of potassium permanganate brought into contact with the pulp for a determined time. In the presence of lignin, there is consumption of permanganate which must be between 20% and 60% of the initial quantity.
• the reaction is blocked by adding a solution of potassium iodide.
• the liberated iodine is then determined by a solution of sodium thiosulphate in an acid medium (ISO 302: 2004 standard, Pulps - Determination of Kappa number, 2nd edition, French Association of Standardization (AFNOR), 2004).
• Kappa index (V - V b
• Vbianc corresponds to the volume of Na 2 S 2 0 3 consumed using only water (without paste).
• St-DVB-AQ, St-EGDMA-AQ and St-DEGDMA-AQ monoliths have been found to be resistant under cooking conditions and do not degrade.
• Example 7 Recycling Catalysts Example 7.1.
• the monoliths are recovered completely and without loss during a first cooking and are tested again during a second cooking. Between two cooking, Monoliths are kept in black liquor and used without any purification steps. Black liquor keeps them in the same state of swelling and hydration at the end of cooking.
• the Kappa index which accounts for the residual lignin content on the fibers (the lower it is, the better the delignification has been), was measured on graded pasta. This classification consists of separating the fibers from the incuits. Measurement of the Kappa index is the measurement of the kappa index at the end of the process, eliminating incuits.
• Table 1 Classified Kappa Index ([IK] C ) according to the number of monolith recycling for active alkali of 22% compared to control cooks.
• Table 2 Kappa index Classified according to the number of monoliths recycling for an active alkali of 26% compared to control cooks.
• the first two bakes were made with a lot of wood different from the last three.

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