WO2012013735A1

WO2012013735A1 - Composition comprising catalyst and lignin and its use for producing an aromatic composition

Info

Publication number: WO2012013735A1
Application number: PCT/EP2011/062962
Authority: WO
Inventors: Emmanouil Pantouflas; Roman Prochazka; Stephan Schunk
Original assignee: Basf Se
Priority date: 2010-07-29
Filing date: 2011-07-28
Publication date: 2012-02-02

Abstract

The present invention relates to a composition ("composite") which comprises lignin and at least one catalyst dispersed in the composition. The invention further relates to a process for producing this type of composition comprising catalyst and lignin and its use for producing an aromatic composition.

Description

Catalyst and lignin-containing composition and their use for the preparation of an aromatic composition

description

The present invention relates to a composition ("composite") containing lignin and at least one catalyst dispersed in the composition. The invention further relates to a process for the preparation of such a catalyst and lignin-containing composition and their use for the preparation of a flavor composition.

The large quantities of biomass constantly produced by nature are so far only used to a limited extent as renewable raw materials for material use or for energy production. In order to protect raw material resources, processes are needed that enable the replacement of fossil raw materials with biomass raw materials. The aim is to achieve a high efficiency as complete as possible use of biomass material once provided.

In processes for the production of cellulose fall as by-product larger amounts of lignin in the form of black liquor. In classical pulping processes, such as power digestion (sulfate digestion), this black liquor is typically thermally recovered in the paper mill, and the remaining ash is worked up and reused in the leaching process of the wood. New processes, such as the Ligno-Boost process, offer the possibility of separating lignin from the black liquor and of supplying it to alternative uses. From a chemical point of view, lignin is interesting as a source of aromatics, if it succeeds to extract these in high yield from the resulting lignin. Both the recovery of so-called "monomeric" aromatics of interest, ie of aromatics having a benzene nucleus, but different substitution patterns, as well as the recovery of "oligomeric" aromatic (including in the context of this invention compounds having up to 15 aromatic Rings) or "polymeric" aromatics (which in the context of this invention are compounds having more than 15 aromatic rings), ie aromatics in which numerous aromatic nuclei are linked to one another, each of which may have identical or different substitution patterns. Low molecular weight aromatic compounds and especially phenolic compounds have found wide use as intermediate and value products. They serve z. As a precursor for various resins, surface-active compounds, specialty chemicals, etc. It is known to subject streams of various digestion processes of lignin or lignocellulosic materials to aftertreatment for the production of valuable substances. An overview of the development of catalytic pyrolysis of biomass starting materials can be found in G. Centi, R. van Santen, Catalysis for Renewables, From Feedstock to Energy Production, Wiley-VCH, Weinheim (2007), pages 1 19-147.

G.W. Huber et al. describe in Chem. Rev. 2006, 106, 4044-4098, the synthesis of fuels from biomass. After that, lignocellulosic materials can in principle be converted to three routes into liquid fuels which differ in their primary step: gasification to syngas, pyrolysis to bio-oil, hydrolysis to give sugars and lignin. The bio-oils obtained in the pyrolysis can then be subjected to hydrodeoxygenation in the presence of hydrogen or steam reforming.

US 2,057,117 discloses a process for producing vanillin which comprises heating a starting material selected from lignocellulose, a crude lignin extract and lignosulfonic acid with an aqueous alkali metal hydroxide solution under elevated pressure and adding sulfuric acid to the resulting reaction mixture to form organic To precipitate components and convert the vanillin into a soluble form.

WO 99/10450 describes a process for converting lignin into a hydrocarbon fuel. Lignin undergoes base-catalyzed depolymerization and subsequent hydroprocessing.

WO 2008/027699 A2 describes a process in which lignin originating from pyrolysis of biomass is decarboxylated and hydrodeoxygenated after separation of water-soluble constituents and the organic products from this process step are subsequently subjected to hydrocracking.

WO 2010/026244 describes an integrated process for the production of pulp and of at least one low molecular weight valuable material in which

a) providing a lignocellulose-containing starting material and subjecting it to digestion with a treatment medium,

b) isolating from the digested material a cellulose-enriched fraction and at least one cellulose-depleted fraction, the cellulose-depleted fraction comprising at least part of the treatment medium from step a), c) subjecting the cellulose-depleted fraction to a treatment to obtain at least one low molecular weight valuable substance, and

d) isolated from the treatment product obtained in step c) the valuable material (s).

In one embodiment of this process, a cellulose-enriched fraction and a lignin-enriched fraction are isolated from the digested material, subjected to lignin-enriched fraction of a depolymerization and isolated from the Depolymerisationsprodukt an aromatic composition. WO 2009/108601 describes a process for producing a starting material for biorefinery processes for producing a biofuel from a lignin-containing starting material. Lignin from a black liquor of the pulping process or else the black liquor itself is subjected to hydroprocessing in the presence of a hydrogen-containing gas and a catalyst on an amorphous or crystalline oxidic support. Specifically, a heterogeneous molybdenum sulfide catalyst is used.

WO 2009/108599 has a disclosure content comparable to WO 2009/108601 with a focus on papermaking.

US 2009/0227823 describes a process for preparing at least one liquid hydrocarbon product from a solid hydrocarbon feedstock (eg, a lignocellulosic material) by subjecting the feedstock to catalytic pyrolysis and subjecting the pyrolysis products to a catalysed sequential reaction to give liquid products ,

The unpublished European patent applications 10162255.3, 10162256.1 and 10162259.5 describe the production of organic recyclables from the digestion of lignocellulose-containing starting materials.

M. Stoecker describes in the Angew. Chem. 2008, 120, 9340 - 9351, the catalytic conversion of lignocellulose-rich biomass for the recovery of BTL (biomass-to-liquid) fuels in biorefineries. The use of a lignin material obtained from the biomass in a pyrolysis to bio oil and a further work-up to phenolic resins, synthesis gas, etc. are also shown schematically.

Under bio oil is generally a liquid fraction from the pyrolysis of lignin or a lignin-containing starting material, eg. As a lignocellulosic material of wood and / or vegetable fibers understood. This is a cooperation containing higher molecular weight, non-water-soluble organic compounds, which are mainly aromatic compounds (arenes). In today's processes for lignin pyrolysis, the highest possible proportion of bio-oil is generally sought as an important intermediate in the production of biofuels and chemicals.

It is an object of the present invention to provide an improved process for the pyrolytic production of an aromatics-containing product mixture from a lignin-containing starting material. The process should have at least one of the following properties:

1 . ) the total yield of aromatics based on the starting material should be as high as possible,

2.) the proportion of monomeric aromatics in the product mixture should be as high as possible,

3.) tar formation and / or the buildup of adherent coke layers in the reactor space should be avoided as far as possible,

4.) the method is the cost effective application of a catalytically active

Component on the feed lignin allow.

Another object is to provide a catalyst-containing composition which is advantageously suitable for use in such a process. It has surprisingly been found that the abovementioned disadvantages are reduced or avoided by subjecting a lignin-containing starting material to pyrolysis, the lignin-containing starting material being partly or wholly present as a composite ("composite") containing at least one catalyst distributed therein. It is particularly advantageous if the composite is subjected to compaction on contacting the lignin-containing starting material with the catalyst and / or subsequently.

A first subject of the invention is a composite containing lignin and at least one pyrolysis catalyst dispersed in the composite.

Another object of the invention is a composite which is obtainable by a process in which one provides a lignin-containing starting material and brings intimately into contact with at least one pyrolysis catalyst. Another object of the invention is a process for preparing a composite, in which one provides a lignin-containing starting material and intimately brings into contact with a pyrolysis catalyst. A further subject of the invention is a process for the preparation of an aroma composition from a lignin-containing starting material, in which a composite containing lignin and at least one pyrolysis catalyst dispersed in the composite is subjected to pyrolysis. In the case of the abovementioned objects, the material is subjected to compaction during and / or after contacting the lignin-containing starting material with the pyrolysis catalyst.

A further subject matter of the invention is a process for the preparation of a flavoring composition from a lignin-containing starting material, in which: a) a lignin-containing starting material is provided,

b) bringing the lignin-containing starting material into contact with a pyrolysis catalyst and subjecting it to compaction,

c) subjecting the compacted composite obtained in step b) to pyrolysis in a pyrolysis zone,

d) subjecting the effluent from the pyrolysis zone to separation to give the following three streams:

D1) of a solid catalyst-containing fraction,

D2) an aromatic-enriched fraction,

D3) of a fraction enriched in by-products which are lighter than D2),

e) the fraction D1) obtained in step d) is at least partially recycled to the pyrolysis zone.

The aromatic composition obtained by the process according to the invention corresponds in composition to a high-grade bio-oil. It is characterized by its high content of low molecular weight and higher molecular weight, non-water soluble organic compounds, which are mainly aromatic compounds. It is therefore particularly suitable as an intermediate for the production of biofuels and chemicals.

The aromatic composition obtained by the process according to the invention has a high proportion of aromatic compounds with up to 15 aromatic Wrestling up. The content of aromatic compounds having up to 15 aromatic rings is at least 50% by weight, based on the total weight of the aromatic composition. The aromatic composition obtained by the process according to the invention has a high content of mononuclear aromatic compounds. Mononuclear aromatics are also referred to in the context of the invention as "monomeric aromatics". Polynuclear aromatics having from 2 to 15 aromatic rings are also referred to as "oligomeric aromatics". Preferably, the flavor composition obtained by the process according to the invention contains at least 1% by weight, more preferably at least 2% by weight, of mononuclear aromatic compounds. The aroma composition obtained by the process according to the invention can advantageously be subjected to a subsequent dealkylation. The dealkylation products obtained in this way have a markedly increased content of mononuclear dealkylated aromatics compared with the aromatics composition used.

In particular, the process according to the invention makes it possible to prepare an aromatic composition containing monomeric aromatic compounds selected from benzene, toluene, xylenes, ethylbenzene, phenol, phenol ethers, cresols, xylenols, guasols, veratroles, resorcinols, catechols, hydroquinones and others thereof Links.

In the context of the invention, pyrolysis is understood as meaning a thermal treatment of the lignin-containing starting material, molecular oxygen being not or only to a small amount being supplied. A small amount is to be understood as an amount which is significantly less than the amount necessary for a complete oxidation of the carbon contained in the lignin-containing starting material to CO2. The amount of molecular oxygen fed in the pyrolysis is preferably at least 50 mol%, more preferably at least 75 mol%, in particular at least 90 mol% below the amount necessary for a complete oxidation of the carbon contained in the lignin-containing starting material to CO2 is necessary. Pyrolysis is generally endothermic.

composite

In the context of the invention, a composite designates a composition for the production of which a lignin-containing starting material and at least one pyrolysis catalyst are brought into intimate contact with one another. The composite according to the invention is comparable to a dispersion in which the catalyst is finely dispersed as a dispersed phase is present in the lignin-containing starting material as a continuous phase. Preferably, lignin-containing starting material and pyrolysis catalyst are subjected to compaction during and / or after contacting. Compression is a physical treatment in which the components are subjected to a treatment under elevated pressure. Conventional compression methods generally lead to the components being brought into intimate contact. The compression is associated with at least one of the following effects:

Intimately contacting lignin-containing starting material and pyrolysis catalyst,

fine distribution of the pyrolysis catalyst in the lignin-containing starting material,

Increase in density,

Increase in particle size,

- If necessary, reducing the content of at normal conditions (20 ° C, 1013 mbar) liquid components.

With regard to suitable and preferred compacting devices and compaction methods, reference is made to the statements below. Also with regard to suitable and preferred lignin-containing starting materials and pyrolysis catalysts, reference is made to the statements below below.

The composite of the invention contains the lignin preferably in an amount of 60 to 99 wt .-%, particularly preferably from 70 to 95 wt .-%, based on the total weight of the composite.

The composite according to the invention preferably contains the pyrolysis catalyst in an amount of from 0.1 to 20% by weight, more preferably from 0.2 to 5% by weight, based on the total weight of the composite.

The composite preferably has a content of at normal conditions (20 ° C, 1013 mbar) liquid components of at most 20 wt .-%, particularly preferably of at most 5 wt .-%. In particular, the composite preferably has a water content of at most 20% by weight, particularly preferably at most 5% by weight.

The composite preferably has an average particle size in the range from 1 to 2000 μΐτι, particularly preferably from 100 to 1000 μΐτι on. The d90 value of the composite is preferably at most 2500 μιτι, particularly preferably at most 2000 μιτι. The d50 value of the composite is preferably at most 1500 μιτι, more preferably at most 1250 μιτι.

The d10 value of the composite is preferably at most 600 μιτι, more preferably at most 500 μιτι.

The determination of the above-mentioned particle sizes can be carried out by known methods, for. B. dynamic laser light scattering done. To set a desired average particle size and a desired particle size distribution, the usual screening devices can be used.

The composite preferably has a bulk density in the range from 0.3 to 0.8 g / l, more preferably from 0.4 to 0.7 g / l.

Production of the composite

Another object of the invention is a method for producing a composite containing lignin and at least one distributed in the composite pyrolysis catalyst. In this case, a lignin-containing starting material is provided and intimately brought into contact with the pyrolysis catalyst. Preferably, during and / or after the contacting of the lignin-containing starting material with the pyrolysis catalyst, densification takes place, ie. H. the contacting and compacting can take place separately from each other or partially or completely together.

Provision of a lignin-containing starting material

The following statements on lignin-containing starting materials relate in full to both the preparation of the composites according to the invention and the preparation of an aroma composition by the process according to the invention described below.

Suitable lignin-containing starting materials are pure lignin and lignin-containing compositions. In this case, the lignin content of the compositions is not critical over a wide range, only if the lignin contents are too low can the process no longer be operated economically. Preferably, a lignin-containing starting material is provided, which contains at least 10 wt .-%, preferably at least 15 wt .-%, based on the dry matter of the material, lignin. Preferably suitable are lignin-containing compositions containing 10 to 100 wt .-%, particularly preferably 15 to 95 wt .-%, based on the dry matter of the material, lignin. In the context of this invention, the term dry matter is understood in the sense of the standard ISO 1 1465.

Also suitable for providing a lignin-containing starting material are lignocellulose-containing materials. Lignocellulose forms the structural framework of the plant cell wall and contains lignin, hemicelluloses and cellulose as main components. Further constituents of the plant cell wall and thus obtained lignocellulose-containing materials are, for. As silicates, extractable low molecular weight organic compounds (so-called extractives such as terpenes, resins, fats), polymers such as proteins, nucleic acids and gum (so-called exudate), etc.

Lignin is a biopolymer whose basic unit is essentially phenylpropane, which, depending on the natural source, may be substituted with one or more methoxy groups on the phenyl rings and with a hydroxy group on the propylene units. Thus, typical structural units of lignin are p-hydroxyphenylpropane, guaiacylpropane, and syringylpropane linked together by ether bonds and carbon-carbon bonds.

Both lignocellulose-containing materials which are used without further chemical treatment in natural composition, such as. As wood or straw, as well as lignocellulosic streams from the processing of lignocellulose, z. B. from processes for cellulose production (pulp process).

The lignocellulosic materials which can be used according to the invention are e.g. B. from wood and vegetable fibers available as starting material. Preferred lignocellulosic materials are those of wood and residues of the woodworking industry. These include z. B. the various types of wood, ie hardwoods, such as maple, birch, pear, oak, alder, ash, eucalyptus, hornbeam, cherry, linden, walnut, poplar, willow, etc. and conifers such as Douglas fir, spruce, yew, Hemlock, pine, larch, fir, cedar, etc. Wood can be distinguished not only in deciduous and coniferous wood, but also in so-called "hardwoods" and "softwoods", which is not synonymous with the terms deciduous or conifers. Softwood, in contrast to hardwood, is lighter in weight Wood (ie wood with a density of less than 0.55 g / cm ³ , such as willows, poplars, linden and almost all conifers). In principle, all hard and all softwoods are suitable for use in the production of the composites of the invention and in the process according to the invention for the preparation of an aromatic composition. The wood used can also be made up, eg. In the form of pellets. Suitable residues in the woodworking industry are not only wood waste but also sawdust, parquet sanding dust, etc. Suitable lignocellulosic materials are still natural fibers such as flax, hemp, sisal, jute, straw, coconut fibers, switchgrass (Panicum virgatum) and other natural fibers. Suitable lignocellulosic materials also fall as a residue in agriculture, z. B. in the harvest of grain (wheat straw, corn straw, etc.), corn, sugar cane (bagasse), etc. Suitable lignocellulosic materials are also available as a residue in forestry, z. In the form of branches, barks, wood chips, etc. A good source of lignocellulosic materials are also short rotation crops, which enable high biomass production in a relatively small area.

Preferably, to provide the lignin-containing starting material, a lignin-containing stream from the digestion of a lignocellulosic material is used to produce cellulose (pulp). The digestion permits at least partial separation of the lignocellulose-containing starting material into cellulose and cellulose accompanying substances, the latter also including lignin.

In a preferred embodiment, a lignocellulose-containing material is provided, subjected to digestion and isolated from the digested material, a cellulose-enriched fraction and a lignin-enriched (and simultaneously depleted in cellulose) fraction.

Processes for the digestion of lignocellulose-containing materials for the production of cellulose are known in principle. In principle, lignin-containing streams are suitable for use in the process according to the invention from all the digestion processes known to those skilled in the art. In principle, these processes can be classified with regard to the treatment medium used in aqueous-alkaline processes, aqueous-acidic processes and organic processes. An overview of these methods and the digestion conditions can be found z. In WO 2010/026244.

The treatment medium used to digest the lignocellulosic materials is capable of solubilizing at least a portion of the lignin. By contrast, the cellulose contained in the lignocellulose-containing material is generally not or only partially solubilized in the treatment medium. In front- Preferably, the separation of a cellulose-enriched fraction is then carried out by filtration or centrifugation.

Preferably, a lignin-containing (cellulose-depleted) fraction is isolated from the digested material, which contains in addition to lignin at least one further component which is selected from hemicellulose, cellulose, degradation products of the aforementioned components, digestion chemicals and mixtures thereof.

In many cases, it is not critical for the preparation of the composites of the invention and the pyro- lysis for the preparation of an aroma composition if a lignin-containing starting material is used which contains at least one further component in addition to lignin.

If a lignin-containing fraction which contains at least one further component in addition to lignin is used to provide the lignin-containing starting material, then at least some of the compounds other than lignin can be removed before being brought into contact with the pyrolysis catalyst. The components removed from the lignin-containing fraction (organic components and / or inorganic process chemicals) are preferably subjected to further work-up and / or thermal recovery, preferably in the course of the cellulose production process from which the lignin-containing fraction was obtained.

To remove at least a portion of the compounds other than lignin, the pH of the lignin-containing fraction can first be adjusted to a suitable value. Lignin-containing fractions from aqueous-alkaline processes (such as the Kraft process) can be treated with an acid to adjust the pH. Suitable acids are, for. B. CC> 2 (or resulting therefrom with water carbon dioxide), mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid. Lignin-containing fractions from aqueous-acidic processes can be mixed with a base to adjust the pH. Suitable bases are, for. As alkali metal bases, such as sodium hydroxide or potassium hydroxide, alkali metal carbonates, such as soda or potassium carbonate, alkali metal bicarbonates, such as sodium bicarbonate or potassium bicarbonate and alkaline earth metal bases, such as calcium hydroxide, calcium oxide, magnesium hydroxide or magnesium carbonate, and ammonia or amines.

Preferably, at least a portion of the lignin-distinct compounds are removed from the lignin-containing fraction by filtration, centrifugation, extraction, precipitation, distillation, stripping or a combination thereof. The person skilled in the art can use the separation process to determine the composition of the lignin-containing compounds Control the fraction and thus the composite. The at least partial separation of the components other than lignin can be carried out in one or more stages. Usual filtration methods are z. Cake and depth filtration (eg described in A. Rushton, AS Ward, RG Holdich: Solid-Liquid Filtration and Separation Technology, VCH Verlagsgesellschaft, Weinheim 1996, pages 177ff., KJ Ives, in A. Rushton (Ed.): Mathematical Models and Design Methods in Solid-Liquid Separation, NATO ASI Series E No. 88, Martinus Nijhoff, Dordrecht 1985, pages 90ff.) And cross-flow filtrations (e.g. Altmann, S. Ripperger, J. Membrane Sci. 124 (1997), pages 1 19-128). Usual centrifugation are z. See, for example, G. Hultsch, H. Wilkesmann, "Filtering Centrifuges," DB Purchas, Solid-Liquid Separation, Upland Press, Croydon 1977, pp. 493-559; and in H. Trawinski, The Equivalent Clarifying Surface of Centrifuges, Chem. Ztg. 83 (1959), pages 606-612. For extraction z. For example, a solvent which is immiscible with the treatment medium from pulp production or at least one solvent having a miscibility gap can be used, in which lignin and optionally further desired components are soluble in a sufficient amount. The separation of components which can be decomposed without decomposition from the lignin-containing fraction can be carried out by customary distillation methods known to the person skilled in the art. Suitable apparatus for working up by distillation include distillation columns, such as tray columns, which may be equipped with bells, sieve plates, sieve trays, packings, random packings, valves, side draws, etc., evaporators, such as thin film evaporators, falling film evaporators, forced circulation evaporators, Sambay evaporators, etc., and combinations from that. In a specific embodiment, a lignin-containing stream from the digestion of a lignocellulosic material which comprises at least part of the liquid treatment medium from the digestion is used to provide the lignin-containing starting material. Preferably, the lignin-containing stream is then subjected to precipitation of a lignin-containing fraction, followed by partial or complete removal of the liquid components, to provide the lignin-containing starting material for the preparation of the composite of the present invention.

Preferably, a lignin-containing stream from the digestion of a lignocellulosic material with an alkaline treatment medium is used to provide the lignin-containing starting material. Particularly preferably, a black liquor is used, in particular a black liquor from the sulfate digestion (power digestion). To provide a lignin-containing material, a black liquor from the Kraft digestion can first be acidified to precipitate at least a portion of the lignin contained and then the precipitated lignin can be isolated. For acidification the aforementioned acids are suitable. Preferably, the pH of the

Black liquor lowered to a value of at most 10.5. The isolation of the precipitated lignin is preferably carried out by a filtration process. Suitable filtration methods are those mentioned above. If desired, the isolated lignin may be subjected to at least one further work-up step. This includes z. B. a further cleaning, preferably a wash with a suitable washing medium. Suitable washing media are for. For example, mineral acids such as sulfuric acid, preferably in aqueous solution. Particularly suitable is the so-called lignoboost process. Lignoboost methods are described in WO 2006/038863 (EP 1797236 A1) and WO 2006/031 175 (EP 1794363 A1), to which reference is made here.

In a special embodiment, the lignin-containing starting material is already subjected to compaction before being brought into contact with the pyrolysis catalyst. Even with such a "precompacting" is carried out during and / or after contacting with the pyrolysis catalyst usually a further compaction.

Pyrolysis Catalyst In the context of the invention, the term "pyrolysis catalyst" also refers to catalyst precursors which are converted into the catalytically active form only before or during pyrolysis.

Preferably, an acidic pyrolysis catalyst is used as the pyrolysis catalyst. Suitable acidic pyrolysis catalysts are Lewis acidic and Bröstedt acidic pyrolysis catalysts.

The pyrolysis catalysts suitable for use in the composites of the invention are preferably selected from:

I) water-insoluble catalysts

II) water-soluble catalysts, and

Mixtures thereof.

Preferred water-insoluble catalysts I) are characterized by a defined acidity. Suitable catalysts I) are oxidic catalysts, which are preferably selected from oxides, oxide mixtures or mixed oxides of the main and sub-group elements. Oxide mixtures are mixtures which have at least two oxides of the main and subgroup elements.

Mixed oxides (also referred to as multimetal oxides) have, in addition to oxygen, at least two different metal atoms, which may be metals which differ from one another or identical metals in different oxidation states. Mixed oxides have a radiographically uniform phase.

The catalysts I) may be crystalline, partially crystalline or amorphous. Particularly preferred water-insoluble catalysts I) are oxides, mixed oxides or mixed oxides of the elements magnesium, boron, silicon, aluminum, phosphorus, iron, nickel, cobalt, calcium, sodium and sulfur. Particularly preferred are oxides, mixed oxides or mixed oxides of the elements magnesium, boron, silicon, aluminum, phosphorus, iron and sulfur. Especially preferred are oxides, mixed oxides or mixed oxides of the elements boron, silicon and aluminum. The oxides, mixed oxides or mixed oxides can each be crystalline, partially crystalline or amorphous.

Particularly preferred water-insoluble catalysts I) are also solid compounds having acidic properties (so-called solid acids). These include zeolites. Suitable zeolites are, in principle, the crystalline, naturally occurring or synthetic framework silicates known under this name. These may vary in composition, but generally have at least one alkali and / or alkaline earth metal in addition to silicon, aluminum and oxygen. In a special embodiment, a naturally occurring zeolite is used.

Also suitable are zeolite-analogous structures, acidic aluminas and modifications thereof. Preferred are modifications which have an influence on the strength or number of acidic centers. A first subject of the invention is therefore a nickel-containing catalyst obtainable by treating a zeolite with an acidic aqueous nickel salt solution and then calcining.

For the preparation of a modified zeolite z. For example, a zeolite may be subjected to modification with metal cations. This includes z. As the treatment with an acidic nickel salt solution. The treatment of the zeolite with the acidic aqueous metal salt solution is usually carried out by intimately contacting each other. This results in an ion exchange of cations of the zeolite (alkali / alkaline earth metal cations) against metal cations of the treatment solution. The contacting of the zeolite with the salt solution preferably takes place by customary dipping and impregnating methods, as are known for catalyst preparation. The adjustment of the pH can be carried out by addition of inorganic acids, such as hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid. For example, a nickel salt whose aqueous solution already has a suitable acidic pH is used to prepare the modified zeolites. The nickel salts used are preferably nickel (II) salts. These are used in particular in the form of nitrates, sulfates or acetates.

Suitable water-insoluble catalysts I) are furthermore crystalline or partially crystalline or amorphous oxides, mixed oxides or mixed oxides which are obtained in a catalyst factory as a by-product in the case of crushing or sieving. Also suitable are catalysts which are removed as deactivated catalysts in certain processes, for example in the FCC process.

Preferred water-soluble catalysts II) in combination with the lignin-containing starting material used for the production of the composites according to the invention have a specific acidity profile which has an advantageous effect in the context of the process according to the invention.

Particularly preferred water-soluble catalysts II) are selected from compounds of groups 1, 2, 3 to 12, and 13 to 16 of the Periodic Table of the Elements and mixtures thereof. In particular, the water-soluble catalysts II) contain at least one compound containing one of the following elements: Na, K, Mg, Ca, Sr, La, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, B Al, Si, P and S. Specifically, the water-soluble catalysts II) contain at least one compound containing one of the following elements: Na, Ca, La, V, Mn, Fe, B, Al, Si, P and S.

Suitable water-soluble catalysts II) are in principle covalent compounds, complex compounds and salts of the abovementioned elements. Suitable salts of these elements may include inorganic or organic counterions. Suitable water-soluble catalysts II) are, in particular, those compounds which are cost-effective and / or which do not introduce any undesired components into the pyrolysis reaction which have to be removed by complicated work-up steps. Such undesirable components may be, for example, halogens such as chlorine or bromine or their compounds. Preference is given to those compounds which do not have to be removed from the pyrolysis process or whose decomposition products do not have to be removed from the pyrolysis process. These include salts whose anions are preferably selected from sulfate, sulfide, sulfite, acetate, hydroxide, carbonate or nitrate. If a solvent is used for the preparation of the composites of the invention, preference is given to catalysts which are readily soluble in the solvents used to prepare the composites. If in one special embodiment for the preparation of the composite according to the invention a solvent other than water or a water-containing or anhydrous solvent mixture is used, catalysts are preferred which are soluble therein.

The pyrolysis catalysts used for preparing the composites of the invention are preferably selected from boric acid, zeolites, silicic acid, alumina, aluminosilicates, zirconium oxide, titanium dioxide, water-soluble nickel salts and water-soluble cobalt salts.

A special pyrolysis catalyst is boric acid.

Another special pyrolysis catalyst is a zeolite ZSM-5.

In a further specific embodiment, a naturally occurring zeolite is used as pyrolysis catalyst.

Another special pyrolysis catalyst is boehmite, as z. B. under the name Disperal offered by Sasol Germany GmbH.

Another special pyrolysis catalyst is nickel acetate.

Another special pyrolysis catalyst is cobalt acetate. In a specific embodiment, the pyrolysis catalyst comprises the catalyst-containing solid reactor effluent from a pyrolysis in the presence of a composite, as defined above.

Contacting and compacting

The preparation of the composite according to the invention comprises contacting the lignin-containing starting material with the pyrolysis catalyst (= step a)).

The production of the composite according to the invention also optionally comprises the combined densification of the lignin-containing starting material and the pyrolysis catalyst.

In a first preferred embodiment, the step a) is carried out alone, ie there is no additional compression of the lignin-containing starting material and of the pyrolysis catalyst. Suitable devices for the sole implementation of step a) are z. As drum mixer, rotary tubes or other suitable mixing plants.

In a second particularly preferred embodiment, the lignin-containing starting material and the pyrolysis catalyst are subjected to compaction during and / or after the contacting (steps a) and b)).

Preferably, the compaction is carried out by compacting, extruding, tableting or a combination of at least two of these measures.

The steps a) and b) can be carried out separately in time or partially or completely together. In a preferred embodiment, first the lignin-containing starting material is brought into contact with the pyrolysis catalyst under conditions in which essentially no compression takes place and the mixture thus obtained is subsequently compressed. Compression is usually associated with intimate contacting of the components. The steps a) and b) can therefore also be carried out together in a compacting device. If the contacting of the lignin-containing starting material with the pyrolysis catalyst takes place in the presence of a liquid treatment medium, it is preferable to carry out steps a) and b) separately from one another in terms of time. Thus, partial or complete removal of liquid components prior to compaction is enabled. If a solid lignin-containing starting material is brought into contact with a solid pyrolysis catalyst, it is possible to carry out steps a) and b) separately in time or partially or completely together.

The contacting of the lignin-containing starting material with the pyrolysis catalyst takes place in a first embodiment in the presence of a liquid treatment medium. Preferably, the liquid treatment medium is selected from water, water-miscible organic solvents and mixtures thereof. Suitable water-miscible organic solvents are alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, di- and polyols, such as ethanediol and propanediol, tetrahydrofuran, ketones, such as acetone and methyl ethyl ketone, and mixtures thereof. Preferred water-miscible organic solvents are methanol and / or ethanol.

Preferably, the water content of the liquid treatment medium is at least 70 wt .-%, more preferably at least 90 wt .-%, based on the total weight of the liquid treatment medium. In particular, water is used as the liquid treatment medium. The pyrolysis catalyst is preferably brought into contact with the lignin-containing starting material as a preparation in the liquid treatment medium. The liquid preparation may be present in the form of a solution, colloidal dispersion or dispersion of the catalyst in the treatment medium. For example, the usual immersion and impregnation processes, as known for catalyst preparation, are suitable for contacting. Preferably, the catalyst preparation in the liquid treatment medium during the treatment of the lignin-containing starting material is moved past this, z. B. by stirring or pumping.

Preferably, the liquid treatment medium is removed after contacting. These are the usual methods, eg. B. by concentration, optionally at elevated temperature and / or under reduced pressure. In a specific embodiment, the contacting of a preparation of the pyrolysis catalyst in the liquid treatment medium with the lignin-containing starting material is carried out by a modified "incipient wetness method". Excess treatment medium is removed after contacting. The contacting of the pyrolysis catalyst in a liquid treatment medium with the lignin-containing starting material is preferably carried out at a temperature of at least 10 ° C, more preferably of at least 20 ° C. The maximum temperature in the treatment is generally not critical, but is for practical reasons preferably below the boiling point of water, eg. B. at most 95 ° C.

The duration of the contacting of the pyrolysis catalyst in a liquid treatment medium with the lignin-containing starting material is preferably at least 30 minutes, in particular at least one hour.

Before the densification step, the treated lignin-containing starting material can additionally be subjected to drying. The temperature during the drying is preferably 30 to 100 ° C, more preferably 40 to 95 ° C. The drying can be done in customary devices, for. As drying cabinets and drying chambers done. For drying, a gas stream (eg an air stream) may additionally be conducted past the treated lignin-containing starting material.

The contacting of the lignin-containing starting material with the pyrolysis catalyst takes place in a second embodiment in the absence of a liquid treatment. development medium. Suitable methods for mixing a solid catalyst with the lignin-containing starting material are known mixing methods, for. B. for the preparation of powder mixture. For this purpose, devices known to those skilled in the art, such as drum mixers, rotary kilns or other suitable mixing plants, can be used.

The compression can be carried out in a conventional device.

Suitable extruders are single-screw machines, intermeshing screw machines or even multi-screw extruders, in particular twin-screw extruders. These may be rotating in the same direction or in opposite directions and optionally equipped with kneading disks. When a solvent needs to be evaporated during extrusion, the extruders are generally equipped with an evaporation section. Particular preference is given to extruders of the ZKS series by Werner and Pfleiderer. For tabletting a conventional device can be used.

Particularly preferably, the compaction is carried out by compaction. The compacting can be carried out in a conventional apparatus. These include roller compactors, as z. B. from the company Powtec available.

The resulting composite may be subjected to particle size separation in a suitable apparatus. These include the usual screening devices. The fraction having a sufficiently large particle size can be separated as a product. The fine material in the composite with too small a particle size is usually fed back to the compression.

The resulting composite can be subjected to comminution if desired. The comminution preferably takes place simultaneously with a separation on a screening machine.

When used in pyrolysis, the composites according to the invention and produced by the process according to the invention have a particularly advantageous property profile. This includes at least one of the following properties: 1.) High overall yield of liquid or liquefiable recyclable material

(In the context of the invention, this is understood as meaning an organic compound or a composition of at least two organic compounds which are liquid under normal conditions (20 ° C., 1013 mbar) or which are liquefiable without being liquefied; in the liquid state of aggregation in the sense of melting and not solubilization with the addition of a solvent),

2.) high overall yield of aromatics based on the starting material,

3.) high proportion of monomeric aromatics in the pyrolysis product,

4.) low proportion of compounds which have low volatility under the pyrolysis conditions,

5.) Prevention of tar formation and / or the buildup of adherent coke layers in the reactor space and other parts of the plant,

6.) Formation of a (catalyst-containing) coke with a defined granular structure, which facilitates transport through the plant and / or is easily recyclable.

pyrolysis

The composites according to the invention described above and the composites obtained by the process according to the invention described above are advantageously suitable for use in pyrolysis, wherein an aromatics composition is obtained as a desired product.

The invention therefore also provides a process for preparing an aroma composition from a lignin-containing starting material, in which a composite containing lignin and at least one acidic pyrolysis catalyst dispersed in the composite is subjected to pyrolysis. With regard to suitable and preferred embodiments of the lignin-containing starting material, the pyrolysis catalyst and the composite, reference is made in full to the information given above.

For pyrolysis, the lignin-containing starting material can be used partially or completely in the form of a composite. Preferably, the lignin-containing starting material is used to at least 50 wt .-%, preferably at least 70 wt .-%, in particular at least 90 wt .-% in the form of a composite. In a specific embodiment, the lignin-containing starting material for pyrolysis is used completely in the form of a composite.

The pyrolysis can be carried out batchwise or continuously. Continuous pyrolysis is preferred.

The pyrolysis takes place in at least one pyrolysis zone. In a preferred embodiment, the pyrolysis zone comprises at least one fixed bed. The fixed beds may comprise at least one inert fixed bed. Also possible is the use of at least one catalytically active fixed bed. The pyrolysis catalyst is preferably used completely in the form of a composite by the process according to the invention. If the process according to the invention is operated with at least one fixed bed as the pyrolysis zone, then an interval operation may be advantageous in which a pyrolysis phase is followed by a burn-off phase in order to remove low-volatility components from the fixed bed. In an alternative embodiment, the pyrolysis zone also z. B. be configured as a rotary kiln or fluidized bed. Both stationary and circulating fluidized beds are suitable. In the execution of the pyrolysis as a fluidized bed a fluidizing gas and as a fluidized material under the given conditions inert granular additive is supplied. Particularly suitable as an additive is quartz sand. Such a fluidized bed process is z. For example, in US 4,409,416 A described.

For pyrolysis, a feed gas is preferably fed into the pyrolysis zone.

Preferred feed gases contain at least one gas which is selected from nitrogen, carbon dioxide, water vapor, etc. or mixtures of these gases. In addition, the feed gas may contain at least one additional gas, the z. B. is selected from hydrogen, methane, carbon monoxide, etc.

In a first preferred embodiment, the pyrolysis is not carried out with the addition of hydrogen and / or hydrogen-containing gases and / or hydrogen-transferring compounds. In particular, water vapor also belongs to the hydrogen-transferring compounds. In this embodiment, substantially no hydrogenating reaction takes place in the course of the pyrolysis. In a second preferred embodiment, the pyrolysis with the addition of

Hydrogen and / or hydrogen-containing gases and / or hydrogen-transferring compounds carried out. This embodiment of the pyrolysis can also be referred to as "hydrocracking". In this embodiment, the aromatic lignin degradation products formed during the pyrolysis are at least partially converted by the action of hydrogen and / or water vapor so that substituents are replaced by hydrogen and / or several compounds containing aromatic nuclei are cleaved to compounds with a smaller number of nuclei become. Also included are reactions such as dehydroxylation, dealkoxylation, aromatic cleavage, etc. The substituents replaced by hydrogen are preferred. selected from among alkyl groups, hydroxy groups, alkoxy groups and aryloxy groups. The feed gas used for the hydrocracking preferably has a water vapor content of from 2 to 90% by volume, particularly preferably from 5 to 80% by volume, in particular from 10 to 70% by volume. In the case of steam dealkylation, the hydrogen required for the reaction is formed in situ by reaction of water with (mainly organic) components which are either present in the starting material mixture or are formed in the course of steam dealkylation. As an example, the formation of hydrogen from methane and water can be named according to the equation CH4 + H2O - CO + 3 H2. If the pyrolysis is carried out with the addition of hydrogen and / or hydrogen-containing gases and / or hydrogen-transferring compounds, an aromatic compound is formed as the target product of the process according to the invention, which contains low molecular weight aromatic compounds, which are preferably selected from benzene and phenolic compounds, such as phenol and / or dihydroxybenzenes. The aroma composition then has, in particular, lower proportions of the following components than in the case of pyrolysis in the absence of hydrogen and / or hydrogen-containing gases and / or hydrogen-transferring compounds: mono-, di- and polyalkylated phenols; Alkoxyphenols, such as methoxyphenols; polyalkylated benzenes; Compounds containing two or more aromatic rings.

The temperature in the pyrolysis is preferably in a range of 200 to 1500 ° C, more preferably 350 to 950 ° C, especially 380 to 850 ° C.

The pressure in the pyrolysis is preferably in a range of 0.5 to 250 bar (absolute), preferably 1, 0 to 40 bar (absolute).

The residence time at the pyrolysis temperature can be a few seconds to several days. In a specific embodiment, the residence time at the pyrolysis temperature is 0.5 second to 5 minutes, more specifically 2 seconds to 3 minutes.

Suitable processes for the catalyzed pyrolysis of lignin are, for. B. also in

WO 96/09350 (Midwest Research Institute, 1996) or US 4,409,416 (Hydrocarbon

Research Institute, 1983), which is incorporated herein by reference. In the pyrolysis zone, the lignin is converted into a mixture of components which under the conditions of pyrolysis are partly gaseous ("pyrolysis gas") and partly solid and / or liquid (eg tarry or "coke") , A discharge is taken from the pyrolysis zone, whereby it is generally expedient discharge the pyrolysis gases and the solid and / or liquid components separately.

Preferably, the effluent from the pyrolysis zone is subjected to separation to obtain the following three streams:

D1) of a solid catalyst-containing fraction,

D2) an aromatic-enriched fraction,

D3) of a fraction which is enriched in by-products which are lighter than D2).

As a rule, in order to obtain the discharge from the pyrolysis zone, the procedure is such that a gas discharge is taken off continuously or at intervals in the course of the pyrolysis. This contains all volatile under the pyrolysis conditions components. These include the aromatic composition desired according to the invention and lighter than these volatile components. The non-volatile under the pyrolysis solid and / or liquid components are discharged separately after completion of the pyrolysis. The discharged from the pyrolysis solid and, if present, liquid components are, for. Example, formed during the pyrolysis low volatility components (coke) and the pyrolysis catalyst. If at least one solid aggregate is used for the pyrolysis, the discharge from the pyrolysis zone may also contain fractions of the aggregate. If the pyrolysis gas still contains solid and / or liquid components, these can by means of a suitable device, for. As a cyclone, are separated from the pyrolysis gas. To obtain fraction D1), the catalyst is separated from the solid, strongly coked by-products of the pyrolysis reaction. In principle, several options are available in the context of the method. For example, after thermal utilization of the coke-containing by-product, a digestion of the mineral ash can take place. Soluble catalysts can then be separated with suitable solvents. Suitable solvents are the same as those used to treat the lignin-containing starting material with the fresh catalyst. Insoluble catalysts can be freed of all soluble components and so separated. Preferred solvents are water, ethanol and methanol, particularly preferred as the solvent is water or solvent having a water content greater than 70 vol.%, Particularly preferably with a water content greater than 90 vol.%. The dislocation of the ash with disintegrants, such as alkalis or other useful chemicals known to those skilled in the art, and the performance of suitable, the specialist known method, such as thermal or hydrothermal treatment, is also explicitly included in the method according to the invention.

In principle, however, the solid mineral containing the used catalyst pyrolysis residue can also be transferred directly by mechanical methods in a suitable fraction and reacted directly with the lignin-containing starting material. It may be useful to add a certain amount of fresh catalyst in order to achieve the desired properties. Preferably, in the process of the invention, when the catalyst is reused, only a small amount of fresh catalyst is added. Fresh catalyst additions of less than 90%, particularly preferably less than 50%, very particularly preferably less than 30%, based on the starting weight of the recycled catalyst material, are preferred. It is also possible to use catalysts or catalyst precursors which, because of their price or other prerequisites, do not have to be recycled to the pyrolysis process. In this case, preference is given in particular to those catalysts or catalyst precursors which, after combustion of the coke, return to a leaching process, as described, for example, in US Pat. B. is carried out as part of a wood pulp, z. As a force process, can be traced.

The pyrolysis product contains substituted aromatics and / or polynuclear aromatics. The pyrolysis product may contain, in addition to aromatics, other components selected from water vapor, inert gas (eg, nitrogen), non-aromatic hydrocarbons, H 2, CO, CO 2, sulfur-containing compounds, such as. As H2S, etc. and mixtures thereof. The non-aromatic hydrocarbons are preferably degradation products, such as methane.

The pyrolysis product may be subjected to separation to obtain fractions D2) and D3). For this purpose, customary thermal separation processes, such as distillation or adsorption, can be used.

Fraction D2) is the intended target aromatic composition and has a high proportion of aromatic compounds with up to 15 aromatic rings. The content of aromatic compounds having up to 15 aromatic rings is at least 50% by weight, based on the total weight of the aroma composition. The fraction D2) has a high content of mononuclear aromatic compounds. The fraction D2) preferably contains at least 1% by weight, more preferably at least 2% by weight, of mononuclear aromatic compounds. The monomeric aromatics contained in fraction D2) are preferably selected from benzene, toluene, xylenes, ethylbenzene, phenol, phenol ethers, cresols, xylenols, gujacols, veratroles, resorcinols, catechols, hydroquinones and other compounds which are different therefrom. The fraction D3) contains components which, for. B. are selected from non-aromatic hydrocarbons, especially methane, hydrogen, carbon monoxide, carbon dioxide and mixtures thereof. Depending on the lignin-containing starting material provided in step a), the stream D3) may contain further components. When using a lignin-containing starting material from the Kraft process, this includes sulfur-containing by-products, especially H2S.

The fraction stream D3), which is depleted of aromatics and enriched in highly volatile by-products, can be put to various uses. This includes on the one hand the combustion. When the process according to the invention is spatially close to a pulp process, it may be advantageous to feed fraction D3) into an apparatus of the pulp process. The fraction D3) is particularly preferably fed into the waste liquor combustion (recovery boiler). This embodiment has the advantage that no additional devices for steam or power generation or flue gas desulphurisation are required in the combustion of fraction D3). In another variant, the combustion of the fraction D3) is a desulfurization, z. B. in the form of a hydrogen sulfide removing gas scrubber, followed by a conversion of the formed H2S in elemental sulfur, upstream. The formation of sulfur can by known methods, for. As the Claus process done.

c) subjecting the composite obtained in step b) to pyrolysis in a pyrolysis zone, d) subjecting the effluent from the pyrolysis zone to separation to give the following three streams:

D1) of a solid catalyst-containing fraction,

D2) an aromatic-enriched fraction,

D3) a fraction enriched in by-products which are lighter than D2);

e) the fraction D1) obtained in step d) is at least partially recycled to the pyrolysis zone. With regard to suitable and preferred embodiments of the method steps a) to e), reference is made in full to the previous statements relating to these steps.

The pyrolysis product according to the invention or the aromatic-enriched fraction D2 can advantageously be subjected to a dealkylation for further work-up. A dealkylation process serves the primary purpose of obtaining a higher proportion of low molecular weight aromatic recyclables. In the context of the invention, "dealkylation" refers to a reaction of the substituted and / or polynuclear aromatic compounds present in an aromatic composition in the presence of hydrogen and / or water vapor, which are at least partially converted so that substituents are replaced by hydrogen and / or several aromatic nuclei containing compounds are cleaved to compounds with a smaller number of nuclei. The hydrogen-substituted substituents are selected from alkyl groups, hydroxy groups, alkoxy groups, aryloxy, etc. In the context of the invention, the term "dealkylation" also encompasses various reactions associated with molecular weight degradation, such as dehydroxylation, dealkoxylation, aromatic cleavage. Aromatea cleavage refers to a reaction in which essentially the number of aromatic nuclei per molecule is reduced without the aromatic nuclei themselves being destroyed.

In dealkylation, the aromatic lignin degradation products formed during pyrolysis are at least partially converted by the action of hydrogen and / or water vapor so that substituents are replaced by hydrogen and / or several aromatic nuclei-containing compounds are cleaved to compounds with a smaller number of nuclei. As has already been stated, "dealkylation" thus also denotes reactions in which no alkyl substituent is exchanged for hydrogen, such as dehydroxylation, dealkoxylation, aromatic salts. tion, etc. The hydrogen-substituted substituents are preferably selected from alkyl groups, hydroxy groups, alkoxy groups and aryloxy groups.

Suitable dealkylation processes include hydrodealkylation, steam dealkylation or mixtures thereof. In the case of pure hydrodealkylation according to the invention, in addition to the pyrolysis product, molecular hydrogen is fed into the dealkylation zone (in pure form or mixed with other components, such as CO), but no water. In the case of a pure steam dealkylation according to the invention, water is fed into the dealkylation zone in addition to the pyrolysis product (in pure form or in a mixture with other components), but no molecular hydrogen. The dealkylation process can also be designed as a mixed form of hydrodealkylation and steam dealkylation. Then, in addition to the pyrolysis product, both water and molecular hydrogen are fed into the dealkylation zone. In the following, suitable and preferred process parameters are specified in part especially for the hydrodealkylation or the steam dealkylation. With this information, the person skilled in the art is able to determine suitable and preferred process parameters for a mixed form of hydrodealkylation and steam dealkylation. Preferably, the reaction gas used for dealkylation then has a mixing ratio of H2 to H2O in the range from about 0.1: 99.9 to 99.9: 0.1. A particularly suitable mixing ratio of H 2 to H ₂ 0 is in the range of about 40: 60 to 60: 40th

The hydrogen required for the reaction is formed in situ in the case of steam dealkylation by reaction of water with (mainly organic) components which are either present in the educt mixture of the steam dealkylation or are formed in the course of steam dealkylation. As an example, the formation of hydrogen from methane and water can be named according to the equation CH ₄ + H2O - CO + 3 H2. Preferably, the temperature in the dealkylation zone is in a range from 400 to 900 ° C, more preferably from 500 to 800 ° C.

The absolute pressure in the dealkylation zone is preferably in the range from 1 to 100 bar, particularly preferably from 1 to 20 bar, in particular from 1 to 10 bar.

In a first preferred embodiment, the pyrolysis product is subjected to hydrodealkylation. For this purpose, the reaction takes place in the presence of hydrogen. The temperature in the dealkylation zone for the hydrodealkylation is preferably in the range from 500 to 900 ° C., particularly preferably from 600 to 800 ° C.

The absolute pressure in the dealkylation zone for the hydrodealkylation is preferably in the range from 1 to 100 bar, particularly preferably from 1 to 20 bar, in particular from 1 to 10 bar.

For the hydrodealkylation, the feed ratio of H 2 to H 2 (stoichiometric) is preferably in a range from 0.02 to 50, more preferably from 0.2 to 10. H 2 (stoichiometric) stands for the amount H 2, which theoretically is just the complete one Reaction of the supplied into the Dealkylierungszone aromatics to benzene is required, assuming that per mole of substituent 1 mole of H2 reacted.

For the hydrodealkylation, the residence time in the dealkylation zone is preferably in the range from 0.1 to 500 s, more preferably from 0.5 to 200 s.

In a second preferred embodiment, the pyrolysis product is subjected to steam dealkylation. For this, the reaction takes place in the presence of water vapor.

The temperature in the dealkylation zone for the vapor dealkylation is preferably in the range from 400 to 800 ° C., particularly preferably from 475 to 600 ° C., in particular from 525 to 600 ° C. The absolute pressure in the dealkylation zone for the vapor dealkylation is preferably in a range from 1 to 100 bar, particularly preferably from 1 to 20 bar, in particular from 1 to 10 bar.

The steam dealkylation can be carried out in the presence or absence of a catalyst. In a specific embodiment, steam dealkylation is carried out in the absence of a catalyst. A catalyzed process for steam dealkylation is in

WO 2008/148807 A1. Reference is made in its entirety to this document and the references cited therein to suitable catalysts. Further information on catalyst types and process steps of steam dealkylation can be found in WO 2007/051852 A1, WO 2007/051851 A1, WO 2007/051855 A2, WO 2007/051856 A1, WO 2008/135581 A1 and WO 2008/135582 A1

(EP 2008055585), without thereby limiting. US 3,775,504 describes that steam dealkylation actually consists of a combination tion of steam dealkylation and hydrodealkylation, since systemically inherent at least a portion of the hydrogen produced is reacted again immediately.

In the dealkylation step, at least one low molecular weight aromatic valuable substance is formed as the target product of the process according to the invention. The low molecular weight aromatic valuable substances are preferably selected from benzene and phenolic compounds, such as phenol and / or dihydroxybenzenes.

In particular, they have lower proportions of the following components than the pyrolysis effluent before being fed into the dealkylation step: mono-, di- and polyalkylated phenols; Alkoxyphenols, such as methoxyphenols; polyalkylated benzenes; Compounds containing two or more aromatic rings.

figure description

FIG. 1 shows a device suitable for carrying out the method according to the invention with a fluidized-bed reactor.

FIG. 2 shows a scanning electron micrograph of the composite from Example 8 based on a zeolite as pyrolysis catalyst after pyrolysis.

The invention will be further illustrated by the following non-limiting examples. Examples

In all the examples given here, the pyrolysis was carried out in a simple shaft reactor in which the lignin samples were introduced as a fixed bed. The resulting gaseous pyrolysis product was discharged continuously, collected in a receiver and the composition was determined gravimetrically after the end of the experiment. After completion of the pyrolysis of the solid reactor contents was discharged, the formed catalyst-containing coke from the inert material (metal balls, diameter 1, 5 to 2 mm) separated and the composition of the coke also determined gravimetrically. A gas analysis was not carried out, a determination of the gaseous fraction was carried out by subtraction. The reactor was heated with a radiant heater within 15 minutes to a temperature of 400 ° C. With the feed gas, a GHSV (gas hourly space velocity) of 20 000 h ¹ , based on the lignin volume used, set (weight 2.5 g). The reactor had a diameter of 9 mm. Equal volumes of metal spheres and lignin were used. set. When using soluble catalysts precompacted lignin was used, this premixed with the inert metal balls and then applied the catalyst by the Incipient Wetness method and then dried at 80 ° C. When using solid catalysts, all solids were mixed by mixing with a drum mixer mixed ceramic balls as mixing elements and then compacted on a compactor Powtec .. The compaction was carried out with the following parameters:

Roller pressure: 250 bar

Sieve insert: 1000 μιτι

Speed of the Rotary Sieve Mill: 100 min ¹

Speed rolling mill: 5 min ¹

Roll type: grooved

Repetitions: 10

For all pyrolysis a composite with a particle size of 500 to 1000 μιτι, determined by sieve analysis, was used.

All yields are based on the dried weight of lignin.

Example 1 (Comparative) Following the general procedure described above, an untreated lignin (softwood lignin from a lignoboost process) was subjected to pyrolysis. When nitrogen was used as the feed gas, a coke content of 38.5% was obtained. When using a mixture of 70% nitrogen and 30% water vapor as feed gas, a coke content of 36% was obtained. When nitrogen was used as the feed gas, a bio-oil yield (aromatics-containing product) of 38.5% was obtained. The yield of mononuclear aromatic was 5.4 wt .-%, based on the flavor tenanteil in the starting material. When using a mixture of 70% nitrogen and 30% water vapor as feed gas, a bio-oil yield (aromatic-containing product) of 36% was obtained. The yield of mononuclear aromatic was 3.5% by weight, based on the aromatic content in the starting material. After expanding the fixed

In the reactor contents, tarry and coke-like adhesions were observed on the steel balls.

Example 2

Following the general procedure described above, a lignin (soft lignin from a lignoboost process) loaded with 2% by weight of a zeolite (ZSM-5, Module 40, manufactured by Zeochem) over solid mixture and then compacted Subjected to pyrolysis. When using nitrogen as Feed gas was obtained a coke content of 38.5 wt .-%. When using a mixture of 70% nitrogen and 30% water vapor as feed gas, a coke content of 36% by weight was obtained. When nitrogen was used as the feed gas, a bio-oil yield (aromatic-containing product) of 53% by weight was obtained. The yield of mononuclear aromatic was 3.4 wt .-%, based on the aromatic content in the starting material. When using a mixture of 70% nitrogen and 30% hydrogen as feed gas, a bio-oil yield (aromatics-containing product) of 39 wt .-% was obtained. The yield of mononuclear aromatic was 9.5 wt .-%, based on the aromatic content in the starting material. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls.

Example 3

Following the general procedure described above, a lignin (soft lignin from a lignoboost process) loaded with 1% by weight boric acid via aqueous impregnation and previously compacted was subjected to pyrolysis. When nitrogen was used as the feed gas, a coke content of 36% by weight was obtained. When using a mixture of 70% nitrogen and 30% water vapor as feed gas, a coke content of 35 wt .-% was obtained. When using nitrogen as feed gas, a bio-oil yield (aromatics-containing product) of 65% by weight was obtained. When using a mixture of 70% nitrogen and 30% hydrogen as feed gas, a bio-oil yield (aromatics-containing product) of 62% by weight, based on dry lignin, was obtained. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls.

Example 4

Following the general procedure described above, a lignin (soft lignin from a lignoboost process), which was loaded with 3.3% by weight of disperal (Saasol) over solid mixture and then compacted, was subjected to pyrolysis. When nitrogen was used as the feed gas, a coke content of 47% by weight was obtained. When nitrogen was used as the feed gas, a bio-oil yield (aromatic-containing product) of 40% by weight, based on dry lignin, was obtained. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls.

Example 5 Following the general procedure described above, a lignin (soft lignin from a lignoboost process) loaded with 1% by weight boric acid via aqueous impregnation and previously compacted was subjected to pyrolysis. When nitrogen was used as the feed gas, a coke content of 36% by weight was obtained. When using a mixture of 70% nitrogen and 30% water vapor as feed gas, a coke content of 35 wt .-% was obtained. When nitrogen was used as the feed gas, a bio-oil yield (aromatic-containing product) of 65% by weight was obtained. When using a mixture of 70% nitrogen and 30% hydrogen as feed gas, a bio-oil yield (aromatics-containing product) of 62% by weight, based on dry lignin, was obtained. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls.

Example 6 Following the general procedure described above, a lignin (soft lignin from a lignoboost process) loaded with 1% by weight of Ni (based on metal) by aqueous impregnation with nickel acetate and previously compacted was subjected to pyrolysis subjected. When nitrogen was used as the feed gas, a coke content of 48% by weight was obtained. When nitrogen was used as the feed gas, a bio-oil yield (aromatic-containing product) of 52% by weight, based on dry lignin, was obtained. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls.

Example 7

According to the general procedure described above, a lignin (soft lignin from a lignoboost process) loaded with 5 wt% Co (based on metal) by aqueous impregnation with cobalt acetate and previously compacted was subjected to pyrolysis. When nitrogen was used as the feed gas, a coke content of 64% by weight was obtained. When using nitrogen as

Feed gas was a bio-oil yield (aromatics-containing product) of 33 wt .-%, based on dry lignin, obtained. After removal of the solid reactor contents, no tar and coke-like buildup was observed on the steel balls. Example 8: Pyrolysis in a circulating fluidized bed

General Procedure: A system was used as shown in FIG. A continuously fed, catalyst-modified and compacted amount of ligin was pyrolyzed in a circulating fluidized bed. The supply of ligament Nin-composites took place via a metering screw. The supplied amount of lignin was determined gravimetrically. The catalyst-modified and compacted lignin had a particle size between 0.5 and 2 mm. The pyrolysis reactor (circulating fluidized bed) had a diameter of 80 mm and a height of 1900 mm. It was electrically heated to 1 100 ° C. Quartz sand with a mean particle size of 250 μιτι was used as bed material. The quartz sand was returned to the reactor after pyrolysis via a cyclone. The plant was operated at a pressure of 1, 2 bar. The fluidizing gas used was an Is / steam mixture containing 40% by volume and 80% by volume of steam. The gas residence times ranged from 0.5 to 2 s. The reaction temperature investigated was between 500 and 800 ° C.

In the plant described above, a zeolite catalyst-modified and compacted lignin according to Example 2 was subjected to pyrolysis. For this purpose, 2.7 kg of lignin were fed into the reactor over 45 minutes (3.6 kg / h). The reactor temperature was 650 ° C. The fluidizing gas consisted of 19 kg / h of N ₂ and 12 kg / h of steam, so that the gas velocity in the reactor was 4 m / s. From the pyrolysis, a coke content of 26.4 wt .-%, based on the lignin used, was obtained. The bio-oil yield was 41.1% by weight. based on lignin used. The proportion of mononuclear aromatics was 22.6 wt .-%, and the proportion of polynuclear aromatics was 18.5 wt .-%, each based on the lignin used. The uncondensed gases (CO, CO2, CnHm) had a content of 21, 1 wt .-%, based on the lignin used.

An essential advantage when using a catalyst modified and compacted lignin according to the invention is that it results in the formation of larger spherical coke particles, which can then be better separated from the quartz sand.

Claims

claims

Composite comprising lignin and at least one pyrolysis catalyst distributed in the composite.

Composite according to claim 1, which contains lignin in an amount of 60 to 99 wt .-%, preferably from 70 to 95 wt .-%, based on the total weight of Kompos, contains.

Composite according to one of the preceding claims, which contains the pyrolysis catalyst in an amount of 0.1 to 20 wt .-%, preferably from 0.2 to 5 wt .-%, based on the total weight of the composite.

Composite according to one of the preceding claims, which has a content of at normal conditions (20 ° C, 1013 mbar) liquid components of at most 20 wt .-%, preferably of at most 5 wt .-%.

Composite according to one of the preceding claims, which has an average particle size in the range of 1 to 2000 μΐτι, preferably from 100 to 1000 μΐτι having.

Composite according to one of the preceding claims, which has a bulk density in the range of 0.3 to 0.8 g / L, preferably from 0.4 to 0.7 g / L.

A method of making a composite comprising lignin and at least one pyrolysis catalyst dispersed in the composite comprising providing a lignin-containing feedstock and intimately contacting the pyrolysis catalyst.

The method of claim 7, wherein during and / or after contacting the lignin-containing starting material with the pyrolysis catalyst, the material is subjected to a densification.

The method of claim 8, wherein the densification is by compacting, extruding, tableting or a combination of at least two of these measures.

10. The method of claim 8, wherein the compaction is done by compaction.

1 1. A method according to any one of claims 7 to 10, wherein a lignin-containing starting material is provided which contains at least 10% by weight, preferably at least 15% by weight, based on the dry matter of the material, of lignin.

A process according to any one of claims 7 to 11, wherein a lignocellulosic material of wood and / or vegetable fibers is used to provide the starting material containing ninin.

A process according to any one of claims 7 to 12, wherein a lignocellulosic stream from the digestion of a lignocellulosic material for the production of cellulose (pulp) is used to provide the starting material containing ninin.

The method of claim 13, wherein for providing the lignin-containing starting material, a lignin-containing stream from the digestion of a lignocellulosic material is used with an alkaline treatment medium, preferably a black liquor, in particular a black liquor from the lignoboost process.

The method of any one of claims 7 to 14, wherein the lignin-containing starting material is subjected to compacting prior to contacting with the pyrolysis catalyst.

A process according to any one of claims 7 to 15, wherein the pyrolysis catalyst is selected from boric acid, zeolites, silicic acid, alumina, aluminosilicates, zirconia, titania, water-soluble nickel salts, water-soluble cobalts salts and mixtures thereof.

The process of any one of claims 7 to 15, wherein the pyrolysis catalyst comprises the catalyst-containing solid reactor effluent from pyrolysis in the presence of a composite containing lignin and at least one composite pyrolysis catalyst.

A composite obtainable by a process as defined in any one of claims 7 to 17.

19. A process for preparing a flavor composition from a lignocellulosic starting material comprising subjecting a composite containing lignin and at least one pyrolysis catalyst dispersed in the composite to pyrolysis.

20. The method of claim 19, wherein lignin-containing starting material is provided completely in the form of a composite.

21. Process according to one of Claims 19 or 20, in which the pyrolysis product is at least partially fed into a dealkylation zone and reacted in the presence of hydrogen and / or water vapor.

22. The method according to any one of claims 16 or 17, wherein the discharge from the pyrolysis zone is subjected to a separation to obtain the following three streams:

D1) of a solid catalyst-containing fraction,

D2) an aromatic-enriched fraction,

D3) of a fraction which is enriched in by-products which are lighter than D2).

23. The method according to claim 18, wherein the fraction D1) is at least partially recycled to the pyrolysis zone.

24. A process for the preparation of an aromatic composition from a lignin-containing starting material, comprising: a) providing a lignin-containing starting material,

D1) of a solid catalyst-containing fraction,

D2) an aromatic-enriched fraction,

D3) a fraction enriched in by-products which are lighter than D2);

25. The method according to any one of claims 22 to 24, wherein the aromatics enriched fraction D2) is at least partially fed into a Dealkylierungszone and reacted in the presence of hydrogen and / or water vapor.