The selective dehydration of sugars and alcohols, such as xylose, fructose, glucose etc. into defined platform molecules such as furfural and 5-hydroxymethylfurfural is a key technology to implement renewable resources into the value chain of chemical industries. Conventional mineral acids, such as sulfuric acid, phosphoric acid or super phosphate, can be used as homogeneous catalysts for the dehydration of monosaccharides. However, these mineral acids lead to serious corrosion, safety problems, and difficulty in catalyst separation from the reaction prod- ucts, excessive waste disposal, extensive side reactions (<50% selectivity), and moderate STY due to long residence times (L. Lin, Biomass and Bioenergy 39, 2012, 73-77; M. Tsapatsis, Mi- croporous Mesoporous Materials 153 (2012) 55-58).

By means of acidic zeolites as catalysts, these issues can be tackled. In addition, the defined pore structures of zeolites can be used to enhance the product selectivity and suppress at the same time the formation of side-products which lead to the deactivation of the catalytic active component.

In recent publications the use of microporous and mesoporous acid catalysts with acidic properties are used to convert different sugars e.g. xylose and glucose into furfural and 5- hydroxymethylfurfural. The use of MCM-41 is described in Biomass and Bioenergy (2012), 39, 73-77. In Applied Catalysis, A: General (2012), 417-418, 243-252 the use of MCM-22 and ITQ-2 is described. Energies (Basel, Switzerland) (201 1 ), 4, 669-684 discloses the use of SBA-15. The use of USY, M FI and BEA is described in Korean Journal of Chemical Engineering (201 1 ), 28(3), 710-716.

The most prominent and best studied example for a zeolitic material with a BEA-type framework structure is zeolite beta, which is a zeolite containing Si02 and AI203 in its framework and is considered to be one of the most important nanoporous catalysts with its three-dimensional 12- membered-ring (12MR) pore/channel system and has been widely used in petroleum refining and fine chemical industries. Zeolite beta was first described in U.S. Patent No. 3,308,069 and involved the use of the tetraethylammonium cation as the structure directing agent. Although numerous alterations and improvements had since then been made to the preparation procedure, including the use of other structure directing agents such as dibenzyl-1 ,4- diazabicyclo[2,2,2]octane in U .S. Patent No. 4,554,145 or dibenzylmethylammonium in U.S. Patent No. 4,642,226, the known processes for its preparation still relied on the use of organic template compounds. In US Patent No. 5,139,759, for example, it is reported that the absence of an organic template compound in the synthetic procedure of zeolite beta leads to the crystallization of ZSM-5 instead. Furthermore, the use of organic template compounds in the synthesis of these zeolitic materials possesses the major disadvantage that the tetraalkylammonium salts and other organic compounds employed therein are expensive fine chemicals. In addition to this, the resulting products inevitably contains the organotemplates which are encapsulated in the zeolitic framework created around them, such that a removal step becomes necessary in order to open the porous volume of the material for actual utilization, e.g. in catalysis.

Complete removal of the organic template compound, however, is difficult and is normally only achieved by calcination at higher temperatures, normally at 200 - 930 °C or even higher. This procedure not only greatly increases the production costs since the organic template is destroyed in the process and may not be recycled, it also further increases the production time, results in excess energy consumption, and produces harmful gases and other unwanted waste products. In addition to these major disadvantages, the harsh thermal treatment ultimately limits the production to thermally stable zeolite Beta, in particular to high-silica zeolite Beta. Although ion- exchange methods have been developed as an environmentally friendly alternative to calcination for removing the organotemplate, only part of the organic templates may successfully be recycled, the remainder interacting too strongly with the zeolite framework for removal.

Thus, although zeolitic materials having a BEA framework structure such as zeolite Beta exhibit excellent properties in a series of catalytic reactions, their further potential applications are still greatly limited due to the use of organic templates in the synthesis thereof. It has been discovered that zeolite beta and related materials may be prepared in the absence of the organotemplates which until then had always been used as structure directing agent. Thus, in Xiao et al., Chem. Mater. 2008, 20, pp. 4533-4535 and Supporting Information, a process for the synthesis of zeolite beta is shown, in which crystallization of an aluminosilicate gel is conducted using zeolite beta seed crystals. There is, however, no indication whatsoever in said document relating to the use of different starting materials for the preparation of an aluminosilicate gel, nor does said document indicate the possibility of including elements suited for isomorphous substitution in the mixture for crystallization. In WO 2010/146156 A the organo- template-free synthesis of zeolitic materials having the BEA-type framework structure, and in particular to the organotemplate-free synthesis of zeolite beta is described. In Majano et al., Chem. Mater. 2009, 21 , pp. 4184-4191 , on the other hand, Al-rich zeolite beta materials having Si/AI ratios as low as 3.9 are discussed which may be obtained from reactions employing seeding in the absence of organic templates. Besides the considerable advantage of not having to use costly organotemplates which required subsequent removal from the microporous framework by calcination, the new organotemplate-free synthetic methodologies further allowed for the preparation of Al-rich zeolite beta with unprecedentedly low Si/AI ratios. Based on the high concentration of incorporated Al-sites in the organotemplate-free prepared BEA framework, the zeolite contains a remarkable higher number of acid sites, which are important for the degradation of polymeric sugar molecules. Zeolites typically comprise silicon and aluminum as the metal centers. Zeolites possessing metal centers that are selected from the group consisting of silicon and tin are known in the literature. Their synthesis is e.g. described in Angewandte Chemie, International Edition (2012), 51 (47), 1 1906 and Catalysis Today (2007), 121 (1 -2), 39-44.

The term "organotemplate-free" is typically used when during the synthesis of the respective zeolite no structure-directing agent (SDA) has been used.

It was an objective of the present invention provide a method for dehydration of compounds comprising, in the chain form, at least one hydroxyl group and at least one carbonyl functionality.

A further aim was that the dehydration leads to high conversion. 'High conversion' means that only few or no starting material can be detected in the reaction product mixture. Instead most or even all starting material is converted.

A further aim was that the dehydration leads to high selectivity. 'High selectivity' means that the amount of the wanted product when compared to side products is as high as possible. In the ideal case, no side products and exclusively the wanted product is produced.

It was also an objective to provide zeolites that promote such dehydration of compounds comprising at least one hydroxyl group and at least one carbonyl functionality.

The present invention relates to isomorphously substituted zeolites obtainable from an organo- template-free synthetic process, a method of dehydration of sugars in the presence of such zeolites and a method of regeneration of such zeolites.

One aspect of the present invention is a method of dehydration of at least one compound (A) comprising, in the chain form

- at least one hydroxyl group and

- at least one carbonyl functionality selected from the group consisting of aldehyde (CHO), ketone (CO) and carboxylic acid (COOH) and mixtures thereof,

in the presence of at least one zeolite which is

(a) obtainable from an organotemplate-free synthetic process and

(b) isomorphously substituted comprising silicon, aluminum and at least one further metal wherein the at least one further metal is selected from the group consisting of the elements of

Group 3 to 14 in Period 4 to 6 and mixtures thereof.

Preferred compounds (A) are sugars and hydroxyl-substituted carboxylic acids.

Therefore, a preferred method according to the invention is a method wherein the at least one compound (A) is a sugar. The term "sugar" shall be used for the group consisting of monosaccharides, disaccharides and oligosaccharides.

Monosaccharides have the general formula C _n H2nO _n with n = 2 (diose), 3 (those), 4 (tetrose), 5 (pentose), 6 (hexose) or 7 (heptose). They exist as several isomers with D- and L- forms. Many pentoses and hexoses can form ring structure.

Preferred sugars are pentoses (formula C5H10O5) and hexoses (formula

More preferred monosaccharides are glucose, fructose, galactose, xylose and ribose.

Disaccharides have the general formula C12H22O11 : They are formed by the combination of two monosaccharides with the exclusion of a molecule of water.

Preferred disaccharides are sucrose, maltose and lactose. The acyclic mono- and disaccharides contain either aldehyde groups or ketone groups.

Polysaccharides are long chain carbohydrate molecules of monosaccharide units joined together by glycosidic bonds. Preferred polysaccharides are cellulose, cellobiose, inulin, starch and glycogen.

More preferred sugar compounds are xylose, glucose, fructose, cellobiose, cellulose, inulin and mixtures thereof. Therefore, a more preferred method according to the invention is a method wherein the at least one sugar is selected from the group consisting of xylose, glucose, fructose, cellobiose, cellulose, inulin and mixtures thereof.

Another preferred method according to the invention is a method wherein the at least one com- pound (A) is a hydroxylic acid with at least one hydroxyl group and at least one carboxylic group.

Preferred hydroxylic acid compounds comprise at least one hydroxyl group and one carboxylic group. A particular preferred hydroxylic acid compound is lactic acid.

Other preferred hydroxylic acid compounds comprise at least one hydroxyl group and two carboxylic groups. Particular preferred hydroxylic acid compounds are tartaric acid and glucaric acid. Other preferred hydroxylic acid compounds comprise at least one hydroxyl group and three carboxylic groups. Typically zeolites are produced by means of so-called structure directing agents (SDAs). These are usually small organic molecules. Depending on the size, shape and chemistry of these molecules a certain type of zeolite can be produced preferredly over other types or even exclusively. Therefore, the SDAs act as a sort of template.

This method has different disadvantages: one is that some SDAs are expensive. On the other hand, the SDA has to be burned after formation of the zeolite.

More recently it has been found that zeolites can be produced without SDAs. The term "organotemplate-free" means, within the frame of the application under regard, that during the synthesis of the respective zeolite no SDA has been used.

A preferred method according to the invention is a method wherein the at least one zeolite has a silica-to-alumina mole ratio of 20 or less.

In a preferred method the at least one zeolite is selected from the group consisting of MFI, BEA, CHA and mixtures thereof.

'Isomorpohously substituted' means within the frame of this application that the respective metal is integrated into the zeolite framework structure.

In the following the terms "Group" and "Period" are used according to the nomenclature by the International Union of Pure and Applied Chemistry (lU PAC) for the Periodic Table of the Elements (PTE) as of June 01 , 2012.

The elements of Group 3 to 14 in Period 4 to 6 comprise the elements 21 to 32, 39 to 50 and 57 to 82. These include Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, TI and Pb.

Preferred metals are Sn, Zn, Zr, Ti, V, Ta, Ga, Ge and Cr and mixtures thereof. More preferred the metal is Sn.

Therefore, a preferred method according to the invention is a method wherein the at least one further metal is selected from the group consisting of Sn, Zn, Zr, Ti, V, Ta, Ga, Ge and Cr and mixtures thereof, preferred Sn. A preferred product is furfural and/or 5-hydroxylmethylfurfural.

Therefore, a preferred method according to the invention is a method for the production of furfural and/or 5-hydroxylmethylfurfural.

A preferred method according to the invention is a method which further comprises a regenera- tion step. A particularly preferred embodiment is a method of dehydration of at least one compound (A) comprising, in the chain form,

- at least one hydroxyl group and

- at least one carbonyl functionality selected from the group consisting of aldehyde (CHO), ke- tone (CO) and carboxylic acid (COOH) and mixtures thereof,

in the presence of at least one zeolite which is

(a) obtained from an organotem plate-free synthetic process and

(b) isomorphously substituted comprising silicon, aluminum and at least one further metal wherein the at least one further metal is selected from the group consisting of the elements of Group 3 to 14 in Period 4 to 6 and mixtures thereof.

A further aspect of the present invention is a isomorphously substituted zeolite comprising silicon, aluminum and at least one further metal wherein the at least one further metal is selected from the group consisting of the elements of Group 3 to 14 in Period 4 to 6 and mixtures thereof wherein the zeolite is obtainable from an organotemplate-free synthetic process.

A preferred zeolite according to the invention has a silica-to-alumina mole ratio of 20 or less.

A preferred zeolite is selected from the group consisting of M FI, BEA, CHA and mixtures there- of.

A more preferred zeolite according to the invention is one wherein the at least one further metal is selected from the group consisting of Sn, Zn, Zr, Ti, V, Ta, Ga, Ge and Cr and mixtures thereof, preferred Sn.

In a preferred embodiment the zeolite is obtained from an organotemplate-free synthetic process.

The dehydration can be performed at a pressure of from 0.1 bar to 100 bar, preferred the dehy- dration is performed at a pressure of from 0.5 bar to 10 bar, more preferred the dehydration is performed at a pressure of from 1 bar to 5 bar. Most preferred the dehydration is performed in a closed autoclave under inherent pressure.

The dehydration can be performed at a temperature of from 15°C to 300°C, preferred the dehy- dration is performed at a temperature of from 20°C to 250°C, more preferred the dehydration is performed at a temperature of from 50°C to 250°C, even more preferred the dehydration is performed at a temperature of from 100°C to 200°C. An even more preferred temperature range is of from 150°C to 200°C. Most preferred the dehydration is performed at a temperature of from 160°C to 190°C.

The dehydration can be performed with or without protective atmosphere, e.g. a noble gas or nitrogen. Preferred it is performed with a protective atmosphere, more preferred under a nitrogen atmosphere. The dehydration must be performed in the presence of a zeolite. The at least one compound (A) and the at least one zeolite are present in the reaction mixture in a ratio of from 1 :10 to 10:1 , more preferred in a ration of from 1 :5 to 5:1 , even more preferred in a ration 1 :2 to 2:1. The dehydration can be performed with or without solvent. Preferred it is performed with a solvent. The solvent can be a pure solvent or a mixture of solvents. Preferred solvents are toluene, dimethyl sulfoxide, tetrahydrofuran, linear or branched Ci to Cio alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol (2-butanol), i-butanol (2-methyl-1 - propanol), tert-butanol; dimethylformamid, 2-Methoxy-2-methylpropan, 2-propanon, 4- methylpentan-2-on, deionized water and mixtures thereof. More preferred solvents are toluene, dimethyl sulfoxide, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol (2- butanol), i-butanol (2-methyl-1 -propanol), tert-butanol, 4-methylpentan-2-on, deionized water and mixtures thereof. The dehydration can be performed as batch process, a semi-batch process or as continuous process.

The dehydration can be performed in a number of parallel reactors whereof in some reactors the dehydration is performed and whereof some reactors are regenerated.

The following examples shall further illustrate the process and the materials of the present invention without limiting the invention unduely.

Examples

I) Dehydration of Xylose

Example 1. Organotemplate-free hydrothermal synthesis of isomorphously substituted Sn-BEA (TF-Sn-BEA) a) Organotemplate-free hydrothermal synthesis of the sodium form

4.03 g of NaAIC>2 was dissolved in 88.03 g of distilled water under stirring, followed by addition of 0.90 g of zeolite Beta seeds (commercially obtained from Zeolyst International, product name: CP814C. Prior to the synthesis, the product was calcined at 500 °C for 5 h (heating ramp 1 °C/min to obtain the H-Form)). The mixture was placed in a 250 ml Teflon-lined autoclave and 88.18 g sodium waterglass was slowly added. 1.26 g SnS0 ₄ was dissolved in 17.29 g Ludox AS40 and the mixture was added to the autoclave and stirred for two minutes, affording an alu- minosilicate gel with a molar ratio of 1.00 Si0 ₂ : 0.042 Al ₂ 0 ₃ : 0.29 Na ₂ 0 : 0.012 Sn0 ₂ : 17.5 H ₂ 0. Crystallization took place at 120 °C for 216 h. After the reaction mixture was cooled down to room temperature, the solid was separated by filtration, repeatedly washed with distilled water and then dried at 120 °C for 24 h affording 19.6 g of a white crystalline product. Chemical analysis showed that the material has a S1O2 : AI2O3 ratio of 1 1 .1 and 6.98 wt% of Na20 on a calcined basis. SnC>2 content is found to be 2.64 wt% on a calcined basis. XRD indicated that pure Beta structure has been obtained. b) Synthesis of the H-form by ammonium-exchange of the product of a) and subsequent calcination

5.0 g sodium form of the crystalline product was added to 50.0 g of a 10wt% solution of ammonium nitrate. The suspension was heated to 80 °C and kept at this temperature under continuous stirring for 2h. The solid was filtered hot (without additional cooling) over a Buechner funnel with appropriate filter paper. The filter cake was then washed with distilled water (room temperature wash water) until the conductivity of the wash water was below 200 cm ¹ . This procedure was repeated once, affording ion exchanged of the crystalline product TF-Sn-BEA in its ammonium form. The filter cake was then dried for 16 h at 120 °C. A following calcination step at 500 °C for 5 h (heating ramp 1 °C/min) led to 4.8 g of ion exchanged crystalline product TF- Sn-BEA in its H-form. Chemical analysis revealed a Si0 ₂ : Al ₂ 0 ₃ ratio of 10.78 and 0.12 wt% of Na20 on a calcined basis. SnC>2 content was determined with 2.95 wt% on a calcined basis. XRD indicated that a pure Beta phase has been produced by this method.

The specific surface area (BET-method) is 175 m ² /g. Ammonia-temperature programmed de- sorption reveals a total uptake of 1.88 mmol ammonia per gram TF-Sn-BEA.

The incorporation of Sn into the framework can be observed through diffuse reflectance spec- troscopy revealing a sharp UV-absorbance around 216 nm (Figure 1 , example 2); this signal is characteristic of isolated, tetrahedral SnIV species within the zeolite framework.

Example 2: H-Beta (TF -BEA) a) Organotemplate-free hydrothermal synthesis of the sodium form of Beta

335.1 g of NaAIC>2 were dissolved in 7314 g of H2O while stirring, followed by addition of 74.5 g of zeolite Beta seeds (commercially obtained from Zeolyst International, product name:

CP814C. Prior to the synthesis, the product was calcined at 500 °C for 5 h (heating ramp 1 °C/min to obtain the H-Form)). The mixture was placed in a 20 L autoclave together with 7340 g sodium waterglass and 1436 g Ludox AS40, affording an aluminosilicate gel with a molar ratio of 1.00 Si0 ₂ : 0.042 AI2O3 : 0.57 Na ₂ 0 : 17.5 H ₂ 0. Crystallization took place at 120 °C for 1 17 h. After the reaction mixture was cooled down to room temperature, the solid was separated by filtration, repeatedly washed with distilled water and then dried at 120 °C for 16 h affording 1337 g of a white crystalline product.

Chemical analysis indicated a S1O2 : AI2O3 ratio of 10.89 and 6.69 wt% of Na20 on a calcined basis. XRD indicated that Beta phase has been obtained. b) Synthesis of the H-form by ammonium-exchange of the product of a) and subsequent calcination

1000 g sodium form of the crystalline product from a) was added into 10,000 g of a 10wt% solu- tion of ammonium nitrate. The suspension was heated to 80 °C and kept at this temperature under continuous stirring for 2h. The solid was filtered hot (without additional cooling) over a filter press. The filter cake then was then washed with distilled water (room temperature wash water) until the conductivity of the wash water was below 200 cm ¹ . The filter cake was dried for 16 h at 120 °C. This procedure was repeated once, affording ion exchanged crystalline TF- BEA product in its ammonium form. A following calcination step at 500 °C for 5 h (heat ramp 1 °C/min) afforded ion exchanged crystalline TF-BEA product in its H-form. Chemical analysis indicated a S1O2 : AI2O3 ratio of 10.51 and 0.08 wt% of Na20 on a calcined basis.

The specific surface area (BET-method) is 458 m ² /g. Ammonia-temperature programmed de- sorption reveals a total uptake of 1 .86 mmol ammonia per gram BEA.

Example 3: Dealuminated H-Beta (TF-BEA deal.) 171 .5 g TF-Beta in its H-Form from example 2 was suspended in 514.5 g of diluted nitric acid (4%) and stirred for 2h at 60 °C. After filtration and washing with distilled water until the conductivity of the wash water was below 200 cm ¹ the filter cake was dried for 20 h at 120 °C and calcined at 600 °C for 5h (heat ramp 1 °C/min). The obtained zeolite was then suspended in the seven fold amount of water and heated to 90 °C for 9 h. The water phase was removed and the zeolite was dried for 16 h at 120 °C. The procedure was repeated three times followed by an additional dealumination step employing 15wt% of nitric acid. After filtration and washing with distilled water until the conductivity of the wash water was below 200 cm ¹ the filter cake was dried for 24 h at 120 °C. A calcination step at 600 °C for 5 h (heat ramp 1 °C/min) afforded 1 1 1.0 g dealuminated crystalline TF-BEA deal. Chemical analysis indicated a S1O2 : AI2O3 ratio of 49.15 and < 0.01 wt% of Na ₂ 0 on a calcined basis.

The specific surface area (BET-method) is 554 m ² /g. Ammonia-temperature programmed desorption reveals a total uptake of 0.41 mmol ammonia per gram BEA. Peak Number Temperature at Quantity

Maximum (°C) (mmol/g)

1 177.8 0.18

2 328.9 0.23

Comparative example 1 : H-Beta from commercially available BEA (CP814C) A Beta was commercially obtained from Zeolyst (product name: CP814C) in its NhU-form and calcined at 500 °C for 5 h (heating ramp 1 °C/min) for use as a reference material. The composition of the CP814C in its H-form was 38 Si0 ₂ : Al ₂ 0 ₃ and 0.01 Na ₂ 0 on a calcined basis. The specific surface area (BET-method) is 606 m ² /g. Ammonia-temperature programmed de- sorption reveals a total uptake of 0.91 mmol ammonia per gram BEA.

Catalytic tests: Dehydration of Xylose on TF-BEA zeolites

A series of batch experiments were carried out to assess the catalytic activity of the zeolites in the Dehydration reaction of xylose to furfural.

General procedure:

To a 300 ml. Hastelloy C autoclave was added 1 g (6.66 mmol) xylose, 1 g of the respective zeolite catalyst, 130.5 g toluene, 5.50 g dimethyl sulfoxide and 45.0 g of deionized water. The autoclave was then purged twice with 20 bars of nitrogen. The stirred mixture was heated to 180 °C and allowed to react for 1 h at the resulting pressure. Subsequently the reaction mixture was allowed to cool to ambient temperature and any residual pressure was slowly relaxed. The crude mixture was obtained as a reddish-brown biphasic system. The phase boundary was ob- scured by a suspension. This precluded the exact measurement of the weights of the aqueous and organic phases. The weight of the organic phase was taken to be equal to the weight of the utilized toluene, while the weight of the aqueous phase was taken to be equal to the weight of the water-dimethyl sulfoxide mixture.

A sample was taken from the organic and aqueous phase. Each sample was subjected to cali- brated HPLC analysis (column: Waters XBridge Amide 3.5; eluent: water/acetonitrile 1 :1 ; temperature: 35 °C; injection volume 5 μΙ; detector: RID, UV). The amount of furfural formed was obtained by addition of the amount of furfural detected in the aqueous and organic phases. The amount of xylose consumed was calculated by subtracting the detected amounts of xylose from the initial amount. The selectivity of furfural formation was calculated as the ratio of furfural formed to xylose consumed.

The results are presented in the table below.

II) Dehydration of Glucose, Fructose and other Polysaccharides on TF-BEA zeolites Catalyst Examples:

For the preparation of a suitable catalyst Example 2 a), i.e. the Na-Form was ion exchanged with two different methods:

Example 4: NhU-Exchange method No 1 :

In the first step, 10g TF-BEA according to Example 2 a) were dispersed in 500 ml of a 1 M aqueous solution of N H4NO3. The dispersion was heated to 80°C and stirred for 1 h. Afterwards the solid was separated from the aqueous phase by filtration. The ion exchange was repeated under the above mentioned conditions. Afterwards, the solid was washed with Dl H2O until the conductivity of the wash water was below 200 cm ¹ . Then, the sample was first dried at 120°C for 5h and the calcined at 500°C for 5h.

Example 5: NhU-Exchange method No 2:

In the first step, 100g TF-BEA according to Example 2 a) were dispersed in 200 ml of a 12.5M aqueous solution of N H4NO3. Under stirring, the dispersion was heated to 90°C for 1 h. After- wards, the solid was separated from the aqueous phase by filtration. The ion exchange was repeated twice under above mentioned conditions. Afterwards, the solid was washed with Dl H2O until the conductivity of the wash water was below 200 cm ¹ . Then, the sample was first dried at 120°C for 5h and the calcined at 620°C for 2h. Then, the sample was treated analog to the description NhU-Exchange method No 1. Catalysis Results:

The following results were measured under the below given conditions: Batch reaction in a stirred stainless 50 ml autoclave. The organic phase of the reaction mixture was analyzed with GC (column: Polydimethylsiloxane, Initial Temperature: 40°C, Injection volume, FID-Detector) The aqueous phase was analyzed with HPLC: Column: Ion-exclusion column, Eluent: 5mM H2SO4, Temperature: 50°C, Injection Volume 10μΙ. Detector: RID, UV

Dehydration of glucose:

Catalyst B/L Conversion Selectivity

(%-C)

(%) Fructose HMF LVA Furfural AHG c ₃ Unknown

Example 1 .8 85 7 63 1 4 3 2 20 4

Example 0.85 88 10 43 2 7 3 2 33 5

Catalyst, 0.1 g; Glucose, 0.67 mmol; Water, 4.5 ml; DMSO 0.5 ml; THF, 15 ml; Temperature, 180 °C; Time 3 h (HMF = 5-Hydroxylmethylfurfural, AHG = Anhydroglucose, LVA = Levulinic Acid)

Dehydration of fructose:

Catalyst B/L Conversion Selectivity

(%-c)

(%) Glucose HMF LVA Furfural AHG c ₃ Unknown

Example 1 .8 94 3 76 2 4 1 1 13 4

Example 0.85 97 9 57 6 6 2 1 19 5

Catalyst, 0.1 g; Fructose, 0.67 mmol; Water, 4.5 ml; DMSO 0.5 ml; THF, 15 ml; Temperature, 180 °C; Time 1 h (HM F = 5-Hydroxylmethylfurfural, AHG = Anhydroglucose, LVA = Levulinic Acid)

Dehydration of other Polysaccharides:

Substrate Time Product

yield (%- C)

(h) Glucose Fructose HMF LVA Furfural AHG c ₃

Glucose 4 1 Ca. 0 72 3 4 0 1

Cellobiose 4 2 3 67 2 4 1 2

Cellulose 6 3 2 32 3 3 1 1

Fructose 1 3 7 71 2 3 1 1

Inulin 1 3 5 65 2 3 1 1 Catalyst, Example 4, 0.1 g; Substrate, 0.67 mmol calculated by monomer unit; Water, 4.5 ml; DMSO, 0.5 ml; THF, 15 ml; Temperature, 180°C (HMF = 5-Hydroxylmethylfurfural, AHG = An- hydroglucose, LVA = Levulinic Acid) IV) Regeneration of the Catalyst:

Recycling Procedure:

The spend catalyst Example 4 from the dehydration reaction of glucose (reaction conditions are given above) was calcined at 500°C for 5h. Afterwards, the sample was treated according to the description of "NhU-Exchange method No 1 ." and reused in catalysis:

Characterization of the catalysts by ²⁷ AI-MAS-NMR:

Dehydration of glucose:

Catalyst Conversion Selectivity

(%-C)

(%) Fructose HMF LVA Furfural AHG c ₃ Unknown

Example 4 85 7 63 1 4 3 2 20

(fresh)

Example 4 99 5 65 2 4 1 1 22

(regenerated)

Catalyst, 0.1 g; Glucose, 0.67 mmol; Water, 4.5 ml; DMSO 0.5 ml; THF, 15 ml; Temperature, 180 °C; Time 3 h (HMF = 5-Hydroxylmethylfurfural, AHG = Anhydroglucose, LVA = Levulinic Acid)