DE102008056243A1 - Preparation of phenol from benzene with aqueous hydrogen peroxide in the presence of a titanium-silicon-containing catalyst, which has zeolite structure with structural defect sites, useful as an intermediate for preparing chemicals - Google Patents

Abstract

Preparation of phenol from benzene with aqueous hydrogen peroxide in the presence of a titanium-silicon-containing catalyst, which has zeolite structure with structural defect sites, is claimed.

Description

State of the art

phenol and the higher hydroxylated aromatics such as resorcinol, Hydroquinone and catechol are very important intermediates for Production of a wide range of chemicals. The current one Industrial production of phenol is mostly based on a 3-step process d. H. the cumene route, which as the end products phenol and acetone in stoichiometric amounts. The economy Such a process depends on the demand for that unmissable byproduct acetone in the market. Come in addition, that multi-stage reaction processes have a great need to require energy especially in the processing part. Demand for phenol is increasing much more than the acetone requirement. Therefore, acetone will only continue at cheap prices can be marketed and the cumene process is growing become less economical.

Around Overcoming these disadvantages concentrates much research on the single-step process through insertion a hydroxyl group, the aromatic ring, thus directly phenol and / or other hydroxylated aromatics and thus the To avoid co-production of acetone.

To use hydrogen peroxide as an oxidant, you could z. B. on the article in Applied Clay Science 33 (2006) 1-6 in which the hydroxylation of benzene to phenol is reported by the use of acetic acid as the solvent. Under mild reaction conditions of 40 ° C, a selectivity of 94% at 14% benzene conversion was achieved on a clay-supported vanadium oxide catalyst

It can be up Applied Catalysis A: General 278 (2005) 251-261 Scientists report on the use of hydrogen peroxide as an oxidant in the hydroxylation of benzene in the presence of a co-solvent. A phenol selectivity of 91% and a yield of 26% were observed at room temperature on a vanadium-substituted heteropolymolybdate catalyst.

It may refer to the article in Advanced Synthesis & Catalysis 349 (2007) 979-986 be taken. Here reported Bianchi et al. on the hydroxylation of benzene to phenol with hydrogen peroxide as an oxidant on a modified titanium silicalite (TS-1). A benzene conversion of 8.6% and 91% phenol selectivity was achieved at 100 ° C using sulfolane as a co-solvent.

In US Patent 20080234524A1 , 2008 describes a process of liquid phase hydroxylation of benzene with hydrogen peroxide over vanadyl pyrophosphate catalysts and acetonitrile as a solvent under mild conditions. The process delivers a benzene conversion of up to 70% and a selectivity of phenol up to 100%.

In US Pat. No. 6,180,836B1 describes a one-step process for the production of phenol by oxidation of benzene with hydrogen peroxide, wherein the reaction is catalyzed by molecular sieves mixed with copper ions. A phenol yield of 15-35% with selectivity close to 100% was achieved using the correct solvent.

State of the art

The Sales published in the prior art to phenol and other hydroxylated aromatics are in need of improvement. The disadvantage of the processes described above using Co-solvent is that more energy is needed in the Separation units of a one-stage co-solvent free process. In addition, known single-stage take into account Processes for the production of phenol not the hydrogen peroxide Consumption which is relative in price far higher than benzene. That's why it's so big Interest, a "quasi-solvent" free Process for the one-step hydroxylation of benzene to phenol and to develop further hydroxylated aromatics, which are less Separation effort has. Furthermore, a maximum is hydrogen peroxide Recycling a desirable goal.

Therefore It was desirable to have a process for dissection of phenol in one step from benzene by the use of hydrogen peroxide as an oxidant without additional solvent to provide a heterogeneous catalyst. Another perspective is to create a phenol production process that is mild under Conditions is performed.

Surprisingly, it has now been found that with the aid of a titanium-silicon-containing catalyst contains the structural defects in the MFI structure and in addition to the microporosity meso and / or macropores, these above-mentioned disadvantages can be overcome, working in a quasi "solvent-free" medium.

Detailed description of the invention

The submitted invention describes the process of production of Phenol and other hydroxylated aromatics such as hydroquinone and Catechol by hydroxylation of benzene using hydrogen peroxide as an oxidant on a titanium-silicon-containing catalyst with structural defects in the "virtually solvent-free system". The reaction is carried out by heating a suspension of titanium-silicon-containing Catalysts with structural defects in water at desired Reaction temperature z. B. executed in a batch reactor. After reaching the desired temperature benzene is added, being an excessive benzene evaporation avoided during the heating process and drop by drop Hydrogen oxide with vigorous stirring of the mixture is added. After the reaction, the mixture is in cooled down in an ice bath. The unreacted hydrogen peroxide is destroyed by added manganese oxide to more Reactions of hydroxilated products with hydrogen peroxide in GC columns to avoid. The catalyst particles are separated by using a centrifuge. The reaction products be in the GC with a packed column and a FID detector analyzed.

The Reaction temperature is in the range of 20-100 ° C, preferably at 40-80 ° C, more preferably at 60-70 ° C. The amount of catalyst is between 0.1 g to 2.5 g and preferably 1-1.5 g at 56 mmol Benzene used. The molar ratio of benzene / hydrogen peroxide is 0.1: 1 to 10: 1, preferably 2: 1 to 7: 1, and more particularly preferably 4: 1 to 6: 1 is selected. The reaction is completed in a range of 0.5-24 h, and preferably 1-5 H. The set pressures can normal pressure, Be under pressure and excessive pressure. Prefers are atmospheric pressure and pressures from 1 to 20 bar.

When Reactors are used in slurry reactors with batchwise operation, Autoclaves, loop reactors. Tricklebettreaktoren with Rieselfahrweise or marshy way. But it can also be continuous fixed bed reactors be used.

Titanium-silicon molecular sieves containing titanium as the T atom in the crystal structure are widely known. These and in particular TS-1 are used in many organic reactions, in particular in oxidations with hydrogen peroxide as oxidant (see US Pat. 4410501 ).

It is believed that for a typical microporous TS-1 pentasil zeolite containing predominantly isolated Ti ⁴⁺ ions in lattice positions, a co-solvent is needed to activate the H ₂ O ₂ molecules for oxidation reactions. On the other hand, a TS-1 catalyst whose structure is distorted by non-isomorphously replaced titanium ions can activate H ₂ O ₂ even in the absence of a co-solvent ( Halasz et al., Catalysis Today 81 (2003) 227-245 ). Furthermore, the typical TS-1 hydrophobic properties were reported to be critical for reactions using H ₂ O ₂ as the oxidant. This has led to the development of non-alkoxide technology-based MFI-type microporous titanium silicates by PQ Corporation (see US Patent Application US20030152510A1, 2003). This catalyst is called TS-PQ ^™ . TS-PQ ^TM does not now contain isolated, tetrahedrally coordinated titanium atoms and not only exhibits hydrophobic properties, but also absorbs H ₂ O ₂ in the presence of large hydrocarbons ( Halasz et al., Stud. Surf. Sci. Catal. 158 (2005) 647-654 ). The catalyst was used in the oxyfunctionalization of n-Haxan with H ₂ O ₂ , where it showed superior activity compared to TS-1 in a solvent-free system ( Halasz et al., Catalysis Today 81 (2003) 227-245 ).

The use of TS-PQ ^™ in the hydroxylation of benzene has not previously been described.

The TS-PQ ^™ catalyst used in the example below shows, similar to TS-1, an XRD spectrum that corresponds to an MFI structure (see 1 ). The N ₂ adsorption / desorption isotherm in 2 has a hysteresis characteristic indicating that the TS-PQ ^™ material contains some mesopores. The Si / Ti ratio of the example shown below was 46. The BET surface area was 454 m ² / g, with a micropore area contribution of 243 m ² / g. The BJH micropore volume of the catalyst was added to 0.1167 cm ³ / g; certainly. The proportion of mesopores contributing to the total surface had an average pore size of 151 Å. The micropore diameter of TS-PQ ^™ according to Horvath-Kawazoe is about 5.5 Å (see 3 ). The FT-IR spectrum of the catalyst shows a band at 960 cm ^-1 corresponding to titanium incorporated into the lattice structure. Similar to TS-1, but with additional absorption bands (s. 4 ). The crystallite size was determined after SEM images (s. 7 )) is estimated to be 100-300 nm.

However, the TS-PQ ^™ used in the present invention showed differences to other titania silica molecular sieves such as TS-1, not only in the presence of the mesopores.

Further differences could be observed by DRUV-Vis spectroscopy. A typical, defect-free TS-1 shows an adsorption band at 210 nm, which corresponds to isolated tetrasorically coordinated titanium atoms in the silica lattice ( Halasz et al., Catalysis Today 81 (2003) 227-245 ). In contrast, TS-PQ ^TM contains not only these titanium atoms. The spectrum shows a small shoulder of the adsorption band at about 220 nm, which is not observed for typical TS-1. In addition, the catalyst has adsorption bands at 240 nm, which may correspond to octahedrally coordinated titanium (s. 6 ). IR spectroscopy of TS_PQ ^TM silanol groups (Si-OH) next to the Ti-O-Si bridges in well-synthesized TS-1 (s. 5 ).

The the following examples are given to illustrate the invention, but not the submitted invention in any way limit.

Examples

The following materials are used: benzene (99%) from Panreac; aqueous hydrogen peroxide solution (30wt%) from Fischer or Degussa AG, distilled water. The TS-PQ ^™ catalyst was supplied by PQ Corporation.

In these examples, phenol, 1,4-benzoquinone, catechol, and hydroquinone were identified as reaction products and quantitatively analyzed by gas chromatography. Conversion of H ₂ O ₂ to organic compounds was calculated on the basis of the consumption of hydrogen peroxide needed to make the products. One mole of phenol consumes one mole of H ₂ O ₂ and one mole of 1,4-benzoquinone or hydroquinone or catechol consumes two moles of H ₂ O ₂ . The product selectivity was calculated based on the molar amount of the desired product based on the moles of all products produced.

example 1

This example demonstrates the effectiveness of the stirring rate and temperature in H ₂ O ₂ conversion and phenol selectivity. 56 mmol was used for benzene and the benzene / H ₂ O ₂ molar ratio was 5: 1. 0.2 g of TS-PQ ^™ catalyst was used. 20 ml of water were added in addition. The reaction was carried out under atmospheric pressure in a slurry reactor for 3 hours.

Table 1 shows the results of benzene hydroxylation catalyzed with a TS-PQ ^™ catalyst at different temperatures and stirring rates. 1100 rpm stirring rate gave the highest H ₂ O ₂ conversion to organic compounds. This indicates. that diffusion problems occur and have an influence on the reaction. The optimum reaction temperature was 70 ° C. Table 1 Effect of stirring speed and temperature of H ₂ O ₂ conversion to organic compounds and product selectivity. H ₂ O ₂ conversion to Temperature (° C) Stirring speed (rpm) organic compounds% Phenol selectivity% 70 500 14.9 95 70 900 17.3 91 70 1100 19.4 92 65 1100 14.9 82 75 1100 17.9 90

Example 2

This example demonstrates the influence of molar benzene / H ₂ O ₂ ratio on H ₂ O ₂ conversion to organic compounds and product selectivities. The amount of H ₂ O ₂ was kept constant at 11 mmol while the amount of benzene increased.

0.2 g of TS-PQ ^™ catalyst was used. 20 ml of water were added in addition. The reaction was carried out under atmospheric pressure and 70 ° C in a slurry reactor for 3 hours.

The results in Table 2 show that H ₂ O ₂ conversion to organics increases from 7% to 19% as the benzene / H ₂ O ₂ molar ratio is increased from 1: 1 to 5: 1. Thereafter, benzene conversion remained stable even when the ratio increased to 10: 1. Table 2 Effect of benzene / H ₂ O ₂ molar ratio on H ₂ O ₂ conversion to organics and product selectivities Molar ratio Sales H ₂ O ₂ % Phenol selekt%. 1,4-benzoquinone select. % Catechol select. % Hydroquinone select. % 1: 1 7:37 89.20 8.10 0 2.69 5: 1 19:35 92.42 6.25 0 1:33 10: 1 19:21 92.03 6.17 12:02 1.78

Example 3

This example demonstrates the effect of a volume of additional water on H ₂ O ₂ conversion and product selectivities. 56 mmol of benzene was used and the benzene / H ₂ O ₂ molar ratio was 5: 1. 0.2 g of TS-PQ ^™ catalyst was used. 20 ml of water were added in addition. The reaction was carried out under atmospheric pressure and 70 ° C in a slurry reactor for 3 hours.

The results in Table 3 show that additional water increases H ₂ O ₂ conversion to organic compounds. Table 3 Influence of the volume of additional water added on H ₂ O ₂ conversion to organic compounds and product selectivities Additional sales of water ml H ₂ O ₂ % Phenol selekt%. 1,4-benzoquinone select. % Catechol select. % Hydroquinone select. % 0 9.60 65.64 30.94 12:04 3:37 15 16:42 87.67 9.86 12:01 2:45 20 19:35 92.42 6.25 0 1:33 40 22:54 96.35 1.77 12:03 1.85 50 19.79 94.75 12:02 12:03 5.20 60 18.70 98.18 12:01 12:02 1.79

Example 4

This example demonstrates the effectiveness of the amount of catalyst on H ₂ O ₂ conversion to organic compounds and product selectivities. 56 mmol of benzene was used and the benzene / H ₂ O ₂ molar ratio was 5: 1. 0.2 g of TS-PQ ^™ catalyst was used. 40 ml of water were added in addition. The reaction was carried out under atmospheric pressure and 70 ° C in a slurry reactor for 3 hours.

The results in Table 4 show the increased H ₂ O ₂ conversion to organic compounds by increasing the amount of catalyst. The highest conversion was about 95% when using 1.5 g of catalyst. Table 4 Influence of the amount of catalyst on the benzene hydroxylation with H ₂ O ₂ to organic compounds and their product selectivities. Catalyst amount in g Sales H ₂ O ₂ % Phenol selekt%. 1,4-benzoquinone select. % Catechol select. % Hydroquinone select. % 0.2 22:54 96.35 1.77 12:03 1.85 0.6 57.25 69.04 2.11 8:01 11.93 1.0 81.81 58.75 1.80 15:16 24.29 1.3 86.44 57.62 1:48 2.16 24.88 1.5 95.12 53.61 0 5.20 26.34 2.0 95.71 55.08 0 17.66 27.26

Example 5

This example demonstrates the effectiveness of the reaction time on H ₂ O ₂ conversion to organic compounds and their product selectivities. 56 mmol of benzene was used and the benzene / H ₂ O ₂ molar ratio was 5: 1. 0.2 g of TS-PQ ^™ catalyst was used. 40 ml of water were added in addition. The reaction was carried out under atmospheric pressure and 70 ° C in a slurry reactor for 3 hours.

The results in Table 5 show the increase of H ₂ O ₂ conversion to organic compounds from 25% to 95% with increasing reaction time from 0.5 hours to 3 hours. Thereafter, the system is stable, even if the reaction time is increased to 5 hours. The optimal reaction time in this process is about 3 hours. Table 5 Influence of the reaction time on H ₂ O ₂ conversion to organic compounds and their product selectivities Reaction time in hours Sales H ₂ O ₂ % Phenol selekt%. 1,4-benzoquinone select. % Catechol select. % Hydroquinone select. % 0.5 25.26 87.47 9:52 12:10 2.91 1 64.24 66.20 15.72 10:20 7.88 2 87.54 59.56 1.78 15.94 22.73 3 95.12 53.61 0 5.20 26.34 5 95.02 54.01 0 20.97 25.02

Brief description of the pictures

• Fig. 1 XRD recording of TS-PQ ^TM .
• Figure 2 N ₂ adsorption-desorption isotherm at 77 K.
• Image. 3 Horvath-Kawazoe differential pore volume of TS-PQ ^TM
• Image. 4 FT-IR Spectrum from TS-PQ ^TM in the wavelength range 650 cm ^-1 and 1050 cm ^-1 .
• Image. 5 FT-IR Spectrum from TS-PQ ^TM in the wavelength range 1500 cm ^-1 and 4000 cm ^-1 .
• Image. 6 DRUV-Vis Spectrum from TS-PQ ^TM
• Image. 7 SEM image of TS-PQ ^TM .

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 20080234524 A1 [0006]
• - US 6180836 B1 [0007]
• US 4410501 [0014]

Cited non-patent literature

• - Applied Clay Science 33 (2006) 1-6 [0003]
• Applied Catalysis A: General 278 (2005) 251-261 [0004]
• Advanced Synthesis & Catalysis 349 (2007) 979-986 [0005]
• Bianchi et al. [0005]
• Halasz et al., Catalysis Today 81 (2003) 227-245 [0015]
• Halasz et al., Stud. Surf. Sci. Catal. 158 (2005) 647-654 [0015]
• Halasz et al., Catalysis Today 81 (2003) 227-245 [0015]
• Halasz et al., Catalysis Today 81 (2003) 227-245 [0019]

Claims (14)

Process for the preparation of phenol from benzene with aqueous hydrogen peroxide in the presence of a titanium-silicon-containing catalyst, characterized in that the titanium-silicon-containing catalyst has a zeolite structure with structural defects. Method according to claim 1, characterized in that that the structural defects of the titanium-silicon-containing catalyst by IR spectroscopy, UV-Vis spectroscopy and pore size and pore distribution can be characterized. Method according to claim 1, characterized in that that the titanium-silicon-containing catalyst is not a pure microporous Has zeolite structure, but also meso- and / or macropores contains. Method according to claim 1, characterized in that that the reaction takes place at a temperature between 20 ° C and 100 ° C is performed. Method according to claim 1, characterized in that that the concentration of hydrogen peroxide ranges from 1% to 70%. Method according to claim 1, characterized in that that in the reaction, the molar ratio of hydrogen peroxide to benzene from 1:10 to 1: 0.1 is enough. Method according to claim 1, characterized in that that the reaction is under atmospheric or reduced or high pressure is performed. Method according to claim 1, characterized in that that strong stirring is used. Process according to Claim 1, characterized in that the titanium-silicon-containing catalyst is TS-PQ ^™ . Process according to claims 1 and 9, characterized characterized in that the hydrothermal production and / or treatment the catalyst includes a step with acid. Method according to claim 9, characterized in that the catalyst is dried before use. Method according to claim 1, characterized in that that in addition to water and the reactants no additional Solvent added to the reaction medium becomes. Method according to claim 1, characterized in that that the volume ratio of benzene to the attached Water aside from the hydrogen peroxide solution 1: 0 until 1:20 is. Method according to claim 1, characterized in that that the catalyst contains at least 0.2wt% of the aromatic Mixture is used.