CN103289727B - A kind of method of selective oxidation of sulfur containing compounds in particular - Google Patents

Abstract

The invention discloses a method for oxidizing sulfur-containing compounds. The method includes contacting the sulfur-containing compounds with an oxidizing agent under oxidation reaction conditions, and the feature is that the oxidizing agent is a gas containing ozone. The method has high selectivity for sulfones and sulfoxides, and especially in the presence of a titanium-containing catalyst, the effective utilization rate of ozone is greatly improved.

Description

A method for oxidation of sulfur-containing compounds

technical field

The present invention relates to a method for oxidizing sulfur-containing compounds, and more particularly relates to a method for oxidizing sulfur-containing compounds with ozone as an oxidant.

Background technique

With the increasingly stringent requirements for environmental protection around the world, the quality requirements for vehicle fuels in various countries are also becoming increasingly stringent. In recent years, with the rapid increase in the number of motor vehicles, motor vehicle exhaust has become the main source of urban air pollution, and the key to reducing pollutant emissions is to reduce the sulfur content of petroleum products (especially gasoline and diesel). The traditional mainstream desulfurization technology for fuel oil is hydrodesulfurization (HDS), but the desulfurization effect on multi-substituted dibenzothiophene derivatives, such as 4,6-dimethyldibenzothiophene, is poor.

Organic sulfides can be oxidized to sulfones and sulfoxides, where sulfoxides are a class of organic compounds containing sulfinyl (>S=0) functional groups, which can be obtained by oxidation of sulfides; A class of organic compounds characterized by attachment of two carbon atoms (eg, to two hydrocarbyl groups or a simple divalent radical), generally crystalline and stable compounds. Based on this, the oxidative desulfurization technology has been formed. Compared with the hydrodesulfurization process, it can better remove thiophene and its alkyl substitutes. Benzothiophene sulfides are more easily oxidized into more polar sulfones and Sulfoxides. Oxidative desulfurization technology usually reacts under normal pressure and mild conditions of <100°C. It does not require hydrogen sources, pressure-resistant reactors, or special refining methods. Super-deep desulfurization of gasoline and diesel oil saves energy and is a true green chemical industry. As a desulfurization technology with low investment and low operating cost, oxidative desulfurization has attracted more and more attention.

Contents of the invention

The object of the present invention is to provide a method for oxidation of sulfur-containing compounds that can be applied to the fuel oil desulfurization industry, has simple process, low cost, and good selectivity for sulfones and sulfoxides.

The invention discloses a method for oxidizing sulfur-containing compounds. The method includes contacting the sulfur-containing compounds with an oxidizing agent under oxidation reaction conditions, and the feature is that the oxidizing agent is a gas containing ozone.

The method for oxidation of sulfur-containing compounds provided by the present invention uses ozone as an oxidizing agent, without adding any inhibitor or initiator in the feed gas, so as to obtain high overall selectivity of sulfones and sulfoxides and a high effective utilization rate of ozone, Especially in the presence of a titanium-containing catalyst, the effective utilization rate of ozone is further improved. In addition, the process of the method provided by the invention is simple and easy to control, can be applied to the fuel oil desulfurization industry, and has very broad application prospects.

Detailed ways

The invention discloses a method for oxidizing sulfur-containing compounds. The method includes contacting the sulfur-containing compounds with an oxidizing agent under oxidation reaction conditions, and the feature is that the oxidizing agent is a gas containing ozone.

According to the method of the present invention, an ozone-containing gas is used as an oxidizing agent. Ozone (molecular formula is O ₃ , also known as triatomic oxygen, commonly known as "Fu oxygen, super oxygen, active oxygen") is a light blue gas at normal temperature and pressure. The inventors of the present invention found during the research process that using ozone-containing gas as an oxidant to oxidize sulfur-containing compounds has high selectivity for sulfones and sulfoxides, and the process is simple and easy, and the operating conditions are mild. Moreover, ozone can be decomposed into oxygen by itself at room temperature, and there will be no disadvantages such as the need to process a solution containing hydrogen peroxide, which is faced when hydrogen peroxide is used as an oxidant. Therefore, the method according to the invention is environmentally friendly.

According to the method of the present invention, the ozone-containing gas may be ozone, or a mixed gas of ozone and diluent gas. According to the method of the present invention, the gas containing ozone is preferably a mixed gas of ozone and diluent gas, so that the concentration of ozone can be adjusted conveniently, so as to better control the reaction rate.

In the present invention, when the ozone-containing gas is a mixed gas of ozone and a diluent gas, the concentration of ozone in the mixed gas can be properly selected according to specific oxidation reaction conditions. Preferably, based on the total volume of the mixed gas, the content of ozone in the mixed gas is more than 1% by volume. More preferably, based on the total volume of the mixed gas, the content of ozone in the mixed gas is more than 5% by volume. Generally, based on the total volume of the mixed gas, the content of ozone in the mixed gas may be 5-80% by volume, preferably 5-50% by volume, more preferably 5-20% by volume.

The present invention has no particular limitation on the type of the diluent gas, for example, the diluent gas may be at least one of oxygen, carbon dioxide, nitrogen, argon, helium, neon and air. Preferably, the diluent gas is at least one of oxygen, carbon dioxide, helium and air. According to the present invention, ozone can be mixed with the above diluent gas to prepare the ozone-containing mixed gas; since air contains oxygen, carbon dioxide and nitrogen, ozone can also be mixed with air to prepare the ozone-containing mixed gas. According to the method of the present invention, when an ozone generator is used to generate ozone on site, oxygen can be used as the oxygen source of the ozone generator, and air can also be used to provide oxygen to the ozone generator. The purity of the ozone that adopts oxygen as the oxygen source of described ozone generator to obtain is higher, can obtain higher total selectivity of sulfone and sulfoxides and high effective utilization rate of ozone; Adopt air as the oxygen source of described ozone generator , it can further reduce the operating cost.

According to the method of the present invention, when the oxidizing agent is a mixed gas of ozone and diluent gas, and there are two or more kinds of diluent gases, the present invention does not specifically limit the content of each diluent gas, as long as the final ozone-containing In the gas, it is enough that the content of ozone can oxidize the sulfur-containing compound, for example: the content of ozone can be the above-mentioned ozone content.

In a preferred embodiment of the present invention, the ozone-containing gas is ozone or a mixed gas of ozone and diluent gas, and based on the total volume of the mixed gas, the amount of ozone in the mixed gas The content is more than 1% by volume, and the diluent gas is at least one of oxygen, carbon dioxide, nitrogen, argon, helium, neon and air. In a more preferred embodiment according to the present invention, based on the total volume of the mixed gas, the content of ozone in the mixed gas is more than 5% by volume, and the diluent gas is oxygen, carbon dioxide, helium At least one of gas and air.

According to the method of the present invention, realize the preparation of sulfone and sulfoxide with mild operating conditions and higher selectivity by adopting the gas containing ozone as the oxidant, while also not causing serious corrosion to the equipment, the present invention is for There is no special requirement for the molar ratio of the sulfur-containing compound to the ozone in the oxidizing agent, and can be properly selected according to specific application occasions. Under the conditions of ensuring the conversion rate of sulfur-containing compounds and the selectivity of sulfone and sulfoxide, from the perspective of further reducing the amount of ozone, and further reducing the cost of the method according to the present invention, the sulfur-containing compound and the oxidant The molar ratio of ozone is preferably 1:0.1-10, more preferably 1:0.1-5, even more preferably 1:0.5-5.

According to the method of the invention, the contacting of the sulfur-containing compound with the oxidizing agent is preferably carried out in the presence of a titanium-containing catalyst. The inventors of the present invention found in the research process that when the contact between the sulfur-containing compound and the oxidizing agent is carried out in the presence of a titanium-containing catalyst, the conversion rate of the sulfur-containing compound in the method of the present invention can be improved, especially the ozone can be greatly improved. effective utilization.

According to the method of the present invention, the amount of the titanium-containing catalyst can be properly selected according to specific application occasions. Preferably, based on titanium dioxide, the molar ratio of the titanium-containing catalyst to the sulfur-containing compound is 1:0.1-100. More preferably, based on titanium dioxide, the molar ratio of the titanium-containing catalyst to the sulfur-containing compound is 1:1-50.

According to the method of the present invention, the titanium-containing catalyst may be various forms of titanium-containing catalysts. Preferably, the titanium-containing catalyst is at least one of titanium-containing molecular sieves, shaped catalysts containing titanium molecular sieves, amorphous silicon titanium and titanium dioxide. More preferably, the titanium-containing catalyst is titanium-silicon molecular sieve with MFI structure (such as TS-1), titanium-silicon molecular sieve with MEL structure (such as TS-2), titanium-silicon molecular sieve with BEA structure (such as Ti-Beta), MWW Structured titanium-silicon molecular sieve (such as Ti-MCM-22), hexagonal structure titanium-silicon molecular sieve (such as Ti-MCM-41, Ti-SBA-15), MOR structure titanium-silicon molecular sieve (such as Ti-MOR), TUN structure At least one of titanium-silicon molecular sieves (such as Ti-TUN), titanium-silicon molecular sieves of other structures (such as Ti-ZSM-48) and titanium dioxide. More preferably, the titanium-containing catalyst is a titanium-silicon molecular sieve with an MFI structure (such as TS-1). The above-mentioned molecular sieves can be obtained commercially, or synthesized by methods known in the art, and will not be described in detail herein.

According to the method of the present invention, the titanium-containing catalyst is most preferably a titanium-silicon molecular sieve with an MFI structure of hollow structure crystal grains, the radial length of the cavity part of the hollow structure is 5-300 nanometers, and the titanium-silicon molecular sieve is The benzene adsorption measured under the conditions of 25°C, P/P ₀ =0.10, and adsorption time of 1 hour is at least 70 mg/g, and the low-temperature nitrogen adsorption of the titanium-silicon molecular sieve is between the adsorption isotherm and the desorption isotherm There is a hysteresis loop. Hereinafter, this type of titanium-silicon molecular sieve is called hollow titanium-silicon molecular sieve.

According to the method of the present invention, the contact between the sulfur-containing compound and the oxidant is preferably carried out in the presence of a solvent, which can make the contact between the sulfur-containing compound and the oxidant more uniform, thereby better controlling the reaction rate. The present invention has no particular limitation on the type of the solvent, and the solvent may be various solvents commonly used in the art. Preferably, the solvent is at least one of water, C ₁ -C ₁₀ alcohol, C ₃ -C ₁₀ ketone, C ₂ -C ₈ nitrile and C ₁ -C ₆ carboxylic acid. For example, the solvent may be at least one of water, methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone, acetonitrile and acetic acid. The inventors of the present invention unexpectedly found in the research process that when the solvent is a C ₁ -C ₄ alcohol and/or a C ₃ -C ₈ ketone, the conversion rate of sulfur-containing compounds and the conversion of sulfone and sulfoxide can be further improved selectivity. Further preferably, the solvent is methanol and/or acetone.

According to the method of the present invention, the amount of the solvent can be conventionally selected in the art. From the perspective of further reducing the cost of the method of the present invention, the molar ratio of the sulfur-containing compound to the solvent is preferably 1:1-150, more preferably 1:1-100, and even more preferably 1:1-50.

According to the method of the present invention, there is no special requirement for the oxidation reaction conditions, which may be conventional oxidation reaction conditions. Preferably, the oxidation reaction conditions include: the temperature can be 0-180°C, preferably 20-160°C, more preferably 20-120°C; the pressure can be 0.1-3MPa, preferably 0.1-2.5MPa, more preferably It is 0.v2MPa. According to the method of the present invention, the contact time of the sulfur-containing compound and the oxidizing agent can be properly selected. Generally, the contacting time may be 0.1-10 hours, preferably 1-5 hours. It should be noted that, when the required pressure can be generated at the temperature, the pressure can be an autogenous pressure; when the pressure generated by the temperature cannot reach the required pressure at the temperature, The pressure can be achieved by external pressure, which is a well-known technique in the art, and will not be described in detail herein.

In the method provided by the present invention, the sulfur-containing compound can be simple mercaptans, thioethers, or substitution or derivatives of sulfur-containing heterocyclic compounds such as thiophene, such as 2-methylthiophene, 2-chlorothiophene, benzene thiophene, 4-methylbenzothiophene, 4,6-dimethylbenzothiophene, etc. Further, the sulfur-containing compound in the present invention can be mercaptan, thioether, benzothiophene, 2-methylthiophene, 2-chlorothiophene, 4-methylbenzothiophene, 4,6-dimethylbenzothiophene Thiophene etc.

The following examples will further illustrate the present invention, but do not limit the content of the present invention thereby.

In the examples, unless otherwise specified, the reagents used are commercially available analytical reagents, and the reactor used is a general-purpose 250mL stainless steel autoclave reactor.

In the embodiment, the ozone used is provided by the NLO-15 ozone generator produced by Fujian Newland Environmental Protection Technology Co., Ltd. The ozone concentration is adjustable, and the maximum volume concentration can reach 80%. In the following examples, unless otherwise specified, an oxygen source is used to prepare ozone.

In the embodiment, the titanium-silicon molecular sieve (TS-1) catalyst used is the TS-1 molecular sieve sample prepared by the method described in the literature [Zeolites, 1992, Vol.12 pages 943-950], and the titanium oxide content is 2.4% by weight.

In the embodiment, the hollow titanium-silicon molecular sieve HTS used is an industrial product of the titanium-silicon molecular sieve described in CN1301599A (manufactured by Hunan Jianchang Petrochemical Co., Ltd., analyzed as a titanium-silicon molecular sieve of MFI structure by X-ray diffraction, and the low-temperature nitrogen of the molecular sieve There is a hysteresis loop between the adsorption isotherm and the desorption isotherm, the grains are hollow grains and the radial length of the cavity part is 15-180 nanometers; the molecular sieve sample is at 25°C, P/P ₀ =0.10, The benzene adsorption measured under the condition of an adsorption time of 1 hour was 78 mg/g), and the titanium oxide content was 2.5% by weight.

In the present invention, the analysis of each composition in the system is carried out by gas chromatography, and the quantification is carried out by the calibration and normalization method, both of which can be carried out with reference to the prior art. On this basis, evaluation indicators such as the conversion rate of the reactant and the selectivity of the product are calculated.

In the example:

Example 1

At a temperature of 60° C. and a pressure of 0.5 MPa, with ozone (15% by volume, the rest being oxygen) as an oxidant, ethyl sulfide, ozone and solvent acetone were reacted in a molar ratio of 1:1:1. The results of the reaction for 2 hours are as follows: the conversion rate of ethyl sulfide is 57%; the effective utilization rate of ozone is 41%; the selectivity of sulfone and sulfoxide is 68%.

Example 2

At a temperature of 20°C and a pressure of 1.5 MPa, with ozone (30% by volume, the rest being air) as an oxidant, isopropyl mercaptan, ozone and solvent acetic acid are reacted in a molar ratio of 1:1:5 . The results of the reaction for 5 hours are as follows: the conversion rate of isopropyl mercaptan is 32%; the effective utilization rate of ozone is 31%; the selectivity of sulfone and sulfoxide is 72%.

Example 3

At a temperature of 100°C and a pressure of 2.0 MPa, with ozone (10% volume ratio, the rest being equal volumes of helium and oxygen) as the oxidant, 2-chlorothiophene, ozone and solvent acetonitrile were prepared in a ratio of 1:2:60. react at a molar ratio. The results of the reaction for 1 hour are as follows: the conversion rate of sulfur compounds is 48%; the effective utilization rate of ozone is 35%; the selectivity of sulfones and sulfoxides is 90%.

Example 4

At a temperature of 40° C. and a pressure of 0.1 MPa, with ozone (15% by volume, the rest being oxygen) as an oxidant, methylthiophene, ozone and solvent acetone were reacted in a molar ratio of 1:4:50. The results of the reaction for 3 hours are as follows: the conversion rate of methylthiophene is 42%; the effective utilization rate of ozone is 31%; the selectivity of sulfones and sulfoxides is 83%.

Example 5

This example illustrates the reaction procedure and results in the presence of a catalyst.

TS-1 was used as the catalyst, the molar ratio of the catalyst to the sulfur-containing compound was 1:100, the ozone volume space velocity was 20h ^-1 , and other reaction conditions were the same as in Example 4. The results of the reaction for 3 hours are as follows: the conversion rate of sulfur compounds is 55%; the effective utilization rate of ozone is 63%; the selectivity of sulfones and sulfoxides is 91%.

Example 6

This example illustrates the reaction procedure and results in the presence of a catalyst.

The reaction was carried out according to the reaction conditions of Example 5, except that HTS was used instead of TS-1 as the catalyst. The results of the reaction for 3 hours are as follows: the conversion rate of sulfur compounds is 67%; the effective utilization rate of ozone is 69%; the selectivity of sulfones and sulfoxides is 96%.

Example 7

At a temperature of 50° C. and a pressure of 1.0 MPa, with ozone (10% by volume, the rest being air) as an oxidant, benzothiophene, ozone and solvent water are reacted in a molar ratio of 1:0.3:3. The results of the 8-hour reaction are as follows: the conversion rate of sulfur compounds is 11%; the effective utilization rate of ozone is 35%; the selectivity of sulfones and sulfoxides is 78%.

Example 8

At a temperature of 120°C and a pressure of 1.5MPa, with ozone (20% by volume, the rest being carbon dioxide and oxygen at a volume ratio of 7:10) as an oxidant, 4,6-dimethylbenzothiophene, ozone and solvent Acetone was reacted at a molar ratio of 1:0.6:25. The results of the reaction for 3 hours are as follows: the conversion rate of sulfur compounds is 20%; the effective utilization rate of ozone is 39%; the selectivity of sulfones and sulfoxides is 82%.

Example 9

This example illustrates the reaction procedure and results in the presence of a catalyst.

TiO ₂ was used as catalyst (commercially available, anatase type), the molar ratio of catalyst to sulfur-containing compound was 1:20, the volume space velocity in ozone was 5000h ^-1 , and other reaction conditions were the same as in Example 8. The results of the reaction for 3 hours are as follows: the conversion rate of sulfur compounds is 32%; the effective utilization rate of ozone is 63%; the selectivity of sulfones and sulfoxides is 90%.

Example 10

At a temperature of 100°C and a pressure of 2.0 MPa, with ozone (20% volume ratio, the rest being helium and oxygen at a volume ratio of 7:10) as the oxidant, benzothiophene, ozone and solvent acetonitrile were mixed in a ratio of 1:2 : 10 molar ratio to react. The results of the reaction for 4 hours are as follows: the conversion rate of sulfur compounds is 38%; the effective utilization rate of ozone is 42%; the selectivity of sulfones and sulfoxides is 87%.

Example 11

This example illustrates the reaction procedure and results when the solvent is methanol.

The reaction was carried out according to the reaction conditions of Example 10, except that methanol was used instead of acetonitrile as the solvent. The results of the reaction for 4 hours are as follows: the conversion rate of sulfur compounds is 46%; the effective utilization rate of ozone is 50%; the selectivity of sulfones and sulfoxides is 89%.

Example 12

This example illustrates the reaction procedure and results in the presence of a catalyst.

HTS was used as the catalyst, the molar ratio of the catalyst to the sulfur compound was 1:10, the ozone volume space velocity was 1000h ^-1 , and other reaction conditions were the same as in Example 11. The results of the reaction for 4 hours are as follows: the conversion rate of sulfur compounds is 62%; the effective utilization rate of ozone is 71%; the selectivity of sulfones and sulfoxides is 94%.

Claims (7)

1. the method for a selective oxidation of sulfur containing compounds in particular, the method is: under temperature is 0-180 DEG C and pressure is the oxidation reaction condition of 0.1-3.0MPa, by sulfocompound and oxidising agent, it is characterized in that, the method is carried out under catalyst-free participates in, said oxygenant is the gas containing ozone, the mol ratio of the ozone in said sulfocompound and oxygenant is 1:0.1-10, said contact is carried out in the presence of solvent, the mol ratio of sulfocompound and solvent is 1:1-100, and said solvent is water, C ₁-C ₁₀alcohol, C ₃-C ₁₀ketone, C ₂-C ₈nitrile and C ₁-C ₆carboxylic acid at least one.

2. according to the method for claim 1, wherein, the said gas containing ozone is the mixed gas of ozone or ozone and diluent gas, and with the cumulative volume of described mixed gas for benchmark, in described mixed gas, the content of ozone is 1 more than volume %, and described diluent gas is at least one in oxygen, carbonic acid gas, nitrogen, argon gas, helium, neon and air.

3. according to the method for claim 2, wherein, with the cumulative volume of described mixed gas for benchmark, in described mixed gas, the content of ozone is 5 more than volume %, and described diluent gas is at least one in oxygen, carbonic acid gas, helium and air.

4., according to the process of claim 1 wherein, described solvent is C ₁-C ₄alcohol and C ₃-C ₈ketone at least one.

5. according to the method for claim 4, wherein, described solvent is acetone and/or methyl alcohol.

6., according to the method for claim 1, said sulfocompound is mercaptan, thioether, thionaphthene, 2-thiotolene, 2-chlorothiophene, 4-methyl benzothiophene, 4,6-dimethyldibenzothiophenes.

7., according to the method for claim 1, it is characterized in that temperature of reaction is 20-160 DEG C, reaction pressure is 0.1-2.5MPa.