CN111471480B - Deep desulfurization method for diesel oil by 380-780 nm visible light catalytic oxidation - Google Patents

Abstract

The invention belongs to the technical field of catalytic chemistry and environmental protection, and relates to a deep desulfurization method for 380-780 nm visible light catalytic oxidation diesel oil. The desulfurization method includes the following steps: 1. preparing a TiO ₂ catalyst supported by a heteropolyacid; 2. adding the catalyst into diesel oil, and photocatalytic oxidation desulfurization under the condition of visible light of 380-780 nm. The method of the invention uses the _TiO2 nanomaterial supported by the heteropolyacid as the catalyst, in order to solve the problem that the titanium dioxide material as a diesel photocatalytic oxidation desulfurization catalyst has less energy utilization under the visible light in the sunlight region, and the photocatalytic efficiency is seriously caused by the photogenerated electron and hole recombination phenomenon. low problem. The invention is used for the visible light catalytic oxidative desulfurization of model diesel. The technological process of the invention is simple to operate, the reaction conditions are mild, and the catalyst can be recycled. The catalytic activity of the desulfurization reaction is very high, and the desulfurization rate is up to 100%.

Description

380~780 nm Visible Light Catalytic Oxidation Diesel Deep Desulfurization Method

technical field

The invention relates to the field of homocatalysis, and relates to a 380-780 nm visible light catalytic oxidation diesel deep desulfurization method, in particular to a preparation method of a heteropolyacid modified TiO ₂ photocatalyst and a 380-780 nm visible light diesel desulfurization method.

Background technique

With the rapid development of industry, the excessive use of a large number of non-renewable resources such as coal, oil and natural gas, the increasing scarcity of fossil energy, the increasing popularity of private cars, the demand for fuel oil has increased significantly. The sulfur-containing compounds in diesel are emitted into the atmosphere, becoming the main source of air pollution, the main factor leading to the formation of acid rain and smog, and have a non-negligible impact on all aspects of our human life. Therefore, to improve the purification efficiency of sulfur-containing compounds, the sulfur content in the fuel oil must be controlled. The sulfur-containing compounds that are difficult to remove are mainly inactive sulfur-containing compounds, thiophenes, such as benzothiophenes and sulfur thiophenes, which belong to aromatic heterocyclic systems. Therefore, the sulfur content in the fuel oil is controlled, and the sulfur content is reduced by catalytic conversion, which is economical and safe, and can reduce the harm to the environment, which meets the requirements of green chemistry.

Titanium dioxide is used as a desulfurization catalyst in the prior art, but the desulfurization effect is poor, especially when the diesel sulfur content is lower than 500 ppm, it is difficult to further remove the sulfur compounds in the diesel oil thoroughly and deeply. Therefore, the present invention relates to a A 380-780 nm visible light catalytic oxidation diesel deep desulfurization method is proposed, focusing on the desulfurization method when the sulfur content is less than 500 ppm, and the sulfide is completely removed.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a 380-780 nm visible light catalytic oxidation diesel deep desulfurization method, more specifically a heteropolyacid modified TiO ₂ photocatalyst and a preparation method thereof, as well as a diesel deep desulfurization method.

The technical scheme that the present invention solves the above-mentioned technical problems is as follows:

380~780 nm visible light catalytic oxidation diesel deep desulfurization method, the steps are as follows:

Step 1. Mix the titanium source and the heteropoly acid in a pure aqueous solution according to the molar ratio of 1~5:1, heat the reaction in a 90 ^o C water bath to a sol state, centrifuge, wash, and dry, and place it in a muffle furnace at 1 ^o C. The heating rate of /min is 350~450 ^o C and calcined for 0.5~3h, then take out and grind to powder to obtain heteropolyacid-modified _TiO2 photocatalyst,

in,

The titanium source is any one of titanium isopropoxide (Ti[OCH(CH _{3 ) 2} ] ₄ ), tetrabutyl titanate, and titanium tetrachloride,

The heteropolyacids are (NH ₄ ) ₄ ZnH ₆ Mo ₆ O ₂ , (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ , (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O, Na ₅ [IMo ₆ O ₂₄ ] any of the

Step 2. The heteropolyacid-modified TiO ₂ photocatalyst prepared in step 1 is mixed with DBT in the model diesel according to the mass ratio of 1~5:1, and then placed in the photocatalytic reactor at 0~60 ^o C, protected from light , Under the condition of circulating water, the stirring reaction is 0.2~1h to reach the extraction equilibrium.

Then add oxygen from the photocatalytic reactor, and the molar ratio of oxygen to sulfur in the oxygen source and the model diesel DBT is 3~5:1, and then, under the condition of 380~780 nm light, visible light catalytic oxidation The desulfurization reaction is completed in 2~5h to complete the deep desulfurization.

in,

The sulfur content of the diesel DBT is less than or equal to 500 ppm,

The oxygen source is any one of H ₂ O ₂ , O ₂ and tert-butyl hydroperoxide,

Step 3. After the reaction is completed, let stand until layering, and the upper layer diesel oil is decanted and poured out to obtain the desulfurized diesel oil.

Preferably, the aqueous solution in step 1 is replaced with an aqueous solution of nitric acid with a concentration of 0.5-20%, and the specific surface area between the reactants is increased to prepare a heteropolyacid-modified _TiO2 photocatalyst with uniform and stable particles.

Preferably, the titanium source in step 1 is titanium isopropoxide (Ti[OCH(CH _{3 ) 2} ] ₄ ).

Preferably, the oxygen source in step 1 is H ₂ O ₂ .

Another technical solution that the present invention solves the above-mentioned technical problem is as follows:

In the above-mentioned catalytic oxidation diesel desulfurization method, the heteropolyacid-modified TiO ₂ photocatalyst prepared in step 1 is used.

As we all know, DBT has stable performance and is not easy to be oxidized. The innovative feature of the present invention is that the catalysis of metal active sites in the heteropolyacid-modified _TiO2 photocatalyst can catalyze oxidation of sulfides in model diesel to sulfones, and then extract and separate to achieve deep desulfurization; further analysis, The catalyst prepared by the invention utilizes the multi-center metal structure of the heteropolyacid to modify the titanium dioxide, inserts the center metal of the heteropolyacid into the skeleton of the titanium dioxide to effectively combine the structure of the heteropolyacid with the titanium dioxide and form a stable and recyclable solid phase Further, as shown in Figure 1, under the condition of 380-780 nm illumination, there is a strong interaction between the multi-metal modified catalyst prepared by the present invention and sulfide (DBT) after excitation by visible light. The photogenerated electrons are transferred into the heteropolyacid molecule, and the heteropolyacid molecule oxidizes DBT under the activation of the oxygen source to form sulfones, and at the same time, the heteropolyacid molecule undergoes a redox reaction, and the hole is transferred back to the titanium dioxide molecule, causing it to occur. Oxidation reaction to sulfones and separation, thus solving the problem of low photocatalytic efficiency due to the serious recombination of photogenerated electrons and holes due to the low energy utilization of TiO2 as a diesel photocatalytic oxidative desulfurization catalyst under visible light in the sunlight region.

The beneficial effects of the present invention are:

1) The technological process of the present invention is simple to operate, the reaction conditions are mild, and the heteropolyacid-modified TiO ₂ photocatalyst of the present invention can be recycled.

2) The desulfurization effect of the visible light method with a wavelength of 380 to 780 nm of the present invention can reach 90% to 100%, with strong photoselectivity for desulfurization, and the desulfurization effect is much higher than the photocatalytic desulfurization effect of titanium dioxide in the prior art (≤50%) , wherein, the optimal (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ /TiO ₂ (ie Zn-Mo/TiO ₂ ) catalyst desulfurization rate can reach 100% and completely remove sulfur.

3) The deep desulfurization reaction time of diesel oil of the present invention is short, and the reaction can be completed in 1-5 hours.

4) The deep desulfurization of diesel oil of the present invention is effective for visible light with a wavelength of 380-780 nm.

5) The process of the present invention can not only selectively and deeply remove sulfides in diesel, but also the catalyst preparation process is simple and efficient, avoiding the use of precious metals, reducing the desulfurization cost and having great economic benefits, and the catalyst can be recycled and green. No pollution.

Description of drawings

The accompanying drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. They are used to explain the technical solutions of the present invention together with the specific embodiments of the present application, and do not limit the technical solutions of the present invention.

Figure 1 shows the catalytic performance mechanism of the desulfurization process of the present invention (where e is an electron and h is a hole).

Figure 2 is a TEM test chart of the catalyst prepared in Example 1 of the present invention.

Figure 3 is an XPS test chart of the catalyst prepared in Example 1 of the present invention.

Fig. 4 is the XRD test chart of the catalyst prepared in Example 1 of the present invention.

Fig. 5 is the catalytic performance test diagram of the catalyst recycling in Example 1 of the present invention (5 cycles).

6 is a comparison diagram of the catalytic effect of (Zn-Mo/TiO ₂ , (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ , TiO ₂ ) in Example 1 of the present invention.

Figure 7 is a test diagram of the catalytic performance of the catalyst in Example 1 of the present invention under different illumination conditions (380-780 nm, 200-380 nm, dark).

FIG. 8 is a test chart of light absorption ability of different catalysts (Zn-Mo/TiO ₂ , (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ , TiO ₂ ) in Example 1 of the present invention.

FIG. 9 is a scanning electron microscope image of the catalyst Ni-Mo/TiO ₂ in Example 2 of the present invention.

FIG. 10 is a test diagram of catalytic performance of catalysts Ni-Mo/TiO ₂ , (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ and TiO ₂ in Example 2 of the present invention.

FIG. 11 is a test diagram of Mo3d element in XPS of catalyst Mo/TiO ₂ in Example 3 of the present invention.

FIG. 12 is a test diagram of catalytic performance of catalysts Mo/TiO ₂ , (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O and TiO ₂ in Example 3 of the present invention.

Figure 13 is the XRD test chart of the catalyst prepared in Example 4 of the present invention.

Figure 14 shows the catalytic performance measurement of catalyst I-Mo/TiO ₂ , Na ₅ [IMo ₆ O ₂₄ ] and TiO ₂ in Example 4 of the present invention

attempt.

Figure 15 is a TEM test chart of the catalyst prepared in Example 5 of the present invention.

Figure 16 is a test diagram of the catalytic performance of the catalyst prepared in Example 5 of the present invention under different illumination conditions (380-780 nm, 200-380 nm, dark).

Detailed ways

The present invention will be described in more detail below with reference to the accompanying drawings, in which preferred embodiments of the invention are shown, it should be understood that those skilled in the art can modify the invention described herein and still achieve the beneficial effects of the invention. Therefore, the following description should be construed as widely known to those skilled in the art and not as a limitation of the present invention.

In the interest of clarity, not all features of an actual embodiment are described. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention with unnecessary detail. It should be recognized that in the development of any actual embodiment, a number of implementation details must be made to achieve the developer's specific goals.

The principles and features of the present invention are described below. The examples are only used to explain the present invention, not to limit the scope of the present invention. It should be noted that the DBT content of the model diesel tested in the following examples is ≤500 ppm.

Example 1

1) Preparation of (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ /TiO ₂ (ie Zn-Mo/TiO ₂ ) catalyst: heteropolyacid (NH ₄ ) ₄ ZnH ₆ Mo ₆ O ₂ : titanium isopropoxide=1: 7 (mass ratio), and heated to a sol state under stirring in a 90°C water bath. After the reaction was completed, it was cooled to room temperature, centrifuged, dried, washed, and placed in a muffle furnace for calcination at 450 ^oC for 0.5 h at a heating rate of 1 ^oC /min, and then ground to powder to obtain Zn-Mo/ _TiO2 catalyst, as shown in Figure 2. Show. The XPS test of the catalyst in Fig. 3 and the XRD test of the catalyst in Fig. 4 show that the organic combination of titanium dioxide and heteropolyacid in the catalyst contains Ti, O, Zn, Mo and C elements, which proves the successful synthesis of Zn-Mo/TiO ₂ catalyst .

Desulfurization reaction: add 20 mL of 500 ppm model oil and 0.1 g of catalyst to the photocatalytic reactor, and stir for 0.5 h under the conditions of dark light, 30 ^o C and circulating water to reach the extraction equilibrium.

Then, pipette 0.176 mL of 30% H ₂ O ₂ (O/S=5) into the mixed solution, turn on the xenon lamp and carry out the visible light catalytic oxidation reaction experiment (reaction time 3h) under the condition of 380~780nm visible light illumination.

Qualitative and quantitative analysis of desulfurization reaction: GC (FuLi 9750, HP-5 column), chromatographic column: DB-1 capillary column, detector: hydrogen flame ionization detector (FID).

The test results show that the desulfurization rate reaches 100% in 3 h.

2) Zn-Mo/ _TiO2 catalyst cycle test:

After the reaction, the reaction substrate in the photocatalytic reactor was centrifugally washed with deionized water and ethanol, and the collected Zn-Mo/TiO ₂ catalyst was obtained after drying in an oven, and then the catalyst was recycled for desulfurization.

The same model diesel as in the above-mentioned embodiment was selected, and the separated Zn-Mo/TiO ₂ catalyst was used repeatedly for 5 times to carry out deep desulfurization according to the same test parameters and steps.

After the desulfurization is completed, the five deep desulfurization tests are qualitatively and quantitatively analyzed: as shown in Figure 5, the first 3h desulfurization rate is 100%, the second 3h desulfurization rate is 98.6%, the third 3h desulfurization rate is 98%, and the second 3h desulfurization rate is 98%. The desulfurization rate of the 4th 3h is 96.6%, and the 5th 3h desulfurization rate is 96.4%, which proves that the heteropolyacid-modified _TiO2 photocatalyst of the present invention can be recycled, and the catalytic oxidation effect hardly changes. Among them, the desulfurization effect The difference lies in the inevitable losses during the catalyst collection process.

3) Comparative test of heteropolyacid (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ and TiO ₂ catalysts:

The test method steps are the same as those in the above embodiment, the difference is that the catalyst Zn-Mo/TiO ₂ is replaced with a heteropolyacid (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ catalyst. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 61.8 %.

The test method steps are the same as those in the above-mentioned embodiment, except that the catalyst Zn-Mo/TiO ₂ is replaced with a TiO ₂ catalyst. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 45.6%.

As shown in Figure 6, the Zn-Mo/TiO ₂ catalyst was compared with the heteropolyacid (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ and TiO ₂ catalyst, and the Zn-Mo/TiO ₂ catalyst was under the visible light condition of 380~780 nm. can be completely desulfurized. It shows that the catalyst of the present invention has significantly improved catalytic effect. Compared with using the two catalysts alone, the catalytic efficiency is greatly improved, which proves the unique structure of the synthesized new catalyst, which is a new type of catalyst more suitable for oxidative desulfurization.

4) 200~380 nm UV light comparison test:

The same test method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination conditions are replaced by 200-380 nm ultraviolet light, and the qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is only 72%.

The same test method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination conditions are replaced with no illumination conditions. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3 hours is 58%.

As shown in Figure 7, the catalyst of the present invention can only be 100% desulfurized under the condition of 380-780 nm visible light, but the desulfurization reaction cannot occur smoothly under the condition of 200-380 nm ultraviolet light or no illumination. The Zn-Mo/TiO ₂ catalyst is suitable for the excitation of visible light at 380-780 nm, and it is easier to generate electronic transition, while the ultraviolet light of 200-380 nm cannot excite the electronic transition because of insufficient energy level matching. This test shows that the light condition has a great influence on the desulfurization effect, which confirms the particularity of the Zn-Mo/TiO ₂ catalyst of the present invention to the light range.

At the same time, the light absorption test of Zn-Mo/TiO ₂ catalyst, heteropolyacid (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ and TiO ₂ , as shown in Figure 8, confirms the light absorption of the Zn-Mo/TiO ₂ catalyst of this example. Compared with heteropolyacid (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ and TiO ₂ , its light absorbing ability in the visible light region is significantly enhanced, confirming that the Zn- Sensitivity of Mo/ _TiO catalysts to the illumination interval.

Example 2

1) Preparation of (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ /TiO ₂ (ie Ni-Mo/TiO ₂ ) catalyst: heteropolyacid (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ : titanium isopropoxide=3: 7 (mass ratio) mixed, heated to 90 ° C, vigorously stirred, and then hydrothermally reacted for 13 h. After the reaction was completed, it was cooled to room temperature, and the Ni-Mo/TiO ₂ catalyst was obtained by centrifugal drying and washing. As shown in Figure 9, it is the scanning electron microscope image of the prepared catalyst.

Desulfurization reaction: add 20 mL of 400 ppm model oil and 0.1 g of catalyst to the photocatalytic reactor, and stir for 0.5 h under the conditions of dark light, 30 ^o C and circulating water to reach the extraction equilibrium.

Then, pipette 0.176 mL of 30% H ₂ O ₂ (O/S=5) into the mixed solution, turn on the xenon lamp and carry out the visible light catalytic oxidation reaction experiment (reaction time 3h) under the condition of 380~780nm visible light illumination.

Qualitative and quantitative analysis of desulfurization reaction: GC (FuLi 9750, HP-5 column), chromatographic column: DB-1 capillary column, detector: hydrogen flame ionization detector (FID).

The test results show that, as shown in Figure 10, the desulfurization rate reaches 92% in 3 h.

2) Ni-Mo/ _TiO2 catalyst cycle test:

After the reaction, the reaction substrate in the photocatalytic reactor is centrifugally washed with deionized water and ethanol, and the collected Ni-Mo/TiO ₂ catalyst is obtained after drying in an oven, and the catalyst can be recycled for desulfurization.

The same model diesel as in the above-mentioned example was selected, and the separated Ni-Mo/TiO ₂ catalyst was used repeatedly for 4 times to carry out deep desulfurization according to the same test parameters and steps.

After the desulfurization was completed, the four deep desulfurization tests were qualitatively and quantitatively analyzed: the first 3h desulfurization rate was 98%, the second 3h desulfurization rate was 97.6%, the third 3h desulfurization rate was 96.4%, and the fourth 3h desulfurization rate was 96.4%. 95%, which proves that the heteropolyacid-modified TiO ₂ photocatalyst of the present invention can be recycled, and the catalytic oxidation effect hardly changes, and the difference in desulfurization effect lies in the inevitable loss in the catalyst collection process.

3) Comparative test of heteropolyacid (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ and TiO ₂ catalysts:

As shown in Figure 10, the test method steps are the same as those in the above-mentioned embodiment, the difference is that the catalyst Ni-Mo/TiO ₂ is replaced by a heteropolyacid (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ catalyst, the test is qualitative and quantitative analysis, the test It shows that the desulfurization rate in 3h is 61.2%.

As shown in Figure 10, the test method steps are the same as those in the above embodiment, the difference is that the catalyst Ni-Mo/TiO ₂ is replaced by a TiO ₂ catalyst. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 45.1%.

4) 200~380 nm UV light comparison test:

The same experimental design as the above-mentioned embodiment, the 380-780 nm visible light illumination condition was replaced with 200-380 nm ultraviolet light, and the qualitative and quantitative analysis of the test showed that the desulfurization rate in 3h was only 68%.

The same experimental design as the above-mentioned embodiment, the 380-780 nm visible light illumination condition is replaced by the condition without illumination, the qualitative and quantitative analysis of the test shows that the desulfurization rate of 3h is 49%.

Example 3

Preparation of (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ (ie Mo/TiO ₂ ) catalyst: Heteropolyacid (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O: Titanium dioxide=3:7 (mass ratio) mixed, heated to 90 °C, vigorously stirred, and then hydrothermally reacted for 13 h. After the reaction was completed, it was cooled to room temperature, and the Mo/TiO ₂ catalyst was obtained by centrifugal drying and washing.

1) Preparation of (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ (ie Mo/TiO ₂ ) catalyst: heteropolyacid (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O: titanium isopropoxide 1 : 7 (mass ratio), and heated to a sol state under stirring in a water bath at 90 °C. After the reaction was completed, it was cooled to room temperature, centrifuged, dried, washed, and placed in a muffle furnace for calcination at 450 ^o C for 0.5 h at a heating rate of 1 ^o C/min, and then ground to powder to obtain Mo/TiO ₂ catalyst. Figure 11 shows the test chart of Mo3d element in XPS prepared catalyst.

Desulfurization reaction: add 20 mL of 500 ppm model oil and 0.1 g of catalyst to the photocatalytic reactor, and stir for 0.5 h under the conditions of dark light, 30 ^o C and circulating water to reach the extraction equilibrium.

Then, pipette 0.176 mL of 30% H ₂ O ₂ (O/S=5) into the mixed solution, turn on the xenon lamp and carry out the visible light catalytic oxidation reaction experiment under the condition of 380-780 nm visible light (reaction time 3h).

Qualitative and quantitative analysis of desulfurization reaction: GC (FuLi 9750, HP-5 column), chromatographic column: DB-1 capillary column, detector: hydrogen flame ionization detector (FID).

The test results show that, as shown in Figure 12, the desulfurization rate reaches 100% in 3 h.

2) (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ catalyst cycle test:

After the reaction, the reaction substrate in the photocatalytic reactor is centrifugally washed with deionized water and ethanol, and the collected (NH ₄ ) ₆ Mo ₇ O _{24.4H 2} O ^/ TiO ₂ catalyst is obtained after drying in an oven, The catalyst can be recycled for desulfurization.

The same model diesel as in the above-mentioned embodiment was selected, and the separated (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ catalyst was used repeatedly for 4 times to carry out deep desulfurization according to the same test parameters and steps.

After the desulfurization was completed, the four deep desulfurization tests were qualitatively and quantitatively analyzed: the first 3h desulfurization rate was 100%, the second 3h desulfurization rate was 98.1%, the third 3h desulfurization rate was 97%, and the fourth 3h desulfurization rate was 97%. 95.6%, which proves that the heteropolyacid-modified _TiO2 photocatalyst of the present invention can be recycled, and the catalytic oxidation effect hardly changes, and the difference in the desulfurization effect lies in the inevitable loss in the catalyst collection process.

3) Comparative test of heteropolyacid (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O and TiO ₂ catalysts:

The same test method steps as the above-mentioned embodiment, the difference is that the catalyst (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ is replaced by a heteropolyacid (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O catalyst, The qualitative and quantitative analysis of the test showed that the desulfurization rate in 3h was 61.8%.

The same test method steps as the above-mentioned embodiment, the difference is that the catalyst (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ is replaced by a TiO ₂ catalyst. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 45.9%.

As shown in FIG. 12 , the comparison between (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ catalyst, heteropolyacid (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O and TiO ₂ catalyst illustrates the present invention The (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O/TiO ₂ has a significantly improved catalytic effect.

4) 200~380 nm UV light comparison test:

The same test method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination conditions are replaced by 200-380 nm ultraviolet light, the qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is only 64%.

The same test method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination conditions are replaced with no illumination conditions. The qualitative and quantitative analysis of the test shows that the 3h desulfurization rate is 52%.

Example 4

Preparation of Na ₅ [IMo ₆ O ₂₄ ]/TiO ₂ (i.e. I-Mo/TiO ₂ ) catalyst: Heteropolyacid Na ₅ [IMo ₆ O ₂₄ ]: Titanium dioxide=3:7 (mass ratio) mixed, heated to 90℃ , vigorously stirred, and then hydrothermally reacted for 13 h. After the reaction was completed, it was cooled to room temperature, and the I-Mo/TiO ₂ catalyst was obtained by centrifugal drying and washing.

1) Preparation of I-Mo/TiO ₂ catalyst: Heteropolyacid Na ₅ [IMo ₆ O ₂₄ ]: titanium isopropoxide 1:7 (mass ratio) was mixed and heated to a sol state with stirring in a water bath at 90 °C. After the reaction was completed, it was cooled to room temperature, centrifuged, dried, washed, and placed in a muffle furnace for calcination at 450 ^o C for 0.5 h at a heating rate of 1 ^o C/min, and then ground to powder to obtain I-Mo/TiO ₂ catalyst. The XRD patterns of the prepared catalysts are shown in FIG. 13 .

Desulfurization reaction: add 20 mL of 450 ppm model oil and 0.1 g of catalyst to the photocatalytic reactor, and stir for 0.5 h under the conditions of dark light, 30 ^o C and circulating water to reach the extraction equilibrium.

Then, pipette 0.176 mL of 30% H ₂ O ₂ (O/S=5) into the mixed solution, turn on the xenon lamp and carry out the visible light catalytic oxidation reaction experiment (reaction time 3h) under the condition of 380~780nm visible light illumination.

Qualitative and quantitative analysis of desulfurization reaction: GC (FuLi 9750, HP-5 column), chromatographic column: DB-1 capillary column, detector: hydrogen flame ionization detector (FID).

The test results show that, as shown in Figure 14, the desulfurization rate reaches 100% in 3 h.

2) I-Mo/ _TiO2 catalyst cycle test:

After the reaction, the reaction substrate in the photocatalytic reactor is centrifugally washed with deionized water and ethanol, and the collected I-Mo/TiO ₂ catalyst is obtained after drying in an oven, and the catalyst can be recycled for desulfurization.

The same model diesel as in the above-mentioned embodiment was selected, and the separated catalyst was used repeatedly for 4 times to carry out deep desulfurization according to the same test parameters and steps.

After the desulfurization was completed, the four deep desulfurization tests were qualitatively and quantitatively analyzed: the first 3h desulfurization rate was 99%, the second 3h desulfurization rate was 97.8%, the third 3h desulfurization rate was 96.3%, and the fourth 3h desulfurization rate was 96.3%. 95.2%, which proves that the heteropolyacid-modified _TiO2 photocatalyst of the present invention can be recycled, and the catalytic oxidation effect hardly changes, and the difference in desulfurization effect lies in the inevitable loss during the catalyst collection process.

3) Comparative test of heteropolyacid Na ₅ [IMo ₆ O ₂₄ ] and TiO ₂ catalysts:

The same test method steps as the above-mentioned example, the difference is that the catalyst I-Mo/TiO ₂ is replaced with a heteropolyacid Na ₅ [IMo ₆ O ₂₄ ] catalyst. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 58.8%.

The same test method steps as the above-mentioned embodiment, the difference is that the catalyst I-Mo/TiO ₂ is replaced with a TiO ₂ catalyst, and the qualitative and quantitative analysis of the test shows that the desulfurization rate of 3h is 45.6%.

As shown in FIG. 14 , the comparison of I-Mo/TiO ₂ catalyst, heteropolyacid Na ₅ [IMo ₆ O ₂₄ ], and TiO ₂ catalyst shows that the catalyst I-Mo/TiO ₂ of the present invention has a significantly improved catalytic effect.

4) 200~380 nm UV light comparison test:

The same method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination condition is replaced by 200-380 nm ultraviolet light, and the qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is only 65%.

The test method steps are the same as those in the above embodiment, the difference is that the 380-780 nm visible light illumination condition is replaced by the condition without illumination. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is 48%.

Example 5

1) Preparation of (NH ₄ ) ₄ H ₆ ZnMo ₆ O ₂₄ /TiO ₂ -2 (ie Zn-Mo/TiO ₂ -2) Catalyst: Heteropolyacid (NH ₄ ) ₄ ZnH ₆ Mo ₆ O ₂ : Tetratitanate Butyl esters were mixed at 1:7 (mass ratio), and heated to a sol state with stirring in a 90 °C water bath. After the reaction was completed, it was cooled to room temperature, centrifuged, dried, washed, and placed in a muffle furnace for calcination at 450 ^o C for 0.5 h at a heating rate of 1 ^o C/min, and then ground to powder to obtain a Zn-Mo/TiO ₂ -2 catalyst, as shown in the figure. 15 shows the TEM image of the prepared catalyst.

Desulfurization reaction: add 20 mL of 450 ppm model oil and 0.1 g of catalyst to the photocatalytic reactor, and stir for 0.5 h under the conditions of dark light, 30 ^o C and circulating water to reach the extraction equilibrium.

Then, pipette 0.176 mL of 30% H ₂ O ₂ (O/S=5) into the mixed solution, turn on the xenon lamp and carry out the visible light catalytic oxidation reaction experiment under the condition of 380-780 nm visible light (reaction time 3h).

Qualitative and quantitative analysis of desulfurization reaction: GC (FuLi 9750, HP-5 column), chromatographic column: DB-1 capillary column, detector: hydrogen flame ionization detector (FID).

The test results show that, as shown in Figure 16, the desulfurization rate reaches 86% in 3 h.

The test shows that the effect of preparing heteropolyacid catalyst using tetrabutyl titanate (86%) is not as good as that of titanium isopropoxide (100%). The reaction proceeds.

2) Zn-Mo/TiO ₂ -2 catalyst cycle test:

After the reaction, the reaction substrate in the photocatalytic reactor is centrifugally washed with deionized water and ethanol, and the collected Zn-Mo/TiO ₂ -2 catalyst is obtained after drying in an oven, and the catalyst can be recycled for desulfurization.

The same model diesel as in the above-mentioned embodiment was selected, and the separated Zn-Mo/TiO ₂ -2 catalyst was repeatedly used for three times to carry out deep desulfurization according to the same test parameters and steps.

After the desulfurization is completed, the three deep desulfurization tests are qualitatively and quantitatively analyzed: the first 3h desulfurization rate is 83%, the second 3h desulfurization rate is 81%, and the third 3h desulfurization rate is 78%. The difference in desulfurization effect lies in the above Inevitable losses during catalyst collection.

3) 200~380 nm UV light comparison test:

The same test method steps as the above-mentioned embodiment, the difference is that the 380-780 nm visible light illumination condition is replaced by 200-380 nm ultraviolet light, and the qualitative and quantitative analysis of the test shows that the desulfurization rate in 3h is only 62%.

The test method steps are the same as those in the above embodiment, the difference is that the 380-780 nm visible light illumination conditions are replaced with no illumination conditions. The qualitative and quantitative analysis of the test shows that the desulfurization rate in 3 hours is 46%.

As shown in Figure 16, it shows the catalytic performance of the catalyst under different illumination conditions. It can be seen from the figure that it has the best desulfurization effect under the illumination condition of 380-780 nm visible light, indicating that this catalyst is more suitable for visible light conditions.

The specific examples 1-5 of the present invention show that the deep desulfurization method of diesel oil and the heteropolyacid-modified _TiO photocatalyst of the present invention have a strong desulfurization effect under the condition of 380-780 nm visible light (the best can be 100% complete In addition, the stable and recyclable solid-phase catalyst prepared by the present invention can be recycled, which overcomes the shortcomings that the current catalysts are mostly precious metals and have poor recyclability, and has the advantages of green and pollution-free, cheap and easy-to-obtain raw materials, and stable recyclability.

Above, the analysis reason is that the central metal of the heteropolyacid is inserted into the skeleton of titania to effectively combine the structure of the heteropolyacid with titania and form a stable and recyclable solid-phase catalyst. Example 1 is used as an example to illustrate, as shown in Figures 3 and 4 The XPS test shows that the organic combination of titanium dioxide and heteropolyacid in the catalyst contains Ti, O, Zn, Mo and C elements, and the corresponding binding energy position of each element shows that Zn and Mo elements are inserted into the framework of titanium dioxide, Furthermore, the catalytic effect of the metal active sites in the heteropolyacid-modified _TiO2 photocatalyst of the present invention can catalyze the oxidation of sulfide (DBT) in the model diesel to sulfones and then extract and separate to achieve deep desulfurization. Example 1 is illustrated as an example. As shown in Figures 7 and 8, the light absorption capacity of the catalyst of the present invention is significantly enhanced in the visible light region of 380-780 nm. The 380 nm ultraviolet light cannot excite electron transitions because of insufficient energy level matching. It is well known that DBT has stable performance and is not easy to be oxidized. There is a strong interaction between the multi-metal modified catalyst prepared by the present invention and sulfide (DBT) after being excited by visible light at 380-780 nm. In the acid molecule, the heteropolyacid molecule oxidizes DBT under the activation of the oxygen source to form sulfones, and at the same time, the heteropolyacid molecule undergoes a redox reaction, and the holes are transferred back to the titanium dioxide molecule, which is oxidized to the sulfone and carried out. Separation, overcoming and solving the problem that DBT performance is stable and not easy to be oxidized.

In addition, it should be noted that although the desulfurization effect of the heteropolyacid-modified _TiO2 photocatalyst within the protection scope of the present invention is slightly different, in the comparison of Example 1 with the best desulfurization effect and Example 5, although titanic acid The effect of tetrabutyl ester to prepare heteropolyacid catalyst is not as good as that of titanium isopropoxide (the reason is that the catalyst particles prepared from titanium isopropoxide are more uniform and stable, and the larger specific surface area is conducive to the catalytic reaction), but it is also far better than the existing titanium dioxide catalyst. The effect of photocatalytic diesel desulfurization, that is, the present invention solves the problem of low photocatalytic efficiency due to the serious recombination of photogenerated electrons and holes due to the low energy utilization of titanium dioxide material as a diesel photocatalytic oxidative desulfurization catalyst under visible light in the sunlight region.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1.380～780 nm visible light catalytic oxidation diesel deep desulfurization method is characterized in that the steps are as follows: Step 1. Mix the titanium source and the heteropoly acid in a pure aqueous solution according to the molar ratio of 1~5:1, heat the reaction in a 90 ^o C water bath to a sol state, then centrifuge, wash, and dry, and place it in a muffle furnace for 1 ^o The heating rate of C/min is 350~450 ^o C and calcined for 0.5~3h, then take out and grind to powder to obtain the heteropolyacid modified _TiO2 photocatalyst, in, The titanium source is any one of titanium isopropoxide (Ti[OCH(CH _{3 ) 2} ] ₄ ), tetrabutyl titanate, and titanium tetrachloride, The heteropolyacids are (NH ₄ ) ₄ ZnH ₆ Mo ₆ O ₂ , (NH ₄ ) ₄ NiH ₆ Mo ₆ O ₂ , (NH ₄ ) ₆ Mo ₇ O ₂₄ ^. 4H ₂ O, Na ₅ [IMo ₆ O ₂₄ ] any one of; Step 2. The heteropolyacid-modified TiO ₂ photocatalyst prepared in step 1 is mixed with DBT in diesel according to the mass ratio of 1~5:1, and then placed in a photocatalytic reactor at 0~60 ^o C, protected from light, Under the condition of circulating water, the stirring reaction is carried out for 0.2~1h to reach the extraction equilibrium. Oxygen is then added to the photocatalytic reactor, and the molar ratio of oxygen in the oxygen source to sulfur in the diesel DBT is 3-5:1, and then catalyzed oxidative desulfurization reaction under 380-780 nm light conditions 1~5h to complete the deep desulfurization, in, The sulfur content of the diesel DBT is less than or equal to 500 ppm, The oxygen source is any one of H ₂ O ₂ , O ₂ and tert-butyl hydroperoxide; Step 3. After the reaction is completed, let stand until layering, and the upper layer diesel oil is decanted and poured out to obtain the desulfurized diesel oil. 2. The method for deep desulfurization of diesel oil according to claim 1, wherein the pure aqueous solution described in step 1 is replaced with an aqueous nitric acid solution with a concentration of 0.5 to 20%. 3 . The method for deep desulfurization of diesel oil according to claim 1 , wherein the titanium source in step 1 is titanium isopropoxide (Ti[OCH(CH _{3 ) 2} ] ₄ ). 4 . 4 . The method for deep desulfurization of diesel oil according to claim 1 , wherein the oxygen source in step 1 is H ₂ O ₂ . 5 . 5. The heteropolyacid-modified _TiO2 photocatalyst prepared in step 1 in the deep diesel desulfurization method according to any one of claims 1-4.

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