Preparation method and application of H2O2-modified TiO2/mesoporous glass catalyst

a H₂o₂Modified Ti o₂Preparation method and application technical field of mesoporous glass catalyst

The invention belongs to the processing technical field of oil product, be specifically related to a kind of h₂o₂Modified TiO₂The invention discloses a preparation method and application of a mesoporous glass catalyst, which is a preparation method and application of a photocatalytic oxidation-adsorption coupled desulfurization catalyst.

Background technique

Can release a large amount of SOx gas after the combustion of multiple organic sulfides remaining in the refined petroleum products such as gasoline, diesel oil, these gases gather in the air and are one of the most important reasons that cause acid rain and air pollution. In order to reduce the damage of sulfur compounds to the environment, it is becoming more and more important to develop and produce ultra-clean fuels. The industrialized hydrodesulfurization process is currently a widely used desulfurization technology, but the conditions of the hydrodesulfurization process are harsh, and it usually operates at high temperature and high pressure. It is only effective for the removal of simple acyclic and aliphatic sulfides. The species removal efficiency is insufficient. In addition, in order to increase the depth of hydrodesulfurization, it is usually at the expense of sacrificing octane number and increasing hydrogen consumption and energy consumption. Therefore, it is of great significance to develop non-hydrogenation desulfurization technologies with mild reaction conditions such as extractive desulfurization, adsorption desulfurization, and oxidative desulfurization.

The adsorption desulfurization process carried out under ambient conditions is considered to be an effective method for producing clean fuels, but in actual oil products due to the strong competitive adsorption of coexisting aromatic compounds (such as polyaromatic hydrocarbons and nitrogen compounds) and thiophenes lead to desulfurization The problem of low efficiency cannot be ignored. In order to improve the adsorption selectivity of the adsorbent and expand its potential application value, people have adopted a variety of methods to functionalize the adsorbent materials, among which the photocatalytic oxidation-adsorption coupled desulfurization technology is the most promising. Nanoscale TiO₂Due to its high photocatalytic activity, stable properties and low cost, it is widely used in photocatalytic desulfurization process. However, due to its small particle size, it is easy to agglomerate itself, resulting in a decrease in the specific surface area, resulting in a small reaction contact area between the catalyst and the fuel, and low light absorption efficiency. In addition, nano-scale catalysts are difficult to recover after use, and the separation cost is high. These shortcomings limit the use of nano-scale TiO₂photocatalytic oxidative desulfurization activity. Therefore, using supports to disperse and immobilize nanoscale TiO₂, While uniformly dispersing nanoparticles, it can also adsorb sulfide, effectively enhancing mass transfer. by TiO₂The photocatalytic oxidation-adsorption synergistic effect with the carrier further improves the desulfurization activity of the catalyst.

Contents of the invention

The object of the present invention is to provide a kind of H₂o₂Modified TiO₂The preparation method and application of mesoporous glass catalyst are applied to the removal of thiophene sulfides in fuel oil. The present invention takes the removal of dibenzothiophene as an example, and realizes the effective removal of sulfides without introducing an oxidizing agent. Removal provides a solution to the problem of low mass transfer efficiency caused by the extreme liquid between fuel and oxidant. By constructing a photocatalytic oxidation-adsorption in situ coupling reaction system, the competitive adsorption caused by aromatics in the oil is effectively suppressed, and the initial conversion rate hardly changes after multiple regenerations. The preparation method of the catalyst provided by the invention is simple and the process operation requirements required for application are not high, which meets the needs of industrialized production.

The technical solution that the present invention solves its technical problem adopts is: a kind of H₂o₂Modified TiO₂/Mesoporous glass catalyst, the mesoporous glass in the catalyst is used as a carrier, the mesoporous glass has a fibrous filamentous structure, and nano-TiO₂As a photocatalytic active component, it is uniformly dispersed on the surface of the carrier, based on the carrier, TiO₂Loading capacity is 0~25wt%.

The preparation method of above-mentioned mesoporous glass carrier is as follows: the solid glass microsphere and deionized water that diameter is about 100um are placed in high temperature and high pressure reactor, reactor pressure is raised to 4.5~12.5MPa, in this subcritical The state is kept for 1~3h. After the reactor temperature dropped to room temperature, the etched glass microspheres were separated from water by filtration and washed with deionized water

Several times to PH = 7, then dry for later use.

A kind of H₂o₂Modified TiO₂The preparation method of the mesoporous glass catalyst is as follows: 0.15~0.92mL tetrabutyl titanate is added to 5~20mL hydrogen peroxide and 10~30mL isopropanol solvent, after obtaining a yellow transparent solution, add 0.01~0.1g hexadecanol Alkyl ammonium bromide and 0.5~1.0g mesoporous glass carrier, after ultrasonic dispersion is uniform, add dropwise the mixed solution of 1~10mL deionized water and 5~25mL isopropanol, heat to 30~60 °C and hydrolyze for 1~3h, The resulting mixture was transferred to a stainless steel autoclave, crystallized at 100-150°C for 2-6 hours, the product was centrifuged, washed three times with acetone and dried at 60°C for 24 hours, and roasted at 350-550°C for 2 hours under air conditions. ~6h, obtain target catalyst.

Preferably, described mesoporous glass carrier etching pressure is 11.2~12.5MPa, and the time is 2~3h.

Preferably, described tetrabutyl titanate add-on is 0.49~0.92mL, TiO₂Loading capacity is 15~25wt%.

Preferably, described hydrogen peroxide add-on is 10~15mL, and Virahol solvent add-on is 20~30mL.

Preferably, the cetyl ammonium bromide add-on is 0.03~0.05g, and the mesoporous glass carrier add-on is 0.5~0.7 g_o

Preferably, described deionized water add-on is 3~7mL, and Virahol add-on is 10~20mL.

Preferably, described tetrabutyl titanate hydrolysis temperature is 45~55 °C, and hydrolysis time is 1~2h.

Preferably, described crystallization reaction temperature is 130~140 °C, and crystallization time is 4~5h.

Preferably, described calcination temperature is 400~450 °C, and calcination time is 2~3h.

[0017] The present invention also provides the application of the photocatalytic oxidation-adsorption desulfurization catalyst prepared by the preparation method described in the above technical scheme in the removal of thiophene sulfur-containing compounds.

Preferably, described application comprises the steps:

Dibenzothiophene is added in n-octane, is configured as the desulfurization solution that sulfur content is 300PPm, adds 50mL in reactor and treats desulfurization solution and the photocatalytic preparation method described in 0.1g above-mentioned technical scheme and prepares The oxidation-adsorption desulfurization catalyst reacts for 1 hour under dark reaction conditions, and uses a 500W mercury lamp as a light source to irradiate it for 4.5 hours to complete the desulfurization process.

[0020] The reaction liquid obtained in the desulfurization process is subjected to solid-liquid separation to obtain desulfurization liquid and used catalyst.

[0021] After the desulfurization solution is filtered through the filter membrane, the residual sulfide content is measured in a three-stage tandem quadrupole mass spectrometer.

Utilize adsorption kinetics to measure sulfide concentration: the photocatalytic oxidation-adsorption desulfurization catalyst is added to concentration in the desulfurization solution to be 300 ppm for 5h, every 0.5h takes out a sample, separates, measures sulfide after filtering concentration.

[0023] Utilize adsorption thermodynamics to measure sulfide concentration: the photocatalytic oxidation-adsorption desulfurization catalyst is added respectively in the desulfurization liquid to be desulfurized at various concentrations (150, 200, 250, 300, 350 and 400ppm). Stir at 150 rpm for 4 h at 30°C. Take out a sample every 0.5h, separate and filter to measure the sulfide concentration.

[0024] The present invention also provides a regeneration method for the photocatalytic oxidation-adsorption desulfurization catalyst prepared by the preparation method described in the above technical solution.

Preferably, the steps of the regeneration method are as follows: after the used catalyst obtained after the solid-liquid separation is washed three times with acetone, it is dried at 60°C for 24h, and calcined at 450°C for 3h to obtain regeneration photocatalytic oxidation-adsorption desulfurization catalyst.

The beneficial effects of the present invention are:

(1) catalyst provided by the invention, with H₂o₂Modified Hydrothermal Synthesis of TiO₂loaded mesoporous glass microspheres, the modified TiO₂Nanoparticles go through the process of hydrolysis, condensation and polymerization, through h₂o₂The strong interaction with the titanium source controls its morphology, and synthesizes TiO with large specific surface area, narrow particle size distribution and uniform dispersion.₂The mesoporous glass core-shell structure improves the reaction contact area and light absorption capacity between the catalyst and fuel oil, and improves the photocatalytic oxidation-adsorption desulfurization performance.

(2) Catalyst provided by the invention, with the mesoporous glass with ordered fiber filamentous structure as carrier, the larger specific surface area of described carrier can accelerate the mass transfer of sulfide by physical adsorption, can effectively disperse again and immobilized nanoscale TiO₂Particles together construct a photocatalytic oxidation-adsorption in situ coupling system. The TiO₂The particles act as photocatalytic active centers to oxidize thiophene sulfides to more polar sulfones. Compared with aromatic hydrocarbons, the sulfones have higher polarity, so they are selectively adsorbed on the catalyst adsorption center, effectively solving the problem of The problem of low desulfurization efficiency caused by competitive adsorption of aromatics.

(3) the application of catalyst provided by the invention in the removal of thiophene sulfur compounds, without additional introduction of oxidant (such as h₂o₂etc.), compared with the desulfurization method with an external oxidant, it solves the problem of low mass transfer efficiency caused by the comparison between fuel oil and oxidant extreme liquid. In addition, the addition of no oxidant makes the operation easier and safer, and reduces the post-processing steps.

(4) the application of catalyzer provided by the invention in the removal of thiophene sulfur compound, its application operation requirement is not high, and reaction condition is mild, environmentally friendly, after completing desulfurization process, can make catalyzer and The desulfurization liquid is separated, and the catalyst can be regenerated only by simple heat treatment, which provides a new way for green and low-cost desulfurization.

Description of drawings

Fig. 1 is the scanning electron micrograph of the mesoporous glass carrier prepared in embodiment 1;

Fig. 2 is the H prepared in embodiment 1₂o₂Modified TiO₂/SEM photo of mesoporous glass catalyst;

Fig. 3 is the TiO prepared in comparative example 2₂/SEM photo of mesoporous glass catalyst;

Fig. 4 is the H of the mesoporous glass carrier prepared in embodiment 1~5 and different loads₂o₂Modified TiO₂/Mesoporous glass catalysts (5, 10, 15, 20 and 25wt%) and H prepared in Comparative Example 1₂o₂Modified TiO₂XRD pattern of the catalyst;

Fig. 5 is to data in embodiment 6, comparative example 3 and comparative example 4 through membrane diffusion model fitting gained adsorption kinetics curve;

Fig. 6 is to the data in embodiment 6, comparative example 3 and comparative example 4 through internal diffusion model fitting gained adsorption kinetics curve;

Fig. 7 is to the data in embodiment 7 and comparative example 5 through Langmuir model fitting gained adsorption thermodynamics curve.

Detailed ways

Embodiment Below in conjunction with specific embodiment, the present invention is described in detail. Embodiments of the present invention are not limited to the scope shown in the examples.

Embodiment 1

5g glass microspheres and 200mL deionized water are placed in high temperature and high pressure reactor, reactor pressure is raised to 12.5MPa, and temperature is 325 °C, keeps 2h in this subcritical state, treats that reactor temperature is down to room temperature Finally, the etched glass microspheres were separated from water by filtration , washed several times with deionized water to pH = 7, and dried for later use.

0.15mL tetrabutyl titanate is joined in the mixed solution of 13mL hydrogen peroxide and 20mL Virahol, after obtaining yellow transparent solution, add 0.03g cetyl ammonium bromide and 0.65g mesoporous glass carrier, After ultrasonic dispersion is uniform, add dropwise to the mixed solution of 5mL deionized water and 10mL isopropanol, heat to 50°C for hydrolysis for 1h, transfer the resulting mixture to a stainless steel autoclave, crystallize at 140°C for 4h, centrifuge and wash the product and dried, and calcined at 450 °C for 3 h under air conditions to obtain H with a loading capacity of 5 wt%.₂o₂Modified TiO2/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst.

Embodiment 2

Prepare H according to the method for embodiment 1₂o₂Modified TiO₂/Mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, no

The difference is that the addition of tetrabutyl titanate is 0.31mL, and the titanium dioxide loading of the obtained catalyst is 10wt%.

Embodiment 3

Prepare H according to the method for embodiment 1 O modified butyl bis/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, difference is, tetrabutyl titanate add-on is 0.49mL, and the titania load capacity of gained catalyst is 15wt%.

Embodiment 4

Prepare H according to the method for embodiment 1 O modified butyl bis/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, difference is, tetrabutyl titanate add-on is 0.691nL, and the titania load capacity of gained catalyst is 20wt%.

Embodiment 5

Prepare H according to the method for embodiment 1 O modified butyl bis/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, difference is, tetrabutyl titanate add-on is 0.92mL, and the titania load capacity of gained catalyst is 25wt%.

Comparative example 1

Prepare H according to the method for embodiment 1 O Modified butylbis/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, difference is, do not add mesoporous glass carrier, obtain H O Modified 70ζ catalyst.

Comparative example 2

Prepare H according to the method for embodiment 1 O Modified butyl bis/mesoporous glass photocatalytic oxidation-adsorption desulfurization catalyst, difference is, do not add H . ?, to obtain UTiOz/mesoporous glass catalyst.

Fig. 1 is the scanning electron micrograph of the mesoporous glass carrier prepared in embodiment 1, as can be seen from Fig. 1 mesoporous glass carrier has fiber filiform structure, and fiber gap forms pore structure, and fiber diameter is 0.18 (± 0.055 ) μ1n, the average diameter of the mesoporous glass carrier is 125.0 (±8.36) wn. Fig. 2 is the scanning electron micrograph of the h2o Modified TiO / mesoporous glass catalyst prepared in Example 1, and Fig. 3 is the scanning electron micrograph of the 1N / mesoporous glass catalyst prepared in Comparative Example 2, and the comparison of the two figures can It is found that there are a large number of aggregated or 02 clusters in the TiOz/mesoporous glass catalyst, and a more uniform distribution of TiO2 nanoparticles can be observed in the ratio 02 modified 702/mesoporous glass catalyst. Due to the strong interaction between tetrabutyl titanate and %02, it can slow down the hydrolysis, inhibit the growth of different particle sizes, and increase the specific surface area of the catalyst.

For verification H2.2 inhibition, m-adsorption test is carried out to the prepared catalyzer of embodiment 1~5 and comparative example 1 and 2, gained specific surface area, mean aperture and pore volume change are shown in the table below. It can be seen from the data in the table that with the increase of TiOz loading, the specific surface area of HO modified TiOz/mesoporous glass catalyst showed a trend of first increasing and then decreasing, and an inflection point appeared when the loading amount was 15wt%.

<td></td><td>project</td><td>BET specific surface area (m7 g)</td><td>Average pore size (n1n)</td><td>Pore volume (m'/g)</td>

<td></td><td>Comparative example 2</td><td>172.573</td><td>3. 661</td><td>0. 264</td>

<td></td><td>Example 1</td><td>186.184</td><td>4. 228</td><td>0. 334</td>

<td>[0056]</td><td>Example 2</td><td>259.033</td><td>I 203</td><td>0. 266</td>

<td></td><td>Example 3</td><td>299.127</td><td>3. 626</td><td>0. 276</td>

<td></td><td>Example 4</td><td>242.029</td><td>3. 667</td><td>0. 220</td>

<td></td><td>Example 5</td><td>216.766</td><td>3. 866</td><td>0. 303</td>

<td></td><td>Comparative example 1</td><td>90. 415</td><td>18,316</td><td>0. 173</td>

Fig. 4 is the ratio of the mesoporous glass carrier prepared in embodiment 1~5 and different loading capacity 0 Modified TiO / mesoporous glass catalyst (5,10,15,20 and 250t%) and comparative example 1 The M1 ^ diagram of the ratio 02 modified 702 catalyst prepared in . No clear crystalline peaks were observed on the mesoporous glass support, which indicated that the mesoporous glass support was amorphous. The position of the h2o? modified 70Z diffraction peak conforms to the standard card (JCPDS 86-1157) as the anatase phase. In square 02 loading of 5wt% than 02 modified Ti0₂/ The characteristic peak of TiOZ was not observed in the mesoporous glass catalyst, which may be because TiO2 is highly dispersed on the surface of the support and the crystal size is small, which exceeds the detection limit. When the TiO2 loading is greater than 5wt%, a strong characteristic peak appears at the anatase TiO2, and the characteristic peak intensity increases gradually with the increase of TiOz content.

Dibenzophenone is added in n-octane, is configured as the simulated oil that sulfur content is 300ppm, adds 50mL simulated oil and the photocatalytic oxidation that the preparation method described in 0.1g above-mentioned technical scheme prepares in reactor -Use a 500W mercury lamp as the light source to irradiate the adsorption desulfurization catalyst for 4.5 hours, use a triple quadrupole mass spectrometer to measure the concentration of dibenzophenone in the solution, and calculate the desulfurization rate.

Project embodiment 1 embodiment 2 embodiment 3 embodiment 4 embodiment 5 comparative example 1 comparative example 2 [0059]--desulfurization rate 61.4 86.5 94.2 99.7 96.2 78.4 91.1

Embodiment 6

The prepared loading capacity in the described embodiment 4 is that 20wt% photocatalytic oxidation-adsorption desulfurization catalyst is added to the concentration to be 300ppm in the desulfurization solution for 5h, every 0.5h takes out a sample, separates, measures after filtering sulfide concentration.

Comparative example 3

The adsorption kinetics curve of catalyst is measured according to the method for embodiment 6, and difference is that the catalyst added is h2 in comparative example 1. Modified T i o2.

Comparative example 4

The adsorption kinetics curve of catalyst is measured according to the method for embodiment 6, and difference is that the catalyst added is the mesoporous glass carrier in embodiment 1.

[0066] A membrane diffusion model and an intradiffusion model were used to process fit the data. The linear expression of the membrane diffusion model is as follows:_{Γ T} (ln(l -F) = -kt

Μ { F = q&amp;

Wherein, k is adsorption rate constant, and F is the realization index of balance, and t is reaction time, and Qf is the adsorption capacity at t moment, and Qet is the adsorption capacity when reaching equilibrium.

The linear expression of internal diffusion model is as follows:

[0070] q_t = k Wherein, t is consistent with the above-mentioned definition, and k is the rate constant, and the unit is mg/ (g min⁰'⁵)。

Described data fitting result is as shown in figure (Fig. 5, Fig. 6), and relevant fitting parameter is listed in the following table. It can be seen from the fitting results that, compared with the internal diffusion model, the membrane diffusion model is more appropriate for describing the adsorption process. That is to say, the molecular diffusion process is the rate-determining step in the adsorption process of sulfide, while the internal diffusion process of particles only has a certain influence.

<td rowspan="2"></td><td rowspan="2">project</td><td>membrane diffusion model</td><td colspan="2">internal diffusion model</td>

<td>k/min Μ</td><td>k/ (mg. g^-1;^{-0 5})</td><td>Η</td>

<td>[0072]</td><td>Example 6</td><td>0.0331 0.9884</td><td>7.1038</td><td>0*7314</td>

<td></td><td>Comparative example 3</td><td>0.0157 0.9875</td><td>7.2442</td><td>0. 8920</td>

<td></td><td>Comparative example 4</td><td>0.0188 0.9907</td><td>4. 1568</td><td>0. 9325</td>

[0073] The load prepared in Example 4 is that the 20wt% photocatalytic oxidation-adsorption desulfurization catalyst is added to the desulfurization solution at various levels of concentration (150, 200, 250, 300, 350 and 400ppm). Stir at 150 rpm for 4 h at 30°C. Take out a sample every 0.5h, separate and filter to measure the sulfide concentration.

Comparative example 5

The adsorption thermodynamic curve of catalyzer is measured according to the method for embodiment 7, and difference is that the catalyzer that adds is the mesoporous glass carrier in embodiment 1.

The data were fitted using the Langmuir model. The linear expression of the Langmuir model is as follows:_e 1

[0077] —= — +-—

Qet Qm /qm

Wherein, Ce is the concentration of desulfurization liquid to be treated under equilibrium state, and unit is mg/L, and qet and Qm are respectively the adsorption capacity and saturated absorption capacity of adsorbent after adsorption reaches equilibrium, and unit is mg/g, and KL is Adsorption equilibrium constant.

Described data fitting result is as shown in figure (Fig. 7), and relevant fitting parameter is listed in the following table. From the fitting results, it can be seen that the data of Example 4 and Comparative Example 5 are in line with the Langmuir model. Compared with the mesoporous glass carrier used in Comparative Example 5, the modified 1 sub/mesoporous glass used in Example 4 is also 02 Catalytic oxidation-adsorption Both the litter and mouthpiece values of the catalyst increased, indicating that the adsorption capacity and the density of adsorption sites of the catalyst increased after loading for 1 Å.

<td></td><td rowspan="2">project</td><td></td><td>Langmuir model</td><td></td>

<td></td><td>qj (mg. g</td><td>KJ (L.g¹)</td><td>R²</td>

<td>LUUOU"</td><td>Example 7</td><td>87. 95</td><td>0. 142</td><td>0.9923</td>

<td></td><td>Comparative example 5</td><td>40. 91</td><td>0.016</td><td>0.9879</td>

After the one-way reaction ends, after the catalyst is washed with acetone, dry, regenerate 3h00.1g regeneration photocatalytic oxidation-adsorption desulfurization catalyst at 450 DEG C and continue to drop into the simulated oil (50mL) that sulfur content is 300ppm, in 500W mercury Irradiate in the light source for 4, 5h to complete another desulfurization cycle. In the cycle, the initial conversion rate of the photocatalytic oxidation-adsorption desulfurization catalyst remained basically unchanged after three regenerations, and a beneficial regeneration phenomenon appeared.