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WO2019114767A1 - 用于催化氯代芳硝基化合物选择加氢的催化剂及制备方法 - Google Patents

用于催化氯代芳硝基化合物选择加氢的催化剂及制备方法 Download PDF

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WO2019114767A1
WO2019114767A1 PCT/CN2018/120710 CN2018120710W WO2019114767A1 WO 2019114767 A1 WO2019114767 A1 WO 2019114767A1 CN 2018120710 W CN2018120710 W CN 2018120710W WO 2019114767 A1 WO2019114767 A1 WO 2019114767A1
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catalyst
sba
tio
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platinum
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周继承
张燕吉
王非
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Xiangtan University
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Xiangtan University
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Priority claimed from CN201711340016.7A external-priority patent/CN108031485B/zh
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
    • B01J29/0316—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing iron group metals, noble metals or copper
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    • B01J29/041—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41
    • B01J29/042—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41 containing iron group metals, noble metals or copper
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/343—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of ultrasonic wave energy
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    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/344—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy
    • B01J37/345—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy of ultraviolet wave energy
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
    • C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
    • C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
    • C07C209/365—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst by reduction with preservation of halogen-atoms in compounds containing nitro groups and halogen atoms bound to the same carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C211/00—Compounds containing amino groups bound to a carbon skeleton
    • C07C211/43—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
    • C07C211/44—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring
    • C07C211/52—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring the carbon skeleton being further substituted by halogen atoms or by nitro or nitroso groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/15—X-ray diffraction

Definitions

  • the invention belongs to the field of catalytic hydrogenation, and particularly relates to a catalyst for preparing selective hydrogenation of a chloroaromatic compound and a preparation method thereof.
  • P-chloroaniline is an important organic intermediate widely used in the synthesis of dyes, pharmaceuticals and pesticides.
  • Most of p-chloroaniline is prepared by reduction of p-chloronitrobenzene.
  • the reduction methods mainly include metal reduction method, electrochemical reduction method, non-hydrogen reducing agent reduction method, catalytic hydrogenation reduction method, etc.
  • the reduction process has advanced technology and high yield, which is more in line with the requirements of modern workers for atomic economy. Among them, the precious metal catalytic hydrogenation method is dominant.
  • the heterogeneous catalytic reduction method under high temperature and high pressure was mainly used, but the microcrystals were at high temperature.
  • the surface of the carrier tends to aggregate, affecting its dispersibility, and thus affecting the catalytic activity of the catalyst.
  • heterogeneous catalysis at low temperature and low pressure has gradually attracted the interest of researchers.
  • the key point of the catalytic hydrogenation process is how to control the selectivity of the reaction and prevent the occurrence of dechlorination side reactions.
  • the patent CN201510129577 catalyzes the hydrogenation reaction by using a platinum catalyst and a dechlorination inhibitor, including the use of 2-chloro-6-nitrotoluene as a raw material in the presence or absence of a solvent, in the presence of a hydrogenation catalyst or a dechlorination inhibitor.
  • the hydrogenation reduction reaction is carried out, and the catalyst is filtered off at a certain temperature to obtain 3-chloro-2-methylaniline; and the product is 2,6-diaminotoluene by an aminolysis reaction.
  • the modification of the hydrogenation catalyst generally involves the following three aspects: (1) selecting an appropriate carrier and a catalyst precursor to adjust the interaction between the metal and the support. (2) alloying the catalyst active metal with other metals or adding appropriate ions to treat the catalyst; (3) changing the size of the active metal particles by changing the preparation manner of the catalyst.
  • patent CN200810183391 provides a p-chloroaniline catalyst for hydrogenation of p-chloronitrobenzene, which comprises the active component platinum and the support attapulgite.
  • Patent CN201210366514 provides a method for preparing 3,4-dichloroaniline, which comprises catalytic hydrogenation reaction in the presence of a Pt catalyst using 3,4-dichloronitrobenzene as a raw material without using a solvent, and the reaction pressure is 1.0 MPa.
  • the reaction temperature is 75 ° C ⁇ 120 ° C;
  • the Pt catalyst consists of the active component Pt, carrier C and additives, wherein the mass percentage of Pt is 0.5% to 5%, the auxiliary agent is Fe2O3, auxiliary The mass percentage is 0.05% to 0.5%, and the balance is C. That is, the catalyst used therein contains platinum carbon and iron oxide.
  • Patent CN201310009679 provides a method for producing chloroaniline by hydrogenation of a solventless method of chloronitrobenzene, using chloronitrobenzene as a raw material, chloronitrobenzene in the presence of a catalyst and an auxiliary agent at 80-100 ° C And reacting with hydrogen at 0.3-2.5 MPa, without adding a solvent, after completion, water is separated to obtain chloroaniline.
  • the catalyst used therein is a platinum carbon catalyst.
  • Patent CN2012103303921 provides a method for preparing o-chloroaniline by solvent-free catalytic hydrogenation, using o-nitrochlorobenzene as a raw material, wherein a vanadium-doped platinum carbon catalyst is used to catalyze hydrogenation to suppress dechlorination side reaction.
  • the patent CN201510128466 provides a process for the continuous catalytic hydrogenation of dichloronitrobenzene to produce dichloroaniline, wherein the dechlorination side reaction is inhibited by catalytic hydrogenation using a catalyst containing platinum carbon plus vanadium or tin.
  • the nano platinum catalyst with excellent performance should have the following characteristics in structure: the active component platinum is highly uniformly dispersed on the surface of the carrier, the platinum component of the active component is low, the surface is exposed to many atoms, and the specific surface area of the carrier is large.
  • some preparation conditions are severe in the preparation method, the reagents used are not environmentally friendly, the dispersion of platinum is not good, and the particle size is large.
  • the catalytic reaction temperature is high, the reaction time is long, and the selective hydrogenation conversion rate and selectivity of chloronitrobenzene have certain limitations under mild conditions.
  • the supported platinum-based catalyst has good hydrogenation performance, and is commonly used for selective hydrogenation of enyne, nitro, aldehyde, ketone, etc.; particle size of active component platinum, dispersibility on the surface of the carrier, and The interaction between the metal platinum and the support affects the catalytic activity of the catalyst.
  • the commonly used methods for preparing platinum-based catalysts at home and abroad, such as impregnation method, sol-gel method, ion exchange method, etc. have the disadvantages of complicated preparation process, easy aggregation of platinum nanoparticles and non-green, which affect the overall performance of the catalyst.
  • the present invention first provides a catalyst for the selective hydrogenation of a chlorinated aryl nitro compound, characterized in that the catalyst is a Pt/TiO 2 /SBA-15 catalyst or a Pt/ZrO 2 /SBA-15 catalyst.
  • the content of platinum in the catalyst is from 0.01 to 0.3% by weight, preferably from 0.05 to 0.15% by weight, more preferably from 0.08 to 0.10% by weight.
  • TiO 2 accounts for 5-20% by weight, preferably 10-15% by weight, based on the total weight of the composite support TiO 2 /SBA-15;
  • ZrO 2 accounts for 5 ⁇ of the total weight of the composite support ZrO 2 /SBA-15 20% by weight, preferably 10 to 15% by weight.
  • the present invention there is a strong interaction between platinum and the semiconductive metal oxide TiO 2 to form a composite nanostructure catalyst Pt/TiO 2 /SBA-15; in particular, the nano noble metal platinum and the nano titanium dioxide synergistically catalyze in the catalyst can make The amount of platinum in the catalyst of the present invention is reduced to a limit low.
  • the invention also provides a preparation method of the catalyst, which comprises first loading TiO 2 on SBA-15 by sol-gel method, or loading ZrO 2 on SBA-15 by precipitation method to obtain SBA A composite carrier of one or more layers of nano TiO 2 film or nano ZrO 2 film is laid on -15, and the active component platinum is loaded onto the composite carrier by photocatalytic reduction to obtain the Pt/TiO 2 /SBA. -15 catalyst or Pt/ZrO 2 /SBA-15 catalyst.
  • the step of sonicating SBA-15 with absolute ethanol is also included.
  • the sol-gel method comprises adding butyl titanate to anhydrous ethanol containing SBA-15, further adding water to continue stirring to hydrolyze butyl titanate, and heating the hydrolysis mixture to 35 ⁇ It was made into a gel at 45 ° C and dried under vacuum at 60 to 90 ° C to obtain a TiO 2 /SBA-15 composite carrier.
  • the photocatalytic reduction method comprises dispersing a TiO 2 /SBA-15 composite carrier or a ZrO 2 /SBA-15 composite carrier in deionized water, and ultrasonically impregnating with a solution of methanol and chloroplatinic acid. The mixture was placed under ultraviolet light, stirred, solid-liquid separated and washed with water until neutral and dried to obtain the Pt/TiO 2 /SBA-15 catalyst or Pt/ZrO 2 /SBA-15 catalyst.
  • the mass ratio of methanol to water used in the photocatalytic reduction is 1:5 to 15, and the ultraviolet light irradiation time is 5 to 20 hours.
  • the invention also provides a catalyst prepared by the above-mentioned catalyst or the preparation method as described above for catalyzing the selective hydrogenation of p-chloronitrobenzene to prepare p-chloroaniline.
  • the invention also provides a process for the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline, which comprises using a catalyst comprising platinum and titanium dioxide or zirconium dioxide and catalyzing the chlorine in a hydrogen atmosphere and under heating conditions.
  • the selective hydrogenation of nitrobenzene to produce p-chloroaniline results in a significant reduction in the dechlorination side reaction during hydrogenation.
  • the catalyst is a Pt/TiO 2 /SBA-15 or Pt/ZrO 2 /SBA-15 catalyst.
  • the content of platinum in the catalyst is from 0.01 to 0.3% by weight, preferably from 0.05 to 0.15% by weight, more preferably from 0.08 to 0.10% by weight.
  • the selective hydrogenation reaction uses anhydrous ethanol as a solvent, and the temperature of the selective hydrogenation is 40 to 90 ° C, preferably 50 to 70 ° C.
  • the catalyst is used to catalyze the selective catalytic hydrogenation of p-chloronitrobenzene to produce p-chloroaniline.
  • the conversion and selectivity are very high, both of which can be as high as 99%, and the dechlorination side reaction is greatly reduced.
  • the catalyst structure is novel, the amount of platinum in the catalyst is small, and the catalyst cost is low.
  • the composite nanostructure catalyst Pt/TiO 2 /SBA-15 or Pt/ZrO 2 /SBA-15 provided by the invention has the advantages of simple preparation method, short production cycle and low platinum loading, no need to add reducing agent during preparation, and good platinum dispersion. High catalytic activity.
  • the preparation process of the TiO 2 /SBA-15 composite carrier in the invention is simple, the reaction time is short, the solvent is green and pollution-free, and high-temperature calcination is not required, and the surface dispersion of TiO 2 on the mesoporous silicon material SBA-15 is high, so that the subsequent load
  • the nano-platinum on it and the nano-TiO 2 produce synergistic catalysis
  • the preparation process of the ZrO 2 /SBA-15 composite carrier is simple, the reaction time is short, the solvent is green and non-polluting, and the ZrO 2 is on the surface of the mesoporous silicon material SBA-15.
  • the high degree of dispersion enables the synergistic catalysis of nano-platinum on the subsequent loading with nano-ZrO 2 .
  • Figure 1 is an XRD pattern of a 10% TiO 2 /SBA-15 composite support.
  • Figure 2 is an XRD pattern of a 15% TiO 2 /SBA-15 composite support.
  • Example 3 is an XRD pattern of a 0.08% Pt/10% TiO 2 /SBA-15 catalyst prepared in Example 2.
  • Example 4 is an XRD pattern of a 0.1% Pt/10% TiO 2 /SBA-15 catalyst prepared in Example 1.
  • the mesoporous silicon material SBA-15 was added to 15 mL of absolute ethanol and ultrasonically shaken for 2 h to obtain a treated mixture of SBA-15 and absolute ethanol. Under stirring, 0.5 mL of butyl titanate was dropwise added to the above mixture, and stirred for 1 h; 1 mL of water was slowly added to the mixture to hydrolyze the butyl titanate, and stirring was continued for 1 h to completely hydrolyze the butyl titanate. . The mixture was heated and stirred at 40 ° C to make the mixture liquid. It was dried under vacuum at 80 ° C overnight to obtain a 10% TiO 2 /SBA-15 composite support (the TiO 2 content in the composite support was 10% by weight).
  • TiO 2 /SBA-15 composite carrier 0.702 g was dispersed in 100 mL of deionized water, 10 mL of anhydrous methanol was added, ultrasonic dispersion was carried out for 10 min, 0.1 mL of chloroplatinic acid solution was added, ultrasonic dispersion was carried out for 20 min, and then the solution was placed under stirring. Under ultraviolet light for 12 h, the solution was filtered and washed, and vacuum dried at 80 ° C to obtain a Pt/TiO 2 /SBA-15 catalyst with a Pt mass fraction of 0.1% (Pt content in the catalyst was 0.1 wt%), ie 0.1% Pt/10 % TiO 2 /SBA-15.
  • Example 2 The same as in Example 1, except that the mass fraction of Pt in Pt/TiO 2 /SBA-15 was 0.08%, that is, 0.08% Pt/10% TiO 2 /SBA-15.
  • Example 2 The same as in Example 1, except that the mass fraction of TiO 2 in the composite carrier in Pt/TiO 2 /SBA-15 was 15%, that is, 0.1% Pt/15% TiO 2 /SBA-15.
  • the 0.1% Pt/10% TiO 2 /SBA-15 prepared in the above Example 1 was used to catalyze the hydrogenation of p-chloronitrobenzene. Take 0.401g of the chloro-nitrobenzene, 0.1g 0.1% Pt / 10% ethanol, and after 20mL of an air autoclave in an autoclave, into H 2 substitution TiO 2 / SBA-15, H 2 Close The valve, when the temperature in the autoclave reached a reaction temperature of 70 ° C, the reaction was carried out by introducing H 2 , stirring was started, and the reaction was started for 1 h. After the reaction was completed, the mixture was cooled, and 10 mL of the reaction solution was centrifuged for gas chromatography analysis. The conversion of p-chloronitrobenzene was 100% and the selectivity to p-chloroaniline was 98.44%.
  • Example 4 the catalyst prepared in Example 1 was added with 0.1% Pt/10% TiO 2 /SBA-15 0.1 g, 0.401 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 70 ° C for 0.5 h.
  • the conversion of p-chloronitrobenzene was 98.32%, and the selectivity to p-chloroaniline was 98.60%.
  • Example 4 the catalyst prepared in Example 1 was added with 0.1% Pt/10% TiO 2 /SBA-15 0.1 g, 0.401 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 50 ° C for 1.5 h.
  • the conversion of p-chloronitrobenzene was 99.36%, and the selectivity to p-chloroaniline was 99.13%.
  • Example 4 the catalyst prepared in Example 2 was added with 0.08% Pt/10% TiO 2 /SBA-15 0.1 g, 0.317 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 70 ° C for 1 h.
  • the conversion of p-chloronitrobenzene was 84.71%, and the selectivity to p-chloroaniline was 99.50%.
  • the catalytic reaction time is not long enough to cause the conversion of p-chloronitrobenzene to be not high.
  • Example 2 In the same manner as in Example 4, the catalyst prepared in Example 2 was added with 0.08% Pt/15% TiO 2 /SBA-15 0.1 g, 0.317 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 70 ° C for 1.5 h. The conversion of p-chloronitrobenzene was 99.25%, and the selectivity to p-chloroaniline was 99.22%.
  • Example 4 The solution after the reaction of Example 4 was centrifuged, the reaction solution was removed, washed with a plurality of absolute ethanol, and then dried in a vacuum oven at 40 ° C overnight, and the catalyst after secondary recovery was subjected to the method of Example 4.
  • the reaction was carried out in steps, the conversion of p-chloronitrobenzene was 97.77%, and the selectivity to p-chloroaniline was 97.23%. It is indicated that the catalytic activity of the catalyst for secondary recovery is still high.
  • the different platinum mass fraction catalysts prepared by this method are active for the selective hydrogenation reaction of p-chloronitrobenzene, and the overall amount of platinum is low and the catalytic hydrogenation conversion rate is high. At the same time, there are few dechlorination reactions.
  • the preparation of the catalyst was substantially the same as in Example 1, except that the titanium dioxide layer was not provided in the catalyst, and a 0.1% Pt/SBA-15 catalyst (mass fraction of platinum in the catalyst was 0.1%) was prepared by photocatalytic reduction.
  • the catalyst was subjected to selective hydrogenation in the same manner as in Example 4, and 0.1 g of a 0.1% Pt/SBA-15 catalyst, 0.401 g of p-chloronitrobenzene, and 20 mL of absolute ethanol were added, and the reaction was carried out at 70 ° C for 2.0 h.
  • the conversion of p-chloronitrobenzene was 13.05%, and the selectivity to p-chloroaniline was about 100%.
  • the preparation of the catalyst was substantially the same as in Example 1, except that the titanium dioxide layer was not provided in the catalyst, and a 0.1% Pt/SBA-15 catalyst (mass fraction of platinum in the catalyst was 0.1%) was prepared by photocatalytic reduction.
  • the catalyst was subjected to selective hydrogenation in the same manner as in Example 4, and 0.1 g of a 0.1% Pt/SBA-15 catalyst, 0.401 g of p-chloronitrobenzene, and 20 mL of absolute ethanol were added, and the reaction was carried out at 70 ° C for 3.0 h.
  • the conversion of p-chloronitrobenzene was 53.7%, and the selectivity to p-chloroaniline was about 100%.
  • the preparation of the catalyst was substantially the same as in Example 1, except that the titanium dioxide layer was not provided in the catalyst, and a 2% Pt/SBA-15 catalyst (the mass fraction of platinum in the catalyst was 2%) was prepared by photocatalytic reduction.
  • the catalyst was subjected to selective hydrogenation in the same manner as in Example 4, and 2% Pt/SBA-15 catalyst 0.1 g, 0.401 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 70 ° C for 1.0 h were added.
  • the conversion of p-chloronitrobenzene was 91.51%, and the selectivity to p-chloroaniline was 86.56%.
  • FIGS. 1 and 2 are XRD patterns of a TiO 2 /SBA-15 composite support
  • FIGS. 3 and 4 are XRD patterns of a Pt/TiO 2 /SBA-15 catalyst. From the comparison of Figs. 3 to 4 and Figs. 1 to 2, it is understood that the diffraction peak of platinum is hardly observed in the XRD pattern, which indicates that the loading of the catalyst prepared by the method described in the present invention is very low.
  • Example 10 The same as in Example 10, except that the mass fraction of Pt in Pt/ZrO 2 /SBA-15 was 0.08%, that is, 0.08% Pt/10% ZrO 2 /SBA-15.
  • Example 10 Same as in Example 10, except that the mass fraction of ZrO 2 in the composite carrier in Pt/ZrO 2 /SBA-15 was 15%, that is, 0.1% Pt/15% ZrO 2 /SBA-15.
  • the 0.1% Pt/10% ZrO 2 /SBA-15 prepared in the above Example 10 was used to catalyze the hydrogenation of p-chloronitrobenzene. Take 0.401 g of p-chloronitrobenzene, 0.1 g of 0.1% Pt/10% ZrO 2 /SBA-15 and 20 mL of absolute ethanol in an autoclave, and then pass H 2 to displace the air in the reaction vessel, then close H 2 .
  • the valve when the temperature in the autoclave reached a reaction temperature of 40 ° C, the reaction was carried out by introducing H 2 , stirring was started, and the reaction was started for 40 min.
  • Example 13 the catalyst prepared in Example 10 was added with 0.1% Pt/10% ZrO 2 /SBA-15 0.1 g, 0.401 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 40 ° C for 30 min.
  • the conversion of p-chloronitrobenzene was 99.57%, and the selectivity to p-chloroaniline was 98.77%.
  • Example 13 the catalyst prepared in Example 10 was added with 0.1% Pt/10% ZrO 2 /SBA-15 0.1 g, 0.401 g of p-chloronitrobenzene, 20 mL of absolute ethanol, and reacted at 30 ° C for 40 min.
  • the conversion of p-chloronitrobenzene was >99.9%, and the selectivity to p-chloroaniline was 98.98%.
  • Example 13 The solution after the reaction of Example 13 was centrifuged, the reaction solution was removed, washed with a plurality of absolute ethanol, and then dried in a vacuum oven at 80 ° C overnight, and the catalyst after the second recovery was reacted at 40 ° C for 40 min.
  • the conversion of p-chloronitrobenzene was 94.03%, and the selectivity to p-chloroaniline was 97.25%.
  • the catalytic activity of the second recovered catalyst is still high.
  • the scope of the present invention is not limited to the above examples, and the catalyst of the present invention can be sufficiently reacted for the hydrogenation of p-chloronitrobenzene as long as the mass fraction of the active component of the catalyst and the reaction conditions including temperature and time are controlled. Good results.

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Abstract

一种用于催化氯代芳硝基化合物选择加氢的催化剂及其制备方法，所述催化剂为Pt/TiO 2/SBA-15或Pt/ZrO 2/SBA-15催化剂，且催化剂中铂的含量为0.01～0.3wt％。以及使用该催化剂用于氯代芳硝基苯选择性加氢制备对氯苯胺的方法。该催化剂用于催化氯代芳硝基苯选择性加氢制备对氯苯胺时表现出优越的催化活性，转化率和选择性均可达99％以上，脱氯副反应大幅降低。该复合纳米结构催化剂制备方法简单、生产周期短、催化剂成本低，制备时不需要加入还原剂。

Description

用于催化氯代芳硝基化合物选择加氢的催化剂及制备方法 技术领域
本发明属于催化加氢领域，具体涉及一种用于催化氯代芳硝基化合物选择加氢的催化剂及制备方法。
背景技术
对氯苯胺是一种重要的有机中间体，广泛应用于染料、医药和农药等的合成。目前，大部分对氯苯胺都是由对氯硝基苯还原制得，还原方法主要有金属还原法、电化学还原法、非氢还原剂还原法、催化加氢还原法等，其中催化加氢还原法工艺先进，收率高，更符合现代化工对原子经济性的要求；其中贵金属催化加氢法占主要地位，过去主要采用高温高压下的多相催化还原法，但由于高温下微晶在载体表面易聚集，影响其分散性，进而影响催化剂催化活性，近年来低温低压下的多相催化逐渐吸引科研工作者的兴趣。催化加氢法的关键点是如何控制反应的选择性，防止脱氯副反应的发生。
目前主要有两种方法：一是靠加入脱氯抑制剂或使加氢催化剂预先毒化等方法来防止脱氯，二是加氢催化剂的改性，来达到抑制脱氯的目的。
如专利CN201510129577通过使用铂催化剂和脱氯抑制剂催化加氢反应，包括先以2-氯-6-硝基甲苯为原料在有溶剂或无溶剂条件下，在加氢催化剂、脱氯抑制剂存在条件下，进行加氢还原反应，反应液在一定温度下滤除催化剂后得3-氯-2-甲基苯胺；再通过氨解反应得到产物2,6-二氨基甲苯。
但脱氯抑制剂的加入会增加二次污染，影响产品品质，而毒化加氢催化剂则会使催化剂活性大大降低。
而加氢催化剂的改性通常涉及以下三个方面：(1)选择适当的载体和催化剂前体，以调整金属与载体之间的作用。(2)将催化剂活性金属与其它金属形成合金或添加适当的离子来处理催化剂；(3)通过改变催化剂的制备方式来改变活性金属粒子的大小。
如专利CN200810183391提供一种对氯硝基苯加氢合成对氯苯胺催化剂，其中包含活性组分铂和载体凹凸棒土。专利CN201210366514提供一种制备3，4-二氯苯胺的方法，包括以3，4-二氯硝基苯为原料，不使用溶剂，在Pt催化剂存在下进行催化加氢反应，反应压力1.0MPa～3.0Mpa，反应温度75℃～120℃；所述Pt催化剂由活性组分Pt、载体C和助剂组成，其中Pt的质量百分含量为0.5％～5％，助剂为Fe2O3，助剂的质量百分含量为 0.05％～0.5％，其余为C。即其中使用的催化剂中包含铂碳和氧化铁。
专利CN201310009679提供一种无溶剂法氯代硝基苯加氢制备氯代苯胺的生产方法，以氯代硝基苯为原料，氯代硝基苯在催化剂及助剂存在下，在80-100℃及0.3-2.5MPa下与氢气反应，不添加溶剂，完成后分水得到氯代苯胺。其中使用的催化剂为铂碳催化剂。
专利CN2012103303921提供一种无溶剂催化加氢制备邻氯苯胺的方法，以邻硝基氯化苯为原料，其中使用加钒的铂碳催化剂来催化加氢以抑制脱氯副反应。同样地，专利CN201510128466中提供一种二氯硝基苯连续催化加氢制备二氯苯胺的方法，其中通过使用含铂碳加钒或锡的催化剂催化加氢以抑制脱氯副反应。
一般认为，性能优良的纳米铂催化剂在结构上应该具有以下特征：活性组分铂在载体表面高度均匀分散、活性组分铂载量低、表面裸露原子多、载体比表面积大。但上述现有技术中总存在一些问题：如制备方法中有些制备条件苛刻，所用试剂对环境不友好，铂的分散性不好，颗粒尺寸较大。而在应用方面则要求催化反应温度高，反应时间长，在温和条件下对氯硝基苯选择性加氢转化率和选择性有一定的局限性的缺陷。
综上所述，负载型铂基催化剂具有良好的加氢性能，常用于烯炔、硝基、醛、酮等的选择性加氢；活性组分铂的颗粒尺寸、在载体表面的分散性以及金属铂与载体之间的相互作用均会影响催化剂的催化活性。目前国内外制备铂基催化剂的常用方法浸渍法、溶胶凝胶法、离子交换法等方法，因其存在制备过程复杂、铂纳米颗粒易聚集、非绿色等缺点，影响催化剂的整体性能。因此，开发简单绿色、分散性好、贵金属载量低且具有高活性及稳定性的铂基催化剂和提供一种优异的对氯硝基苯选择性加氢制备对氯苯胺的方法具有重要意义。
发明内容
因此，本发明首先提供一种用于催化氯代芳硝基化合物选择加氢的催化剂，其特征在于，所述催化剂为Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂，且催化剂中铂的含量为0.01～0.3wt％，优选0.05～0.15wt％，更优选0.08～0.10wt％。
在一种具体的实施方式中，TiO 2占复合载体TiO 2/SBA-15总重量的5～20wt％，优选10～15wt％；ZrO 2占复合载体ZrO 2/SBA-15总重量的5～20wt％，优选10～15wt％。
本发明中，铂与半导体金属氧化物TiO 2之间存在强相互作用，形成复合纳米结构催化剂Pt/TiO 2/SBA-15；具体地，该催化剂中纳米贵金属铂与纳米二氧化钛协同催化，可以使得本发明催化剂中铂的用量降低至一个极限低值。
在一种具体的实施方式中，所述Pt/TiO 2/SBA-15催化剂中TiO 2呈薄膜层、以单层或多 层形式平铺在载体SBA-15上，而活性组分铂则锚定在TiO 2薄膜层上；所述Pt/ZrO 2/SBA-15催化剂中ZrO 2呈薄膜层、以单层或多层形式平铺在载体SBA-15上，而活性组分铂则锚定在ZrO 2薄膜层上。
本发明还提供一种所述催化剂的制备方法，所述制备方法包括先采用溶胶凝胶法将TiO 2负载在SBA-15上，或采用沉淀法将ZrO 2负载在SBA-15上，得到SBA-15上平铺一层或多层纳米TiO 2薄膜或纳米ZrO 2薄膜的复合载体，再采用光催化还原法将活性组分铂负载到所述复合载体上得到所述Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂。
在一种具体的实施方式中，将TiO 2负载在SBA-15上之前，还包括使用无水乙醇对SBA-15进行超声预处理的步骤。
在一种具体的实施方式中，所述溶胶凝胶法包括将钛酸丁酯加入含SBA-15的无水乙醇中，再加水继续搅拌使得钛酸丁酯水解，将水解混合物加热至35～45℃使其呈凝胶状，再在60～90℃下真空干燥后得到TiO 2/SBA-15复合载体。
在一种具体的实施方式中，所述光催化还原法包括将TiO 2/SBA-15复合载体或ZrO 2/SBA-15复合载体分散于去离子水中，加入甲醇和氯铂酸溶液超声浸渍，再将混合液置于紫外光照下，搅拌、固液分离并用水洗涤至中性和干燥后得到所述Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂。
在一种具体的实施方式中，所述光催化还原中使用的甲醇与水的质量比为1：5～15，且紫外光照时间为5～20小时。
本发明还提一种如上所述催化剂或如上所述制备方法制备得到的催化剂在催化对氯硝基苯选择性加氢制备对氯苯胺中的应用。
本发明还提一种对氯硝基苯选择性加氢制备对氯苯胺的方法，所述方法包括使用一种含铂和二氧化钛或二氧化锆的催化剂和在氢气环境以及加热条件下催化对氯硝基苯选择性加氢制备对氯苯胺，使得加氢时脱氯副反应大幅降低，所述催化剂为Pt/TiO 2/SBA-15或Pt/ZrO 2/SBA-15催化剂。
在一种具体的实施方式中，所述催化剂中铂的含量为0.01～0.3wt％，优选0.05～0.15wt％，更优选0.08～0.10wt％。
在一种具体的实施方式中，所述选择性加氢反应中使用无水乙醇作为溶剂，所述选择性加氢的温度为40～90℃，优选50～70℃。
本发明至少具有如下有益效果：
1)该催化剂用于催化对氯硝基苯选择性加氢制备对氯苯胺时表现出优越的催化活性， 转化率和选择性非常高，均可高达99％以上，脱氯副反应大幅降低。
2)催化剂结构新颖，催化剂中铂的用量少因而催化剂成本低。本发明提供的复合纳米结构催化剂Pt/TiO 2/SBA-15或Pt/ZrO 2/SBA-15制备方法简单、生产周期短、铂负载量低，制备时不需要加入还原剂，铂分散性好，催化活性高。
3)催化加氢反应时反应条件温和，反应时间短，催化剂与反应液易分离，有较好的应用前景。
4)本发明中TiO 2/SBA-15复合载体的制备过程简单，反应时间短，溶剂绿色无污染，不需要高温煅烧，TiO 2在介孔硅材料SBA-15表面分散度高，使得后续负载其上的纳米铂与纳米TiO 2产生协同催化作用；本发明中ZrO 2/SBA-15复合载体的制备过程简单，反应时间短，溶剂绿色无污染，ZrO 2在介孔硅材料SBA-15表面分散度高，使得后续负载其上的纳米铂与纳米ZrO 2产生协同催化作用。
5)本发明中将铂负载在复合载体上时，光催化剂还原过程中给予足时足量的光照，Pt 2+能全部还原为Pt 0，无需添加额外的还原剂，不需使用惰性气体，不需使用氢气还原铂。催化剂中的铂纳米颗粒锚定或镶嵌在TiO 2膜层上。本发明催化剂中由于TiO 2或ZrO 2的修饰作用，使Pt纳米颗粒在SBA-15载体上完全均匀分布，铂纳米颗粒分散度高，粒径小，因而铂的用量很小即可以取得很好的选择性催化加氢效果。
附图说明
图1为10％TiO 2/SBA-15复合载体的XRD图。
图2为15％TiO 2/SBA-15复合载体的XRD图。
图3为实施例2制备的0.08％Pt/10％TiO 2/SBA-15催化剂的XRD图。
图4为实施例1制备的0.1％Pt/10％TiO 2/SBA-15催化剂的XRD图。
具体实施方式
以下结合附图及实施例，对本发明进行详细说明。
本发明中实验Pt/TiO 2/SBA-15或Pt/ZrO 2/SBA-15催化对氯硝基苯选择性加氢制备对氯苯胺具体步骤如下：
1)取一定比例的对氯硝基苯和催化剂于反应釜中，加入适量溶剂，通入H 2置换出反应釜中的空气后，关闭H 2阀门，设定反应温度和H 2压力。
2)当釜内温度达到设定反应温度后，通入H 2，打开搅拌，开始反应。
3)反应结束后，冷却，取适量反应液离心分离，进行气相色谱分析。
实施例1
将介孔硅材料SBA-15加入15mL无水乙醇中，超声震荡2h，得到处理过的SBA-15和无水乙醇混合液。在搅拌条件下，将0.5mL钛酸丁酯逐滴滴入上述混合液中，搅拌1h；缓慢添加1mL水至混合物中，水解钛酸丁酯，再继续搅拌1h，使钛酸丁酯水解完全。40℃加热搅拌使上述混合液呈凝胶状。80℃真空干燥过夜，得到10％TiO 2/SBA-15复合载体(复合载体中TiO 2含量为10wt％)。取0.702gTiO 2/SBA-15复合载体分散在100mL去离子水中，加入10mL无水甲醇，超声分散10min，再加入0.1mL氯铂酸溶液，超声分散20min，然后在搅拌条件下，将溶液置于紫外光下光照12h，所得溶液过滤洗涤，80℃真空干燥，得到Pt质量分数为0.1％的Pt/TiO 2/SBA-15催化剂(催化剂中Pt含量为0.1wt％)，即0.1％Pt/10％TiO 2/SBA-15。
实施例2
同实施例1，不同的是Pt/TiO 2/SBA-15中Pt的质量分数为0.08％，即0.08％Pt/10％TiO 2/SBA-15。
实施例3
同实施例1，不同的是Pt/TiO 2/SBA-15中TiO 2在复合载体中的质量分数为15％，即0.1％Pt/15％TiO 2/SBA-15。
实施例4
将上述实施例1中制备的0.1％Pt/10％TiO 2/SBA-15用于催化对氯硝基苯加氢反应。取0.401g对氯硝基苯、0.1g 0.1％Pt/10％TiO 2/SBA-15和20mL无水乙醇于高压反应釜中，通入H 2置换出反应釜中的空气后，关闭H 2阀门，当釜内温度达到70℃反应温度后，通入H 2，打开搅拌，开始反应，反应1h，反应结束后，冷却，取10mL反应液离心分离，进行气相色谱分析。对氯硝基苯转化率为100％，对氯苯胺选择性为98.44％。
实施例5
同实施例4，加入实施例1制备的催化剂0.1％Pt/10％TiO 2/SBA-15 0.1g、0.401g对氯硝基苯，20mL无水乙醇，70℃反应0.5h。对氯硝基苯转化率为98.32％，对氯苯胺选择性为98.60％。
实施例6
同实施例4，加入实施例1制备的催化剂0.1％Pt/10％TiO 2/SBA-15 0.1g、0.401g对氯硝基苯，20mL无水乙醇，50℃反应1.5h。对氯硝基苯转化率为99.36％，对氯苯胺选择性 为99.13％。
实施例7
同实施例4，加入实施例2制备的催化剂0.08％Pt/10％TiO 2/SBA-15 0.1g、0.317g对氯硝基苯，20mL无水乙醇，70℃反应1h。对氯硝基苯转化率为84.71％，对氯苯胺选择性为99.50％。
该实施例中在铂含量较低的情况下，催化反应时间不够长导致对氯硝基苯转化率不高。
实施例8
同实施例4，加入实施例2制备的催化剂0.08％Pt/15％TiO 2/SBA-15 0.1g、0.317g对氯硝基苯，20mL无水乙醇，70℃反应1.5h。对氯硝基苯转化率为99.25％，对氯苯胺选择性为99.22％。
实施例9
将实施例4反应后的溶液进行离心分离，去除反应液，用无水乙醇多次离心洗涤，然后放入真空干燥箱40℃干燥过夜，将二次回收后的催化剂按照实施例4中的方法步骤进行反应，对氯硝基苯转化率为97.77％，对氯苯胺选择性为97.23％。说明二次回收的催化剂催化活性依然很高。
由以上实施例可知，由此方法制备的不同的铂质量分数的催化剂对于对氯硝基苯选择性加氢反应均有活性，整体说来铂的用量低且在高的催化加氢转化率的同时脱氯副反应少。
对比例1
催化剂的制备大致与实施例1相同，但催化剂中未设置二氧化钛层，采用光催化还原法制备得到0.1％Pt/SBA-15催化剂(催化剂中铂的质量分数为0.1％)。
催化剂催化选择性加氢的方法与实施例4相同，加入0.1％Pt/SBA-15催化剂0.1g、0.401g对氯硝基苯，20mL无水乙醇，70℃反应2.0h。对氯硝基苯转化率为13.05％，对氯苯胺选择性约100％。
对比例2
催化剂的制备大致与实施例1相同，但催化剂中未设置二氧化钛层，采用光催化还原法制备得到0.1％Pt/SBA-15催化剂(催化剂中铂的质量分数为0.1％)。
催化剂催化选择性加氢的方法与实施例4相同，加入0.1％Pt/SBA-15催化剂0.1g、0.401g对氯硝基苯，20mL无水乙醇，70℃反应3.0h。对氯硝基苯转化率为53.7％，对氯苯胺选择性约100％。
对比例3
催化剂的制备大致与实施例1相同，但催化剂中未设置二氧化钛层，采用光催化还原法制备得到2％Pt/SBA-15催化剂(催化剂中铂的质量分数为2％)。
催化剂催化选择性加氢的方法与实施例4相同，加入2％Pt/SBA-15催化剂0.1g、0.401g对氯硝基苯，20mL无水乙醇，70℃反应1.0h。对氯硝基苯转化率为91.51％，对氯苯胺选择性为86.56％。
从对比例1和对比例3的比较可知，如果不先将二氧化钛分散在SBA-15上，而直接将铂负载在SBA-15上，则催化剂中需要的铂含量较高，催化剂才能有较好的催化活性，此时原料转化率上升，但同时脱氯副反应也明显加强。只有先将二氧化钛分散在SBA-15上，再将铂分散在二氧化钛上，才能够在铂载量很低时，制备得到催化活性和目地产物选择性都很优异的催化剂。
从对比例1～对比例3和实施例的比较可知，本发明催化剂制备过程中先后将二氧化钛和铂分散在载体SBA-15上，用于催化对氯硝基苯选择性加氢制备对氯苯胺时，既可以仅用很少量的贵金属铂即可达到优异的催化活性，且明显可以降低脱氯副反应的发生。
图1和图2为TiO 2/SBA-15复合载体的XRD图，图3和图4为Pt/TiO 2/SBA-15催化剂的XRD图。从图3～4与图1～2的比较可知，XRD图中基本不能观察到铂的衍射峰，这说明使用本发明中所述方法制备得到的催化剂中铂的载量很低。
实施例10
将0.302g ZrOCl 2·8H 2O加入到30mL去离子水中，加热搅拌使温度升为85℃。向上述混合液中投入1g介孔硅材料SBA-15，搅拌均匀后，用稀释后的氨水调pH为4～6。常温搅拌0.5h，超声0.5h，静置陈化过夜。然后抽滤，用去离子水洗涤，110℃放干燥箱干燥过夜。500℃马弗炉煅烧得到所述的10％ZrO2/SBA-15复合载体。取0.702g ZrO2/SBA-15分散在100mL去离子水中，加入10mL无水甲醇，超声分散10min，再加入0.1mL氯铂酸溶液，超声分散20min，然后在搅拌条件下，将溶液置于紫外光下光照12h，所得溶液过滤洗涤，80℃真空干燥，得到Pt质量分数为0.1％的Pt/ZrO 2/SBA-15催化剂，即0.1％Pt/10％ZrO 2/SBA-15。
本实施例中在制备ZrO 2/SBA-15复合载体时，使用沉淀法代替制备TiO 2/SBA-15复合载体时的溶胶凝胶法，可以得到与溶胶凝胶法制备的TiO 2/SBA-15复合载体结构相似的ZrO 2/SBA-15复合载体。
实施例11
同实施例10，不同的是Pt/ZrO 2/SBA-15中Pt的质量分数为0.08％，即0.08％Pt/10％ZrO 2/SBA-15。
实施例12
同实施例10，不同的是Pt/ZrO 2/SBA-15中ZrO 2在复合载体中的质量分数为15％，即0.1％Pt/15％ZrO 2/SBA-15。
实施例13
将上述实施例10中制备的0.1％Pt/10％ZrO 2/SBA-15用于催化对氯硝基苯加氢反应。取0.401g对氯硝基苯、0.1g 0.1％Pt/10％ZrO 2/SBA-15和20mL无水乙醇于高压反应釜中，通入H 2置换出反应釜中的空气后，关闭H 2阀门，当釜内温度达到40℃反应温度后，通入H 2，打开搅拌，开始反应，反应40min，反应结束后，冷却，取10mL反应液离心分离，进行气相色谱分析。对氯硝基苯转化率为100％，对氯苯胺选择性为99.47％。
实施例14
同实施例13，加入实施例10制备的催化剂0.1％Pt/10％ZrO 2/SBA-15 0.1g、0.401g对氯硝基苯，20mL无水乙醇，40℃反应30min。对氯硝基苯转化率为99.57％，对氯苯胺选择性为98.77％。
实施例15
同实施例13，加入实施例10制备的催化剂0.1％Pt/10％ZrO 2/SBA-15 0.1g、0.401g对氯硝基苯，20mL无水乙醇，30℃反应40min。对氯硝基苯转化率>99.9％，对氯苯胺选择性为98.98％。
实施例16
将实施例13反应后的溶液进行离心分离，去除反应液，用无水乙醇多次离心洗涤，然后放入真空干燥箱80℃干燥过夜，将二次回收后的催化剂在40℃条件下反应40min，对氯硝基苯转化率为94.03％，对氯苯胺选择性为97.25％。二次回收的催化剂催化活性依然很高。
本发明的范围并不局限于以上实施例，只要控制好催化剂活性组分质量分数以及包括温度和时间在内的反应条件，本发明所述催化剂对于对氯硝基苯加氢反应均可达到很好的效果。
以上内容是结合具体优选实施方式对本发明作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演和替换，都应当视为属于本发明的保护范围。

Claims (12)

  1. 一种用于催化氯代芳硝基化合物选择加氢的催化剂，其特征在于，所述催化剂为Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂，且催化剂中铂的含量为0.01～0.3wt％，优选0.05～0.15wt％，更优选0.08～0.10wt％。
  2. 根据权利要求1所述催化剂，其特征在于，TiO 2占复合载体TiO 2/SBA-15总重量的5～20wt％，优选10～15wt％；ZrO 2占复合载体ZrO 2/SBA-15总重量的5～20wt％，优选10～15wt％。
  3. 根据权利要求1所述催化剂，其特征在于，所述Pt/TiO 2/SBA-15催化剂中TiO 2呈薄膜层、以单层或多层形式平铺在载体SBA-15上，而活性组分铂则锚定在TiO 2薄膜层上；所述Pt/ZrO 2/SBA-15催化剂中ZrO 2呈薄膜层、以单层或多层形式平铺在载体SBA-15上，而活性组分铂则锚定在ZrO 2薄膜层上。
  4. 一种如权利要求1～3中任意一项所述催化剂的制备方法，所述方法包括先采用溶胶凝胶法将TiO 2负载在SBA-15上，或采用沉淀法将ZrO 2负载在SBA-15上，得到SBA-15上平铺一层或多层纳米TiO 2薄膜或纳米ZrO 2薄膜的复合载体，再采用光催化还原法将活性组分铂负载到所述复合载体上得到所述Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂。
  5. 根据权利要求4所述的制备方法，其特征在于，将TiO 2负载在SBA-15上之前，还包括使用无水乙醇对SBA-15进行超声预处理的步骤。
  6. 根据权利要求5所述的制备方法，其特征在于，所述溶胶凝胶法包括将钛酸丁酯加入含SBA-15的无水乙醇中，再加水继续搅拌使得钛酸丁酯水解，将水解混合物加热至35～45℃使其呈凝胶状，再在60～90℃下真空干燥后得到TiO 2/SBA-15复合载体。
  7. 根据权利要求4所述的制备方法，其特征在于，所述光催化还原法包括将TiO 2/SBA-15复合载体或ZrO 2/SBA-15复合载体分散于去离子水中，加入甲醇和氯铂酸溶液超声浸渍，再将混合液置于紫外光照下，搅拌、固液分离并用水洗涤至中性和干燥后得到所述Pt/TiO 2/SBA-15催化剂或Pt/ZrO 2/SBA-15催化剂。
  8. 根据权利要求7所述的制备方法，其特征在于，所述光催化还原中使用的甲醇与水的质量比为1：5～15，且紫外光照时间为5～20小时。
  9. 一种如权利要求1～3中任意一项所述催化剂或如权利要求4～8中任意一项所述制备方法制备得到的催化剂在催化对氯硝基苯选择性加氢制备对氯苯胺中的应用。
  10. 一种对氯硝基苯选择性加氢制备对氯苯胺的方法，所述方法包括使用一种含铂和 二氧化钛或二氧化锆的催化剂和在氢气环境以及加热条件下催化对氯硝基苯选择性加氢制备对氯苯胺，使得加氢时脱氯副反应大幅降低，所述催化剂为Pt/TiO 2/SBA-15或Pt/ZrO 2/SBA-15催化剂。
  11. 根据权利要求10所述的制备对氯苯胺的方法，其特征在于，所述催化剂中铂的含量为0.01～0.3wt％，优选0.05～0.15wt％，更优选0.08～0.10wt％。
  12. 根据权利要求10或11所述的制备对氯苯胺的方法，其特征在于，所述选择性加氢反应中使用无水乙醇作为溶剂，所述选择性加氢的温度为40～90℃，优选50～70℃。
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